Reserpine(Structure Elucidation, Extraction and Isolation)

Reserpine(Structure Elucidation, Extraction and Isolation)
Introduction
Constitution of reserpine
Structure of Reserpic acid
Structure of Yobyrine
Synthesis of Yobyrine
Structure of Reserpine
Synthesis of Reserpine
Classification
Extraction
Isolation:
Identification test
Mode of Action

1. Reserpine ( Structural elucidation, Extraction & Isolation) Prepared By: MOHAMMAD KHALID (Assistant Professor ) Krishna Pharmacy College, Bijnor (UP)

2. content Introduction Constitution of reserpine Structure of Reserpic acid Structure of Yobyrine Synthesis of Yobyrine Structure of Reserpine Synthesis of Reserpine Classification Extraction Isolation: Identification test Mode of Action 16-Apr-20 Krishna Pharmacy College, Bijnor 2

3. introduction Reserpine is the main constituent of Rauwolfia species,perticularly Rauwolfia serpentina & Rauwolfia vomitoria . It is mainly used for the treatment of hypertension, headache, tension, asthma & dermatological disorders. 16-Apr-20 Krishna Pharmacy College, Bijnor 3

4. Constitution of reserpine 1. Molecular formula:- C 33 H 40 N 2 O 9 2. Presence of five methoxy groups:- By zeisel method i.e. when treated with HI yields five molecules of methyl iodide indicating the presence of five methoxy groups . 3. Nature of ‘N’ atom:- a) Secondary ‘N’ – Formation of monoacetyl derivative with acetic anhydride indicates secondary ‘N’ . b) Tertiary ‘N’- Reserpine forms quaternary ammonium salts with CH 3 I that indicating one of ‘N’ is tertiary . 16-Apr-20 Krishna Pharmacy College, Bijnor 4

5. 4. Hydrolysis:- Hydrolysis of reserpine yields mixture of i) Methyl alcohol ii) 3,4,5-trimethoxy benzoic acid iii) Acid (A) of composition 16-Apr-20 Krishna Pharmacy College, Bijnor 5

6. As reserpine does not contain -COOH & -OH groups, hence its hydrolysis product reveal that reserpine is a di-ester. The ester linkage in reserpine has been further confirmed by its reduction with 5 . Reduction:- 16-Apr-20 Krishna Pharmacy College, Bijnor 6

7. Structure of Reserpic acid a ) Molecular formula :- b) Presence of one carboxyl group:- By usual tests e.g. silver salt method c) Presence one –OH group:- Reserpic acid on oxidation yields a ketone that means it has secondary alcoholic group. d) Nature of two methoxy groups:- By zeisels method. e) Nature of two ‘N’ atom:- It shown that it contains two ‘N’ atoms in heterocyclic ring in the form of- i) Secondary ‘N’ ii) Tertiary amino group 16-Apr-20 Krishna Pharmacy College, Bijnor 7

8. f) Reduction of reserpic acid:- On reduction with yields reserpic alcohol. g) Oxidation of reserpic acid:- On oxidation with KMnO 4 it gives 4-methoxy N- oxalyl anthranilic acid. Thus one of the methoxyl group is present in meta position to –NH group 16-Apr-20 Krishna Pharmacy College, Bijnor 8

9. h ) Fusion with KOH :- When reserpic acid is fused with potash it yields 5-hydroxy isophthalic acid. One of the acidic groups of isophthalic acid must be present in m- position to each other this confirm by the fact that reserpic acid when heated with acetic anhydride yields a gamma lactone. 16-Apr-20 Krishna Pharmacy College, Bijnor 9

10. i) Dehydrogenation:- When methyl reserpate is dehydrogenated with selenium it yields a hydrocarbon of molecular formula - This hydrocarbon is also obtained by dehydrogenation of Yohimbine with selenium & was therefore named as Yobyrine . 16-Apr-20 Krishna Pharmacy College, Bijnor 10

11. Structure of Yobyrine 1. Molecular formula:- 2. Zinc Distillation:- 3. Oxidation:- When yobyrine is oxidized with permangnate it yields phthalic acid 16-Apr-20 Krishna Pharmacy College, Bijnor 11

12. 4. Condensation with aldehydes:- Yobyrine gives condensation products suggesting the presence of pyridine ring with a methylene substitution adjacent to the nitrogen. On the basis of above facts following structure has been postulated for yobyrine . 16-Apr-20 Krishna Pharmacy College, Bijnor 12

13. Synthesis of Yobyrine 16-Apr-20 Krishna Pharmacy College, Bijnor 13

14. j) As Yobyrine is formed from reserpic acid it means that reserpic acid may possesses the following types of skeleton structures. k ) From the fact 5(g) it follows that one of the methoxyl group is present in m-position to the NH group of indole i.e. on C-11 i.e. Ome is at C-11 . 16-Apr-20 Krishna Pharmacy College, Bijnor 14

15. Reserpic acid when dehydrogenated yields 11-hydroxy-16-methyl yobyrine,this may be only formed if –COOH group is present on C-16 From the step (h) it follows that –COOH & -OH group are in m-position to each other but –COOH group is present at C-16 therefore –OH group must be at C-18. 16-Apr-20 Krishna Pharmacy College, Bijnor 15

16. From purely biogenic reasons, the 2 nd methoxyl group has been assigned position C-17. On the basis above mentioned facts the structure of reserpic acid may be 16-Apr-20 Krishna Pharmacy College, Bijnor 16

17. Structure of Reserpine As reserpine is di-ester of reserpic acid, it means that , 16-Apr-20 Krishna Pharmacy College, Bijnor 17

18. Synthesis of Reserpine The structure of reserpine has been confirmed by its synthesis given by Woodward et.al. 16-Apr-20 Krishna Pharmacy College, Bijnor 18

19. Synthesis continue ….. 16-Apr-20 Krishna Pharmacy College, Bijnor 19

20. Synthesis continue….. 16-Apr-20 Krishna Pharmacy College, Bijnor 20

21. Synthesis continue….. 16-Apr-20 Krishna Pharmacy College, Bijnor 21

22. Synthesis continue….. 16-Apr-20 Krishna Pharmacy College, Bijnor 22

23. Synthesis continue….. 16-Apr-20 Krishna Pharmacy College, Bijnor 23

24. classification Kingdom : Plantae Division : Magnoliophyta Class : Magnoliopsida Order : Gentianales Family : Apocynaceae Genus : Rauwolfia Species : serpentina 16-Apr-20 Krishna Pharmacy College, Bijnor 24

25. Geographical Source: Asia, America Morphology: Snake shaped, brown coloured, longitudinal wrinkles tapering towards the end 16-Apr-20 Krishna Pharmacy College, Bijnor 25

26. extraction Plant material Macerated with alcohol Alcholic extract Reduce in volume and residue is treated in water Filter Ppt insoluble in water Ppt contain reserpine 16-Apr-20 Krishna Pharmacy College, Bijnor 26

27. ISOLATION: Ppt of crude drug Add benzene with continuous stirring Filter, concentrate it Filter Filtrate Ppt remove Dry in vaccum Add 150 ml acetic acid in methanol and ammonium solution pH is adjusted to 8.5 and stand Crystalline substance appear Dry, add benzene Then it is chromatographed on 100 gm acid washed alumina Further fraction eluted with sequance of solvent from chloroform And crystallized from benzene 16-Apr-20 Krishna Pharmacy College, Bijnor 27

28. Chemistry: Reserpine is an indole Alkaloid Structure: IUPAC Name: ( 3 β ,16 β ,17 α ,18 β ,20 α )- 11,17-Dimethoxy-18-[( 3,4,5-trimethoxybenzoyl)oxy]yohimban-16-carboxylic acid methyl ester 3,4,5-trimethoxybenzoyl methyl reserpate Melting point : 262-270 C . 16-Apr-20 Krishna Pharmacy College, Bijnor 28

29. Identification test Chemical test: Freshly fractured surface of the root when treated with concentrated HNO 3 shows red coloured medullary rays. Reserpine gives a violet colour with vanillin in acetic acid Rauwolfia serpentina . Other test for alkaloid: Dragondrof test Mayer test Hagers test Wagners test Tannic acid test 16-Apr-20 Krishna Pharmacy College, Bijnor 29

30. Mode of Action Reserpine acts by blocking the vasicular monoamine transporter VMAT , which normally transports free norepinephrine, serotonin , and dopamine from the cytoplasm of the presynaptic nerve into vesicles for subsequent release into the synaptic cleft . The unprotected neurotransmitters then metabolized by MAO and therefore never reach the synapse. By this mode of action this give mainly the antihypertensive action and also use in the treatment of dykynesia mania etc. 16-Apr-20 Krishna Pharmacy College, Bijnor 30

31. Therapeutic application: Essential hypertension Mild anxiety Dyskinesia Psychosis symptoms Maintenance dose: 100 to 250 mg (once a day) Side effects: Nasal congestion Nausia Vomiting Gastric intolerance Gastric ulceration diarrhoeia 16-Apr-20 Krishna Pharmacy College, Bijnor 31

32. References 1)“ Organic Organic Chemistry of Natural Products ”- by Gurudeep Chatwal , Vol -I. 2)“ Organic Chemistry ”by I.L.Finar , Vol -II . 3)“ Pharmacognosy ” by C.K.Kokate , A.P.Purohit , S.B.Gokhale 4) http://www.authorstream.com/Presentation/agarawaldinesh47-1168554-reserpine / 5)http ://www.authorstream.com/Presentation/abdulrazzaqM.PHARM-642751-reserpine-structural-elucidation/ 16-Apr-20 Krishna Pharmacy College, Bijnor 32

33. Any Question? 16-Apr-20 Krishna Pharmacy College, Bijnor 33

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