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European Journal of Medicinal Plants4(11): 1324-1335, 2014

SCIENCEDOMAIN internationalwww.sciencedomain.org

The Effect of Different Drying Methods on thePhytochemicals and Radical Scavenging

Activity of Ceylon Cinnamon(Cinnamomum zeylanicum) Plant Parts

Darfour Bernard1*, Asare Isaac Kwabena1, Ofosu Daniel Osei1,G. Achel Daniel2, S. Achoribo Elom2 and Agbenyegah Sandra2

1Radiation Technology Centre, Biotechnology and Nuclear Agriculture Research Institute,Ghana Atomic Energy Commission, Ghana.

2Radiological and Medical Sciences Research Institute, Ghana Atomic Energy Commission,Ghana.

Authors’ contributions

All authors participated in carrying out this research work. At each point of the research fromthe idea development through the laboratory and data analyses to write up, all authors

played almost equal parts. All authors read and approved the final manuscript.

Received 13th June 2014Accepted 14th July 2014Published 26th July 2014

ABSTRACT

Aim: The research aimed at ascertaining whether the different drying methods and plantparts have effect on the radical scavenging activity and phytochemical properties ofcinnamon as an herb/spice.Methodology: Fresh samples of the cinnamon (Cinnamomum zeylanicum) was collectedat the Aburi Botanical Gardens, Ghana. Some of the samples were sun, oven, room andfreeze dried. The dried and fresh samples were extracted with methanol and water andthe extract analyzed.Results: Only the sun dried samples had the total phenolic and total flavonoid beendegraded compared to the fresh sample. The flavonoid and phenolic contents and theDPPH radical scavenging activity were significantly expressed in different amounts in theroot, stem, leaf and seed.Conclusion: Generally, the drying influenced the phytochemical contents which aremajor contribution to the radical scavenging activity of the cinnamon.

Original Research Article

European Journal of Medicinal Plants, 4(11): 1324-1335, 2014

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Keywords: Cinnamon; phytochemicals; radical scavenging activity; drying methods.

1. INTRODUCTION

Some medicinal plants contain various natural antioxidants such as phenolic acids,flavonoids, tannins, etc which are associated with higher antioxidant activity compared tothat of dietary plants [1].

The phytochemical content of herbs/spices may differ depending on the solvent used forextraction and harvesting season [2,3] and between geographical origins [4]. Theconcentration of phytochemicals in the plant part (seed, leaf, root bark and stem bark) maynot be uniform and moreover, the fresh or dried method (sun, shade, freeze and oven) usedfor extraction of phytochemicals may cause quantitative changes in the phytochemicalconstitution. Drying of medicinal herb/spice materials help to keep them for future cooking aswell as reduce the risk of bacterial or fungal contamination. Since many herbs are used inthe dried form, drying process may affect their phytochemical content and radicalscavenging activity, therefore, it is necessary to determine the best method of drying tomaintain or enhance the radical scavenging activity and phytochemical content.

Cinnamon is an aromatic tree which grows in the wild and is a native of Southern Asia andSouth America. Cinnamon is a favorite spice around the world because of its health benefitsand aroma in foods [5]. Its bark is one of the few herbs/spices that can be consumeddirectly.

This research work was to ascertain whether the different drying methods and plant partshave effect on the radical scavenging activity and phytochemical properties of cinnamon asan herb/spice.

2. MATERIALS AND METHODS

2.1 Plant Materials

Fresh samples of stem bark, root bark, seeds and leaves of the cinnamon (Cinnamomumzeylanicum) was collected at the Aburi Botanical Gardens of the Ghana Parks and GardensDepartment.

2.2 Sample Preparation

The fresh samples (seeds, leaves, stem bark and root bark) were washed under running tapwater and then drained thoroughly on paper towel. The samples were then manually brokeninto pieces and divided into batches of 5 grams each. In one batch, fresh samples weretaken for solvent extraction. Four drying processes used for the other batches were sundrying, shade drying, oven drying and freeze drying.

2.2.1 Sun-drying

The herbs were evenly spread on a tray, covered with the cotton sheets to keep off dust andinsects, turned occasionally and left to dry under the direct exposure to sunlight/rays(33±4ºC) until the samples were brittle and considered to be dry (two days).


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2.2.2 Room-drying

The herbs were evenly spread on a tray, covered with the cotton sheets to keep off dust andinsects, turned occasionally and left to dry in a room (31±4ºC) in appropriate air flow until thesamples were brittle and considered to be dry (four days).

2.2.3 Oven-drying

The samples were evenly spread on a tray and placed in the oven (Gallenkamp, UnitedKingdom). The samples were dried overnight at 50ºC.

2.2.4 Freeze-drying

A vertical freezer with 2520 in 2 of shelf space, designed and built by Labconco, MO, wasused to freeze-dry the samples. Samples were placed in an aluminum foil and treated at -20ºC for 24 hours. The samples were then placed in freeze drier for 3 days at -45ºC.

Both the fresh and dried samples were then ground and stored in air-tight containers at 4ºCpending further analysis

2.3 Methanol and Aqueous Extractions for Phytochemical Analysis

The stored dried and fresh samples were weighed (0.05 g) and extracted in 15 ml deionizedwater or methanol in volumetric flasks at a temperature of 60ºC for 3 hours and thesupernatant recovered for further analyses. After drying the samples in the oven andobtaining constant moisture contents, the dry weights of the samples were calculated for.

2.4 Total Phenolic

The total phenolic contents were measured by the Folin- Ciocalteau [6] method using GallicAcid as standard. A mixture of 50 µl of sample plus 3ml of distilled water, 250 µl of Folin-Ciocalteau (fc 1/10) and 750 µl 20% of Na2CO3 was vortexed to mix, incubated for 30minutes in the dark and the absorbance measured at 760nm.

2.5 Total Flavonoid

The aluminum chloride colorimetric assay method [7] was employed for the total flavonoidcontent. Quercetin was used as standard. Total flavonoid content was determined asmicrogram (µg) Quercetin equivalent using the calibration linear regression equation. 2800µl distilled water, 1500 µl ethanol, 500 µl samples, 100 µl potassium acetate (1M) and 100 µlof 10% aluminum chloride were mixed and incubated in the dark for 30 minutes. Theabsorbance was read at 415 nm.

2.6 DPPH radical Scavenging Activity

The DPPH radical scavenging activity was determined using 2, 2 –diphenyl-1-picylhydrazyl(DPPH) free radical. 200 µl of extracts was added to 3800 µl of 0.004% DPPH in an ethanolsolution. After 30min of incubation at room temperature in the dark, the absorbance wasmeasured at 517nm. Radical scavenging was calculated as follows; 1% = [(Abs0 –Abs 1)/


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Abs0], where Abs0 was the absorbance of 0.004 % DPPH without analyte and Abs1 theabsorbance of 0.004% DPPH plus the test compound.

2.7 Phytochemical Screening of Extracts

The water and methanol extracts were tested for the presence of phytochemicals such assaponins, alkaloids, terpenoids, tannins, phytosterols and phenols using the standardprocedures [8].

2.7.1 Terpenoids

Of the sample extracts, 0.5g were taken. Two millilitres of chloroform and three millilitres ofconcentrated sulphuric acid were carefully added to form a layer (interface) which wasreddish brown in colour [8].

2.7.2 Saponins

Of the sample extracts, 0.5g were taken. Five millilitres of distilled water was added in a testtube and shaken vigorously for stable persistent froth. Three drops of olive oil was thenadded to the frothing and shaken vigorously to observe emulsion [8].

2.7.3 Tannins

Of the sample extracts, 0.5g were taken. Ten millilitres of boiled water was added in a testtube and filtered. Few drops of 0.1% ferric chloride was added till brownish green or blue-black colour was observed [8].

2.7.4 Alkaloids

Of the sample extracts, 0.5g were taken and dissolved in dilute hydrochloric acid andfiltered. The filtrate was then treated with iodine in potassium iodide solution until brown/redcolour was observed [8].

2.7.5 Phenols

Of the sample extracts, 0.5g were taken and treated with 3-4 drops of ferric chloride solutionuntil bluish black colour was formed [8].

2.7.6 Phytosterols

Of the sample extracts, 0.5g were taken and treated with chloroform and filtered. Thefiltrates were treated with few drops of concentrated sulphuric acid, shaken and allowed tostand. Appearance of golden yellow colour indicated the presence of phytosterols [8].

2.8 Statistical Analysis

Statgraphics centurion (version 16) statistical tool was used for the analysis of variance andmean separations. Data obtained were subjected to two way ANOVA. Values wererepresented as mean ± standard error of triplicate data.


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3. RESULTS AND DISCUSSION

3.1 Effect of Drying Methods on Radical Scavenging Activity, Total Phenolicand Flavonoid Content

Drying is considered as a critical factor for the postharvest management and themerchantability of herbs. The drying of herbs inhibits microbial growth and forestallsbiochemical changes but, at the same time, it can give rise to other changes that affect theherb quality. In addition, the drying of herbs is often accompanied with the loss of bioactivecompounds, although some of the phytochemicals are more thermo stable [9,10] which maypossess antioxidant activity and other health-promoting properties [11].

The effect of the different drying methods (freeze, oven, room and sun) on the totalflavonoid, total phenolic and radical scavenging activity varied (Table 1). The samples hadno differences (P ≤ .05) in their dry weight suggesting an equal moisture content. Only thesun dried samples had the total phenolic and total flavonoid been degraded compared to thefresh sample. The degradation was due to the relatively very intense and prolonged sun raysresulting in enzymatic degradation of the phytochemicals [12, 13, 14]. Temperature and timeused in the drying techniques could be the main contributing factor in the degradation. Theloss of macromolecules like phytochemicals during heat treatment might be due to the harshdrying conditions, in particular, the temperature and duration used [15]. Degradation ofphytochemicals upon thermal treatment of broccoli florets had been reported [16].

The higher phytochemical content of the oven dried samples can be attributed to the rapidinactivation of enzymes [13]. Oven drying may be a good method for drying and preservingphytochemicals in cinnamon, in that it can be completed in a shorter time and under moreclosely monitored conditions than the other drying methods. This suggestion was also made[17] on the effect of different drying methods on Bakhtiari savory. There was a contraryreport [18] that, oven drying degraded the flavonoids content of Centella (Centella asiatica)more than the other drying methods.

Several reasons have been given to the degradation in the phytochemical content of freezedried samples. Some schools of thought have attributed the degradation to the wet thermalbreakdown that affects the integrity of the cell structure resulting in leakage or breakdown[19] and degradation of heat-sensitive compounds reported to be minimized at that lowtemperatures [20]. The formation of ice crystals formed within the sample matrix thatraptured the cell structure increases the extractability of the phytochemicals [21]. The roomdrying at low temperatures protects against the degradation of the bioactive constituents, butit is slow and metabolic processes may continue longer, which may lead to quality loss suchas aromatic and phytochemical properties [22].

There was 74% correlation between the antioxidant activity and the phenolic content,however, there was negative correlation between the flavonoid and antioxidant activity andphenolic and flavonoid (Table 5). Similar report had been made on some spices and edibleplants [23,24].


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Table 1. Effect of drying methods on radical scavenging activity, total phenolic and total flavonoid of cinnamon

Phytochemicals Drying methodOven Room Freeze Fresh Sun

DPPH radical scavenging activity (%) 8.441±0.165a 8.266±0.165a 6.988±0.165b 2.442±0.165c 2.760±0.165c

Total phenolic (mg GAE/g DW) 0.238±0.002a 0.152±0.002b 0.153±0.002b 0.120±0.002c 0.084±0.002d

Total flavonoids (mg GAE/g DW)Dry weight (mg/g)

21.246±0.227a

3.270±1.300a6.765±0.227c

5.240±1.300a8.489±0.227b

5.489±1.300a5.568±0.227d

5.568±1.300a5.657±0.227d

3.143±1.300a

Means ± standard error with different superscripts in the same row are significantly different (P ≤ .05) from each other

Table 2. Radical scavenging activity, total phenolic and flavonoid contents in the different parts of the cinnamon plant andin the solvent extracts

Phytochemicals Plant part Solvent extractStem Root Leaf Seed Methanol Water

DPPH radical scavenging activity (%) 12.214±0.147a 8.829±0.147b 1.123±0.147c 0.952±0.147c 7.795±0.104a 3.763±0.104b

Total phenolic (mg GAE/g DW) 0.192±0.002b 0.224±0.002a 0.125±0.002c 0.059±0.002d 0.159±0.001a 0.141±0.001b

Total flavonoids (mg GAE/g DW) 3.293±0.203c 5.061±0.203b 24.280±0.203a 5.547±0.203b 16.160±0.144a 2.930±0.144b

Means ± standard error with different superscripts in the same row are significantly different (P ≤ .05) from each other with respect to the plant partand the solvent extract

Table 3. Screened phytochemicals in cinnamon

Phytochemicals Drying methodsSun Room Oven

Methanol Water Methanol Water Methanol WaterSt Rt Lf Sd St Rt Lf Sd St Rt Lf St St Rt Lf Sd St Rt Lf Sd St Rt Lf Sd

Phytosterols + + + + + + + + + + + + + + + + + + + + + + + +Phenols + + + + + + + + + + + + + + + + + + + + + + + +Tannins + + + + + + + + + + + + + + + + + + + + + + + +Saponins + + + + + + + + + + + + + + + + + + + + + + + +Alkaloids - - - - - - - - - - - - - - - - - - - - - - - -Terpenoids + + + + + + + + + + + + + + + + + + + + + + + +

+ denotes present and – denotes absent; St = Stem, Rt = Root, Lf = Leaf, Sd = Seed


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3.2 Radical Scavenging Activity, Total Phenolic and Flavonoid Potency ofPlant Parts and Extraction Solvent

The stem of cinnamon showed the highest DPPH radical scavenging activity and methanolproved to be the better extraction medium for all the phytochemicals assessed (Table 2).The root showed a significantly high phenolic content, followed by stem, leaf and seed.They were significantly different from each other. Flavonoid contents were significantlyexpressed in different amounts in the root, stem, leaf and seed. The leaf had significantlyhigher flavonoid content than the rest. Root and seed had significantly high amount than thestem, although the root and stem were significantly indifferent.

The quantity and quality of phytochemicals present in plant parts may differ from one part toanother. Successful determination of biologically active compounds from plant material islargely dependent on the type of solvent used in the extraction procedure [25]. Thepresence of total phenolic and flavonoids in the stem and root barks, leaf and seed supportsthe antimicrobial, anti-diarrheal, anti-cancer and anti-helminthic activities [26,8] of thecinnamon plant. The presence of these phytochemicals contribute to the free radicalscavenging ability of the plant. The higher scavenging ability of the stem could be attributedto the fact that, the stem bark is purposed to store phytochemicals than the root and thenthe seed/leaf. The results of this finding suggest that the methanol and water extracts fromthe stem, root, leaf and seed contributed significantly to the medicinal potency of the plantand give credence to the use of these parts in disease control.

3.3 Phytochemical Screening of the Cinnamon Samples

During the screening, saponins, tannins, phenols, terpenoids and phytosterols wereobserved to be present in all the samples studied (Tables 3 and 4). The potency of thescreened phytochemicals have been documented by several researchers. It had beenreported that [8] saponins, tannins and phenols have anti-diarrheal, anti-cancer and anti-helminthic potency; terpenoids have antimicrobial and anti-diarrheal potency [26];phytosterols have anti-diarrheal potency; tannins have stringent properties that hasten thehealing of wound and inflamed mucous membranes [27]. The presence of thephytochemical compounds in the cinnamon plant indicates that the cinnamon plant whetherdried or fresh has medicinal potency and may have the ability as an anti-microbial, anti-diarrheal, anticancer and anti-helminthic agent.

Table 4. Screened phytochemicals in cinnamon

Phytochemicals Drying methodsFresh Freeze

Methanol Water Methanol WaterPhytosterols St Rt Lf Sd St Rt Lf Sd St Rt Lf St St Rt Lf Sd

Phenols + + + + + + + + + + + + + + + +Tannins + + + + + + + + + + + + + + + +Saponins + + + + + + + + + + + + + + + +Alkaloids - - - - - - - - - - - - - - - -Terpenoids + + + + + + + + + + + + + + + +

+ denotes present and – denotes absent; St = Stem, Rt = Root, Lf = Leaf, Sd = Seed


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Table 5. Correlation coefficient of the Phytochemicals

Phenolics Flavanoids DPPHPhenolics - -0.1316 0.7400**Flavanoids -0.1316 - -0.1305DPPH 0.7400** -0.1305 -

** = highly significant at 1%

3.4 Radical Scavenging Activity, Total Phenolic and Flavonoid Contents inRelation to Solvents, Drying Methods and Plant Parts

The flavonoid was best extracted in the methanol solvent. Generally, the sun, freeze, roomand oven dried samples had the best extraction with methanol (Fig. 1). The room driedleaves, seeds and root had the flavonoid best extracted with methanol. The fresh, sun, roomand freeze dried leaves of the methanol extract had substantially higher amount offlavonoid. Thus, the methanol extract of the fresh leaves had the overall significantly highflavonoid content.

Fig. 1. Efficiency of phenolic extraction in relation to the solvents, drying methodsand plant parts

The methanol extracts of the oven, room and freeze dried root and stem had higher radicalscavenging activity (Fig. 2). Comparatively, only the methanol extract of the fresh stem hadhigher radical scavenging activity. The sun dried samples recorded lower radicalscavenging activity in both solvents and all plant parts.

Significantly, the highest phenolic content was recorded in the water extract of the ovendried root (Fig. 3). The water extracts of the sun dried root, freeze dries root and stem, ovendried stem, room dried root and stem had relatively similar phenolic concentrations.Similarly, the methanol extracts of the root and stem of the fresh, oven dried, room driedand freeze dried samples had higher phenolic content. The water and methanol extracts ofthe fresh and dried seeds recorded the least phenolic content.


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Fig. 2. Efficiency of flavonoid extraction in relation to the solvents, drying methodsand plant parts

Fig. 3. Radical scavenging activity in relation to the solvents, drying methods andplant parts

The inconsistency in the concentrations of the phytochemicals in the various part of theplant had also been reported earlier [28] which could be attributed to the drying effects ashighlighted in earlier discussion or could be due to the differences in the secondarymetabolites of the various plant parts [29]. The radical scavenging activity and extraction ofphytochemicals from plants is influenced by the solvent been used for extraction [30].Therefore, using the appropriate solvent for extraction is essential [31].


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4. CONCLUSION

Each plant sample needs a special drying method to show the best radical scavengingactivity and highest phytochemical content, because of differences in the secondarymetabolites.

In general, the drying had effect on the total phenolic and total flavonoid contents which aremajor contribution to the radical scavenging activity of the cinnamon. The best dryingmethod according to this study were the oven drying and room and/or freeze drying. Thepart of the cinnamon plant containing the highest content of total phenolic and totalflavonoids and free radical scavenging ability were the stem and roots. Positive correlationwas obtained between only phenolic and antioxidant activity which was 74 %. Thephytochemicals screened was an indication that cinnamon could be a beneficial medicinalherb and spice. Methanol as a solvent had been established to be best for the extraction ofphytochemicals in the cinnamon.

ACKNOWLEDGEMENT

The authors greatly acknowledge the immense contributions of the technologists andtechnicians in the ARBC laboratory of RAMSRI of Ghana Atomic Energy commission.

CONSENT

Not applicable.

ETHICAL APPROVAL

Not applicable.

COMPETING INTERESTS

Authors have declared that no competing interests exist.

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_________________________________________________________________________© 2014 Bernard et al.; This is an Open Access article distributed under the terms of the Creative CommonsAttribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, andreproduction in any medium, provided the original work is properly cited.

Peer-review history:The peer review history for this paper can be accessed here:

http://www.sciencedomain.org/review-history.php?iid=608&id=13&aid=5489

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