History of herbal medicines with an insight on the pharmacological properties of Tribulus terrestris

Abstract

Phytochemicals have played a vital role in the past and will continue to do so in the future. Although synthetic drugs can produce dramatic results in most cases, the side-effects associated with them are a major concern. The source of many compounds used in modern medicine today can be traced down to plant origin. Whether or not scientific justification is available for the use of most plant products, the continued use of these compounds is due to their safety profile, ease of availability and also economic reasons. Each medicinal plant that has been used in the traditional system of medicine must be scientifically tested in order to bring forth its active principle that might be effectively used as a phytomedicine. In this vast resource of phytoproducts there are various plants that are claimed to improve the sexual deficiency in man. Tribulus terrestris Linn. (TT) is one such plant that has been used for a long time in both the Indian and Chinese systems of medicine. The plant is also said to possess various other pharmacological properties. The extract obtained from the air-dried aerial parts of this plant contains mainly steroidal glycosides, the major saponin being protodioscin (PTN). In our study on this plant product it was observed that PTN produced a moderate increase in testosterone, dihydrotestosterone and dehydroepiandrosterone sulfate levels in primates following bolus intravenous administration of the TT extract at doses of 7.5, 15 and 30 mg/kg body weight. It also improved libido, sexual activity and intracavernous pressure in rats following TT extract administration orally (for 8 weeks at doses of 2.5, 5 and 10 mg/kg body weight) and had a proerectile effect on the corpus cavernosum smooth muscle of rabbits (orally for 8 weeks at doses of 2.5, 5 and 10 mg/kg body weight). In this article, the various pharmacological effects of TT have been reviewed and our studies based on TT extract in relation to male erectile dysfunction have been summarized.