Page 6 - Phytochemistry 2 (06-PG 605)

Properties of Alkaloids

I- Physical Properties:

Most of alkaloids are:

1. Bitter in Taste . √
2. Odorless. √
3. Colorless.
4. Crystalline
5. Optically active.

Exceptions:

 Colored alkaloids: e.g. Colchicine, Berberine,Psychotrine
 Liquid alkaloids
e.g. Pilocarpine , Scopolamine
• Non-volatile liquid e.g. Pelletierine Coniine ,Nicotine

• Volatile-liquid

Optical activity of alkaloids:

Ciral centers → different isomers.

Generally, the levo rotatory l (-) isomers more active pharmacologically than
dextro rotatory d (+) isomers of the same alkaloid.

Exceptions:

• d(+) pilocarpine, d(+) tubocurarine and d(+) quinidine are medically used.

• Another exception is the optically inactive papaverine (has therapeutic
effect).

• Sometimes, the difference in the opt. activity of the same chemical structure
cause change in therapeutic uses .e.g.

l (-) Quinine is antimalarial , while

d (+) Quinidine is used in treatment of auricular fibrillation.

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