Tribulus terrestris

The hormonal effects of Tribulus terrestris and its role in the management of male erectile dysfunction–an evaluation using primates, rabbit and rat.
Gauthaman K, Ganesan AP.
Phytomedicine. 2008 Jan;15(1-2):44-54.

 Hormonal effects of Tribulus terrestris (TT) were evaluated in primates, rabbit and rat to identify its usefulness in the management of erectile dysfunction (ED). TT extract was administered intravenously, as a bolus dose of 7.5, 15 and 30 mg/kg, in primates for acute study. Rabbits and normal rats were treated with 2.5, 5 and 10mg/kg of TT extract orally for 8 weeks, for chronic study. In addition, castrated rats were treated either with testosterone cypionate (10mg/kg, subcutaneously; biweekly for 8 weeks) or TT orally (5mg/kg daily for 8 weeks). Blood samples were analyzed for testosterone (T), dihydrotestosterone (DHT) and dehydroepiandrosterone sulphate (DHEAS) levels using radioimmunoassay. In primates, the increases in T (52%), DHT (31%) and DHEAS (29%) at 7.5mg/kg were statistically significant. In rabbits, both T and DHT were increased compared to control, however, only the increases in DHT (by 30% and 32% at 5 and 10mg/kg) were statistically significant. In castrated rats, increases in T levels by 51% and 25% were observed with T and TT extract respectively that were statistically significant. TT increases some of the sex hormones, possibly due to the presence of protodioscin in the extract. TT may be useful in mild to moderate cases of ED. PMID: 18068966

  The effect of five weeks of Tribulus terrestris supplementation on muscle strength and body composition during preseason training in elite rugby league players.
Rogerson S, Riches CJ, Jennings C, Weatherby RP, Meir RA, Marshall-Gradisnik SM.
J Strength Cond Res. 2007 May;21(2):348-53.

 Tribulus terrestris is an herbal nutritional supplement that is promoted to produce large gains in strength and lean muscle mass in 5-28 days (15, 18). Although some manufacturers claim T. terrestriswill not lead to a positive drug test, others have suggested that T. terrestris may increase the urinary testosterone/epitestosterone (T/E) ratio, which may place athletes at risk of a positive drug test. The purpose of the study was to determine the effect of T. terrestris on strength, fat free mass, and the urinary T/E ratio during 5 weeks of preseason training in elite rugby league players. Twenty-two Australian elite male rugby league players (mean +/- SD; age = 19.8 +/- 2.9 years; weight = 88.0 +/- 9.5 kg) were match-paired and randomly assigned in a double-blind manner to either a T. terrestris (n = 11) or placebo (n = 11) group. All subjects performed structured heavy resistance training as part of the club’s preseason preparations. A T. terrestris extract (450 mg.d(-1)) or placebo capsules were consumed once daily for 5 weeks. Muscular strength, body composition, and the urinary T/E ratio were monitored prior to and after supplementation. After 5 weeks of training, strength and fat free mass increased significantly without any between-group differences. No between-group differences were noted in the urinary T/E ratio. It was concluded that T. terrestris did not produce the large gains in strength or lean muscle mass that many manufacturers claim can be experienced within 5-28 days. Furthermore, T. terrestris did not alter the urinary T/E ratio and would not place an athlete at risk of testing positive based on the World Anti-Doping Agency’s urinary T/E ratio limit of 4:1. PMID: 17530942

  Effect of gross saponins of Tribulus terrestris on cardiocytes impaired by adriamycin
Zhang S, Li H, Xu H, Yang SJ.
Yao Xue Xue Bao. 2010 Jan;45(1):31-6.

 This study is to observe the protection of gross saponins of Tribulus terrestris (GSTT) on cardiocytes impaired by adriamycin (ADR) and approach its mechanism of action. Cardiocytes of neonate rat were cultivated for 72 hours and divided into normal control group, model (ADR 2 mg x L(-1)) group, and GSTT (100, 30, and 10 mg x L(-1)) groups. MTT colorimetric method was deployed to detect cardiocyte survival rate, activities of CK, LDH, AST, SOD, MDA and NO were detected, and apoptosis was detected with flow cytometry. Effect of GSTT on caspase-3 was detected with Western blotting. Compared with control group, contents of CK, LDH, AST, MDA and NO were increased, and activity of SOD was reduced (P < 0.05, P < 0.01, P < 0.001) by ADR. Numbers of survival cells were increased (P < 0.05, P < 0.001), contents of CK, LDH, AST, MDA and NO were decreased, and activity of SOD was increased (P < 0.05, P < 0.01, P < 0.001) by GSTT (100 and 30 mg x L(-1)). Apoptosis of cardiocytes and concentration of caspase-3 can be reduced by GSTT (100 and 30 mg x L(-1)). GSTT can protect cardiocytes impaired by ADR, which are possible involved with its effect of resisting oxygen free radical. PMID: 21351446