Exploring the inhibitory activity and mechanism on lipid production in 3T3-L1 cells by hot water extract derived from Acacia confusa flowers

Acacia confusa Merr. (Fabaceae) (A. confusa) is a native tree species of Taiwan, commonly found in the low-altitude mountains and hilly areas of the Hengchun Peninsula. This evergreen, perennial, and large-sized tree was the focus of a study that employed various chromatographic and spectroscopic methods to analyze the hot water extract of its flowers. The analysis revealed that the major components of the extract were myricitrin, quercitrin, europetin-3-O-rhamnoside, and chalconaringenin-2′-xyloside, with respective concentrations of approximately 0.22, 0.02, 0.26, and 0.10 mg/g of the flowers. Subsequent cell assays were conducted to assess the inhibitory effect of the extract on lipid synthesis in fat cells. Oil Red O staining results indicated that the extract significantly suppressed fatty acid accumulation in 3T3-L1 cells, with the most pronounced effect observed at a concentration of 180 μg/ml. Furthermore, the hot water extract of A. confusa flowers was found to increase the phosphorylation of AMP-activated protein kinase (AMPK), decrease the phosphorylation of cAMP response element-binding protein (CREB), and reduce the expression of glucocorticoid receptor (GR) protein. This, in turn, inhibited the expression of downstream transcription factors such as CCAT/ehancer binding proteins α (C/EBPα), CCAT/ehancer binding proteins β (C/EBPβ), CCAT/ehancer binding proteins δ (C/EBPδ), peroxisome proliferation-actived receptor γ (PPARγ), and sterol regulatory element binding proteins-1 (SREBP-1). Consequently, the expression of lipid synthesis-related proteins acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), and fatty acid translocase (CD36) was reduced, ultimately inhibiting lipid generation. Therefore, the hot water extract of A. confusa flowers shows potential for development as a weight-loss tea.