The Differentiation- and Proliferation-Inhibitory Effects of Sporamin from Sweet Potato in 3T3-L1 Preadipocytes

Abstract

The aim of this study was to investigate the effect of different concentrations of sporamin on the differentiation and proliferation of 3T3-L1 preadipocytes, providing the theoretical basis for the development of food to treat obesity and diabetes. The isolation and purification of sporamin from sweet potato species 55-2 were performed by ammonium sulphate precipitation in combination with ion-exchange and gel filtration chromatography. With berberine as a positive control, different concentrations of sporamin (0.000, 0.125, 0.025, 0.250, 0.500, and 1.000 mg mL −1) were used to treat 3T3-L1 preadipocytes. Intracellular fat accumulation and the degree of adipogenesis were quantified using Oil Red O staining and colorimetry. Preadipocytes differentiation was measured by 3-(4,5-dimethylthiazolyl-2-yl)-2,5-diphenyltetrazolium bromide (MTT) spectrophotometric assay. Two sporamin proteins, which were separated into sporamin A (31 kD) and sporamin B (22 kD), could be purified by ion-exchange and gel filtration chromatography. After being treated by different concentrations of sporamin, the differentiation of 3T3-L1 preadipocytes was significantly inhibited, compared with the positive control. When the sporamin solution concentration was 0.500 mg mL −1, the accumulation of lipid droplets within the cells was significantly decreased and the optical density (OD) value of the solution from destained Oil Red O reached to 0.35, which was the lowest value ( P < 0.05). The proliferation of 3T3-L1 preadipocytes was significantly inhibited by treating at higher sporamin concentrations. In addition, the inhibitory effect was more obvious with the prolonged treatment time ( P < 0.05). The differentiation and proliferation of 3T3-L1 preadipocytes could be inhibited significantly by the addition of higher concentration sporamin. It was, therefore, suggested that the sporamin was potentially effective for weight loss.