Pyrrolidine Alkaloids

2.6.1 Pyrrolidine Alkaloids


The three glaring examples of pyrrolidine alkaloids are, namely: hygrine, cuscohygrine and stachydrine, which would be discussed below:

A. Hygrine

Biological Sources It occurs in the leaves of Erythroxylon coca Lam., (Erythroxylaceae) (Coca); and the roots of Withania somniferum (L.) Dunal. (Solanaceae) (Ashwagandha).
Chemical Structure

Hygrine
(R)-1-(1-Methyl-2-pyrrolidinyl)-2-propanone; (C8H15NO).
Characteristic Features
1. It is a liquid having bp11 76.5°C; bp14 81°C; nD201.4555.
2. It is soluble in dilute mineral acids, chloroform and ethanol; and slightly soluble in water.
Identification Test It forms oxime readily (C8H16N2O) which is obtained as crystals from ether having mp 123-124°C.
Uses The drug is broadly used as a sedative, hypnotic laxative and diuretic.

B. Cuscohygrine

Synonyms Cuskhygrine; Bellaradine.
Biological Sources It is obtained from the roots of Atropa belladona L. (Solanaceae) (Belladona, Deadly Nightshade); roots of Datura innoxia Mill. (Solanaceae) (Thorn Apple) upto 5-30%; seeds of Datura metal L. (Solanaceae) (Unmatal, Metel, Hindu Datura); leaves of Hyocyamus niger L. (Solanaceae) (Henbane, Henblain, Jusquaime); herb of Mandragora officinarum L. (Solanaceae) (Mandrake, Loveapple); rhizome of Scopolia carniolica Jacq. (Solanaceae) (Scopolia); and the roots of Withania somniferum (L.) Dunal (Solanaceae) (Ashwagandha).
Chemical Structure

Cuscohygrine Synonyms Cuskhygrine; Bellaradine
1, 3-Bis (1-methyl-2-pyrrolidinyl)-2-propanone; (C13H24N2O).
Isolation It is isolated from the naturally occurring plant sources by standard method.*
Characteristic Features
1. It is a oily liquid having bp23 169-170°C; bp14 152°C; bp2 118-125°C; d420 0.9733; nD20 1.4832.
2. It is found to be miscible with water; and freely soluble in ethanol, ether, and benzene.
Identification Tests
1. Cuscohygrine Hemiheptahydrate: Its needles have mp 40°C.
2. Cuscohygrine Hydrobromide (C13H24N2O.2HBr): It forms prisms from ethanol having mp 234°C.
C. Stachydrine
Synonyms Methyl hygrate betaine; Hygric acid methylbetaine.
Biological Sources It is obtained from the forage of Achillea millefolium L. (Asteraceae) (Yarrow); flowers of Chrysanthemum cinerarifolium (Trevir.) Vis. (Asteraceae) (Pyrethrum, Dalmatian Insect
Flower); branches of Lagochilus inebrians Bunge (Lamiaceae) (Intoxicating Mint); dry plant of, Leonurus cardiaca (L.) (Lamiaceae) (Motherwort); the ‘betaine fraction’ of alfalfa Medicago sativa L. (Fabiaceae) (Alfalfa) (0.785%); and herbage of Stachys officinalis (L.) Trevisan (Lamiaceae) (Betony).
Chemical Structure

Stachydrine Synonyms Methyl hygrate betaine; Hygric acid methylbetaine
(S)-2-Carboxy-1, 1-dimethylpyrrolidinium inner salt; (C7H13NO2).
Isolation It has been isolated by reported method by Schulze** and Jahns.***
Characteristic Features
1. It is obtained as monohydrate deliquescent crystals having mp 235°C (anhydrous).
2. It is sweetish in taste.
3. It is soluble in water, dilute mineral acids and ethanol;
4. It isomerizes at the mp to methyl hygrate.
Identification Tests
1. Stachydrine Hydrochloride (C7H17NO2.HCl): Its large prisms are obtained from absolute ethanol which gets decomposed at 235°C. It is very soluble in water and soluble in 13 parts of ethanol.
2. Stachydrine Acid Oxalate (C7H13NO2.C2H2O4): Its needles have mp 106°C. It is practically insoluble in absolute ethanol.
3. Stachydrine Aurichloride (C7H13NO2.HAuCl4): Its yellow needles have mp 225°C (rapid heating). It is quite soluble in hot water, but practically insoluble in cold water.
4. Stachydrine Platinichloride Tetrahydrate (C7H17NO2)2.H2PtCl6.4H2O): It is obtained as orange crystals decomposing at 210-220°C (rapid heating). It is found to be very soluble in dilute ethanol and water. It may also be obtained with two moles of water of crystallization.
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* Liebermann, Ber., 22, 679 (1898)
** Sehulze, Ber. 26, 939 (1893);
*** Jahns, Ber. 29, 2065 (1896);

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