This invention provides useful applications of cashew apple. This invention also provides a naturally occurring active ingredient having useful activities, such as alpha-amylase inhibitory activity, lipase inhibitory activity, and antibacterial activity against Propionibacterium acnes. The invention also provides a composition containing cashew apple-derived proanthocyanidin having excellent alpha-amylase inhibitory activity, lipase inhibitory activity, and antibacterial activity against Propionibacterium acnes, which is prepared by allowing a plant fiber-degrading enzyme (e.g., pectinase) to react with a cashew apple and concentrating the resultant with the use of an ultrafiltration membrane. Further, the invention provides a proanthocyanidin compound having a novel structure.