Hepatotoxicity Induced by Sophora flavescens and Hepatic Accumulation of Kurarinone, a Major Hepatotoxic Constituent of Sophora flavescens in Rats.

Our previous study showed that kurarinone was the main hepatotoxic ingredient of Sophora flavescens, accumulating in the liver. This study characterized the mechanism of Sophora flavescens extract (ESF) hepatotoxicity and hepatic accumulation of kurarinone. ESF impaired hepatic function and caused fat accumulation in the liver after oral administration (1.25 and 2.5 g/kg for 14 days in rats). Serum metabolomics evaluation based on high-resolution mass spectrometry was conducted and real-time PCR was used to determine the expression levels of CPT-1, CPT-2, PPAR-α, and LCAD genes. Effects of kurarinone on triglyceride levels were evaluated in HL-7702 cells. Tissue distribution of kurarinone and kurarinone glucuronides was analyzed in rats receiving ESF (2.5 g/kg). Active uptake of kurarinone and kurarinone glucuronides was studied in OAT2-, OATP1B1-, OATP2B1-, and OATP1B3-transfected HEK293 cells. Our results revealed that after oral administration of ESF in rats, kurarinone glucuronides were actively transported into hepatocytes by OATP1B3 and hydrolyzed into kurarinone, which inhibited fatty acid β-oxidation through the reduction of l-carnitine and the inhibition of PPAR-α pathway, ultimately leading to lipid accumulation and liver injury. These findings contribute to understanding hepatotoxicity of kurarinone after oral administration of ESF.