Gitogenin is a natural steroid isolated from the whole plant of Tribulus longipetalus. Gitogenin is a selective inhibitor of UDP-glucuronosyltransferase 1A4 (UGT1A4) and enzyme α-glucosidase with IC50 values of 0.69 μM (use trifluoperazine as a substrate) and 37.2 μM, respectively, and does not inhibit the activities of major human cytochrome P450 isoforms[1][2].
When tamoxifen is used as the substrate metabolized by UGT1A4 in HLMs, Gitogenin exhibits potent inhibition of tamoxifen, with an IC50 value of 6.13 µM. Similarly, for midazolam as the substrate of UGT1A4, the IC50 value is 5.7 µM. In addition, when olanzapine is used as a substrate of UGT1A4, the IC50 value is determined as 6.0 µM. Finally, we also evaluats Gitogenin for asenapine glucuronidation mediated by UGT1A4, and similar inhibition effect is observed, with an IC50 value of 22.0 µM[1].
Stimulation of growth hormone release is investigated on rat pituitary cells in vitro. Gitogenin (20 μg/mL) shows rat growth-hormone (rGH) release stimulating activities (26.1 ng/mL)[3].
[1]. Xu M, et al. Drug interaction study of natural steroids from herbs specifically toward human UDP-glucuronosyltransferase (UGT) 1A4 and their quantitative structure activity relationship (QSAR) analysis for prediction. Pharmacol Res. 2016 Aug;110:139-150. [2]. Naveed MA, et al. Longipetalosides A-C, new steroidal saponins from Tribulus longipetalus. Steroids. 2014 May;83:45-51. [3]. Shim SH, et al. Rat growth-hormone release stimulators from fenugreek seeds. Chem Biodivers. 2008 Sep;5(9):1753-61.