Page 88 - phytochemistry general program

2. Dimeric Vinca Alkaloids (Vindoline + Catharanthine Units)

Vinblastine and vincristine
These are dimeric alkaloids having indole and dihydro-indole (indoline)

nuclei. They differ in the presence of N-methyl group in vinblastine and N-formyl
group in vincristine. They have closely related structures.

N

N
H3COOC

N

H3CO N OCOCH3
HO COOCH3
Vincristine
R R = CHO

Vinblastine R = CH3

Properties

Vinblastine occurs as crystals, m.p. 211-216 °C, it is practically insoluble in
water, soluble in ethanol and chloroform. Vincristine occurs as crystals, m.p. 218-

220 °C.

Tests for identification

1.Vanillin /HCl reagent gives with:

Vinblastine a pink color, and .1
Vincristine an orange-yellow color .2
2.Para-dimethylaminobenzaldehyde (PDAB) reagent (Van-Urk's reagent): gives
vinca alkaloids in presence glacial acetic acid and concentrated H2SO4 a reddish-

brown color.

Uses

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