studying wound healing activity
TRANSCRIPT
REVIEW ON WOUND HEALING
ACTIVITY OF NATURAL PRODUCTS
For the course of pharmaceutical literature and seminar II (Phar 652)
ADDIS ABABA UNIVERSITY
SCHOOL OF GRADUTATE STUDENTS
SCHOOL OF PHARMACY
DEPARTMENT OF PHARMACOGNOSY
By: Michael G/ Hiwot
August 2010
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Acknowledgement
I am highly grateful for Dr Kaleab Asres for giving me this seminar work, so that I could
make an endeavor to know the different scientific aspects while studying the wound healing
activity of natural products.
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Table of Contents
Contents page
ACKNOWLEDGEMENT.............................................................................................I
TABLE OF CONTENTS............................................................................................ II
CONTENTS PAGE...........................................................................II
LIST OF ABBREVIATIONS......................................................................................V
SUMMARY...............................................................................................................VI
1. INTRODUCTION...................................................................................................1
2. TYPES OF WOUNDS............................................................................................2
3. WOUND HEALING AND THE HEALING CASCADES........................................4
4. EXISTING THERAPY AIMED FOR WOUND HEALING.......................................6
5. MODELS TO STUDY WOUND HEALING ACTIVITY...........................................7
5.1. In vivo models................................................................................................................................................7
5.1.1. Incision wound model.............................................................................................................................7
5.1.2. Excision wound model............................................................................................................................7
5.1.3. Dead space analysis.................................................................................................................................7
5.1.4. Burn wound model:.................................................................................................................................8
5.2. In vitro models...............................................................................................................................................8
5.2.1. In vitro test for fibroblast growth stimulation.........................................................................................9
5.2.2. Chorioallantoic membrane (CAM) model:...........................................................................................10
5.2.3. Antioxidant activity...............................................................................................................................10
5.2.4. Antimicrobial activity............................................................................................................................10
6. STUDY PARAMETERS......................................................................................11
6.1. In vivo study parameters............................................................................................................................11
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6.1.1. Wound closure.......................................................................................................................................11
6.1.2. Epithelialization period...........................................................................................................................1
6.1.3. Tensile strength:......................................................................................................................................1
6.1.4. Increase in granulation tissue..................................................................................................................1
6.2. In vitro study parameters.............................................................................................................................2
6.2.1. Antimicrobial activity:.............................................................................................................................2
6.2.2. Angiogenesis...........................................................................................................................................2
7. PHYTOCHEMICALS RESPONSIBLE FOR WOUND HEALING ACTIVITY........3
7.1. Polyphenols (flavonoids and tannins)..........................................................................................................3
7.1.1. Flavonoids...............................................................................................................................................3
7.1.2. Tannins....................................................................................................................................................6
7.2. Phenolic acids.................................................................................................................................................7
7.3. Phenyl propanoids.........................................................................................................................................7
7.4. Terpenes and terpenoids...............................................................................................................................8
7.5. Alkaloids.........................................................................................................................................................8
7.6. Saponins.........................................................................................................................................................9
7.7. Plant vitamins................................................................................................................................................9
7.8. Miscellaneous compounds..........................................................................................................................10
8. PLANTS WITH POTENTIAL WOUND HEALING ACTIVITY..............................12
Achillea kellalensis Bioss. & Hausskn. (Asteraceae).......................................................................................12
Ageratum conyzoides L (Asteraceae).................................................................................................................12
Allium cepa L. (Liliaceae)..................................................................................................................................12
Aloe vera (Asphodelaceae).................................................................................................................................13
Alternanthera brasiliana Kuntz (Amaranthaceae)..........................................................................................13
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Anthocleista nobilis G. don. (Loganiaceae).......................................................................................................13
Areca catechu L. (Arecaceae)............................................................................................................................13
Azardica indica (Meleaceae)...............................................................................................................................14
Calotropis gigantea L. (Asclepiadaceae)...........................................................................................................14
Carica papaya L. (Caricaceae)...........................................................................................................................14
Catharanthus roseus L. (apocyanaceae)...........................................................................................................14
Centella asiatica (Mackinlayoideae)..................................................................................................................15
Cocos nuclifera L. (Arecaceae)..........................................................................................................................15
Cordial dichotoma (Boraginaceae)....................................................................................................................15
Dissotis theifolia (Melastomataceae).................................................................................................................15
Elaeis guineensis Jacq (Mackinlayoideae).......................................................................................................15
Euphorbia heterophylla (Euphorbiaceae).........................................................................................................16
Ficus religiosa (Moraceae).................................................................................................................................16
Ginkgo biloba (Ginkgoaceae).............................................................................................................................16
Helianthus annus L. (Asteraceae).....................................................................................................................16
Hoslundia opposita Vahl (Lamiaceae)..............................................................................................................17
Hydnocarpus wightiana (Flacourtaceae)...........................................................................................................17
Hypericum prolificum (Hypericaceae)..............................................................................................................17
Jasminum auriculatum (Oleaceae)....................................................................................................................17
Jatropha curcas L. (Euphorbiaceae).................................................................................................................18
Lantana camara (Verbenaceae).........................................................................................................................18
Lawsonia inermis L. (Luthraceae).....................................................................................................................18
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Mimosa pudica ( Mimosaceae)...........................................................................................................................18
Napoleona imperialis (Lecythidaceae)..............................................................................................................18
Ocimum kilimandscharicum (Lamiaceae).........................................................................................................19
Ocimum sanctum L. (Labiaceae).......................................................................................................................19
Phyllanthus niruri L. (Euphorbiaceae).............................................................................................................19
Quercus infectoria (Fagaceae)...........................................................................................................................19
Rubia cordifolia L. (Rubiaceae).........................................................................................................................20
Tragia involucrata L. (Euphorbiaceae).............................................................................................................20
Trichosanthes dioica (Cucurbitaceae)...............................................................................................................20
Tridax procumbens (Asteraceae).......................................................................................................................21
Vernonia arborea (Asteraceae)..........................................................................................................................21
9. Reference............................................................................................................22
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List of abbreviations CAF: Chloramphenicol
CAPE: Caffeic Acid Phenylether Ester
CAT: Catalase
DPPH: 2, 2’-diphenyl- picrylhydrazyl
EGCG: Epigallocatechin gallate
FBS: Fetal Bovine Serum
HMF: Hydroxymethylfurfural
MEM: Minimum Essential Medium
MIC: Minimum Inhibitory Concentration
NADH: Nicotinamide adenine dinucleotide
NADPH2: Nicotinamide adenine dinucleotide phosphate
NFkB: Nuclear Factor kappa-light-chain-enhancer of activated B cells
ROS: Reactive Oxygen Species
SOD: Superoxide Dismutase
TBA: Thiobarbituric Acid
TB4: Thymosin beta 4
TGFβ1: Transforming Growth factor β1
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Summary
A wound is a disruption of the continuity of tissues produced by external force. When
considering the manner in which the skin or tissue is broken, there are seven general kinds
of wounds: abrasions, incisions, lacerations, punctures, avulsions, amputations and
contusions. Because the skin serves as a protective barrier against the outside world, any
break in it must be rapidly and efficiently mended. Wound healing involves highly
orchestrated sequences of events, which is triggered by tissue injury and ends in either
partial or complete regeneration or more commonly by repair. Successful wound healing and
tissue regeneration depends on tightly regulated hemostasis, inflammation, matrix synthesis,
proliferation, wound contraction and tissue remodeling to restore tissue function and
integrity.
Wound healing processes are influenced by factors like infections, nutritional status, drugs
and hormones, type and sites of wound, and wasting diseases like diabetes. In folklore
medicine, medicinal plants have been used widely in facilitating wound healing.
Phytochemicals like tannins, flavonoids, polyphenols, alkaloids, terpenes and terpenoids,
and ascorbic acid are known to be responsible for wound healing properties of medicinal
plants. The high degree of successes of medicinal plants in assisting wound healing has
inspired many researches, which are aimed at validating the claims and discovering
mechanisms, which possibly explains the potentials of these herbs on wound repair
processes.
While studying the wound healing activity of medicinal plants, there are in vivo and in vitro
models. The in vivo model includes: incision wound, excision wound, dead space wound
and burn wound models. On the other hand, the in vitro model consists of antioxidant
activity testing, anti-microbial activity testing, in vitro test for fibroblast growth stimulation,
chorioallantoic membrane (CAM) model and others. The in vivo study parameters are time
of epithelialization, wound closure, tensile strength, and increase in granulation tissue. In the
case of in vitro models, the study parameters are angiogenesis, antioxidant activity, and
antimicrobial activity. In this material, the wound healing activity of fourty (40) different
medicinal plant species was reviewed.
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1. Introduction The wound may be defined as a loss or breaking of cellular and anatomic or functional
continuity of living tissues (Nalwaya et al., 2009). Because the skin serves as a protective
barrier against the outside world, any break in it must be rapidly and efficiently mended
(Martin, 1997).
Healing of wounds is an important biological process involving tissue repairs and
regeneration (Esimone et al., 2009). It is a complex and dynamic process of restoring
cellular structures and tissue layers (Mercandetti and Cohen, 2007). Proper healing of
wound is essential for the restoration of disrupted anatomical continuity and disturbed
functional status of the skin (Annan and Dickson, 2008). Current estimates indicate that
nearly 6 million people suffer from chronic wounds worldwide (Sasidharan et al., 2010).
One of the surveys conducted by the WHO reports that more than 80% of the world’s
population still depends upon the traditional medicines for various diseases (Patel et al.,
2009). Some medicinal plants have been employed in folk medicine for wound care. Some
of these plants either possess pro-wound healing activities or exhibit antimicrobial and other
related properties that are beneficial in overall wound care (Esimone et al., 2009). Recently,
the traditional use of plants for wound healing has received attention by the scientific
community. Approximately one-third of all traditional medicines in use are for the treatment
of wounds and skin disorders, compared to only 1-3 % of modern drugs (Ghasemi et al.,
2010). With a view to the increase in the wide spectrum of medicinal usages, the present day
requires a new biologically active ointment which exhibit wound healing activity as local
applications (Roy et al., 2009). Wound healing studies are mainly aim to detect various
means and factor influencing healing process, so they could be either used or avoid in
clinical practice to favorably alter the healing process (Sachin et al., 2009).
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2. Types of wounds
When we consider the manner in which the skin or tissue is broken, there are seven general
kinds of wounds: abrasions, incisions, lacerations, punctures, avulsions, amputations
and contusions. Many wounds, of course, are combinations of two or more of these basic
types (http://www.tpub.com/content/medical/10669-c/css/10669-c_101.htm.).
Abrasions: Injuries where a superficial layer of tissue is removed
(http://www.medstudentlc.com/page.php?id=65). This kind of wound can become
infected quite easily because dirt and germs are usually embedded in the tissues
(http://www.tpub.com/content/medical/10669-c/css/10669-c_101.htm.).
Incisions: Incision wound is characterized by a clean cut, as by a sharp instrument
(http://runonce.msn.com/runonce3.aspx). Incisions tend to bleed freely because the blood
vessels are cut cleanly and without ragged edges. Of all classes of wounds, incisions are the
least likely to become infected, since the free flow of blood washes out many of the
microorganisms that can cause infection
(http://www.tpub.com/content/medical/10669-c/css/10669-c_101.htm.).
Lacerations: These are injuries where by tissue is torn
(http://www.medstudentlc.com/page.php?id=65). A wound made by a dull knife, for
instance, is more likely to be a laceration than an incision. Bomb fragments often cause
laceration. Lacerations are frequently contaminated with dirt, grease, or other material that is
ground into the tissue; they are therefore very likely to become infected
(http://www.tpub.com/content/medical/10669-c/css/10669-c_101.htm.).
Punctures: Wounds made by nails, needles, wire, and bullets are usually punctures. The
possibility of infection is great in all puncture wounds, especially if the penetrating object
has tetanus bacteria on it. To prevent anaerobic infections, primary closures are not
made in the case of puncture wounds
(http://www.tpub.com/content/medical/10669-c/css/10669-c_101.htm.).
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Avulsions: Injuries where a section of tissue is torn off, either partially or in total.
(http://www.medstudentlc.com/page.php?id=65). Bleeding is usually heavy. In certain
situations, the torn tissue may be surgically reattached
(http://www.tpub.com/content/medical/10669-c/css/10669-c_101.htm.).
Amputations: amputation is the removal of the limb from the body. Shock is certain to
develop in these cases. The limb can often be successfully reattached
(http://www.tpub.com/content/medical/10669-c/css/10669-c_101.htm.).
Contusions: Such injuries result from a forceful blow to the skin and soft tissue but, leaving
the outer layer of skin intact. These injuries generally require minimal care as there is no
open wound. However, an expanding hematoma can damage overlying skin and demands
evacuation (http://www.medstudentlc.com/page.php?id=65 ).
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3. Wound healing and the healing cascades
Wound healing involves sequences of events, which is triggered by tissue injury and ends in
either partial or complete regeneration or more commonly by repair (Ather et al., 2007). The
healing cascade begins immediately following injury when the platelets come in contact
with exposed collagen (Nayak, 2006). Wound healing can be classified into any of three
types: healing by first intention, healing by second intention or healing by third intention,
depending on the nature of the edges of the healed wounds (Esimone et al., 2005). Primary
wound healing or healing by first intention occurs within hours of repairing a full-thickness
surgical incision (Mercandetti and Cohen, 2007). In wounds healed by the first intention, the
edges are smoothly closed that no scar is left (Esimone et al., 2005). Wound healing by
second intention involves formation of granulation tissues, which fill up the gaps between
the wound edges and is associated with significant loss of tissue, leaving little scars
(Esimone et al., 2005). In a third type of healing, a full-thickness wound is allowed to close
and heal. It results in an inflammatory response that is more intense than with primary
wound healing (Mercandetti and Cohen, 2007). Most skin lesions are healed rapidly and
efficiently within a week or two. However, the product is neither aesthetically nor
functionally perfect (Martin, 1997). The healing process involves four types of phases
(Shetty et al., 2006).
Clot formation
The formation of a clot is the immediate response to any trauma. The clot has two functions;
it temporarily protects the uncovered tissues and it serves as a provisional matrix for cell
migration (Polimeni et al., 2006).
Inflammation
Within hours of injury, inflammatory cells populate the clot and cleanse the wound from
bacteria and necrotic. Macrophages migrate into the wound area and, in addition to wound
debridement, secrete polypeptide mediators targeting cells involved in the wound-healing
process (Polimeni et al., 2006). Growth factors and cytokines secreted by macrophages are
involved in the proliferation and migration of fibroblasts, endothelial cells, and smooth
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muscle cells into the wound area (Polimeni et al., 2006). If the inflammatory phase is
prolonged, degradation of collagen will exceed its synthesis (Sasidharan et al., 2010).
Granulation
The formation of new vasculature requires extracellular matrix and basement membrane
degradation followed by migration, mitosis, and maturation of endothelial cells (Mercandetti
and Cohen, 2007). Epithelialization of the wound is initiated within hours of injury.
Epithelial cells from the basal layer proliferate and migrate through the fibrin clot and
eventually the breach in the epithelium is sealed (Polimeni et al., 2006).
Remodeling
In this phase the wound undergoes contraction resulting in a smaller amount of apparent scar
tissue (James and Friday, 2010). Remodeling can last for years after the initial injury
occurred. Maximal tensile strength of the wound is achieved by the 12th week, and the
ultimate resultant scar has only 80% of the tensile strength of the original skin (Mercandetti
and Cohen, 2007). Whether the damaged tissues heal by regeneration or repair depends upon
two crucial factors: the availability of cell type(s) needed; and the presence or absence of
signals necessary to recruit and stimulate these cells (Polimeni et al., 2006).
Figure1: Phases of cutaneous wound repair.
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4. Existing therapy aimed for wound healing
Factors like nutritional status, concurrent therapy (such as corticosteroids) and clinical
conditions, such as anemia and diabetes affect the wound healing process. Therefore, the
objective must be the holistic management of the patient and not just the wound (David,
2008). Topical iodine in the form of Lugol’s solution regenerates human scar tissue back to
normal (David, 2008). Povidone-iodine (5% Betadine) cream is also used for wound healing
purpose (Kumar et al., 2009). Topical antimicrobial therapy is one of the most important
methods of wound care (Esimone et al., 2009). As an example neomycin-bacitracin powder
(Cicatrin®), gentamycin ointment, tetracycline ointment, nitrofurazone ointment are among
the standard antibiotic used in wound healing (Esimone et al., 2005; Annan and Dickson,
2008; Esimone et al., 2009; Nalwaya et al., 2009).
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5. Models to study wound healing activity
5.1. In vivo models
In vivo models of wound healing generally use small rodents such as guinea pigs or rats
(Houghton et al., 2005). Granulation, collagen maturation, and scar formation are some of
the many phases of wound healing, which run concurrently, but independent of each other
(Udupa et al., 2005). As a result, the use of a single model is inadequate as different models
provide different information, and there are three in vivo wound study models known so far.
5.1.1. Incision wound model
Wound breaking strength is the important parameter to be studied in incision wound model
(Ghasemi et al., 2010). Two longitudinal paravertebral incisions can be made through the
skin and cutaneous muscles at a distance 1cm from the midline on either side of the
vertebral column of anaesthetized rat (Annan and Dickson, 2008). The parted skin is sutured
and the skin breaking strength of the wound is measured after ten days of wound induction
(Barua et al., 2009).
5.1.2. Excision wound model
Excision wounds are used to study the rate of wound contraction and epithelialization
(Nalwaya et al., 2009). The excision wound is made by excising the full thickness of
circular skin from the animal under anaesthesia (Karodi et al., 2009). Then wound
contraction is assessed by tracing the wound area first on transparent paper and subsequently
transferring to a graph paper (Barua et al., 2009). In excised wound, since the edges are not
in contact with each other, contraction and epithelialization are necessary for the repairing
process (Ghasemi et al., 2010). Hence, epithelialization and wound contraction are the two
parameters to be studied in case of excision wound (Malviya et al., 2009).
5.1.3. Dead space analysis
Dead space wound can be induced by making a pouch through a small cut in the skin of the
rat (Paschapur et al., 2009). A polypropylene tube is implanted subcutaneously beneath the
skin. The day of the wound creation is considered as day zero (Azeez et al., 2007). On day
10, the animals are sacrificed by overdose of anaesthesia, the polypropylene tube are
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carefully removed and dried in an oven at 60°C to a constant weight, and the weight is
recorded. The level of increase (%) in the weight of granuloma tissue formed is calculated
relative to the control (Okoli et al., 2009). The samples are kept at -70°C for biochemical
analysis until assayed. Regenerated tissues is cut in the form of square pieces along with
normal skin on either side of the wound and preserved in 10% buffered formalin for
histological studies. Dead space wound is important to study the physical and mechanical
changes in the granuloma tissue (Paschapur et al., 2009). In dead space wound; granulation
tissue dry weight, breaking strength and hydroxyproline content are the important
parameters to be studied (Malviya et al., 2009).
5.1.4. Burn wound model:
The burn makes an extreme damage to the barrier of the skin and triggers a cascade of
events such as tissue necrosis and body fluid exudation, creating a perfect medium culture to
the bacterium (Feng et al., 2010). Partial thickness burn wound is inflicted upon animals
starved overnight and under anaesthesia, but pouring hot molten wax 800C into a metal
cylinder with circular opening, placed on the back of the animal. Wound contraction and
epithelialization period are the two parameters to be studied in this model (Srivastava and
Durgaaprasad, 2008).
5.2. In vitro models
In vitro tests are now widely employed in ethnopharmacological research because of ethical
reasons and their usefulness in bioactive-guided fractionation and determination of active
compounds. A summary of these tests is shown in table 1 (Houghton et al., 2005).
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Table 1: In vitro assays for different activities associated with wound healing.
Activity Assay Positive control
Anti-inflammatory NFkB synthesis inhibition Actigenin, CAPE
(caffeic acid phenylether
ester)
Eicosanoid synthesis inhibition Indomethacin for
cycloxygenase inhibition
Fibroblast proliferation Natural Red uptake by viable
cells
10% foetal serum
Effect on keratinocytes Involucrin expression A23187
Fibroblast protein
expression
Proteomics Not used
Collagen lattice
formation
Collagen lattice contraction Not used
Antimicrobial activity Serial dilution to determine MIC Miconazole for fungi
and CAF for bacteria
Antioxidant properties DPPH for free radical scavenging Propyl gallate
Malondialdehyde determination
using TBA
Propyl gallate
Ptorection of growing cells
challenged oxidant
Catalase
5.2.1. In vitro test for fibroblast growth stimulation
Fibroblasts are trypsinized, centrifuged and resuspended in MEM/15%FBS/1% L-glutamine
(Annan and Dickson, 2008) Use of trypsin for tissue disaggregation is called trypsinization
(Shenoy, 2007). The cells will be seeded at 37°C in a humidified incubator of 5%C02. The
fibroblast cells will be incubated and assayed after five days using the neutral red assay
method to assess the effect of the extracts on the growth of the cells (Annan and Dickson,
2008).
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5.2.2. Chorioallantoic membrane (CAM) model:
In this model, embryonated chicken eggs (9 days old) are selected and a small window will
be made in the shell (Barua et al., 2009). Albumin is removed on the 4th day after
fertilization to drop the embryo away from the shell and to allow the CAM to develop in a
way that was accessible to treatment (Melkonian et al., 2000). Through the window, a sterile
disc treated with the extract of interest is placed inside the egg at the junction of two blood
vessels. The window is resealed and the egg will be incubated at 370c for three days. The
window will then be opened and the growth of new capillary will be observed as in figure 2
(Barua et al., 2009).
5.2.3. Antioxidant activity
It is believed that reactive oxygen species are deleterious to wound healing due to their
harmful effects on cells and tissues (Annan and Dickson, 2008). DPPH radical scavenging
activity the easiest method assess the antioxidant activity of natural products. The DPPH
scavenging activity of the plant of interest is measured from the bleaching of a purple
colored methanol solution of 2, 2’- diphenyl - picrylhydrazyl (DPPH) which is used as a
reagent in a spectrophotometric assay (Annan and Dickson, 2008).
5.2.4. Antimicrobial activity
Open wounds are particularly prone to infection, especially by bacteria, and provide an entry
point for systemic infections. Infected wounds heal less rapidly and often result in the
formation of unpleasant exudates and toxins will be produced with concomitant killing of
regenerating cells. Antibacterial and antifungal compounds in a traditional remedy may
prevent this occurring and may underlie its use in treating wounds (Houghton et al., 2005).
Figure 2: Emnbryonated chicken egg of 9 days old.
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6. Study parameters
6.1. In vivo study parametersThere are different study parameters while dealing with wound healing in vivo. It includes
wound closure, time of epithelialization, tensile strength and scar size.
6.1.1. Wound closure
More than 50% of connective tissue is made up of collagen in case of sutured wounds.
Hence lying down and weaving of the collagen material into the healing wound is an
important feature. Therefore, it is understandable that substances that influence the collagen
turnover or maturation enhance the process of wound healing (Azeez et al., 2007). Wound
contraction is a process that occurs throughout the healing process (James and Friday, 2010).
It is mainly a part of the proliferative phase of wound healing that occur through the
centripetal movement of the tissues surrounding the wound, which is mediated by
myofibroblasts (Sasidharan et al., 2010). Although myofibroblasts may be important for
long-term wound contraction, scar formation, and matrix remodeling, research a finding
suggest that the organized network of cells containing actin filaments at the edge of the
normal wounds may initiate wound contraction (Bullard et al., 1999).
The presence of myofibroblasts and the apoptosis level can be regulated by both TGFβ1 and
by the extracellular matrix and the tension in the wound bed determines the type of scar at
different body sites (Chipev and Simon, 2002). Contractions of wound is studied by tracing
the raw wound in excision wound model (Annan and Dickson, 2008), and wound
contraction (%) is calculated using the relation below (Okoli et al., 2009).
Where: WD0 = the wound diameter on day zero
WDt = the wound diameter on day t
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6.1.2. Epithelialization period
Epithelialization, which is the process of epithelial renewal after injury, involves the
proliferation and migration of epithelial cells towards the center of the wound (Atala, 2008;
Okoli et al., 2009). The epithelialization time is the time at which a complete scar formation
occur (Sachin et al., 2009).
6.1.3. Tensile strength:Tensile strength is the resistance to breaking under tension. It indicates how much the
repaired tissue resists to breaking under tension and may indicate in part the quality of the
repaired tissue (Rashed et al., 2003). For this purpose, the newly repaired tissue including
scar is excised from treated and control animals and will be loaded between the upper and
lower holder of tensile testing machine, in such a way that the effective load bearing size
with the wound remaining in the centre (Annan and Dickson, 2008). The total breaking load
is calculated the following formula (Kokane et al., 2009).
6.1.4. Increase in granulation tissueIn dead space wound model, increase in granuloma tissue is associated with enhanced
collagen maturation and increased protein content as well as angiogenesis in the wound
(Okoli et al., 2009). It is a well-accepted fact that wounds in most tissues heal by repair, by
laying down non-specific connective tissue, where more than 50% is made up of collagen.
Substances that influence the collagen turnover or maturation enhance the process of wound
healing. Collagen is a fibrous protein component of the connective tissue consisting of
hydroxyproline, hydroxylysine and glycine as principal constituents, among which
Figure 2: Tensiometer to measure tensile strength (Rashed et al., 2003).
12
hydroxyproline is considered a specific aminoacid (Azeez et al., 2007). Hence, the increased
hydroxyproline content of the granulation tissue is an indicative for an increase in collagen
turnover. Increase in breaking strength of granulation tissue indicates the enhanced collagen
maturation by increased cross-linking (Panda and Tripathy, 2009).
6.2. In vitro study parameters
It is generally acknowledged that in vitro tests are too reductionist to extrapolate their results
to provide evidence for clinical efficacy, and that eventually animal testing and clinical trials
have to be performed. The effects of pharmacological agents which modulate many of
wound healing processes, such as fibroblast proliferation or reduction of oxidative stress,
antimicrobial activity can be assessed by in vitro experiments (Houghton et al., 2005).
6.2.1. Antimicrobial activity: Infection is defined as microbial pathogens proliferating in a wound, causing tissue damage
and eliciting a host inflammatory response (Armstrong and Lipsky). A number of
microorganisms have been found to infect wounds among which are Pseudomonas
aeruginosa, Staphylococcus aureus, Staphylococcus faecalis, Escherichia coli, Clostridium
perfringens, Clostridium tetani, Coliform bacilli and enterococcus (Odimegwu et al., 2008;
Odimegwu et al., 2008). As infections being a major cause of morbidity and mortality in
wound patients, these herbal extracts may prevent infection that leads to high risk of sepsis,
and thereby prevents the prolongation of inflammatory phase (Arnold and Barbul, 2006; Li
et al., 2007).
6.2.2. AngiogenesisAngiogenesis is the formation of new blood vessels; it takes place during embryonic
development, wound healing and tumor growth (Hegazy et al., 2009). Angiogenesis during
wound repair serves the dual function of providing the nutrients demanded by the healing
tissues and contributing to the structural repair through the formation of granulation tissue
(Barua et al., 2009). Factors that contribute to angiogenesis include high lactate levels,
acidic pH, and, in particular, decreased oxygen tension (Monaco and Lawrence, 2003).
Angiogenesis can be studied in chorioallantoic membrane (CAM) model (Melkonian et al.,
2000; Barua et al., 2009).
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7. Phytochemicals responsible for wound healing activity
Medicinal plants that possess wound healing activity perform their action through their
phytochemicals they have in them. Not all phytochemicals have wound healing activity,
rather the following are the most responsible group of compound that assist wound healing
process in many ways.
7.1. Polyphenols (flavonoids and tannins)
These diverse groups of compounds have received much attention as potential natural
antioxidant in terms of their ability to act as both efficient radical scavengers and metal
chelators (Nagulendran et al., 2007). High correlation coefficients between the phenolic
content and antioxidant activities have been reported for various food commodities (Akond
et al., 2010). The antioxidant property of honey is well known, because it contains a number
of compounds with antioxidant properties such as, flavonoids, phenolic acids, proteins,
amino acids, ascorbic acid, HMF, and some enzymes (Makawi et al., 2009). Polyphenols
can increase the activity of catalase and glutathione peroxidase, which detoxify H2O2 by
converting it to O2 and H2O (Oaka et al., 2005). Mwh69 They are also known to stimulate
wound healing (Sasidharan et al., 2010). As an example polyphenols of areca have been
stated to promote wound healing of incision and dead space wounds and the period of
epithelialization in the excision wounds (Azeez et al., 2007).
7.1.1. FlavonoidsFlavonoids are a large group of natural products widely distributed in nature (Galicka et al.,
2007). They are present in fruits, vegetables, chocolates, herbs and beverages, such as wine,
tea or beer (table 2) (Callic et al., 2005). The chemical diversity, size, three-dimensional
shape, and physical and biochemical properties of flavonoids allow them to interact with
targets in different subcellular locations to influence biological activity in plants, animals,
and microbes (Buer et al., 2010). They have a C6-C3-C6 backbone, and apart from
modifications to this backbone, the marked structural variety of flavonoids is due to their
conjugation to sugars at different sites of the molecule (Shieber et al., 2009).
14
Food Compound Subclass Amount
(mg/100g)
Cherries (sweet, raw)
Chocolate (dark)
Tea leaves
Wine (red)
Grapefruit (raw)
Celery (raw)
Cranberry (raw)
Garlic (raw)
Orange (raw)
Kale (raw)
Pelargonidin
Catechin
Epicatechin
Catechin
Epicatechin
Malvidin
Catechin
Naringenin
Apigenin
Quercetin
Quercetin
Myricetin
Quercetin
Hesperetin
Kaempferol
Anthocyanidin
Flavan-3-ols
Flavan-3-ols
Anthocyanidin
Flavan-3-ol
Flavanone
Flavone
Flavonol
Flavonol
Flavonol
Flavonol
Flavanone
Flavonol
0.8
12
41.2
157
293.3
4.2
8.9
78.1
6.1
3.5
14
4.3
22.6
39
14.6
.
Any drug that inhibits lipid peroxidation is believed to increase the viability of collagen
fibrils by increasing the strength of collagen fibers, preventing the cell damage and by
promoting the DNA synthesis (Panda and Tripathy, 2009). Flavonoids have been
documented to possess potent antioxidant and free radical scavenging effect, which is
believed to be one of the most important components of wound healing (Shenoy et al.,
2009). Bioflavonoids are thought to benefit connective tissue by binding to elastin,
preventing its degradation by elastases (Galicka et al., 2007). They reduce lipid peroxidation
not only by preventing or slowing the onset of cell necrosis but also by improving
vascularity (Panda and Tripathy, 2009). The high mobility of the electrons in the benzenoid
nucleus of flavonoids accounts for both their antioxidant and free-radical scavenging
properties, whereas the structural resemblance between the flavonoid aglycone and many
Table 2: Some food sources for flavonoids (Callic et al., 2005).
15
Rutin (2)
substances inherent to the biochemistry of normal biological cells, e.g., nucleic acid bases,
coenzymes, steroid hormones, and neurotransmitters, explains their inhibition of enzymes,
cytoplasmic/nuclear hormone receptors, and neurotransmitters, as well as gene induction
(Havsteen, 2002). Many studies have shown that antimicrobial activities of plants can also
be attributed to their flavonoid content (Owoyele et al., 2008); hence, they are helpful in
prevention of wound infection.
Most of the delay in wound healing is due to insufficient or excessive fibroblast activity.
Thus, inhibition of fibroblast growth by flavonoids such as apigenin could be beneficial for
the treatment of any skin injury. Quercetin (1), may be useful in healing after renal
transplantation mwh new5. Quercitrin (1) isolated from Hypericum perforatum, was able to
inhibit the growth of the fungus Fusarium graminearum (Kuster et al., 2009). Flavonoids
like rutin (2), naringin (3) and quercetin (1) protect DNA damage induced by ultraviolet
(Yeh et al., 2005). Strong antihistamine activity has been shown by thymonin (4) from
Mentha spicata var. crispa (Labiatae) mwh new5. Santin (6) may contribute to the well
known anti-inflammatory activity of the plant Tanacetum parthenium by inhibiting the
cyclo-oxygenase and the 5-lipoxygenase pathways mwh new5.
Quercetin (1)Apigenin (5)
Naringin (3)
Thymonin (4)
Santin (6)
16
7.1.2. TanninsTannins are phenolic compounds that typically act as astringents and are found in a variety
of herbal products used for wound healing. Their astringent and antimicrobial property
responsible for wound contraction and increased rate of epithelialization (Panda and
Tripathy, 2009). Medicinal plants that are known and/or used for their wound-healing or
anti-inflammatory properties tend to have high tannin contents (Araújo et al., 2008).
Research results indicated that using the oxidation of linoleic acid as a model system, 3, 4, 5
tri-O-galloylquinic acid (7) displays significantly greater antioxidant properties when
compared with ascorbic acid and the commercially used n-propyl gallate as well as gallic
acid itself. Resveratrol (8), found in red wine have been suggested to be responsible for
health benefits of wine grape through antioxidant mechanism (Yang et al., 2009).
Triphenolic stilbene like epigallocatechin gallate (9), inhibited cell death induced by ter-
butyl hydroperoxide in the presence of ferric ion (Surh, 1999).
.
Resveratrol (8 )
3,4,5 tri-O-galloylquinic acid (7)
Epigallocatechin gallate (9)
17
7.2. Phenolic acids
Phenolics play a beneficial role in protecting tissue from the harmful effects of reactive
oxygen species (ROS) through regulation of antioxidant enzyme response through the
phenolic-dependent peroxidases with dependency on pentose phosphate pathway but with
reduced dependency on SOD and CAT. Oregano being rich in phenolics, as an example
rosmarinic acid (10), is an effective direct quencher of free radicals (Randhir et al., 2005).
7.3. Phenyl propanoids
The phenylpropanoid curcumin (11) and its demethoxy (12) and bisdemethoxy derivatives
(13) are known to possess anti-inflammatory and antioxidant activity (Surh, 1999). Together
with quercetin, curcumin (diferuloylmethane), may be useful in healing after renal
transplantation (Harborne and Williams, 2000). According to the study made in Turkey, a
phenylethanoid glycoside verbascoside (14) was found to show significant inhibitory effect
on carrageenan-induced hind paw edema in mice was shown to possess a significant wound
healing activity in these models mwh new6
Rosmarinic acid (10)
R1=R2=OH, R3=R4=OCH3; Curcumin (11) R1=R2=OH, R3= OCH3, R4=H; Demethoxycurcumin (12) R1=R2=OH, R3=R4=H; Bisdemethoxycurcumin (13)
Verbascoside (14)
18
7.4. Terpenes and terpenoids
Terpenoids are known to promote the wound healing process, mainly due to their astringent
and antimicrobial properties, which seem to be responsible for wound contraction and an
increased rate of epithelialization (Sasidharan et al., 2010). Triterpenes are also responsible
for promotion of rapid wound healing (Raina et al., 2008). Sesquiterpene lactones are
known to possess antioxidant activity property, which may contribute to the wound healing
process (Panda and Tripathy, 2009). Four related terpenoidal compounds from Centella
asiatica; asiatic acid ( ), madecassic acid ( ), asiaticoside ( ) and madecassoside ( ) known to
increase collagen synthesis in dose dependent fashion through modulation of gene
expression (Colen et al., 2003). Asiaticoside ( ), a trisaccharide triterpene, has been
associated with the healing of wounds and duodenal ulcers of the plant Centella asiatica
(Havsteen, 2002).
7.5. Alkaloids
Alkaloids are known to promote wound healing process due to their antioxidant and
antimicrobial activities (Sachin et al., 2009). Extracts from Symphytum asperum and
Symphytum caucasicum contain allantoin (figure), claimed to be a cell proliferation
stimulating agent responsible for their wound-healing propertiy (Barbakadze et al., 2009).
Reportedly the alkaloid fraction of areca enhances the collagen production and hence wound
healing. But contrary to the above study, there was no increase in the hydroxyproline
content of granulation tissue in arecoline and polyphenol treatments (infact, there was a
R=H; Asiatic acid ( )R=Glc-Glc-Rha; Asiaticoside ( )
R=H; Madecassic acid ( )R=Glc-Glc-Rha; Madecassoside ( )
19
decrease) and insignificant change in wound breaking strength of the granulation tissue with
polyphenol treatment of the dead space wound model (Azeez et al., 2007).
7.6. Saponins
Saponins are known to promote wound healing process due to their antioxidant and
antimicrobial activities (Sachin et al., 2009). For example, asiaticoside, a saponin is thought
to be one of its active constituents Centella asiatica. A 0.2% asiaticoside solution applied
topically twice daily for seven days to punch wounds in guinea pigs resulted in 56% increase
in hydroxyproline, 57% increase in tensile strength, increased collagen content, and better
epithelialization (MacKay and Miller, 2003). (MacKay and Miller, 2003). Triterpene
saponins are also reported to possess immunomodulatory properties (Havsteen, 2002).
7.7. Plant vitamins
Vitamin A, C, and E are important in the wound healing process. Vitamin A is required for
epithelial and bone tissue development, cellular differentiation, and immune system
function. Substantial evidence supports the use of vitamin A as a preoperative nutritional
supplement (MacKay and Miller, 2003). Ascorbic acid acts as a cofactor for the synthesis of
collagen as well as elastin fibers (Sasidharan et al., 2010). For example the anti-
Asiaticoside
AllantoinArecoline
20
inflammatory property and the presence of vitamin A & proteins in Curcuma longa L.
(zingiberaceae) result in the early synthesis of collagen fibers by mimicking fibroblastic
activity (Raina et al., 2008). In addition to collagen production, ascorbic acid enhances
neutrophil function, increases angiogenesis, and functions as a powerful antioxidant.
(MacKay and Miller, 2003). There is a paucity of research to support the hypothesis that
vitamin E aids in wound healing; however, many physicians recommend that patients apply
vitamin E to surgical sites with the belief that this will improve the cosmetic outcome of the
scar (Baumann and Spencer, 1999).
7.8. Miscellaneous compounds
Polyunsaturated fatty acids due to their unsaturation possess anti-oxidative effect, which is
related to reacting with reactive oxygen species (ROS) (Zhang et al., 2010). Mwh83 Plant
proteins as papain and chymopapain found in the epicarp of papaya are helpful in wound
healing due to their antimicrobial and antioxidant activity (Anuar et al., 2008). Research
results showed that emodin, an anthraquinone glycoside, promoted repair of rats' excisional
wounds via a complex mechanism involving stimulation of tissue regeneration and
regulating signaling pathway (Tang et al., 2007). A quinone compound embelin isolated
from the leaves of Embelia ribes have signinificant wound healing activity on albino rats
(figure) (Swamy et al., 2007).
Capsaicin (trans-8-methyl-N-vanillyl-6-nonen- amide); (figure) is a principal pungent
ingredient present in hot red and chili pepers that belong to the plant genus Capsicum
(Solanaceae) (Surh, 1999). Pungent vanilloids in ginger, like gingerol and paradol are also
known to possess antioxidant activity (Surh, 1999). A polyphenolic compound lawsone from
Lawsonia inermis were studied for its wound healing activity and gave a significant wound
healing (Sakarkar et al., 2004).
Capsaicin Dihidrocapsaicin
21
EmodinEmbelin
Gingerol
Paradol
Lawsone
22
8. Plants with potential wound healing activity
Some medicinal plants have been employed in folk medicine for wound care that either
promote direct wound repair or exhibit antimicrobial and other related properties which are
beneficial in overall wound care (Odimegwu et al., 2008). Some of the plants used in wound
care have also been shown to possess a combination of these properties (Esimone et al.,
2009).
Achillea kellalensis Bioss. & Hausskn. (Asteraceae)
Achillea kellalensis is known to contain polyphenols and monoterpenoids like camphor,
borneol, α-thujone, cineol, bornyl acetate and camphene. In the study done on the extract of
Punica granatum, the aqueous and alcoholic extracts showed significant increase in the rate
of wound contraction and collagen turnover (Ghasemi et al., 2010).
Ageratum conyzoides L (Asteraceae)
The leaves are applied to the wounds act as septic and heel them quickly. The juice of the
fresh plant and extract of dried plant are used to cure allergic rhinitis and sinusitis (Sachin et
al., 2009). There are reports that Ageratum conyzoides is used in postpartum recovery in
Peninsular Malaysia (Boer and Lamxax, 2009).
Phytochemical investigation of different extract showed the presence of alkaloids, and
tannins. Research suggests that the ointment of the root extract of Ageratum conyzoides has
significant wound healing activity. It may be attributed to antimicrobial and haemostatic
action of ageratum attributed to the individual or combined action of phytoconstituents
present in it (Sachin et al., 2009).
Allium cepa L. (Liliaceae)
Alcoholic extract of tubers of Allium cepa has shown better wound healing activity in
excision, incision and dead space wound models which may be atributed to free radical
scavenging action and the antibacterial property of the phytoconstituents (viz; tannins and
flavonoids) present in it (Shenoy et al., 2009).
23
Aloe vera (Asphodelaceae)It has stiff grey to bright green lance-shaped leaves containing clear gel in a central
mucilaginous pulp. Recent research has shown that the pharmacologically active agent is
concentrated in both the gel and the rind of the Aloe vera leaf (Syed et al., 1996). Topical
application and oral administration of Aloe vera to rats with dermal wounds increased the
collagen content of the granulation tissue as well as the degree of cross-linkage (MacKay
and Miller, 2003). Evidence tends to support that Aloe vera might be an effective
interventions used in burn wound healing for first to second degree burns (Maenthaisong et
al., 2007). However, in some severe burns, aloe gel may actually impede healing (Raina et
al., 2008).
Alternanthera brasiliana Kuntz (Amaranthaceae)
According to research results, topical application of Alternanthera brasiliana has a positive
influence on different phases of wound healing including wound contraction, fibroblastic
deposition and angiogenesis. Phytochemical screening of Alternanthera brasiliana revealed
the presence of alkaloids, steroids and triterpenes (Barua et al., 2009).
Anthocleista nobilis G. don. (Loganiaceae)
On the results of the study conducted in Ghana on invivo and invitro models, Anthocleista
nobilis has significant wound healing activity. This could partly be attributed to its
antibacterial and antioxidant property as evidenced by its ability to inhibit bacteria growth
and protect human fibroblast cells against oxidant injury (Annan and Dickson, 2008).
Areca catechu L. (Arecaceae)
Studies made on Areca catechu indicated that polyphenols and alkaloid fractions have
enhanced the healing of incision wounds by increasing the breaking strength of the wounds.
The polyphenol fraction especially seems to be more effective where the treatment having a
combination of both the alkaloid and polyphenol fractions also has a relatively high wound
breaking strength (Azeez et al., 2007).
24
Azardica indica (Meleaceae)
Neem oil contains margosic acid, glycerides of fatty acids, butyric acid and trace valeric
acid. Alcoholic extract of neem is useful in eczema, ringworm and scabies. Neem leaf
extracts and oil from seeds has proven anti-microbial effect. This keeps any wound or lesion
free from secondary infections by microorganisms. Clinical studies have also revealed that
neem inhibits inflammation as effectively as cortisone acetate; this effect further accelerates
wound healing (Raina et al., 2008).
Calotropis gigantea L. (Asclepiadaceae)
A study was made on Calotropis gigantea on incision wound model and healing by
granulation, collagenation, and tensile strength was measured indirectly to assess the
collagen content and maturation. The results indicated that latex of Calotropis gigantea
significantly promoted collagen (Nalwaya et al., 2009). In incision wound and dead space
wound, topical application of Calotropis gigantea increased breaking strength and
hydroxyproline of wounds (Deshmukh et al., 2009).
Carica papaya L. (Caricaceae)
The papaya-latex is well known for being a rich source of the four cysteine endopeptidases
namely papain, chymopapain, glycyl endopeptidase and caricain and the content may vary
in fruit, leaves and roots (Anuar et al., 2008). These antioxidants are considered to be one of
the potential contributors to wound healing (Anuar et al., 2008; Gurung and Skalko-Basnet,
2009).
Catharanthus roseus L. (apocyanaceae)
The two classes of active compounds in Vinca are alkaloids and tannins. Researches
suggested that the topical administration of ethanol extract of Vinca rosea leaves plays a
major role in diabetic wound healing (Nayak, 2006).
25
Centella asiatica (Mackinlayoideae)
The active principles of Centella asiatica are triterpenes and asiaticoside, which are
responsible for promotion of rapid wound healing. Aqueous extract of Centella asiatica
suspended in 5% propylene glycol promoted wound healing on topical administration in
experimentally induced open wounds in rats (Raina et al., 2008).
Cocos nuclifera L. (Arecaceae)
Coconut oil consists of lauric acid, myristic acid, palmitic acid (saturated fatty acid
components) and linolic acid, which is the only polyunsaturated fatty acid (Srivastava and
Durgaaprasad, 2008). It was reported that Cocos nuclifera has significant improvement in
wound contraction and decreased epithelialization period in burn wound model (Srivastava
and Durgaaprasad, 2008).
Cordial dichotoma (Boraginaceae)
Researches made on Cordial dichotoma, in three animal models, incision wound, excision
wound and dead space wound, revealed that the plant has the potential wound healing
activity supporting the traditional claim (Kuppast and Nayak, 2000).
Dissotis theifolia (Melastomataceae)
A study made in Nigeria demonstrated that Dissotis theifolia has antibacterial and wound
healing effect when formulated as ointment, on infected excision wound model.
Phytochemical studies showed that the crude Dissotis theifolia stem powder and the
methanol extract contain saponins, tannins, glycosides, flavonoids, terpenoids,
carbohydrates, alkaloids and steroids (Odimegwu et al., 2008).
.
Elaeis guineensis Jacq (Mackinlayoideae)
The application of a methanolic extract of Elaeis guineensis was found to improve the
different phases of wound repair, including collagen synthesis and maturation, wound
contraction, and epithelialization. Phytochemical screening studies showed that the plant has
26
tannin, saponin, alkaloid, flavonoid, steroids, reducing sugar and terpenoid (Sasidharan et
al., 2010).
Euphorbia heterophylla (Euphorbiaceae)
Euphorbia heterophylla contains alkaloids, cyanide, tannins, flavonoids and saponins in the
order of decreasing concentration. The aqueous and ethanol extracts showed significant
wound healing activity when topically administered on rats (James and Friday, 2010).
Ficus religiosa (Moraceae)
Hydro alcoholic leaf extracts ointment of Ficus religiosa showed significant wound healing
activity. This was evident by faster rate of wound closure and epithelialization period in
excision wound model and significant increase in skin breaking strength in incision wound
model (Roy et al., 2009).
Ginkgo biloba (Ginkgoaceae)
Its preparations promote epithelization without altering wound contraction. In case of dead
space wounds Ginkgo biloba has increased granulation tissue breaking strength without
altering granulation tissue mass weight. However, it did significantly enhance the content of
hydroxylproline of granulation tissue. The main constituents of Ginkgo biloba are
flavonoids and terpene trilactones and the pro-healing action of the Ginkgo biloba is due to
the presence of flavonoids (Raina et al., 2008).
Helianthus annus L. (Asteraceae)
In a study on the alcoholic extract of whole plant of Helianthus annus applied in the form of
an ointment on the excised wound of rat led to a significant reduction in total healing period.
This has been confirmed by histology where earlier appearances of fibroblasts were seen.
Early appearance and higher accumulation of mucopolysaccharides has been stated as
indicators of hastened repair (Raina et al., 2008).
27
Hoslundia opposita Vahl (Lamiaceae)
Wound healing activity of Hoslundia opposita could partly be attributed to their
antibacterial and antioxidant properties as evidenced in their ability to inhibit bacteria
growth and protect human fibroblast cells against oxidant injury. As research indicate, the
increase in hydroxyproline content (indication of collagen synthesis) and tensile strength of
healing tissue after the administration of the plant extract confirmed the healing potential of
the plant (Annan and Dickson, 2008).
Hydnocarpus wightiana (Flacourtaceae)
The wound healing effect of oil of Hydnocarpus spp. was studied with reference to
collagenation and the strength of scar tissue. Hydnocarpus wightiana oil administered orally
promoted epithelization, but not wound contraction. External application of oil of
Hydnocarpus spp. and its paste significantly shortened the epithelization period when
compared to control group. Oil may act as adjuvant in healing of wounds and ulcer in
leprosy patients and therefore, may be clinically useful (Raina et al., 2008).
Hypericum prolificum (Hypericaceae)
The chemical constituents include anthraquinone derivatives (naphthodianthrones),
flavonoids, prenylated phloroglucinols, tannins and volatile oils. Various types of
preparations, ointments, creams of Hypericum prolificum have been found to possess
wound-healing (Saddiqe et al., 2010). The antibacterial activity of crude extracts can be
related to the use of the herb as a wound healer in ancient times (Raina et al., 2008).
Jasminum auriculatum (Oleaceae)
The juice when applied in the form of jelly, locally on linear uniform excised wound in rats
is found to promote wound healing This has been assessed by histological, biochemical and
contraction rate studies. Fresh juice of the leaves showed an increase and early gain of the
tensile strength in the linear wounds in rats. The study indicated that collagenation
contributed to improved tensile strength in the early phase of healing (Raina et al., 2008).
Mwh13
28
Jatropha curcas L. (Euphorbiaceae)
Research performed on this plant suggest that fresh homogenized crude extract of Jatropha
curcas have beneficial influence on various phases of wound healing such as fibroplasia,
collagen synthesis and wound contraction resulting in faster healing (Shetty et al., 2006).
Lantana camara (Verbenaceae)
The ethanol extract of L.camara increased the rate of wound contraction in burn wound. The
slight reduction in the wound area might be due to the antimicrobial effect of the leaf
extract. The phytochemical analysis of the leaf extract by qualitative method showed the
presence of triterpenoids and flavonoid (Nayak et al., 2008).
Lawsonia inermis L. (Luthraceae)
Wound healing activity of the plant was studied in excision and incision wound models, the
result showing signifi.cant wound healing activities in both models. Flaavonoids, lawsone,
tannins, steroids, saponinis were found to be present in the plant (Sakarkar et al., 2004).
Mimosa pudica ( Mimosaceae)
Mimosa pudica has been reported to contain mimosine (an alkaloid), free amino acids,
sitosterol, linoleic acid and oleic acid. The drug is also found to be rich in tannins and the
total tannin content was reported to be (Kokane et al., 2009). The result of excision wound
model of 2% (w/w) methanolic and 2% (w/w) total aqueous extract indicated significant
increase in the wound contraction, revealing that the extract has ability to induce cellular
proliferation. Increase in tensile strength of the incision wound model also indicates the
promotion of collagen fibers (Kokane et al., 2009).
Napoleona imperialis (Lecythidaceae)
The various ointments prepared with Napoleona imperialis exhibited a good wound healing
effect comparable to those of Cicatrin®, a standard antibiotic used in wound healing. The
best activity was observed in the ointment containing Napoleona imperialis in cationic
29
ointment base. This shows that Napoleona imperialis can effectively be employed as a
cationic emulsifying ointment in wound healing (Esimone et al., 2005).
Ocimum kilimandscharicum (Lamiaceae)
Aqueous extract of leaves of Ocimum kilimandscharicum possesses a definite pro-healing
action. This is demonstrated by a significant increase in the rate of wound contraction and
by enhanced epithelization. Significant increase was also observed in skin breaking strength
and hydroxyproline content which was a reflection of increased collagen levels by increased
cross linking of collagen fibres. In addition, increase in dry granulation tissue weight
indicated the presence of higher protein content. Phytochemical screening revealed the
presence of tannins, flavonoids and proteins (Paschapur et al., 2009).
Ocimum sanctum L. (Labiaceae)
According to the research result done in India, both the alcoholic and aqueous extract of
Ocimum sanctum significantly increased wound breaking strength, hydroxyproline,
hexosamines, superoxide dismutase, catalase, and reduced glutathione (Udupa et al., 2005;
Shetty et al., 2008). The results suggest that Ocimum sanctum may be useful in the
management of abnormal healing and hypertropic scars.
Phyllanthus niruri L. (Euphorbiaceae)
Topical application of methanolic extract caused a significant concentrationrelated reduction
in wound diameter and epithelialization period of excision wounds. Several phytochemical
constituents of this plant have been isolated. Some of these include the alkaloids,
arabinogalactan, ellagic acid, 1-O-galloyl-6-O-luteoyl-alpha-d-glucose, beta-glucogallin,
quercetin, beta sitosterol, gallic acid, lignans and prenylated flavanones (Okoli et al., 2009).
Quercus infectoria (Fagaceae)
Phytochemical work reveals that ethanolic extract of galls of Quercus infectoria contains
high amount of tannins, presence of gallic acid, ellagic acid, syringic acid, ß-sitosterol and
amentoflavone. In the incision wound model, a significant increase was observed in the skin
30
tensile strength of the ethanol extract-treated group. On dead-space wound model the extract
showed a significant increase in dry granuloma weight, granuloma breaking strength and the
level of hydroxyproline content. Histological examination revealed that the plant has the
potential to increase collagen. Studies on the estimation of antioxidant enzyme reveal that
the extract significantly increased the levels of superoxide dismutase and catalase. In studies
using the excision wound model, animals treated with the ethanol extract of Quercus
infectoria showed a significant decrease in the epithelization period. The extract also
facilitated the rate of wound contraction (Umachigia et al., 2008).
Rubia cordifolia L. (Rubiaceae)
Studies made demonstrates the wound healing activity of ethanolic extract and its gel
formulation of the roots of the plant Rubia cordifolia and found to be effective in the
functional recovery of the healing of wounds and also in histopathological alterations.
Phytochemical screening of the ethanolic extract Rubia cordifolia showed the presence of
anthraquinone glycosides, saponins, tannins and phytosterols, of which tannins and
anthraquinones are the major phytoconstituent present in this plant which may be
responsible for wound healing action (Karodi et al., 2009).
Tragia involucrata L. (Euphorbiaceae)
Phytochemical analysis demonstrated the presence of vinyl hexylether, shellsol, 2, 4-
dimethyl hexane, 2-methylnanone and 2,6-dimethyl heptanes. In vitro antibacterial study
and wound healing study on excision wound model indicated that, shellsol and vinyl
hexylether contribute to the scientific basis wound healing (Samy et al., 2009). mwh63
Trichosanthes dioica (Cucurbitaceae)
The methanolic extract ointment showed significant increase in the rate of wound
contraction and by enhanced epithelialization period. Significant increase in tensile strength,
and hydroxyproline content were observed, which was auxiliary supported by
histopathological studies. Preliminary phytochemical screening of methanolic extract of
31
Trichosanthes dioica showed the presence of alkaloids, flavonoids and tannins (Shivhare et
al., 2010).
Tridax procumbens (Asteraceae)
This juice accelerates two phases of healing namely epithelialization and collagenization,
however, it retards scar formation and granulation leaf extracts of this plant also promote
wound healing in both normal and immunocompromised (steroid treated) rats in dead space
wound model (Raina et al., 2008). Mwh13
Vernonia arborea (Asteraceae)
Research made on this plant showed that aqueous and methanolic bark extract of the plant
have significant promotion of wound healing in excision, incision and dead space wound
models. Preliminary phytochemical screening of aqueous extract indicated the presence of
flavonoids, saponins tannins and glycosides, while the methanolic extract showed additional
sesquiterpene and triterpenes (Panda and Tripathy, 2009).
9. Reference
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