Age-Related Variations in Curcumin-Mediated Antioxidant, Hepatoprotective, and Renoprotective Responses: A Comparative Dose–Response Study

Abstract

Curcumin, the principal bioactive polyphenol of Curcuma longa, possesses well-documented antioxidant and hepatoprotective properties. However, the influence of dose and age on its biological efficacy remains poorly understood. This study evaluated the dose-dependent antioxidant and hepatoprotective effects of curcumin in young and adult Wistar rats. Thirty Wistar rats were grouped by age (young or adult) and assigned to a control diet, 1% curcumin-supplemented diet, or 2% curcumin-supplemented diet for 14 days. Oxidative stress biomarkers, including total antioxidant capacity (TAC) and malondialdehyde (MDA), were assessed alongside liver function enzymes (ALT, AST) and renal function markers (urea, creatinine, albumin, and total protein). Histological examination of liver and kidney tissues was performed using Hematoxylin and Eosin and Van Gieson staining. Curcumin supplementation significantly increased TAC and reduced MDA levels in a dose-dependent manner in both age groups, with the 2% dose producing the greatest effect. Treated animals showed lower ALT and AST activities, improved serum albumin and total protein levels, and reduced urea and creatinine concentrations compared with controls. Adult rats exhibited higher baseline oxidative stress but demonstrated a more pronounced response to curcumin treatment. Histological analyses revealed preservation of tissue architecture and improved cellular organization in treated groups, particularly among adults. However, the 2% curcumin diet was associated with increased collagen deposition and mild hepatic remodeling. Curcumin exerts significant dose-dependent antioxidant and hepatoprotective effects, with greater efficacy in adult rats. Nevertheless, higher doses may induce adaptive structural changes in hepatic tissue. These findings highlight the importance of age and dose as determinants of curcumin efficacy and support the need for optimized dosing strategies in its development as a hepatoprotective therapeutic agent.