Zhaohong Ci^{1, 2}, Chengyu Jiang^{1, 2}, Shuo Feng^{1, 2}, Shan Wu^{1, 2}, Yang Cui¹, Yuki Sasaki¹, Michiyuki Kojima^{2, 3,}

Proanthocyanidins are oligomeric or polymeric flavonoids found in several plants. They can be classified into two subgroups, namely A- and B-type proanthocyanidins. The coat of scarlet runner beans contains abundant proanthocyanidins (SRPAs) of the B-type configuration. To evaluate the efficacy of SRPAs as anti-obesity agents, we first examined their effect on lipase activity in vitro and found that they are potent inhibitors of this enzyme. Subsequently, we examined their effect on mice fed a high-fat diet. Male mice were assigned to the following seven-subject dietary groups: (1) high-fat diet; (2) high-fat diet supplemented with 0.5% SRPAs; (3) high-fat diet supplemented with 1.0% SRPAs, and; (4) standard chow for 15 weeks. SRPA supplementation decreased body weight gain; liver and kidney weight; perirenal, peritesticular, and periintestinal fat content; liver cholesterol level, and; serum neutral lipid and cholesterol levels. In contrast, the faecal lipid content and the liver anti-oxidative capacity increased. These findings suggest a potential use of SRPAs as a dietary supplement exerting anti-obesity effects through the inhibition of fat digestive enzymes.

scarlet runner bean coat, anti-obesity, proanthocyanidin, lipase activity inhibition, fat digestion