Soybean β-conglycinin bromelain hydrolysate stimulates cholecystokinin secretion by enteroendocrine STC-1 cells to suppress the appetite of rats under meal-feeding conditions.

A peptic digest of soybean β-conglycinin (BconP) suppresses the appetite in rats through cholecystokinin (CCK) secretion by enteroendocrine cells. We investigate in this study more appetite-suppressing hydrolysates. β-Conglycinin hydrolyzed with food-processing proteases thermolysin (BconT), bromelain (BconB), chymotrypsin, protease S, and protease M was examined for CCK-secreting activity in a CCK-producing cell line for comparison with BconP. The potent CCK-releasing hydrolysates were then tested for their suppression of the food intake by rats. BconB, BconT, and BconP stimulated high CCK secretion, with the highest by BconB. Orogastric preloading by BconB, but not by BconT, suppressed the 60-min food intake. A meal-feeding trial twice a day in the morning (a.m.) and evening (p.m.) for 10 d showed that BconB preloading before every meal attenuated the p.m. meal size, but not that a.m., resulting in an overall reduction of the daily meal size. These results demonstrate that the bromelain hydrolysate of β-conglycinin having potent CCK-releasing activity suppressed the appetite of rats under meal-feeding conditions.