The construction of preclinical evidence for the treatment of liver fibrosis with quercetin: A systematic review and meta-analysis.

Quercetin (3,3',4',5,7-pentahydroxyflavone), a flavonoid, is widely found in fruits and vegetables and exerts broad-spectrum pharmacological effects in the liver. Many studies have explored the bioactivity of quercetin in the treatment of liver fibrosis. Hence, through a systematic review and biological mechanism evaluation, this study aimed to construct a body of preclinical evidence for the treatment of liver fibrosis using quercetin. The literature used in this study was mainly obtained from four databases, and the SYRCLE list (10 items) was used to evaluate the quality of the included literature. A meta-analysis of HA, LN, and other indicators was performed via STATA 15.0 software. Subgroup analyses based on animal species and model protocol were performed to further obtain detailed results. Moreover, the therapeutic mechanism of quercetin was summarized in a directed network form based on a comprehensive search of the literature. After screening, a total of 14 articles (comprising 15 studies) involving 254 animals were included. The results from the analysis showed that the corresponding liver function indexes, such as the levels of HA and LN, were significantly improved in the quercetin group compared with the model group, and liver function, such as the levels of AST and ALT, were also improved in the quercetin group. The species- and model-based subgroup analyses of AST and ALT revealed that quercetin exerts a significant effect. The therapeutic mechanism of quercetin was shown to be related to multiple pathways involving anti-inflammatory and antioxidant activities and lipid accumulation, including regulation of the TGF-β, α-SMA, ROS, and P-AMPK pathways. The results showed that quercetin exerts an obvious effect on liver fibrosis, and more prominent improvement effects on liver function and liver fibrosis indicators were obtained with a dose of 5-200 mg during a treatment course ranging from 4 to 8 weeks. Quercetin might be a promising therapeutic for liver fibrosis.