Indole alkaloids

Question 1

What are alkaloids?

Answer 1

Alkaloids are heterocyclic nitrogenous compounds of plant origin that are physiologically active

Question 2

What are indole alkaloids?

Answer 2

Indole alkaloids are derived from tryptophan and they contain an indole ring which is a bicyclic structure comprising of a benzene ring fused to a five membered nitrogen containing pyrrole ring

Question 3

What are some important drugs of indole alkaloids and their active alkaloids?

Answer 3

1. Rauwolfia: Reserpine
2. Ergot: Ergotamine, ergometrine
3. Nux Vomica: Strychnine, brucine
4. Physostigma: Physostigmine
5. Catharanthus: Vincristine, vinblastine

Question 4

What is Rauwolfia?

Answer 4

Rauwolfia is the dried root of Rauwolfia serpentina, in honor of Dr. Rauwolf and because of its snake like roots

Question 5

Family of Rauwolfia

Answer 5

Apocyanaceae

Question 6

What are the constituents of Rauwolfia?

Answer 6

Contains not less than 0.15% and not more than 0.20% alkaloids calculated as reserpine.
1. Reserpine
2. Rescinnamine
3. Deserpine

Question 7

What are the qualities of Reserpine?

Answer 7

It comprises of white to pale yellow, colorless, crystalline powder that darkens slowly in sunlight and rapidly in solution

Question 8

Deserpine

Answer 8

It is obtained from Rauwolfia canescens

Question 9

Extraction of reserpine

Answer 9

1. Grinding of rauwolfia
2. Extraction with methanol
3. Concentration of methanol by distilling of solvent
4. Mixing with water
5. Washing with chlorinated solvent to remove impurities
6. Alkaloid is obtained

Question 10

Uses of reserpine

Answer 10

Anti-hypertensive, sedative

Question 11

What is ergot?

Answer 11

ergot is obtained from the dried sclerotium of Claviceps purpurea. It is also know as ergot of rye

Question 12

Historical significance of ergot

Answer 12

It contaminated rye fields and caused gangrene in extremities and convulsion which were known as St. Anthony’s Fire. It was known to cause disease in cattle and human which was known as ergotism. Produced convulsions and gangrene.

Question 13

Macroscopy of ergot

Answer 13

1. Externally: Violet to black
2. Internally: white
3. Odor: Characteristic
4. Taste: Unpleasant
5. Shape: Fusiform or slightly curved

Question 14

Active constituents of ergot

Answer 14

Alkaloids may be water soluble or water insoluble:
1. Water soluble: Ergonovine
2. Water insoluble: Ergotamine, Ergotaxine
Synthetically prepared too. They are all derivatives of lysergic acid

Question 15

Uses of ergot

Answer 15

1. rich source of alkaloids
2. used in migraines
3. used to stimulate labor
4. as an abortifacient and to reduce post partum hemorrhage

Question 16

Extraction of ergotamine

Answer 16

1. Parasitic source
2. Saprophytic source

Question 17

What is Nux Vomica?

Answer 17

Nux vomica is the dried, ripe seed of Strychnos Nux vomica.

Question 18

What are the macroscopic characteristics of Nux Vomica?

Answer 18

It is a relatively small tree, only 12 m in height, found in Sri Lanka. It consists of fruits with 3-5 seeds.

Question 19

Constituents of Nux Vomica

Answer 19

1.5-5 % alkaloids strychnine and brucine. Strychnine is located near the center of the seeds and brucine in the outer epirdermis

Question 20

Extraction of nux vomica

Answer 20

Extracted with sulfuric acid, solvent is concentrated and precipitated by lime, separated by means of solvent and purified by recrystallization

Question 21

Uses of nux vomica

Answer 21

source of strychnine and brucine
strychnine is used as vermin killer
brucine is less toxic and used commercially as alcohol denaturant
strychnine is used as central stimulant

Question 22

What is physostigmine?

Answer 22

Physostigmine is the dried, ripe fruit of Physostigma venenosum, yielding not less than 0.15% alkaloids

Question 23

Active constituents of physostigmine?

Answer 23

Contains many alkaloids but the major one is Physostigmine, contained in cotyledons from 0.04 to 0.3%

Question 24

Macroscopic characteristics of physostigmine

Answer 24

white color, odorless and may acquire a red tint on contact with sunlight, air or water or in contact with minerals

Question 25

Uses of physostigmine

Answer 25

Used for glaucome treatment, is cholinesterase inhibitor and is used to contract ciliary muscles and reduce intraocular pressure

Question 26

What is catharanthus?

Answer 26

Catharanthus (aka vinca, madagascar periwinkle and bright eyes) is the dired, whole plant of Cantharanthus roseus

Question 27

Family of catharanthus

Answer 27

Apocynaceae

Question 28

Constituents of catharanthus

Answer 28

more than 70 alkaloids

indole-indoline alkaloids serpentine, locherine, ajmalacine, tetrahydroalstonine

demric indole alkaloids like vincristine, vinblastine, vinrosidine

Question 29

Extraction

Answer 29

aqueous extraction of ground tissue
extraction with organic solvent e.g ethyl acetate

Question 30

Uses

Answer 30

used as remedy for type-2 diabetes, anti-cancer effects by arresting cell division at metaphase and for ornamental purposes