Protective effects of syringic acid in nonalcoholic fatty liver in rats through regulation of Nrf2/HO-1 signaling pathway

Abstract

Nonalcoholic fatty liver disease (NAFLD) is an alarming ailment that leads to severe liver damage and increases the risk of serious health conditions. The prevalence of NAFLD due to oxidative stress could be mitigated by plant-derived antioxidants. This study aims to investigate the effects of syringic acid (SA) on NAFLD in a high-fat diet (HFD) rat model. Twenty-four rats were randomly divided into four groups (n = 6): normal control, HFD, SA-administered HFD, and positive control SA on a normal diet. Rats in the normal control and positive control groups received a normal diet, and the remaining groups received an HFD for 8 weeks. SA (20 mg/kg b.w.) was orally (gavage) administered for 8 weeks. Lipid profiles were controlled by SA against HFD-fed rats (p < 0.05). SA reduced the serum aspartate aminotransferase and alanine aminotransferase levels by 70%–190%. SA also suppressed pro-inflammatory cytokines and attenuated histopathological and immunohistochemical changes against HFD-fed rats. SA reversed oxidative stress by suppressing the malondialdehyde formation by 82% and replenished the nonenzymatic and enzymatic antioxidant activities (p < 0.05). Gene expressions of nuclear factor-erythroid 2-related factor/heme oxygenase 1 (Nrf2/HO-1) were elevated in SA-treated rats. Ameliorative effects of SA on NAFLD induced by an HFD in rats were prominent through the reversal of oxidative stress and inflammation, regulated by an intrinsic mechanism of defense against oxidative stress, the Nrf2/HO-1 pathway.