Hypotensive Constituent, Kuwaman H, a New Flavone Derivative from the Root Bark of the Cultivated Mylberry Tree (Morus alba L.)

Abstract

A new flavone derivative, containing condensed dihydrochalcone partial structure named kuwanon H, was isolated from the root bark of the cultivated mulberry tree ( a variety of Morus alba L.).The structure was shown to be I on the basis -of chemical and spectral data.The compound (I) to rabbit (1 mg/Kg, i.v.) produced a significant hypotension.In the previous communication?we reported that a new flavone derivative, containing a hypotensive effect named kuwanon G (11). was isolated from the root bark of the cultivated mulberry tree (a variety of Morus alba L.), and the structure was shown to be 11.In this paper, we report the isolation and structure determination of a new flavone derivative, kuwanon H (I), isolated from 2 the ethyl acetate extract, and clarified as having hypotensive action in rabbit.The dried root bark of the cultivated mulberry tree was extracted succesively with n-hexane, benzene, and ethyl acetate.The ethyl acetate extract was fractionated sequentially by the polyamide column chromatography, and by combined HPLC Systems (Waters prep PAK-500/C18 followed by Waters prep PAK-500/silica gel) resulting in the isolation of a new prenylated flavone derivative, kuwanon H (I) in 0.13 8 yield.The compound (I) to rabbit (lmg/Kg, i.v.) showed a marked 2 hypotensive effect.3 Kuwanon H (I), amorphous powder, m.p. 186-19O0(decomp.),&lg2 = -536' (c=0.166 in methanol), had a molecular formula of C 45 H 44011(Anal. Calcd.for + C45H44011.HZO: C, 69.40; H, 5.95.Found: C, 69.62; H, 5.85.ms m/e M 760), and showed the following color reactions: Mg-HC1 test (red); Zn-HC1 test (orange); FeC13 test (dark green-dark purple), and showed the following spectra: j 0 :