31 Dextransucraseに対する阻害物質,Ribocitrinの構造

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Dextransucrase of Streptococcus mutans produces from sucrose insoluble polysaccharides which mediate bacterial adhesion on tooth surface and plays an important role in the initiation of dental caries. Ribocitrin, a novel inhibitor of the dextransucrase was isolated from a cultured broth of Streptomyces sp. Hydrolysis of ribocitrin(I) gave D-ribose and (+)-homocitric acid lactone. The result of hydrolysis, FDMS and ^<13>C NMR indicated that ribocitrin(I) consisted of three D-riboses and one (+)-homocitric acid. Oxidation of ribocitrin(I) with sodium periodate followed by reduction with sodium borohydride and mild hydrolysis afforded compound V of which ^<13>C and ^1H NMR spectra showed the elimination of a terminal D-ribose moiety from ribocitrin. Equimolar amounts of 2,3,5-tri-O-methylribose(II), 3,5-di-O-methylribose(III), and 2,5-di-O-methylribose(IV) were obtained by Hakomori methylation of ribocitrin(I) followed by hydrolysis. Hydrolysis of methylated V gave II and IV but not III. Thus the structure of ribocitrin(I) was elucidated to be 2-(S)-[O-α-D-ribofuranosyl-(1→2)-O-α-D-ribofuranosyl-(1→3)-α-D-ribofuranosyloxy]-1,2,4-butanetri-carboxylic acid agreed with the ^<13>C NMR, ^1H NMR, FDMS and IR spectra of ribocitrin(I). The α-anomeric configuration of three glycoside linkages was determined by the vicinal coupling constants (J=3.5 and 4.0Hz) of the anomeric protones in the ^1H NMR spectrum of ribocitrin(I).
天然有機化合物討論会の論文
1981-09-10

31 Dextransucraseに対する阻害物質,Ribocitrinの構造

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