Nine flavonoids and seven Diels-Alder type adducts were isolated from the acetonic extract of MORUS NIGRA I. root bark, and three flavonoids and six Diels-Alder type adducts were isolated from the acetonic extract of M. NIGRA L. callus. However, none of the metabolites isolated from the root bark was found in the cell culture. Moreover, adducts isolated from the plant and cell culture showed not only a different cyclohexene ring substitution but also a different stereochemistry, that was found CIS-TRONS in the metabolites isolated from callus, and TRANS-TRANS in those isolated from the root bark.