Plant secondary metabolites

What are secondary metabolites?
Why they are produced?
Compartment of synthesis
Classes of secondary metabolites
Applications
Conclusion
References

1. “ Plant secondary metabolites” By KAUSHAL KUMAR SAHU Assistant Professor (Ad Hoc) Department of Biotechnology Govt. Digvijay Autonomous P. G. College Raj-Nandgaon ( C. G. )

2. CONTENTS What are secondary metabolites? Why they are produced? Compartment of synthesis Classes of secondary metabolites Applications Conclusion References

3. What are secondary metabolites? Secondary metabolites are  organic compounds that are not directly involved in the normal growth, development, or  reproduction of an organism. Unlike  primary metabolites, absence of secondary metabolites does not result in immediate death, but rather in long-term impairment of the organism's survivability, fecundity, or aesthetics, or perhaps in no significant change at all.

4. WHY THEY ARE PRODUCED? Secondary Metabolites are produced in plants is mainly for: Disease resistance (from fungus, bacteria, viral, and pests), For pollination and To combat in extreme conditions of stress. The stress may be biotic or abiotic [Drought, Cold, Temperature, etc.]

5. Main Groups of Secondary Metabolites- -29,000 terpenes derived from the C5 terpenes- alkaloids. -8,000 phenolics shikimate pathway or phenolics- malonate/acetate pathway in Plants precursor isopentenyl diphosphate (IPP). -12,000 alkaloids - derived from amino acids. Main secondary metabolite- Nitrogen containing compound- Alkaloids(12,000) Non protein amino acid(600) Amines(100) Cynogenic glycosides(100) Glucosinolates(100)

6. Main secondary metabolites- Non nitrogen containing Terpenoids(29,000)- Mono(1,000) Sesquiterpene(3,000) Diterpines(1,000) Triterpines,Steroids,saponines(4,000)

7. Compartmentation of SMs biosynthesis- Mostly in the Cytosol-hydrophilic compounds Chloroplasts-alkaloids (caffeine) and terpenoids (monoterpenes) Mitochondria-some amines, alkaloids Vesicles-alkaloids (protoberberines) Endoplamic reticulum-hydroxylation steps, lipophilic compounds Water soluble compounds- alkaloids, NPAAs,cyanogenic glucosides, glucosinolates, saponines , anthocyanines, flavonoids,cardenolides.

8. Example- Anthocyanines- -Blue-red flavonoid pigments - They are stabilized in the vacuole -Oxidation in cytosole -The sequestration is a detoxification process SMs sequestration in to Vacuoles SMs

9. SMs Vacuoles- Anthocyanin exampleAnthocyanin example- Bz2 mutant an9 mutant -When the BRONZE2gene is not active, anthocyanines accumulate in the cytosol and a tan bronze phenotype of tissue is obtained - BRONZE2is a Glutathione-S-transferase   -Glutathionation of anthocyanines is a pre-requisite for the targeting to the vacuole through a GST-x-pump in the tonoplast membrane.

10. Anthocyanin example-bz2& the an9 mutant& mutant Bz an9

11. Biosynthetic Pathway- • Nucleoside diphosphate sugar pathway: cellulose, hemicellulose, glycosides. • Shikimate-cinnamate pathway: lignin, lignans, hydrolyzed tannins. • Mixed pathways of 3 and 4: some prenylflavonoids, quinones and stilbenes.

12. The Classes of Secondary Metabolites- The majority of secondary metabolites belong to one of a number of families, each of which have particular structural characteristics arising from the way in which they are built up in nature (biosynthesis). The classes of secondary metabolites are: – Polyketides and fatty acids – Terpenoids and steroids – Phenylpropanoids – Alkaloids

13. Terpenes- Isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP) combined to yield geranyl pyrophosphate (GPP), leading to monoterpenes. Similarly, compounds derived from farnesyl pyrophosphate (IPP) lead to sesquiterpenes, and triterpenes are formed from two equivalents of FPP, and triterpenes are formed from two equivalents of FPP. The function of terpenes in plants is generally considered to be both ecological and physiological – Allelophathy – Insecticidal – Insect pollinators – Plant hormone (Abscisic acid, gibberlellin)

14. Myrcene is found in the essential oil of bay leaves as well as hops. It is used as an intermediate in the manufacture of perfumes. Hops ( Humulus lupulus ) Greek Bay ( Laurus nobilis )

15. Geraniol is isomeric with linalool, constitutes the major part of the oil of roses and is also found in essential oils of citronella, lemon grass, and others. Geraniol Linalool Menthol is a well-known monoterpene which is found in the essential oil of peppermint and other members of the mint family.

16. Sesquiterpenoids- • More than 10000 sesquiterpenoids have been identified, representing a wide variety compounds of different skeletal types from acyclic to tetra cyclic systems. - Farnesol is widely distributed in many essential oils such as citronella, neroli, cyclamen, lemon grass, tuberose, rose, musk, and balsam. It is used in perfumery to emphasize the odors of perfumes. The presence of farnesol prevents the yeast-to-mycelium conversion, resulting in actively budding yeasts without influencing cellular growth rates.

17. Nerolidol is present in neroli, ginger, jasmine, lavender, tea tree and lemon grass. The aroma of nerolidol is woody and reminiscent of fresh bark. It is used as a flavoring agent and in perfumery. It was also shown to be produced by the leaves of a large number of plant species in response to herbivory insects and then to be transformed into a C11-homoterpene (4,8-dimethyl-1,3,7-nonatriene) which attracts predatory insects.

18. - Abscisic acid  plays a key role in plants in the regulation of stomatal closure by regulating ion channel activities and water exchanges across the plasma membrane of guard cells. Abscisic acid has also a variety of roles in plant development, bud and seed dormancy, germination, cell division and movement. It induces also storage protein synthesis in seeds  and may be involved in defense against insect attack

19. Phenolic Constituents- -Heartwood and bark contain a large variety of complex aromatic extractives. Most of them are phenolic compounds, and many are derived from the phenylpropanoid structure. - Vanillin   is a   phenolic aldehyde, an   organic compound   with the molecular formula C 8 H 8 O 3 . Its   functional groups   include   aldehyde,   ether, and   phenol. It is the primary component of the extract of the   vanilla   bean. Synthetic vanillin, instead of natural vanilla extract, is sometimes used as a   flavoring agent   in foods, beverages, and pharmaceuticals.

20. - Eugenol  is a phenylpropene, an allyl chain-substituted guaiacol. Eugenol is a member of the  phenylpropanoids class of chemical compounds. It is a clear to pale yellow oily liquid extracted from certain essential oils especially from clove oil, nutmeg, cinnamon, basil and bay leaf.  It is slightly soluble in water and soluble in organic solvents. It has a spicy, clove-like aroma.

21. The Most Important Classes of Phenolic Compounds in Plants number of C-atoms basic skeleton Class 6 C 6 simple phenols, benzoquinones 7 C 6  - C 1 phenolic acids 8 C 6  - C 2 acetophenone , phenylacetic acid 9 C 6  - C 3 hydroxycinnamic acid, polypropene , coumarin , isocoumarin 10 C 6  - C 4 Naphtoquinone 13 C 6  - C 1  - C 6 Xanthone 14 C 6  - C 2  - C 6 stilbene , anthrachinone 15 C 6  - C 3  - C 6 flavonoids , isoflavonoids 18 (C 6  - C 3 ) 2 lignans, neolignans 30 (C 6  - C 3  - C 6 ) 2 Biflavonoids N (C 6  - C 3 ) n (C 6 ) n (C 6  - C 3  - C 6 ) n lignins   catecholmelanine   (condensed tannins)

22. The basic structure of flavonoids is derived from the C 15  body of flavone. They differ from other phenolic substances in the degree of oxidation of their central pyran ring. And, very fundamentally, also in their biological properties. While some classes (the flavonones, for example) are colourless, the members of other classes (the anthocyanes, for example) are always coloured and known as pigments of flowers or other plant parts.

23. The Most Important Classes of Flavonoids and their Biological Significance Class number of known members biological significance (so far as known) anthocyanin(s) 250 red and blue pigments Chalcons 60 yellow pigments Aurones 20 yellow pigments Flavones 350 cream-coloured pigments of flowers Flavonols 350 feeding repellents (?) in leaves Dihydrochalcons 10 some taste bitter Proanthocyanidins 50 astringent substances Catechins 40 some have properties like those of tannins biflavonoids ? 65 ? Isoflavonoids 15 oestrogen effect, toxic for fungi

24. The  lignans  are a group of chemical compounds found in plants. Lignans are one of the major classes of phytoestrogens, which are estrogen-like chemicals and also act as antioxidants. The other classes of phytoestrogens are the isoflavones and coumestans. Plant lignans are polyphenolic substances derived from phenylalanine via dimerization of substituted cinnamic alcohols (see cinnamic acid), known as monolignols, to a dibenzylbutane skeleton 2. This reaction is catalysed by oxidative enzymes and is often controlled bydirigent proteins. Carbohydrates --> Shikimic acid pathway --> Aromatic a.a.'s --> Cinnamic acids --> Lignans ( Steganes )

25. Alkaloids-   Alkaloids are a group of nitrogen-containing bases. Most of them are drugs. Only a few (like caffeine) are derived from purines or pyrimidines, while the large majority is produced from amino acids. Ornithine derivatives - Ornithine is a precursor of the cyclic pyrrolidines that occur in the alkaloids of tobacco (nicotine, nornicotine) and other Solanaceae. Nicotine is a starting compound of numerous further tobacco alkaloids. During the biosynthesis of tropane, intermediates are produced that are at the same time starting compounds for cocaine and hyoscamine.

26. Derivatives of phenylalanine:   The most important are: Ephedra -alkaloids:ephedrine , pseudoephedrine, alkaloids gained from micro-organisms:  cytochalasine B and D, the  Taxus -alkaloids: taxine , the  Lunaria -alkaloids: lunarine and lunaridine , alkaloids of the Lythraceae .

27. Tyrosine derivates-  Synthesis of Benzylisoquinolines, Starting with Two Mol Tyrosine Colchicine , an alkaloid of the naked ladies ( Colchicum autumnale  and the related species  C. byzanthinum ) belongs also to this class. It is a poison best-known as an inhibitor of mitosis. It prevents the aggregation of tubuline dimers so that no micotubuli are formed.

28. Plant products Plant species Industry Industrial uses Codeine (alkaloid) Papaver sominifera Pharmaceutical Analgesic Diosgenin (steroid) Dioscorea deltoidea Pharmaceutical Antifertility agent Quinine (alkaloid) Cinchona leitgeriana Pharmaceutical Antimalaria Digoxin (glycoside) Digitalis lanata Pharmaceutical Cardiactonic Scopolamine (alkaloid) Dhatura stramonium Pharmaceutical Antihypersensitive Vincristine (alkaloid) Catharanthus roseus Pharmaceutical Antileukaemic Taxol Taxus brevifolia Pharmaceutical Ovarian and breast cancer Pyrethrin Chrysanthemum cinerariaefolium Agrochemical Insecticide Quinine (alkaloid) C. ledgeriana Food & drink Bittering agent Jasmine Jasmium sp. Cosmetics Perfume Saffron Crocus sativa Food Flavoring/coloring agent Application-

29. Conclusion Secondary metabolites are not involve in main biosynthetic pathway but it useful for plants. They responsible for protection of plant from stress, help in pollination and gives disease resistivity. They also useful for human in many way like production of drugs, essential oil, flavoring substance and pigments.

30. Reference- Books: Introduction to plant tissue culture By M. K. Razdan 1 st edition 1997 Plant biotechnology: By H. S. Chawla Internet: www.wikipedia.com http://www.biologie.uni-hamburg.de/b-online/e20/20a.htm