<i>Quercus infectoria</i> gall extract modulates adipocyte differentiation and lipid metabolism through dual regulation of adipogenesis and lipolysis in 3T3-L1 adipocytes

<i>Quercus infectoria</i> galls (QIG), traditionally used in Asian and Middle Eastern medicine, have shown lipid-lowering activity by reducing cholesterol, triglycerides, and low-density lipoprotein (LDL) levels. However, their role in regulating adipocyte lipid metabolism remains unexplored. This study aimed to evaluate the anti-obesity potential of QIG extract by investigating its regulatory effects on adipogenesis and lipolysis. The regulatory effects of QIG extract on lipid metabolism were investigated using 3T3-L1 adipocytes. The phytochemical profile of the extract was characterized by LC-QTOF-MS, revealing abundant phenolic constituents, including gallic acid, ellagic acid, and various hydrolyzable tannins. Functional assays demonstrated that the extract markedly suppressed lipid accumulation in a dose-dependent manner, achieving a maximum inhibition of 94.52 ± 2.29% without cytotoxicity. Mechanistically, QIG extract induced G1/S cell cycle arrest, suppressed mitotic clonal expansion, and downregulated key adipogenic transcription factors, adipocyte marker genes, as well as lipogenesis-related genes. In mature adipocytes, the extract significantly promoted lipolysis, increasing glycerol release up to 175.55 ± 5.26% of control levels (<i>p</i> < 0.05). In addition, QIG extract-treated adipocytes exhibited reduced intracellular lipid accumulation and smaller lipid droplets, highlighting its capacity to counteract both adipocyte hyperplasia and hypertrophy. Collectively, these findings provide novel mechanistic evidence that QIG extract exerts dual anti-obesity effects by inhibiting adipogenesis and enhancing lipolysis, supporting its potential development as a natural therapeutic candidate for obesity prevention and metabolic disorder management.