Page 86 - Phytochemistry 2 (06-PG 605)

ecbolic activity. So, it is used during labor to assist uterine

contraction. Also, it is used after child birth to stop post-partum

hemorrhage.

The alkaloid ergotamine is still being used in current medicine

for the treatment of migraine and also as oxytocic agent. Its

dihydro-derivative (in which the 9-10 double bond is

hydrogenated) is a widely used medication of migraine.

Stability

The active l-lysergic acid amide alkaloids are converted to

the inactive d-isomers upon keeping in alcoholic solutions for long

time, or upon boiling their alcoholic solutions. This is due to keto-

enol transformation, which occurs rapidly in presence of alkali, as

follows:

CO-R HO-C-R R-OC H
H

N CH3 N CH3 N CH3

(L) Enol (D)

Thus, in solutions, the active water soluble alkaloid

ergonovine, undergoes gradual conversion to the inactive

ergonovinine, till an equilibrium mixture is achieved.

Prolonged keeping in aqueous acidic solutions, and also

exposure to day-light and /or UV light, causes the saturation of the

double bond at C9-C10 by hydration (addition of one molecule of

water), to give what is called lumi-alkaloids.

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