Extractives of kitakobusi Magnolia kobus DC. var. borealis Sarg., 1: Lignans of leaves

The ethanol extract was obtained fro the leaves of kitakobushi Magnolia kobus DC. var. borealis Sarg. and was successively fractionated by use of column chromatography with n-hexane and dichloromethane as elusion solvents. The crude materials obtained from the dichloromethane solubles were purified by silica gel column high performance liquid with C18 column, thin layer and preparative thin layer chromatographies. Consequently, twelve compounds (I-XII) were obtained. Structural elucidation of these compounds was determined by spectroscopic procedures. They were nine furofuranoid lignans (I-IX) and three tetrahydrofuranoid lignans (X-XII). The aryl groups of furofuranoid lignans (I-IX) were substituted with guaiacyl, vertryl, syringyl, 3,4,5-trimethoxyphenyl and piperonyl groups at 2 and 6 positions on furofuran, 3,7-dioxabicyclo O3,3,0 octane Furthermore, six compounds (I-VI) possessed two aryl groups i equatorial/equatorial form at 2 and 6 positions on furofuran system. On the other, two aryl groups of three compounds VII-IX revealed axial/equatorial from at the same position. These compounds were identified as kobusin(I), aschantin(II), eudesmin(III), magnolin(IV), yangambin(V), medioresinol(VI), fargesin (VII), phillygenin(VIII) and epimagnolin(IX) by the results of spectroscopic analyses. Two (X and XI) of tetrahydrofuranoid lignans were novel compounds. The ultraviolet, infrared, 1H-NMR and mass spectra of compound X named kobushinol A, indicated that methyl, guaiacyl and 3,4-dimethoxybenzyl alcohol groups were substituted at tetrahydrofuran system. A detailed correlation of proton-proton and proton-carbon on tetrahydrofuran ring for compound X was determined by 1H-1H COSY, HMBC, NOESY spectra. The C(2)-H, C(3)-Me and C(4)-C(alpha-4) bonds on the tetrahydrofuran system were assigned to the cis-relation