Inhibitory Effect and Mechanism of Epigallocatechin Gallate on the Differentiation of 3T3-L1 Preadipocytes

Green tea possesses a range of beneficial effects, including anti-obesity, antioxidant, and anti-inflammatory properties, owing to its biologically active components, primarily catechins such as epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC), and epigallocatechin gallate (EGCG). However, few studies have investigated the four catechin monomers simultaneously, and the molecular mechanisms of their anti-obesity effects have not been fully elucidated. In this study, we investigated the effects of four catechin monomers on the differentiation of 3T3-L1 preadipocytes of mice. Our findings demonstrated that four catechin monomers EC/ECG/EGC/EGCG (12, 25, 50 µM) dose-dependently inhibited the differentiation of 3T3-L1 preadipocytes and reduced triglyceride content. EGCG exhibited the most potent inhibitory effect with an optimal concentration of 50 µM. In addition, transcriptome sequencing and lipidomic analysis of EGCG-treated 3T3-L1 preadipocytes revealed that Ptgs2 and Pim1 were the most differentially expressed genes involved in regulating adipocyte differentiation. The results suggested that EGCG up-regulated the expression of the Pla2g2e gene and down-regulated the expression of the Pla2g4a and Pla2g2a genes via the glycerophospholipid metabolic pathway, which subsequently elevated lysophosphatidylcholine (LPC) levels, influencing the differentiation process of 3T3-L1 preadipocytes.