Black soybean anthocyanins inhibit adipocyte differentiation in 3T3-L1 cells

Anthocyanins are naturally occurring polyphenolic pigments in plants that have been shown to decrease weight gain and insulin resistance in mice-fed high-fat diets. We investigated the effects of anthocyanins on cell growth, differentiation, and lipolysis in 3T3-L1 cells to test our hypothesis that anthocyanins could reduce adipose tissue mass by acting directly on adipocytes. Anthocyanin extracts from black soybeans were used and composed of 3 of the following major anthocyanins: cyanidine-3-O-glucoside (68.3%), delphinidin-3-O-glucoside (25.2%), and petunidin-3-O-glucoside (6.5%). Treatment with 12.5 and 50 μg/mL of black soybean anthocyanins exhibited inhibitory effects on the proliferation of both preconfluent preadipocytes (P < .01) and maturing postconfluent adipocytes (P < .01). In fully differentiated adipocytes, the number of viable cells was reduced by black soybean anthocyanins (P < .01). Treatment with 50 μg/mL of black soybean anthocyanins slightly increased epinephrine-induced lipolysis but decreased the basal lipolysis of fully differentiated adipocytes (P < .05). Black soybean anthocyanins also reduced lipid accumulation and suppressed the expression of the peroxisome proliferator–activated receptor γ, a major transcription factor for the adipogenic gene (P < .01). These results suggest that black soybean anthocyanins inhibit adipocyte differentiation and basal lipolysis, which may contribute to their antiobesity and antidiabetic properties.