30 July, 2010

Gymnema sylvestre

Gymnema sylvestre is a herb native to the tropical forests of southern and central India where it has been used as a naturopathic treatment for diabetes.

Sanskrit Name : Meshasringi, Madhinasini or madhoolika, Hindi: Gurmar, Tamil and Malayalam are Sirukurinchaan(சிறுகுரிஞ்சான்), Amudhapushpam, Chakkarakkolli.

Chemical composition

The major bioactive constituents of Gymnema sylvestris are a group of oleanane type triterpenoid saponins known as gymnemic acids. The latter contain several acylated (tigloyl, methylbutyroyl etc.,) derivatives of deacylgymnemic acid (DAGA) which is 3-O-glucuronide of gymnemagenin (3, 16, 21, 22, 23, 28-hexahydroxy-olean-12-ene)2. The individual gymnemic acids (saponins) include gymnemic acids I-VII, gymnemosides A-F, gymnemasaponins

G. sylvestre leaves contain triterpene saponins belonging to oleanane and dammarene classes. Oleanane saponins are gymnemic acids and gymnemasaponins, while dammarene saponins are gymnemasides. Besides this, other plant constituents are flavones, anthraquinones, hentri-acontane, pentatriacontane, α and β- chlorophylls, phytin, resins, d-quercitol, tartaric acid, formic acid, butyric acid, lupeol, β-amyrin related glycosides and stigmasterol. The plant extract also tests positive for alkaloids. Leaves of this species yield acidic glycosides and anthroquinones and their derivatives.

Gymnemic acids have antidiabetic, antisweetener and anti-inflammatory activities. The antidiabetic array of molecules has been identified as a group of closely related gymnemic acids after it was successfully isolated and purified from the leaves of Gymnema sylvestre. Later, the phytoconstituents of Gymnema sylvestre were isolated, and their chemistry and structures were studied and elucidated.

While it is still being studied, and the effects of the herb are not entirely known, the herb has been shown to reduce blood sugar levels when used for an extended period of time. Additionally, Gymnema reduces the taste of sugar when it is placed in the mouth, thus some use it to fight sugar cravings. From extract of the leaves were isolated glycosides known as Gymnemic acids, which exhibit anti-sweet activity.

This effect lasts up to about 2 hours. Some postulate that the herb actually reduces cravings for sugar by blocking sugar receptors in the tongue. This effect was observed in rats in a 2003 study conducted by CH Lemon, et al. It is currently being used in an all natural medication for diabetes with other ingredients such as cinnamon, chromium, zinc, biotin, banaba plant, huckleberry and bitter melon.
The active ingredient is thought to be gurmenic acid which has structure similar to saccharose. Extracts of Gymnema is not only claimed to curb sweet tooths but also for treatment of as varied problems as hyperglycemia, obesity, high cholesterol levels, anemia and digestion. According to the Sushruta of the Ayurveda it helps to treat Madhumeha ie glycosuria.

In 2005, a study made by King’s College, London, United Kingdom, showed that a water-soluble extract of Gymnema Sylvestre, caused reversible increases in intracellular calcium and insulin secretion in mouse and human β-cells when used at a concentration (0.125 mg/ml) without compromising cell viability. Hence forth these data suggest that extracts derived from Gymnema Sylvestre may be useful as therapeutic agents for the stimulation of insulin secretion in individuals with Type 2 Diabetes.

Alternative names
The plants also goes under many other names such as; Gurmari, Gurmarbooti, Gurmar, periploca of the woods and Meshasringa. The Hindi word Gur-mar (Madhunaashini in Sanskrit, Chakkarakolli in Tamil), literally means sugar destroyer. Meshasringa (Sanskrit) translates as "ram's horn", a name given to the plant from the shape of its fruits. Gymnema probably derives from the Latin word meaning naked and sylvestre means from the forest.