Development of New Genipin Derivatives as Potential NASH Treatments: Design, Synthesis and Action Mechanism

Nonalcoholic steatohepatitis (NASH) is a multifaceted liver disease. Endoplasmic reticulum stress (ERS), a key driver in NASH pathogenesis, triggers metabolic irregularities, liver steatosis, and inflammation. Genipin, an iridoid from the traditional Chinese medicine Gardenia jasminoides, has shown significant effects against ERS. In the current work, 33 new genipin derivatives were designed and synthesized to evaluate their potential to treat NASH. Notably, G15 emerged as the most potent candidate, significantly reducing lipid accumulation induced by free fatty acids (FFAs) in L-02 cells. Further investigation indicated that G15's alleviation of ERS primarily involved the inositol-requiring enzyme 1(IRE1) signaling pathway, and that G15 can effectively down-regulate the IRE1 protein level. The downstream expression of X-box binding protein 1(XBP1) and signal transducer and activator of transcription 3(STAT3) proteins are confirmed by Western blot analysis. The results showed that G15 treatment inhibited FFA-induced nitric oxide (NO) production in a concentration-dependent manner, and decreased the production of pro-inflammatory cytokines IL-1β, IL-6, and TNF-α. Collectively, these findings underscore G15's potential as a leading candidate in the development of therapeutics for the treatment of NASH, with IRE1 inhibition being a viable target for intervention.非酒精性脂肪性肝炎（Nonalcoholic steatohepatitis, NASH）是一种多因素肝病。内质网应激（Endoplasmic reticulum stress, ERS）作为NASH发病机制的关键驱动因素，可诱发代谢紊乱、肝脏脂肪变性与炎症反应。京尼平是中药栀子（Gardenia jasminoides）中的环烯醚萜类成分，已被证实可有效对抗内质网应激。本研究设计并合成了33种新型京尼平衍生物，以评估其治疗NASH的潜力。其中，候选化合物G15表现出最强的生物活性，可显著抑制游离脂肪酸（Free fatty acids, FFAs）诱导的L-02细胞脂质堆积。进一步机制研究表明，G15对内质网应激的缓解作用主要通过肌醇需求酶1（Inositol-requiring enzyme 1, IRE1）信号通路介导，且可有效下调IRE1蛋白的表达水平。经蛋白质印迹分析证实，G15可抑制其下游X盒结合蛋白1（X-box binding protein 1, XBP1）与信号转导与转录激活因子3（signal transducer and activator of transcription 3, STAT3）的蛋白表达。实验结果显示，G15可呈浓度依赖性抑制游离脂肪酸诱导的一氧化氮（Nitric oxide, NO）生成，并降低促炎细胞因子IL-1β、IL-6及TNF-α的分泌水平。综上，本研究结果证实G15有望成为治疗NASH的先导候选药物，而靶向抑制IRE1信号通路可作为NASH临床干预的可行策略。