Cryptotanshinone Alleviates Nonalcoholic Fatty Liver Disease by Inhibiting NPC1L1-Mediated Intestinal Cholesterol Absorption

Danshen, a well-known traditional Chinese medicine (TCM), has gained increasing attention due to the protective effects on nonalcoholic fatty liver disease (NAFLD). However, the molecular basis and working mechanism remain to be elucidated. Niemann-Pick C1-like 1 (NPC1L1) is the crucial target mediating intestinal cholesterol absorption and its inactivation has been shown to alleviate NAFLD. Thus, this study aimed to screen NPC1L1 inhibitors in Danshen and investigate the therapeutic effects on NAFLD. A high-throughput screening platform based on the stable Caco2 cell lines expressing human-NPC1L1 (hL1-Caco2) was developed, and we found that tanshinones (Tans), the liposoluble components in Danshen, inhibited NPC1L1-mediated cholesterol absorption in hL1-Caco2 cells. The hepatic steatosis in high-fat diet (HFD)-fed mice was also reduced by Tans treatment. To find the active compounds in Tans, activity-oriented separation was performed by combining the high-throughput screening platform and two-dimensional chromatographic techniques. Ultimately, cryptotanshinone (CTS) was identified as a novel NPC1L1 inhibitor and profoundly decreased hepatic steatosis in HFD-fed mice. The binding modes and stability between CTS and NPC1L1 were confirmed by molecular docking and dynamics simulation. Taken together, our findings demonstrate for the first time that CTS, the liposoluble compound in Danshen, alleviates NAFLD by inhibiting NPC1L1-mediated intestinal cholesterol absorption, suggesting that inhibition of NPC1L1 with CTS may be a potential strategy for the treatment of NAFLD.