Neptunea cumingii Extract Inhibits Adipogenesis and Stimulates Browning of Adipocytes in 3T3-L1 Preadipocytes

This study investigates the potential antiobesity effects of Neptunea cumingii extract (NCE). Our findings illustrate that NCE effectively reduces lipid accumulation and triglyceride content, while simultaneously increasing free glycerol release. The reduction in lipid accumulation and induction of lipolysis were evidenced by the downregulation of lipogenesis proteins, such as fatty acid synthase and lipoprotein lipase, and the upregulation of hormone-sensitive lipase expression. Furthermore, the downregulation of adipogenic transcription factors, including peroxisome proliferator–activated receptor gamma, CCAAT/enhancer-binding protein α, and sterol regulatory element-binding protein 1, indicates the inhibition of adipocyte differentiation. Additionally, NCE treatment induced brown adipocyte phenotype by upregulating brown adipose tissue–specific proteins, such as uncoupling protein 1 and peroxisome proliferator–activated receptor-gamma coactivator 1α. Moreover, NCE led to the phosphorylation of AMPK, the master regulator of energy homeostasis. Pharmacological inhibition of AMPK using an AMPK inhibitor (Compound C) attenuated the lipogenesis inhibitory effect of NCE and reduced lipolysis and adipocyte browning. This suggests that AMPK activation is involved in these processes. GC–MS analysis reveals that NCE primarily consists of cholest-5-en-3-ol (27.15%) along with an array of fatty acids which possess favorable antiobesity properties. Collectively, these results highlight the potential of NCE as a lipid-lowering agent for the intervention of obesity.