Inhibitory Effect of Vitamin U (S-Methylmethionine Sulfonium Chloride) on Differentiation in 3T3-L1 Pre-adipocyte Cell Lines

BACKGROUND: S-methylmethionine sulfonium chloride was originally called vitamin U because of its inhibition of ulceration in the digestive system. Vitamin U is ubiquitously expressed in the tissues of flowering plants, and while there have been reports on its hypolipidemic effect, its precise function remains unknown. OBJECTIVE: This study was designed to evaluate the anti-obesity effect of vitamin U in 3T3-L1 pre-adipocyte cell lines. METHODS: We cultured the pre-adipocyte cell line 3T3L1 to overconfluency and then added fat differentiation-inducing media (dexamethasone, IBMX [isobutylmethylxanthine], insulin, indomethacin) and different concentrations (10, 50, 70, 90, 100 mM) of vitamin U. Then, we evaluated changes in the levels of triglycerides (TGs), glycerol-3-phosphate dehydrogenase (G3PDH), AMP-activated protein kinase (AMPK), adipocyte-specific markers (peroxisome proliferator-activated receptor γ [PPAR-γ], CCAAT/enhancer-binding protein α [C/EBP-α], adipocyte differentiation and determination factor 1 [ADD-1], adipsin, fatty acid synthase, lipoprotein lipase) and apoptosis-related signals (Bcl-2, Bax). RESULTS: There was a gradual decrease in the level of TGs, C/EBP-α, PPAR-γ, adipsin, ADD-1 and GPDH activity with increasing concentrations of vitamin U. In contrast, we observed a significant increase in AMPK activity with increasing levels of vitamin U. The decrease in bcl-2 and increase in Bax observed with increasing concentrations of vitamin U in the media were not statistically significant. CONCLUSION: This study suggests that vitamin U inhibits adipocyte differentiation via down-regulation of adipogenic factors and up-regulation of AMPK activity.