July 1 2017 by Ray Sahelian, M.D.

Protodioscin (3-O-[alpha-L-rhamnopyranosyl-(1-->2)-{alpha-L-rhamnopyranosyl-(1-->4)}-beta-D-glucopyranosyl]-26-O-[beta-D-glucopyranosyl]-(25 R)-furost-5-ene-3 beta,26-diol) is a naturally occurring saponin present in many oriental vegetables and traditional medicinal plants. Protodioscin is one of the active ingredients of the herb Tribulus terrestris.

Protodioscin and sexual function
Sexual effects of puncturevine (Tribulus terrestris) extract (protodioscin): an evaluation using a rat model.
J Altern Complement Med. 2003. Gauthaman K, Ganesan AP, Prasad RN. Department of Obstetrics and Gynaecology, National University Hospital, National University of Singapore, Singapore.
Sexual behavior and intracavernous pressure (ICP) measurements were taken in rats to scientifically validate the claim of Tribulus terrestris [containing protodioscin] as an aphrodisiac. Forty sexually mature male Sprague-Dawley rats were randomly divided into four groups of 10 each. Group I served as a control group and groups II, III, and IV were treated with three different doses of TT extract (2.5, 5 and 10 mg/kg body weight, respectively), orally, once daily for 8 weeks. Weight was recorded and the rats from all four groups were subjected to sexual behavior studies with primed females and various parameters namely mount and intromission frequencies (MF and IF, respectively), mount, intromission and ejaculation latencies (ML, IL, and EL, respectively) as well as postejaculatory interval (PEI) were recorded. In addition, blood pressure and ICP were recorded for all rats at the end of study. The weight gain and improvement in sexual behavior parameters observed in rats could be secondary to the androgen increasing property of TT protodioscin that was observed in our earlier study on primates. The increase in ICP which confirms the proerectile aphrodisiac property of TT could possibly be the result of an increase in androgen and subsequent release of nitric oxide from the nerve endings innervating the corpus cavernosum.

Protodioscin and cancer
In vitro and rodent studies indicate protodioscin has anti cancer potential.

Cancer Invest. 2003. The cytotoxicity of methyl protodioscin against human cancer cell lines in vitro. Methyl protodioscin (NSC-698790) was a furostanol saponin isolated from the rhizome of Dioscorea collettii var. hypoglauca (Dioscoreaceae), a Chinese herbal remedy for the treatment of cervical carcinoma, carcinoma of the urinary bladder, and renal tumors for centuries. To systematically evaluate its potential anticancer activity, methyl protodioscin was tested cytotoxicity in vitro against human cancer cell lines by the NCI's (National Cancer Institute) anticancer drug screen. As a result, methyl protodioscin showed strong cytotoxicity against most cell lines from solid tumors, especially selectively against one colon cancer line (HCT-15) and one breast cancer line (MDA-MB-435) but moderate cytotoxicity was shown against leukemia cell lines with GI50 10-30 microM. The data are consistent with the fact that the rhizome of D. collettii var. hypoglauca has been employed for the treatment of solid tumors rather than leukemia in China for centuries. Based on an analysis using the COMPARE computer program with methyl protodioscin as a seed compound, no compounds in the NCI's anticancer drug screen database have cytotoxicity patterns similar to those of methyl protodioscin, indicating a potential novel mechanism of anticancer action.

Protodioscin in herbs
Various herbs have protodioscin or related compounds.

Dioscorea nipponica Makino has Pseudoprotodioscin, methyl protodioscin and dioscin
Dioscorea septemloba root has dioscin, protodioscin and protogracillin

Pharmacol Res Perspect. 2015. Natural compound methyl protodioscin protects against intestinal inflammation through modulation of intestinal immune responses.