Classification of secondary metabolites and their applications.

in this ppt classification of secondary metabolites are explained along with their major applications.

1. Classification of Secondary Metabolites and Their Applications BY - Saurabh Kumar Research Scholar Dept. Of Chemistry D.E.I

2. Introduction

3. Primary Metabolites Compounds which occur in all cells and play a central role in the metabolism and reproduction of those cells. Examples are - amino acids, proteins, enzymes, sugars, nucleic acids etc. Important for the intrinsic functions of the organism. referred to as central metabolite. Some common examples of primary metabolites are ethanol, lactic acid and certain amino acids.

4. Secondary Metabolites Secondary metabolites can be defined as a heterogeneous group of natural metabolic products that are not essential for vegetative growth of the producing organisms. They are considered differentiation compounds conferring adaptive roles. For example, by functioning as defense compounds or signaling molecules in ecological interactions, symbiosis, metal transport, competition, and so on. The term “secondary” for such natural compounds was introduced by a. Kossel in 1891. Secondary metabolites are derived from primary metabolism.

5. Classification of secondary metabolites Most of these compounds belong to one of several families, each of which have structural characteristics arising from the way in which they are built up in nature, i.e. From their biosynthesis. Based on their biosynthetic origins, secondary metabolites can be divided in to five major groups : Polyketides and fatty acids Terpenoids and steroids Phenylpropanoids Alkaloids Specialized amino acids and peptides

6. Polyketides and fatty acids Polyketides Natural products that are formed by the stepwise condensation of acetate (ethanoate) units. In the resultant carbon chain, alternate carbon atoms come from the methyl and carboxyl groups of the acetate building blocks which leads to forms even-numbered carbon chains. Produced in bacteria, fungi, plants, and certain marine animals. Some examples are -

7. Fatty acids A fatty acid is a carboxylic acid with a long aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, from 4 to 28. Exist as three main classes of esters: triglycerides, phospholipids, and cholesteryl esters. In plants the fatty acids and the corresponding alcohols are found in leaf Waxes and seed coatings. Some common examples are - Myristoleic acid CH 3 (CH 2 ) 3 CH=CH(CH 2 ) 7 COOH Palmitoleic acid CH 3 (CH 2 ) 5 CH=CH(CH 2 ) 7 COOH Sapienic acid CH 3 (CH 2 ) 8 CH=CH(CH 2 ) 4 COOH Oleic acid CH 3 (CH 2 ) 7 CH=CH(CH 2 ) 7 COOH Elaidic acid CH 3 (CH 2 ) 7 CH=CH(CH 2 ) 7 COOH Vaccenic acid CH 3 (CH 2 ) 5 CH=CH(CH 2 ) 9 COOH Linoleic acid CH 3 (CH 2 ) 4 CH=CHCH 2 CH=CH(CH 2 ) 7 COOH

8. Applications of Polyketides and fatty acids Many polyketides are medicinal or exhibit acute toxicity. Geldanamycin, a useful antibiotic. Doxycycline, another important antibiotic. Erythromycin, an antibiotic. Aflatoxin is one of the most carcinogenic compounds known. The arachidonic acid is a precursor of the prostaglandin hormones. Fatty acids are mainly used in the production of cosmetic and soaps. Fatty alcohols and fatty amines are precursors to surfactants, detergents, and lubricants. Other applications include their use as emulsifiers, texturizing agents, wetting agents, anti-foam agents, or stabilizing agents.

9. 2. Terpenes and Steroids Terpenes The terpenes are compounds that are built up from isoprene units. Their structures are divisible into the c 5 isoprene units linked in a head-to-tail manner. Produced by a variety of plants, particularly conifers, and by some insects. Often have a strong odor. The simplest terpene is a pair of isoprenes with formula c 10 h 16 . One such simple terpene is pinene, a component of cannabis extracts with a pine forest scent. Examples -

10. Steroids A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. The steroid core structure is typically composed of seventeen carbon atoms, bonded in four "fused" rings: three six-member cyclohexane and one five-member cyclopentane ring . Steroids vary by the functional groups attached to this four-ring core and by the oxidation state of the rings. Sterols are forms of steroids with a hydroxy group at position three and a skeleton derived from cholestane. Hundreds of steroids are found in plants, animals and fungi. Examples -

11. Applications of Terpenes and Steroids Terpenes are useful natural agricultural pesticides. Higher amounts of terpenes are released by trees in warmer weather and may be a natural form of cloud seeding. The provitamin beta carotene is a terpene derivative called a carotenoid. Terpenes are also major constituents of cannabis sativa plants, which contain at least 120 identified compounds. Similar to lipids, steroids are highly concentrated energy stores. However, they are not typically sources of energy; in mammals, they are normally metabolized and excreted. Steroids play critical roles in several disorders, including malignancies like prostate cancer.

12. 3. Phenylpropanoids The phenylpropanoids are a diverse family of organic compounds that are synthesized by plants from the amino acids phenylalanine and tyrosine. Some of these compounds are associated with the photosensitizing properties of plants of the umbelliferae . Phenylpropanoids are found throughout the plant kingdom. They serve as essential components of several structural polymers, provide protection from ultraviolet light, defend against herbivores and pathogens. Oxidative coupling of two phenylpropanoid units, such as coniferyl alcohol leads to the lignan carbon skeleton. Podophyllotoxin from the hindu drug podophylium emodi ( himalayan mayapple ), is an interesting cytotoxic agent. Some examples are -

13. Applications Hydroxycinnamic acids produces some of the volatile components of herb and flower fragrances, which serve many functions such as attracting pollinators. The phenylpropenes, including eugenol, chavicol, safrole and estragole, are the primary constituents of various essential oils. Coumarins and flavonoids are the diverse class of phytochemicals.

14. 4. Alkaloids Alkaloids are a class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar structure may also be termed alkaloids In addition to carbon, hydrogen and nitrogen, alkaloids may also contain oxygen, sulfur and, more rarely, other elements such as chlorine, bromine, and phosphorus. Alkaloids are produced by a large variety of organisms including bacteria, fungi, plants, and animals. Some examples are -

15. Applications Many alkaloids are used in medicine, usually in the form of salts widely used including the following – Some alkaloids, such as salts of nicotine and anabasine , were used as insecticides. Their use was limited by their high toxicity to humans. Cocaine, caffeine, and cathinone are stimulants of the central nervous system. Mescaline and many indole alkaloids (psilocybin, dimethyltryptamine) have hallucinogenic effect. Morphine and codeine are strong narcotic pain killers. Alkaloid Action Ajmaline antiarrhythmic Emetine antiprotozoal agent , Emesis Ergot alkaloids Vasoconstriction ,  hallucinogenic ,  Uterotonic Morphine analgesic Nicotine stimulant ,  nicotinic acetylcholine receptor agonist Physostigmine inhibitor of  acetylcholinesterase

16. 5. Specialized amino acids and peptides The amino acids are the building blocks for peptides and proteins. Although the amino acids are normally considered as primary metabolites, there are some unusual amino acids that are of restricted occurrence. Some antibiotics such as the penicillins and cephalosporins are formed from small peptides. The diketopiperazine antifungal agents produced by Trichoderma and Gliocladium species, such as gliotoxin are also derived from amino acids.