Ozonated Olive Oil Attenuates Hepatic Steatosis in Obese db/db Mice: Evidence for Triacylglycerol-derived Ozonides as Key Bioactive Species.

Ozonated edible oils have garnered increasing attention as potential functional food ingredients for managing metabolic dysfunction-associated steatotic liver disease (MASLD), a condition primarily driven by oxidative stress and chronic inflammation. This study aimed to elucidate (i) which fraction of ozonated olive oil mediates its hepatoprotective effects and (ii) whether the degree of fatty acid unsaturation influences the physiological responses to ozonated lipids. In Experiment 1, olive oil was fractionated into saponifiable (SAP) and unsaponifiable (unSAP) components, which were then subjected to ozonation, and subsequently incorporated into the diet of db/db mice. Ozonated SAP significantly reduced the hepatic triglyceride accumulation and suppressed the fatty acid synthesis pathway, as indicated by decreased fatty acid synthase (FAS) activity and downregulation of acetyl-CoA carboxylase 1 (ACC1), FAS, and stearoyl-CoA desaturase 1, while attenuating monocyte chemoattractant protein 1 (MCP1)-driven inflammation. Conversely, ozonated unSAP demonstrated no improvement. In Experiment 2, db/db mice were fed diets containing triolein or a mixed triacylglycerol, in ozonated or non-ozonated forms. Data were analyzed using two-way ANOVA to evaluate the main effects of fatty acid type and ozonation. Ozonation markedly reduced liver weight and hepatic triglycerides irrespective of fatty acid type. Serum alanine aminotransferase levels were significantly lowered by ozonation, with the fatty acid type contributing to an additional independent reduction. Mechanistically, ozonation downregulated lipogenic genes (ACC1 and FAS) and reduced the expression of inflammatory markers (MCP1 and interleukin 1β). Heme oxygenase 1 expression was significantly induced by both fatty acid type and ozonation; these independent effects suggest the additive activation of the antioxidant defense pathway. Ozonation modified hepatic lipid mediators, consistent with reduced inflammation and improved metabolism. These findings demonstrate that triacylglycerol ozonation generates bioactive ozonides that mitigate hepatic steatosis and inflammation, supporting their potential use in MASLD management.