1,8-Cineole Alleviates PA-Induced Lipid Accumulation, Oxidative Stress, and Inflammation via the TLR4/MyD88/NF-κB...

The present study investigates the effect of 1,8-cineole on improving lipid metabolism disorder by regulating oxidative stress and inflammation via the TLR4/MyD88/NF-κB pathway. 1,8-Cineole is a monoterpene compound widely found in the essential oils of many plants and has been reported to possess anti-inflammatory and antioxidant activities. However, its role in regulating lipid metabolism disorders remains unclear. This study aimed to investigate the effects of 1,8-cineole on lipid metabolism and explore the potential mechanisms related to oxidative stress and inflammation.

Cell viability was assessed by MTT assay to determine the optimal PA concentration for inducing lipid accumulation and the non-cytotoxic range of 1,8-cineole in HepG2 and AML-12 cells. Lipid droplets were visualized by Oil Red O staining, while triglyceride (TG) and total cholesterol (TC) levels were quantified using enzymatic kits. Oxidative stress markers (ROS by DCFH-DA fluorescence; MDA by TBA method; CAT activity by ammonium molybdate method) and inflammatory cytokines (TNF-α, IL-6, IL-1β, IL-18 by ELISA) were measured. Western blotting analyzed key proteins in the TLR4/MyD88/NF-κB pathway (TLR4, MyD88, p-P65, p-IκBα). Pathway-specific inhibitors were employed for mechanistic validation.

1,8-Cineole (up to 1000 μg/mL) showed no cytotoxicity. It significantly attenuated PA-induced lipid droplet accumulation, reduced TG and TC levels (p < 0.05), and ameliorated oxidative stress by decreasing ROS and MDA while enhancing CAT activity in AML-12 cells (p < 0.01). Furthermore, 1,8-cineole suppressed pro-inflammatory cytokine release (TNF-α, IL-6, and IL-1β; p < 0.01), whereas no significant effect was observed on IL-18 levels. Downregulated TLR4/MyD88/NF-κB pathway activation. Inhibition of TLR4 or NF-κB mirrored these protective effects.

1,8-Cineole alleviates PA-induced lipid metabolism disorders, oxidative stress, and inflammation in hepatocytes, likely through suppression of the TLR4/MyD88/NF-κB signaling pathway.