Protective Effects of Caffeic Acid against Alternate-Day Fasting-Induced Hepatic Oxidative Toxicity in Rats: Modulation of the Glutathione Redox Axis and SOD Expression

Alternate-day fasting (ADF) is widely utilized for metabolic regulation. But its potential to trigger hepatic oxidative stress and perturb redox-sensitive gene expression warrants toxicological evaluation. In this study, we investigated the protective effects of caffeic acid (CA) against ADF-induced hepatic oxidative toxicity and lipid metabolism disorders, focusing on its modulatory role in the glutathione redox axis and superoxide dismutase (SOD) expression. Twenty-eight male Sprague–Dawley rats were assigned to four groups: Control, ADF (24-h cycles for 6 weeks), CA (50 mg/kg/day), and ADF+CA. Enzymatic antioxidant levels of SOD, catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), lipid parameters (total cholesterol, triglycerides) were assessed by ELISA The total antioxidant status (TAS) and total oxidant status (TOS) were analysed using commercial kits and oxidative stress index (OSI) was calculated accordingly. Hepatic mRNA expression of SOD1, SOD2, and SOD3 was quantified by qRT-PCR. ADF significantly reduced hepatic CAT levels and elevated TOS levels relative to control, and significantly increased total cholesterol relative to the ADF+CA group, indicating ADF-induced oxidative and lipid stress. CA co-administration significantly restored SOD and GR levels in the ADF+CA group compared with the ADF, CA, and control groups, and significantly increased GPx and GR relative to ADF alone, while also normalizing cholesterol levels. At the transcriptional level, SOD1, SOD2, and SOD3 mRNA expression showed a numerical downregulation trend under ADF and the most pronounced numerical upregulation in the ADF+CA group (up to 3.10-fold for SOD1), although these differences did not reach statistical significance. Together, these findings indicate that prolonged ADF induces hepatic oxidative stress and disrupts lipid homeostasis, and that CA supplementation confers hepatoprotection primarily by restoring antioxidant enzyme activity and the glutathione redox axis, with a supportive but statistically non-significant trend toward increased SOD gene expression.