Diosbulbin B (DIOB), isolated from herbal medicine Dioscorea bulbifera L. (DB), could induce severe liver injury, and its toxicology was closely associated with CYP3A4-mediated metabolic oxidation of furan moiety to the corresponding cis-enedial reactive metabolite. Glycyrrhizin (GL), the major bioactive ingredient in licorice, can inhibit the activity of CYP3A4. Thus, GL may ameliorate hepatotoxicity of DIOB when GL and DIOB are co-administrated. The study aimed to investigate the protective effect of GL on DIOB-induced hepatotoxicity and the underlying mechanism. Biochemical and histopathological analysis demonstrated that GL alleviated DIOB-induced hepatotoxicity in a dose-dependent manner. In vitro study with mouse liver microsomes (MLMs) demonstrated that GL reduced the formation of metabolic activation-derived pyrrole-glutathione (GSH) conjugates from DIOB. Toxicokinetic studies showed that the pretreatment with GL caused the increase of AUCs and Cmax of DIOB in blood of mice, resulting in accelerating the accumulation of DIOB in the circulation. In addition, the pretreatment with GL alleviated DIOB-induced hepatic GSH depletion. In summary, GL ameliorated DIOB-induced hepatotoxicity, possibly related to the inhibition of the metabolic activation of DIOB. Thus, development of a standardized combination of DIOB with GL may protect patients from DIOB-induced liver injury.
Keywords: diosbulbin B; glycyrrhizin; hepatotoxicity; metabolic activation.
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