Each of an antioxidant, an antimicrobial agent, an antitumor agent, a food and beverage product, cosmetics, a quasi-drug and a pharmaceutical of the present invention contains a new flavanone compound represented by the following structural formula: ##STR00001## Alternatively, each of an antioxidant, an antimicrobial agent, an antitumor agent, a food and beverage product, cosmetics, a quasi-drug and a pharmaceutical of the present invention contains at least one flavanone compound selected from the group consisting of nymphaeol-A, nymphaeol-B, and nymphaeol-C.