Characterization of in Vitro ADME Properties of Diosgenin and Dioscin from Dioscorea villosa

Abstract

Dioscorea villosa (wild yam) is native to North America and has been widely used as a natural alternative for estrogen replacement therapy to improve women’s health as well as to treat inflammation, muscle spasm, and asthma. Diosgenin and dioscin (glycoside form of diosgenin) are reported to be the pharmacologically active compounds. Despite the reports of significant pharmacological properties of dioscin and diosgenin in conditions related to inflammation, cancer, diabetes, and gastrointestinal ailments, no reports are available on ADME properties of these compounds. This study was carried out to determine ADME properties of diosgenin and dioscin and their effects on major drug metabolizing enzymes (CYP 3A4, 2D6, 2C9, and 1A2). The stability was determined in simulated gastric and intestinal fluids (SGF, pH 1.2 and SIF, pH 6.8), and intestinal transport was evaluated in Caco-2 model. Phase I and phase II metabolic stability was determined in human liver microsomes and S9 fractions, respectively. Quantitative analysis of dioscin and diosgenin was performed by UPLC-MS system. Dioscin degraded up to 28.3% in SGF and 12.4% in SIF, which could be accounted for by its conversion to diosgenin (24.2%. in SGF and 2.4% in SIF). The depletion of diosgenin in SGF and SIF was < 10%. Diosgenin was stable in HLM but disappeared in S9 fraction with a half-life of 11.3 min. In contrast, dioscin was stable in both HLM and S9 fractions. Dioscin showed higher permeability across Caco-2 monolayer with no significant efflux, while diosgenin was subjected to efflux mediated by P-glycoprotein. Diosgenin and dioscin inhibited CYP3A4 with IC50 values of 17 and 33 μM, respectively, while other CYP enzymes were not affected. In conclusion, dioscin showed better intestinal permeability. Conversion of dioscin to diosgenin was observed in both gastric and intestinal fluids. No phase I metabolism was detected for both compounds. The disappearance of diosgenin in S9 fraction indicated phase II metabolism.

Diosgenin: Recent Highlights on Pharmacology and Analytical Methodology

“…Remarkably, it was evidenced that dioscin has better intestinal permeability than diosgenin and is converted to diosgenin in both gastric and intestinal fluids. No phase I metabolism was detected for both compounds and diosgenin probably undergoes phase II metabolism [14]. …”

“…In addition, several pharmacokinetics studies [14] involving this compound have been performed in the last years. As such, the development of analytical methods to detect and quantify this important steroid in different matrices assumes major relevance.…”

Metabolic profiles of dioscin in rats revealed by ultra‐performance liquid chromatography quadrupole time‐of‐flight mass spectrometry

“…The results suggested that part of DIS was metabolized. However, in vitro metabolic study found that DIS was stable in both human liver microsome and S9 system (Manda et al ., ), which revealed that DIS might not be metabolized in liver. However, the in vivo conditions are much more complex than in vitro conditions and the liver is not the only site of metabolism in vivo .…”

“…However, to the best of our knowledge, the ultimate fate of DIS is still unclear. The only in vitro metabolic study showed that DIS was stable when it was incubated in human liver microsome and S9 system, which revealed that DIS might not be mainly metabolized in liver (Manda et al, 2013). Therefore, further characterization of the metabolic profiles of DIS is extremely needed.…”

Absorption and metabolism characteristics of pristimerin as determined by a sensitive and reliable LC–MS/MS method

“…The assay conditions and reaction mixtures were similar as reported previously [21,22]. The reaction mixture was incubated at 37°C for 5 min and then pristimerin (100 μM) was added.…”