Synergistic protective effects of curcumin nano-emulsion and virgin coconut oil against thermal oxidation of sunflower oil and its hepatorenal toxicity in rats

Abstract

Introduction Repeated heating of vegetable oils leads to the generation of toxic oxidation products, which activate systemic oxidative stress and cause multi-organ injuries. This study examined the hepatorenal synergistic protection of Curcumin Nano-Emulsion (CNE) and virgin coconut oil (VCO) against the toxicity of thermally stressed sunflower oil (HSO) and explored the underlying antioxidant and anti-inflammatory mechanisms. Methods CNE was characterized by nanoscale particle size, high encapsulation efficiency, and excellent stability. HSO was supplemented with VCO (20% w/w) and CNE (200 ppm) to evaluate improvements in oxidative stability in vitro by measuring peroxide value, p-anisidine value, total polar compounds, and toxic aldehydes. For the in vivo study, sixty-four male Wistar rats were fed different oil-based diets for two months. Biochemical parameters, oxidative stress markers, inflammatory indices, and histopathological changes in liver and kidney tissues were assessed. Immunohistochemical analysis was performed to evaluate NF-κB and Nrf2 signaling pathways. Results Supplementation of HSO with VCO and CNE significantly improved oxidative stability compared with individual treatments and TBHQ, with marked reductions in peroxide value, p-anisidine value, total polar compounds, and toxic aldehydes. HSO induced significant hepatorenal injury, dyslipidemia, oxidative stress, and inflammation in rats. The combined treatment (HSO + VCO + CNE) markedly ameliorated these alterations, nearly restoring biochemical parameters to normal levels and minimizing histopathological damage. A strong downregulation of the NF-κB pathway and activation of the Nrf2 antioxidant pathway were observed. Discussion Co-administration of curcumin nano-emulsion and virgin coconut oil effectively enhances the oxidative stability and safety of thermally stressed edible oils. These findings suggest a promising natural strategy to reduce oil-induced toxicity and support safer industrial oil processing approaches aligned with public health protection.