Secondary metabolite of anthocyanin (Protocatechuic acid) mitigates 2-amino-3-methylimidazole [4, 5-F] quinoline-induced hepatotoxicity via AHR/CYP1A2 axis in vitro and in vivo

• PCA mitigates IQ-induced oxidative stress and inflammation by inhibiting the NLRP3 inflammasome and NF-κB/MAPK pathways. • The protective role of PCA against IQ cytotoxicity is mediated through the AHR-CYP1A2 pathway, regulating IQ's metabolic activation. • PCA exhibits a dose-dependent alleviating effect on IQ-induced liver inflammation in mice, with low-dose (10 mg/kg) intervention being more effective than a high dose. • PCA demonstrates a dual mechanism of action, concurrently enhancing the hepatic antioxidant defense system and suppressing pro-inflammatory signaling cascades. 2-amino-3-methylimidazole [4, 5-F] quinoline (IQ), a heterocyclic amine (HCA) usually formed in thermal processed meat, is classified as a grade 2A carcinogen. Protocatechuic acid (PCA), a phenolic acid compound, is a secondary metabolite of anthocyanin and possesses anti-inflammatory and antioxidant properties. However, the mechanisms underlying PCA's alleviation of IQ-induced hepatic inflammation remain unclear, prompting this study to investigate its protective effects both in vivo and in vitro. The results demonstrated that IQ treatment decreased the activity of antioxidant enzymes, upregulated the expression of NLRP3 inflammasome, and activated the NF-κB/MAPK signaling pathway in HepG2 cells. PCA intervention significantly enhanced the activity of antioxidant enzymes while suppressing the activation of NLRP3 inflammasome and NF-κB/MAPK signaling pathway. Meanwhile, siRNA transfection experiments further confirmed that the protective effect of PCA against IQ-induced cytotoxicity is mediated through the AHR-CYP1A2 pathway, specifically by regulating the metabolic activation of IQ. Furthermore, low-dose PCA (10 mg/kg) alleviated IQ-induced liver inflammation in mice by regulating AHR-CYP1A2-mediated IQ activation, whereas the high-dose (20 mg/kg) intervention proved less effective. Overall, this study provides valuable scientific insights into the protective effects and mechanisms of PCA in alleviating IQ-induced liver inflammation.