PLANT SECONDARY METABOLITES

Dr. Muayad S. Shawkat

University of Baghdad

College of Science

Department of Biotechnology

*These compounds are played many important rules in plant life such as involved in defense against herbivores and pathogens, regulation of symbiosis, control of seed germination, and chemical inhibition of competing plant species (allelopathy), and therefore are an integral part of the interactions of species in plant and animal communities and theadaptation of plants to their environment.

*Plant secondary metabolites are a diverse group of molecules that are involved in the adaptation of plants to their environment but are not part of the primary biochemical pathways of cell growth and reproduction.

* The mechanisms by which these substances have beneficial effects on health may also be related to their toxic effects, and the difference between toxicity and beneficial effects may be dose- and structure-dependent.The term “plant extract" determines the part/parts of a plant used for preparing medicine (for example: leaves, flowers, seeds, roots, barks, stem....etc). Studies on the use of plant extracts for controlling disease have shown the importance of natural chemicals (phytochemicals) as possible sources of non-phytotoxic and easily biodegradable, alternative fungicides and antibiotics

* In addition, plant secondary metabolites are also associated with improved nutritive value and may have beneficial effects on animal health.

* Growing interest in the potential health-promoting effects of plant secondary metabolites in human foods has prompted research on their potential to prevent or treat cancer, circulatory disease, and viral infection.

o Extraction: as the term is used pharmaceutically, involves the separation of medicinally active portions of plant or animal tissues from various parts of plants by using selective solvents in standard extraction procedures. Selection of the solvent depends on the polarity of solvent and solubility of the desired components of the material.

Preparing the plant Material: Plants were dried before extraction. freeing of plant under study from

contamination From other plants from disease

General methods Extraction:

choosing of the precise method of extraction depend on texture and water content of the plant material.

1. Maceration the whole or coarsely powdered crude drug is placed in a container with the solvent and allowed to stand at room temperature for a period of at least 3 days with frequent agitation until the soluble matter has dissolved.

2. Hot Continuous Extraction (Soxhlet)

In this method, the finely ground crude drug is placed in a porous bag or “thimble” made of strong filter paper, which is placed in chamber E of the Soxhlet apparatus. The extracting solvent in flask A is heated, and its vapors condense in condenser D. The condensed extractant drips into the thimble containing the crude drug, and extracts it by contact. When the level of liquid in chamber E rises to the top of siphon tube C, the liquid contents of chamber E siphon into flask A.

CO2

Primary carbon metabolism

Photosynthesis

Phosphoenol pyruvate

Pentose phosphate pathway

Erythrose-4-phosphate

pyruvate

Acetyl Co-ATCA Cycle

Aliphatic amino acid

Shikimic acid Mevalonic acid Pathway

Terpenes

Malonic acid Pathway

Phenolic compounds

Aromatic amino

acids

Nitrogen containing compound

s

A/ TerpenoidsB/ Nitrogen containing secondary metabolitesC/ Phenolic compounds

MAIN GROUPS OF PLANT SECONDARY METABOLITES

ISOPRENE C5 is the basic unit of the terpenoidsProduction in Plants: * Flowers

* Leaves * Fruit

Biological Role(volatile and non volatile): -Flavour, fragrance, scent -Antibiotics -Hormones -Membrane lipids -Insect attractants -Insect antifeedants

THE TERPENOIDS

C5-hemiterpenes -e.g. isopreneC10-monoterpenes -e.g. limoneneC15-sesquiterpene -e.g. abscisic acid (ABA)C20-diterpene -e.g. gibberellinC30-triterpne -e.g. brassinosteroidsC40-tetraterpenes -e.g. carotenoids> carbons -polyterpenes-e.g. ubiquinones, rubber

TERPENOIDS --IMPORTANT MOLECULES !

Nitrogen containing compounds! Alkaloids (pseudo-, True-, proto-) Extremly heterogenous group alkali like have important pharmacological properties further classified in to many groups- Pyridine alkaloids , e.g. nicotine- pyrrolidine alkaloids , e.g. stachydrine- piperidine alkaloids , e.g. coniine- tropane alkaloids , e.g. atropine- quinoline alkaloids , e.g. quinine- Isoquinoline alkaloids , e.g. berberine- Quinolizidine alkaloids , e.g. lupinine- Indol alkaloids , e.g. resrpine- Imidazol alkaloids , e.g. pilocarpine

Phenylalkylamines: e.g. Ephedrine

Pyridine and piperidine e.g. lobeline, nicotine

Tropane e.g. Atropine.

CH2 CH CH3

NH2

N NH

NCH3 OH

Quinoline e.g.quinine and quinidine

Isoquinoline e.g. papaverine

Phenantheren e.g. Morphine

N

N

Indole e.g.ergometrine

Imidazole e.g. pilocarpine

Purine e.g. caffeine

NH

N

N

N

N N

N

H

Purine

1

2

34

56 7

8

9

Steroidal e.g. Solanum and Veratrum

alkaloids

Terpenoide.g. Taxol

Cyanogenic glycosides

widely distributed in plantsvolatile poisons e.g. Lotustraline

Glucosinolates contain nitrogen and sulpher volatile toxins strong deterrent

Cyanogenic Glycosides

Non-Protein amino acids

found in plants of the family leguminosae

e.g. Canavanine resemble in structure with arginine

there are not incorporated in to protiens

Phenolics

• Plants produce a variety of compounds that contain one or more phenol groups - called phenolics

• Thousands of phenolics occur in plants

Phenolics

• Large group of diverse compounds• Many serve as defense compounds against

herbivores and pathogens• Some function in support – primary cmpd• Some attract pollinators• Some absorb UV light• Some reduce growth of competitors

Tannins

• They are high molecular weight phenolic compounds

• They are widely distributed in plants.• capable of precipitation of animal proteins

Classification of Tannins:

True Tannins(High molecular weight compounds)

Hydrolysable Tannins(Pyrogallol)

Condensed Tannins(Catechol)

PseudotanninsLow molecular weight compounds

e.g. Gallic acid, Flavan-3,4-diol

Not hydrolysable ,no sugar in mol.

Uses of Tannins:

• 1) Antioxidant.• 2) Antidiarrheal.• 3) Antidote for heavy metals poisoning.• 4)Treatment of burns, ulcers, inflammations• 4) Astringent to stop bleeding (hemorrhage)• 5)Treatment of Hemorrhoids.• 6) Tanning industry.

Lignin a complex phenolic

• Primary metabolite - secondary cell wall component occurs in all vascular plants

• Structural function• Also protective because deters herbivores

due to its toughness• Blocks growth of many pathogens because

only small group of fungi can degrade

Flavinoids

• One of the largest classes of phenolics• Carbon skeleton has 15 carbons with two

benzene rings connected by a 3-C bridge

-C3-

Anthocyanins

• Colored flavinoids - red, pink, blue, purple pigments

• Attract animal pollinators and seed dispersers

Anthocyanin

- cyanidine cyanidine 3-glucoside cyanidine 3-rutinoside

- peonidine peonidine 3-glucoside peonidine derivative

B

Flavones and Flavonols

• Also flower pigments• Absorb UV not visible light - not visible to

human eye but visible to many insects - maybe be attractants, nectar guides

• Also present in leaves where they protect against UV-B damage

• Appeared to be involved in legume roots in attracting N-fixing bacteria

Some applications of Important plants and their compounds in

biotechnology

Green Tea (Camellia sinensis)

Polyphenols from leaves

anti-cancer inhibiting tumor initiation and cell proliferation

anti-oxidant

Wine Grape (Vitis vinifera) Contains over 50 different

flavonoid phenolics including resveratrol and catechins

Reduces heart disease by inhibiting platelet aggregation, lowering LDL (low density lipoproteins) and acting as antioxidants

Ginger (Zingiber officinale)

from the rhizome Over 12 compounds

with anti-oxidant activities greater than vitamin E

anti-tumor anti-emetic (inhibits

vomiting)

Garli c (Allium sativum)Onion (Allium cepa) Organo-sulfur

compounds from leaves

Anti-carcinogenic and anti-microbial

Anti-atherosclerosis and anti-hypertensive

Toxic in high amounts

Soybeans (Glycine max) Contains phytoestrogens like isoflavones Reduces health risks associated with menopause:

osteoporosis and heart disease in women Reduces prostrate, colon and breast cancer

Thank You