Natural Defense against Atherosclerosis: The Therapeutic Potential of Torenia concolor Lindley var. Formosana Yamazaki Extract in Inhibiting the Formation of Macrophage-derived Foam Cells

Export We previously reported that the ethanolic extract of Torenia concolor Lindley var. formosana Yamazaki (TCEE), a plant native to Taiwan, protects against endothelial dysfunction and atherosclerosis. However, its effects on macrophage-derived foam cell formation and the underlying regulatory mechanisms remain unclear. Since macrophage-derived foam cell accumulation is a key driver for the initiation and progression of atherosclerosis, understanding the role of TCEE in this process is crucial. In this study, we investigated the impact of TCEE on lipid metabolism and inflammatory responses in macrophage-derived foam cells. Treatment with TCEE significantly reduced oxidized low-density lipoprotein (oxLDL)-induced lipid accumulation and suppressed the tumor necrosis factor-α-elicited production of inflammatory mediators in macrophages. Mechanistically, TCEE inhibited scavenger receptor (SR)-AI-mediated oxLDL uptake while promoting cholesterol efflux via ATP-binding cassette transporter A1 and SR-BI. Furthermore, TCEE prevented oxLDL-induced activation of Nicotinamide Adenine Dinucleotide Phosphate (NADPH) oxidase and the subsequent generation of reactive oxygen species, indicating a protective effect against oxidative stress. Notably, TCEE enhanced the total antioxidant capacity of macrophages, as evidenced by increased levels of key antioxidant proteins and small molecules. Specifically, TCEE upregulated the expression of superoxide dismutase-1, catalase, glutathione peroxidase, and heme oxygenase-1, which play crucial roles in cellular defense against oxidative damage. These findings suggest that TCEE mitigates oxLDL-induced lipid accumulation, oxidative stress, and inflammation in macrophage-derived foam cells, highlighting its potential therapeutic role in preventing atherosclerosis progression.