Constituents of Cultivated Mulberry Tree

From the ethyl acetate extract of the cultivated mulberry tree ( Morus alba L.), two new flavonoid derivatives with a fused dihydrochalcone partial moiety were isolated, and named kuwanons K and L. The structures of kuwanons K and L were shown to be 1 and 2 respectively, on the basis of chemical and spectral data. Kuwanons K ( 1 ) and L ( 2 ) are regarded biogenetically as Diels-Alder adducts of a chalcone derivative and a dehydroprenylflavonoid derivative, and are the first example of a flavonoid derivative possessing a cyclohexene ring at a B ring of a flavonoid derivative. Key Word Index Morus alba - Moraceae - Kuwanon K - Kuwanon L - Flavonoid - Diels-Alder adduct 1 Part XI: NOMURA, T., T. F>UKAI, Y. HANO and S. URANO: Planta Med. submitted. 2 A part of this work was presented at the 102th Annual Meeting of the Pharmaceutical Society of Japan, Osaka, April, 1982.