Terpenoids: types, biosynthesis and functions.

Terpenoids

1. TERPENOIDS CLASSIFICATION, BIOSYNTHESIS AND FUNCTION SUBMITTED TO , Dr. ELSAM JOSEPH St TERESA’S COLLEGE SUBMITTED BY ADHITHYA MADHAVAN K S St TERESA’S COLLEGE

2. INTRODUCTION Terpenoids are the group of naturally occurring compounds majority of which occur in plants, a few of them obtained from other sources. Terpenoids are volatile substances They give plants and flowers their fragrance. Occur widely in the leaves and fruits of higher plants, conifers, citrus and eucalyptus.

3. By the modern definition: “Terpenoids are the hydrocarbons of plant origin of their oxygenated, hydrogenated and dehydrogenated derivatives.” General formula (C 5 H 8 )n They have unsaturated molecules composed of linked isoprene units. Isoprene units are 5 carbon unit They are also called isoprenoids

4. ISOPRENE RULE Thermal decomposition of terpenoids give isoprene as one of the product Isoprene rule stats that the “terpenoid molecules are constructed from two or more isoprene unit. Otto Wallach pointed out that terpenoids can be built up of isoprene unit.

5. SPECIAL ISOPRENE RULE Ingold in 1925 formulated a special type of arrangement were found in all terpenoid Based on how isoprene units in terpenoids are linked together The branched end of the isoprene unit is considered as head and other end is tail According to this rule “isoprene unit in head to tail fashion Isoprene units are joined one with other by C1 and C4 position

6. It is not a fixed rule, there are deviation and violation of it Crypton shows an exception case It is a natural terpenoid contains only nine carbon atom instead of ten ,isoprene rule cannot be applied

7. PHYSICAL PROPERTIES OF TERPENOIDS Volatile at room temperature Odorous They produce essence or active constituents of plants hence called essential oil Lighter than water High refractive index Optically active

8. CLASSIFICATION OF TERPENOIDS Most natural terpenoid hydrocarbon have the general formula (C 5 H 8 )n. They can be classified on the basis of value of n or number of carbon atoms present in the structure.

9. Based on number of ring present in structure , it is again subdivided into subclasses Acyclic Terpenoids : They contain open structure. Monocyclic Terpenoids : They contain one ring in the structure. Bicyclic Terpenoids : They contain two rings in the structure. Tricyclic Terpenoids: They contain three rings in the structure. Tetracyclic Terpenoids : They contain four rings in the structure.

10. MONOTERPINOIDS Monoterpenes are a class of terpenes that consist of two isoprene units and have the molecular formula C 10 H 16 . Monoterpenes may be linear (acyclic) or contain rings. Biochemical modifications such as oxidation or rearrangement produce the related monoterpenoids

11. MENTHOL (MONOCYCLIC) Menthol is the major constituent of Mentha Piperita . It is used as an antiseptic and anesthetic. Menthol (also called peppermint camphor or mint camphor) is the major constituent of peppermint oil and is responsible for its odour and taste and the cooling sensation when applied to the skin. It is ingredient in cold balms. Menthol is optically active compound with mol. Formula C 10 H 20 O

12. LIMONENE A colourless liquid at room temperatures with an extremely strong smell of oranges. Limonene is common in cosmetic products. As the main odor constituent of citrus, D - limonene is used in food manufacturing and some medicines e.g., bitter alkaloids, as a flavoring It is also used as botanical insecticide

13. PINENE (BICYCLIC) There are two structural isomers found in nature: α-pinene and β-pinene. As the name suggests, both forms are important constituents of pine resin They used by many insects in their chemical communication system. Selective oxidation of pinene with some catalysts in chemical industry give many components for pharmacy, artificial odorants and so on Anti microbial, anti inflammatory, anti tumor

14. Many monoterpenes found in marine organisms are halogenated , such as Halomon . Halomon is a polyhalogenated monoterpene first isolated from the marine red algae Portieria hornemannii . It has attracted research interest because of its promising profile of selective cytotoxicity that suggests its potential use as an

15. SESQUITERPINOIDS Sesquiterpenes are a class of terpenes that consist of three isoprene units and have the molecular formula C 15 H 24 . Sesquiterpenes may be acyclic or contain rings, including many unique combinations.

16. ZINGIBERENE Zingiberene is  2-Methylcyclohexa-1,3-diene  in which a  hydrogen  at the 5 position is substituted by a 6-methyl-hept-5-en-2-yl group. It is a monocyclic sesquiterpenoid which is the predominant constituent of the oil of ginger It can contribute up to 30% of the essential oils in ginger rhizomes. This is the compound that gives ginger its distinct flavoring.

17. BISABOLOL A natural monocyclic sesquiterpene alcohol A colorless viscous oil A lmost insoluble in water Well soluble in ethanol It has a weak sweet floral aroma and is used in various fragrances. Anti-irritant ,anti-inflammatory ,anti-microbial

18. DITERPENOIDS Diterpenes are composed for four isoprene units and have the molecular formula C 20 H 32 .

19. PHYTOL An acyclic diterpene alcohol that is a precursor for vitamins E and K 1. Phytol is a terpene found in some strains of cannabis, as well as other plants such as green tea Extremely common terpenoid, found in all plants esterified to Chlorophyll to confer lipid solubility. It is found in petroleum sediments

20. TRITERPENOIDS Triterpenes consist of six isoprene units and have the molecular formula C 30 H 48 . The linear triterpene squalene

21. SQUALENE The major constituent of shark liver oil. Squalene is then processed biosynthetically to generate either lanosterol or cycloartenol the structural precursors to all the steroids. It is a colourless oil, although impure samples appear yellow. Squalene is an important ingredient in some  vaccine adjuvents . Squalene has a role in topical skin lubrication and protection

22. Isolation of Mono and Sesquiterpenoids Both mono and sesquiterpenoids have common source i.e essential oils. Their isolation is carried out in two steps: i ) Isolation of essential oils from plant parts ii) Separation of Terpenoids from essential oils. Isolation of essential oils from plant parts: Expression method Steam distillation method Extraction by means of volatile solvents Adsorption in purified fats

23. Steam distillation is most widely used method. Macerated plant material is steam distilled to get essential oils into the distillate form these are extracted by using pure organic volatile solvents If compound decomposes during steam distillation, it may be extracted with petrol at 50 o C. After extraction solvent is removed under reduced pressure.

24. ii) Separation of Terpenoids from essential oil: A number of terpenoids are present in essential oil obtained from the extraction They are separated by fractional distillation. The terpenoid hydrocarbons distill over first followed by the oxygenated derivatives. Different chromatographic techniques have been used both for isolation and separation of terpenoids.

25. BIOSYNTHESIS OF TERPENOIDS

26. The  mevalonate pathway , also known as the  isoprenoid pathway  or HMG-CoA reductase pathway   M evalonate pathway operates in the cytosol. The pathway produces two five-carbon building blocks called  isopentenyl pyrophosphate  (IPP) and  dimethylallyl pyrophosphate  (DMAPP) used to make  isoprenoids

27. REACTIONS

28. METHYL ERYTHRITOL PHOSPHATE PATHWAY (MEP) IPP also can be formed from intermediates of glycolysis or the photosynthetic carbon reduction cycle vis separate set of reactions by MEP pathway. It occurs in chloroplasts.

29. IMPORTANCE OF TERPENOIDS Plants employ terpenoid metabolites for a variety of basic functions in growth and development . Use the majority of terpenoids for more specialized chemical interactions and protection in the abiotic and biotic environment. Plant-based terpenoids have been used by humans in the food, pharmaceutical, and chemical industries. E cological importance of terpenoids has gained increased attention to develop strategies for sustainable pest control and abiotic stress protection.

30. Used worldwide for the treatment of many diseases. Inhibit different human cancer cell and are used as an anticancer drug such as taxol and derivatives. Many flavourings and nice fragrance are consisting on terpenes because of its nice aroma . It is used as antimalarial drugs such as arteminisin and related compounds. Role in traditional herbal remedies. The steroids and sterols in animals are biologically produced from terpenoid precursors.

31. REFERENCES Verma , S. K., & Verma , M. (2008). A textbook of plant physiology, biochemistry and biotechnology. S. Chand Publishing. Goodwin, T. W., & Mercer, E. I. (1983). Introduction to plant biochemistry https://www.ncbi.nlm.nih https://www.slideshare.net/ravi944/terpenoids-127041917 https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/mevalonate-pathway

32. THANK YOU