Abstract
From the underground parts of Cimicifuga japonica were isolated cimigenol xyloside (II), 25-O-acetylcimigenol xyloside (VI), and two new triterpene glycosides, VII named 25-anhydrocimigenol arabinoside, mp 272-274°, [α]D +29.7° and VIII, mp 280-281°, [α]D-23.7°. On acid hydrolysis, VII afforded a ketone (XI), C30H46O4·CH3OH, mp 182-184° (from MeOH), [α]D+35.4°, as the major product of the aglycone part, and arabinose as the sugar part. From chemical properties of XI and comparison of its spectral data with those of dahurinol (III), 16, 23-epoxy-cycloart-25-ene-3β, 24-diol-15-one was proposed as the structure of XI. Degradative hydrolysis of VII with NaIO4-cyclohexylamine gave two products, the genuine aglycone 25-anhydrocimigenol (XIV), C30H46O4, mp 194-195°, [α]D+61.3°, and its 3-formate (XIII), mp 181-183°. On the basis of chemical and spectral evidences, XIV was presumed to be 25-anhydrocimigenol, which was confirmed by chemical derivation of cimigenol (I) to XIV. The formyloxy group of XIII was found to be located in C-3 position from comparison of its NMR spectrum with that of 25-anhydrocimigenol-3-acetate (XVI), indicating the site of the glycosidic linkage of VII. These results showed that VII is 25-anhydrocimigenol arabinoside (formula VII). The ketone (XI) is one of the artificia1 products formed from 25-anhydrocimigenol (XIV) on acid hydrolysis of VII, and a possible reaction mechanism for conversion of XIV into XI was suggested.
