A member of the Zygophyllaceae family, Tribulus terrestris, also known as Gokshura, Gokharu, or puncture vine, is an annual herb; its aerial parts, roots, and fruits have been used in traditional medicine for anti-inflammatory, diuretic, tonic, antimicrobial, and aphrodisiac purposes for thousands of years in China, India, Pakistan, and Sudan.1-3 In modern times, the health benefits of T. terrestris have been attributed to the constituent saponins, flavonoids, alkaloids, lignins, amides, and glycosides that have been isolated and found as bioactive compounds in the plant.2-4
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In an ethnobotanical survey of medicinal plants used in Nepal that was conducted in 2010 and 2011, Singh et al. found that T. terrestris was one of the 66 plant species important in the region. They also reported that it is one of the threatened species requiring conservation efforts.5 Although T. terrestris has long had a reputation for aphrodisiac qualities, critical reviews of the literature have undermined this historical reputation.1,6 Nevertheless, the botanical agent is used most often to treat infertility and loss of libido.4 More germane to the dermatologic realm, T. terrestris is thought to exhibit antioxidant, anticarcinogenic, and immunomodulatory potential, among other health benefits.4
Skin lightening activity
In a study published in 2002, Deng et al. evaluated the effects of a decoction of T. terrestris on tyrosinase activity and melanogenesis on cultured human melanocytes. They found that the amount of melanin increased when the decoction was administered in higher concentrations (optimally 1.5 mg/mL) but the effects were reversed at lower concentrations (0.5 mg/mL). Similarly, tyrosinase activity was facilitated by high concentrations of the decoction (optimally 100 mg/mL) and hindered at low concentrations (10 mg/mL). The investigators concluded that T. terrestris showed intriguing potential for use as a skin lightening agent that warranted further study.7
A mouse study performed by Yang et al. in 2006 revealed that T. terrestris extract administered orally to C57BL/6J mice resulted in a significantly higher expression of melanocyte-stimulating hormone in the hair follicles of treated mice (75%), compared with that in the control group (18.75%). The researchers concluded that T. terrestris galvanizes tyrosinase activity and fosters melanocyte increase, melanin production, and the epidermal movement of dormant melanocytes.8
Anticancer activity
Kumar et al. showed in 2006 that the aqueous extracts of T. terrestris roots and fruits displayed chemopreventive activity in male Swiss albino mice. Specifically, oral administration of T. terrestris before, during, and after papillomagenesis induced by 7, 12-Dimethylbenz(a)anthracene (DMBA) resulted in significant decreases in tumor incidence, tumor burden, and cumulative number of papillomas, as well as a significant increase in average latent period as compared with the control group treated with DMBA and croton oil.9
The next year, Neychev et al. published a study on the effects of T. terrestris–derived saponins on normal human skin fibroblasts with a focus on anticancer activities. The researchers noted that the botanical engendered a dose-dependent reduction in [3H]-thymidine incorporation into the DNA of treated fibroblasts, which was not the case for untreated controls. This and several other metrics suggested that T. terrestris poses much less toxicity to normal human skin fibroblasts than multiple previously explored cancer lines by virtue of the up-regulation and down-regulation of polyamine homeostasis, hampering proliferation, and apoptosis induction.10
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In 2012, Sisto et al. investigated the effects of T. terrestris–derived saponins on apoptosis in normal human keratinocytes exposed to UVB, as well as their antitumoral activity. They found that the saponins blunted UVB-induced apoptosis in normal human keratinocytes and did not render malignant keratinocytes more resistant to UVB in squamous cell carcinomas. The investigators concluded that their findings suggest a preventive capacity of T. terrestris against UVB-induced damage and carcinogenesis.11