Dr Amrit Pal Singh, MD (Alternative Medicine), Medical
Executive.
Dept of Natural Products
Dr A.S Sandhu, M.Sc
(Botany), Dept of Natural Products, National Institute of Pharmaceutical
Education & Research (NIPER), Mohali.
Address for correspondence:
House No.2101, Phase-7
Mohali-160062
Email: amritpal2101@yahoo.com
Abstract
Medicinal
herbs constitute an effective source of traditional (Ayurvedic, Unani and
Homeopathy) and modern medicine. The plant is a biosynthetic laboratory, not
only for chemical compounds, but also a multitude of compounds like glycosides,
alkaloids etc. These exert physiological and therapeutic effect. The compounds
that are responsible for medicinal property of the drug are usually secondary
metabolites. Alkaloids, glycosides, neutral principles, resins, oleoresins,
sesquiterpene lactones are some of the common active constituents of medicinal
herbs. The article reviews distribution of steroid like compounds and their
pharmacological importance.
1The practice of medicinal herbs for treating the
diseases is very well known from ancient times. There are number of
synthetic medicines which have been derived from medicinal herbs. Digioxin,
Aspirin, Reserpine, Ephedrine, Quinine, Vincristine, Vinblastine, Taxol,
Artemisinin, Hypericin, Silymarin are some noteworthy examples and their
mechanism of action is beyond doubt as far as efficacy is concerned. Number of
studies is available to show their effectiveness. These are regarded as active
constituents of the herbs and are present in standardized form in the herbal
extracts, if not isolated as single entity.
In addition to the alkaloids, glycosides, resins, oleo-resins, aromatic
& volatile oils, neutral principles etc, a number of other compounds are
also known to exists in plant flora which are responsible for curative action
of the herbs, although are relatively less known compounds. Recently some light
has been thrown on steroid like compounds present in number of medicinal herbs.
Chemically the compounds are known as sterols and are considered to be
derivatives of the steroids. They resemble in structure with steroids and
modern clinical studies have supported their role as anti inflammatory and analgesic
agents.
2Beta -sitosterol
is the most commonly studied sterol compound isolated from number of medicinal
herbs and it has shown effectiveness in reducing serum cholesterol levels. 3Modern
studies have indicated the usefulness of beta-sitosterol
in benign prostate hypertrophy and the compound has been detected in Serenoa Repens commonly known as Saw
Palmetto. 4The medicinal herb has been traditionally used in
treating prostate symptoms the clinical trials have shown promise in stages 1
& 2 in reducing difficulties associated with BPH but it has nothing to do
with enlarged
size of the gland. In addition the medicinal herb is known to contain sterols
including beta sitosterol-3-o-glycosides,
beta-sitisterol-3-o-glycosides, beta-sitosterol-fatty acid esters and their glycosides.
5,6,7 Disogenin
is another compound present in number of herbs like Hedichyum spicatum, Trigonella foenum- graecum, Pueraria tuberosa &
Dioscorea villosa. Oral contraceptives & sex hormones are derived from Disogenin. It is extracted from
medicinal herbs as well as prepared commercially. Due to wide the distribution
of the compound in above herbs, they have been used in various types of sexual
disorders like impotency. 8Ruscogenins
are other compounds present in Yucca liliaceae that are used in treating pain and
inflammation of arthritis and rheumatism. Yucca
filamentosa is other known species, which contains Ruscogenin as active principle. 9,10Ruscogenins are also present in Ruscus aculeatus and in animal tests; there was
increase in venous tone and an electrolyte-like reaction on the cell wall of
the capillaries.
Smilax officinalis is medicinal herb
that is known to contain steroid like compounds-saponin glycosides and according to some researchers actually the
herb contains male hormones. 11It also has been used in herbal
medicine as an anti-inflammatory agent in curing arthritis and rheumatism. Rubus idaeus,
commonly called as raspberry, is also known to contain such type of compounds.
12
Phyto-estrogens are group of
pharmacologically active compounds present in Asparagus officinalis where they are known as Asparagosides A, B, D, F, G, H $I [16]. Although the herb finds application in
female sexual disorders but effectiveness for the claimed application has not
been sufficiently documented. 13In Asparagus adscendens,
active compounds are called Shatavarins 1-4
and in clinical studies they shown estrogen like activity. According to Mitchell
Deborah these phyto-estrogens inhibit the conversion
of testosterone to dihyrotestosterone, thereby
increasing the count of testosterone in the body. Co- incidentally the role of
the herb has been described in old texts of Ayurveda
as sexual tonic. Coriander sativum [commonly known as
fennel] also contains phyto- estrogens and has shown
promise in treating premenstrual syndrome. Some glycosides on hydrolysis
produce aglycones like gitogenin and tigogenin, which also are being used in
steroid synthesis.
14 Balsamdendron commiphora mukul commonly known as Guggul contains special group of compounds called Guggulsterones, which range from E to Z. 15,16,17They are known as active principle of the herb and accounts for the use of the herb in hyperlipidemia and arthritis. 18Withania sominifera commonly known as Ashwagandha contain pharmacologically active compounds called Withanolides, which are considered to be responsible for various applications of the herb as adaptogen and immunomodulator. 19Withaferin-A is the most important group of Withanolide and has shown promise as potent anti cancer agent. 20The Withanolides are basically steriod lactones and various types have been isolated.
A
special group of compounds called cardioactive steroids [better known as
cardiac glycosides] deserves special mention. Digitalis purpurea, Stropanthus
gratus and Urginea indica are
reputed remedies as cardiac tonics. Clinically they find application in
congestive cardiac failure. All of them contain steroid saponins
as active constituents. 21Calotropis procera is known to contain cardioactive glycoside calotropine, which has shown an
antitumor effect in vitro on human epidermiod carcinoma cells of the
rhinopharynx. Besides it also acts as expectorant and diuretic.
22In
Homeopathic system of medicine, Convallaria
majalis is a reputed remedy in various heart diseases. It also contains
cardioactive steroid glycosides, which vary in the herb according to
geographical source, and main active constituents are convalloside, convallatoxin
and convallatoxol. In clinical
studies they have shown positive inotropic effect on
the myocardium and it lowers the elevated left ventricular pressure as well
pathologically raised venous pressure.
From
above it can be concluded that that sterol compounds are less known for their
medicinal importance. Some of them have been isolated and researchers are
studying hard to find their exact mode of action. In future a number of
compounds can be expected from the sterols that can provide us with life saving
drugs. The only need of the hour is to investigate the compounds with open mind
so that maximum benefit can be withdrawn from them.
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