Fermented Syzygium samarangense leaves mitigate oxidative stress-triggered hepatotoxicity through Nrf2 activation and epigenetic regulation

The liver, which is a vital organ for metabolism and detoxification, is susceptible to damage caused by oxidative stress. Excessive consumption of acetaminophen (APAP), a commonly used analgesic ingredient, can cause liver injury due to oxidative stress. The aim of this study is to examine the protective effects and mechanisms of fermented Syzygium samarangense (wax apple) leaves (FWAL) against damage caused by APAP in mouse AML-12 hepatocytes. Ethanolic and water extracts of FWAL (FWAL-EE and FWAL-WE) were prepared, and both contained significant phenolic compounds such as gallic acid, EGCG, ellagic acid, myricitrin, and myricetin, with potent DPPH scavenging activity. FWAL-EE demonstrated superior effectiveness in lowering the death ratio, LDH leakage, and oxidative stress in APAP-treated AML-12 cells. The protective effects of FWAL-EE included the downregulation of inflammatory markers TNF-α and cox-2 mRNA, as well as the upregulation of Nrf2, HO-1, and NQO1 proteins in APAP-treated hepatocytes. Additionally, FWAL-EE reduced the expression of epigenetic enzymes HDACs 1, 2, 3, and 4, and DNMTs 1 and 3b while causing an increase in unmethylated DNA levels in the Nrf2 promoter region. Furthermore, EGCG, a prominent active compound in FWAL, protected AML-12 hepatocytes from APAP-induced damage by activating Nrf2 and NQO1, while also inhibiting epigenetic DNMTs and HDACs. These results suggested that FWAL-EE may effectively prevent APAP-induced liver damage by enhancing the activation of the Nrf2 antioxidant system through epigenetic regulation. FWAL-EE has potential as a nutraceutical for liver protection.