The investigation on the leaves of Morus alba L. was carried out to find the relationship of the constituents and the pharmacological activities.  The isolation and purification were performed by various  chromatographies such as silica gel, Sephadex LH-20, RP-C₁₈ column chromatography and so on.  Further   detailed investigation on the fraction of the ethanol extract of leaves of Morus alba yielded four Diels-Alder type adducts mulberrofuran F₁ (1), mulberrofuran F (2), chalcomoracin (3), kuwanon J (4), together with two    chalcones morachalcone A (5), isobavachalcone (6), and three flavones norartocarpetin (7), kuwanon C (8), 6-geranylapigenin (9).  Their structures were elucidated by the spectral analysis such as NMR, MS etc.    Compounds 1, 6 were isolated from this plant for the first time, compounds 4–5, 7–9 were isolated from the leaves of Morus alba L. for the first time, among which 1 was a new compound.  Compounds 1–5 were   evaluated for the cytotoxicity against A549, Bel7402, BGC823, HCT-8 and A2780 cell lines in vitro by MTT method, but only compounds 1–3 showed cytotoxicity against several human cancer cell lines.