Pharmacological, pharmacokinetic, toxicological and clinical studies on protodioscin
I. Viktorov, E. Bozadjieva, M. Protich, et al.
Higher Medical Institute; Medical Academy Institute of Endocrinology, Gerontology and Geriatrics; Medical Academy Institute of Obstetrics and Gynecology, Bulgaria
IIMS Therapeutic Focus (1994)

SUMMARY

Clinical investigations on a total of 212 males with disorders of sexual functions confirmed experimental data pointing at a pronounced stimulating effect on these sexual functions by the new phytochemical preparation of Tribulus terrestris extract. Administered in average daily doses of 1.5 g in the course of 30 to 40 days, it restores and improves libido sexualis in all forms of impotentia coeundi.

Studies on the acute, subchronic and chronic toxicities of protodioscin, the active ingredient of Tribulus terrestris extract, determined that the compound is to be classified as a practically non-toxic substances. The harmlessness of the preparation deserves particular attention. No data about toxic manifestations were established under experimental conditions with acute, subchronic and chronic toxicities (behavioral, hematological, biochemical, functional and morphological studies). No data were established concerning carcinogenic and teratogenic effect.

The combined action of the preparation (stimulation of the sexual behavior and spermatogenesis) and the absence of adverse effects characterize the preparation as an original agent for the treatment of males with disorders in the sexual functions.

Changes in hormonal parameters secondary to intravenous administration of Tribulus terrestris extract in primates
A. Gauthaman, P.G. Adaikan, R. Prasad, V. Goh, and S. Ng
National University of Singapore
in preparation for publication

Tribulusamide A and B, new hepatoprotective lignanamides from the fruits of Tribulus terrestris: indications of cytoprotective activity in murine hepatocyte culture.
Li JX, Shi Q, Xiong QB, Prasain JK, Tezuka Y, Hareyama T, Wang ZT, Tanaka K, Namba T, Kadota S
Research Institute for Wakan-Yaku (Traditional Sino-Japanese Medicines), Toyama Medical and Pharmaceutical University, Japan.
Planta Med 1998 Oct;64(7):628-31

Protective effects of Tribulus terrestris L. polysaccharide on genetic damage
Liu Q, Chen Y, Wang J, Chen X, Han Y
Chung Kuo Chung Yao Tsa Chih. 1995 Jul;20(7):427-9, 449

Pro-erectile pharmacological effects of Tribulus terrestris extract on the rabbit corpus cavernosum
P.G. Adaikan, K. Gauthaman, and R.N. Prasad
National University of Singapore and National University Hospital, Department of Obstetrics and Gynecology, Singapore
Ann Acad Med Singapore 2000 Jan; 29(1): 22-26

SUMMARY

INTRODUCTION: The objective of the present study was to investigate the effect of oral treatment of Tribulus terrestris (TT) extract on the isolated corpus cavernosal tissue of New Zealand white (NZW) rabbits and to determine the mechanism by which protodioscin (PTN), a constituent of TT, exerts its pharmacological effects. MATERIAL AND METHODS: Twenty-four NZW rabbits were randomly assigned to 4 experimental groups of 6 each. Group I served as control. Groups II to IV were treated with the extract at different dose levels, i.e. 2.5 mg/kg, 5 mg/kg and 10 mg/kg body weight, respectively. The TT extract was administered orally, once daily, for a period of 8 weeks. The rabbits were then sacrificed and their penile tissue isolated to evaluate the responses to both contracting and relaxing pharmacological agents and electrical field stimulation (EFS). RESULTS: PTN on its own had no effect on the isolated corpus cavernosal strips. The relaxant responses to EFS, acetylcholine and nitroglycerin in noradrenaline precontracted tissues from treated groups showed an increase in relaxation of a concentration dependent nature compared to that of the tissues from control group. However, the contractile, anti-erectile response of corpus cavernosal tissue to noradrenaline and histamine showed no significant change between the treatment and the control groups. CONCLUSIONS: The relaxant responses to acetylcholine, nitroglycerin and EFS by more than 10%, 24% and 10% respectively compared to their control values and the lack of such effect on the contractile response to noradrenaline and histamine indicate that PTN has a proerectile activity. The enhanced relaxant effect observed is probably due to increase in the release of nitric oxide from the endothelium and nitrergic nerve endings, which may account for its claims as an aphrodisiac. However, further study is needed to clarify the precise mechanism of its action.

Aphrodisiac properties of Tribulus terrestris extract (protodioscin) in normal and castrated rats
A. Gauthaman, P.G. Adaikan, R.N. Prasad
National University of Singapore, National University Hospital, Department of Obstetrics and Gynecology, Singapore
Life Sci 2002 Aug 9; 71(12): 1385-96

SUMMARY

Tribulus terrestris (TT) has long been used in traditional Chinese and Indian systems of medicine for the treatment of various ailments and is popularly claimed to improve sexual functions in men. Sexual behavior and intracavernous pressure (ICP) were studied in both normal and castrated rats to further understand the role of TT containing protodioscin (PTN) as an aphrodisiac. Adult Sprague-Dawley rats were divided into five groups of 8 each that included distilled water treated (normal and castrated), testosterone treated (normal and castrated, 10 mg/kg body weight, subcutaneously, bi-weekly) and TT treated (castrated, 5 mg/kg body weight, orally once daily). Decreases in body weight, prostate weight and ICP were observed among the castrated groups of rats compared to the intact group. There was an overall reduction in the sexual behavior parameters in the castrated groups of rats as reflected by decrease in mount and intromission frequencies (MF and IF) and increase in mount, intromission, ejaculation latencies (ML, IL, EL) as well as post-ejaculatory interval (PEI). Compared to the castrated control, treatment of castrated rats (with either testosterone or TT extract) showed increase in prostate weight and ICP that were statistically significant. There was also a mild to moderate improvement of the sexual behavior parameters as evidenced by increase in MF and IFl; decrease in ML, IL and PEI. These results were statistically significant. It is concluded that TT extracts appear to possess aphrodisiac activity probably due to the androgen increasing property of TT (observed in our earlier study on primates).