78(PB2-8) モントブレチアの新サポニンに関する研究(ポスター発表の部)

概要

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From the methanolic extract of the corms of montbretia (Crocosmia crocosmiiflora N.E.Br, Iridaceae), four novel saponins named crocosmiosides A(1), B(2), C(3) and D(4) were isolated. By means of chemical and enzymatic degradations, compounds 5-16 were obtained. On the basis of chemical and spectral evidence, the structures of the saponins and their degradation products were determined as shown in Fig. 1-3. All the saponins are the triterpenoid bisdesmoside consisted of polygalacic acid, glucose, arabinose, fucose, rhamnose, xylose, apiose and a hydroxylated carboxylic acid. Compounds 1, 2 and 4 possess 2,9,16-trihydroxyhexadecanoic acid derivatives and 3 possesses 2,16 -dihydroxy-9-oxohexadecanoic acid derivative as acyl moieties. To our knowledge, crocosmiosides are the first examples of saponins containing such carboxylic acids as acyl moieties. The linkage site of carboxylic acids in 1-4 was determined by comparing the ^1H and ^<13>C-NMR spectra of 1-4 with those of desacyl derivatives. The sapogenin, polygalacic acid, was previously characterized as the aglycone part of polygalacins D and D_2 (saponins of Platycodon grandiflorum), while sugar moieties are similar to those of onjisaponins and senegins. As most saponins so far obtained from monocotyledons are steroid saponins, it is interesting that triterpenoid saponins were obtained from montbretia belonging to monocotyledons.
1987-07-25