71 桑白皮の血圧下降成分Moracenin類の構造

概要

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From the Oriental medicine "sohakuhi", the root bark of Morus plants (Moraceae), novel isoprenoid flavone derivatives, moracenin A, B, C and D, having hypotensive activity were isolated. Moracenin B, C_<40>H_<36>O_<11>, [α]_D-466°, was subjected to spectral analysis to reveal the presence of a 5,7,2',4'-tetrahydroxy-3,8-disubstituted flavone moiety, a 2,4-dihydroxyphenyl group, a 2,4-dihydroxybenzoyl group and a 1-methylcyclohexene ring. The observation of ^<13>C-^1H spin couplings deduced the gross structure of moracenin B to be I. Moracenin A, C_<45>H_<44>O_<11>, [α]_D-427°, moracenin C, C_<45>H_<44>O_<11>, [α]_D-445°, and moracenin D, C_<40>H_<38>O_<12>, [α]_-388°, were similar in spectral properties to moracenin B, which, along with the fact that moracenin A, C and D coexist with moracenin B, indicated that moracenin A, C and D are congeners of moracenin B. Analysis of the spectra led to the conclusion that the gross structures of moracenin A, C and D are represented by formulas II, III and IV (except for stereochemistry). The relative stereostructures of the moracenins were established by the ^1H NMR evidence and the absolute stereostructures deduced by the CD evidence. The moracenins having unique skeletons appear to be biosynthesized from two units of chalcone and two or three isoprene units.
天然有機化合物討論会の論文
1980-09-10