Vinca alkaloids

isolation and identification of vinnca alkaloids

1. VINCA ALKALOIDS Presented by Zulie Shingala, M.Pharm 1 st year. Under the guidance of Mr. Bhavik Chauhan, Ass istant professor, Faculty of Pharmacy, MSU Baroda. 1 1

2. Occurence Vinca alkaloids are obtained from entire plant of Catharanthus roseus. Belonging to family Apocynaceae. The plant is native of Madagascar and is found in many tropical and subtropical countries, especially in India, Australia, South Africa and South America. They called as Indole Alkaloids as they contains Indole ring in its basic structure. The important alkaloids present in Vinca is Vinblastine and Vincristine and they possess definite anticancer activity. They are Dimer Indole alkaloids. Vindoline and Catharanthine are Indole monomer alkaloids. 2 2

3. Biosynthesis of Vinka alkaloids 3 3

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6. Extraction of Vinca alkaloids The dried leaf material is taken and is extracted with a solution of hot ethanol–water–acetic acid in a ratio of 9:1:1 . The solvent is removed and to the residue hot hydrochloric acid solution of 2% is added. The pH of the acidic extract is adjusted to 4, for the precipitation of the non-alkaloidal components, which can be separated by filtration. The pH of the aqueous acidic solution is now adjusted to 7 and then extracted with benzene. The benzene layer is evaporated to obtain vinblastine and other alkaloids 6 6

7. Isolation of Vinblastine and Vincristine The phenolic materials are removed by the washing the extract with dilute alkali . The washed extract is subjected to chromatography on alumina and elution is carried out in 18 fractions starting with benzene–methylene chloride (65:35) mixture to pure methylene chloride . Vinblastine recovered in the ninth fraction. Further elution of the column results in separating the fractions of vincristine 7 7

8. Characterization TLC Vincristine dissolved in 25% water in methanol solution, spotted in Silica gel-G plate and developed using the solvent, acetonitrile: benzene ( 30:70 ). The dried plates are sprayed with 1% solution of ceric ammonium sulphate in 85% phosphoric acid . The Rf value of the appeared spot would be 0.39. 8 8

9. Chemical test for Vinca alkaloids 1. Mayer’s test : Mayer’s reagent (freshly prepared mixture of mercuric chloride (1.36gm) and potassium iodide (5.00gm) in 10 ml of water) is added to the 3 ml of extract. Gives creamy precipitates. 2. Hager’s test : Picric acid solution is added to the extract. It gives yellow precipitates. 9 9

10. Reference Textbook of Pharmacognosy and Phytochemistry by Biren Shah and A. K. Seth,1 st edition, Elsevier Publications. https :// www.sciencedirect.com/science/article/pii/S1572599506800414 https://www.sciencedirect.com/science/article/pii/S1572599506800414 10 10