Biotransformation of bisdemethoxycurcumin was examined using cultured plant cells of Morus bombycis, the Moraceae mulberry family, as biocatalysts. The cultured cells converted bisdemethoxycurcumin into ( R)-hexahydrobisdemethoxycurcumin in 30% yield in 1 day. The ( S)-stereoisomer has been isolated from Betula platyphylla Sukatchev var. japonica.