Many types of glycosides are widely distributed as major constituents in medicinal plants. However, due to their hydrophilic properties, they are poorly absorbed from gastro intestinal tract into body fluid, but their aglycones formed by intestinal bacterial hydrolysis are readily absorbed. Therefore, intestinal bacteria play an important role in increasing absorption and efficacy of drugs including glycosides. In nature, there is a special type of glycoside, C-glycosides, such as those of flavone, isoflavone, chromone, xanthone, anthrone, and gallic acid. Since C-1 of the sugar ring is directly connected to the aglycone by C-C bonding, C-glycosides are usually resistant against acidic and enzymatic hydrolysis in contrast with the corresponding O-glycosides. Thus, with the prospect of improving the stability, various C-glycoside analogues mimicking bioactive but labile O-glycosides have been prepared for developing the new drugs.2) In addition, a lot of publications describing in detail about O-glycosidase appeared, but that of C-glycosidase did not.On the other aspects, in the last two decades, C-glucosyl bond-cleaving reactions by human intestinal bacteria were reported. 1,[3][4][5][6][7][8][9][10][11] Despite of the growing importance of C-glycosides in the field of pharmaceuticals, characteristic features of C-glucosyl bond-cleaving enzymes involved in its metabolism were still remain to be unclear.Recently, we isolated a new bacterial species named strain PUE that transforms a C-glucoside puerarin to its aglycone daidzein.1) The aglycone moiety is normally detected easily because of UV active, however, the liberated sugar segment from C-glucoside has not been yet identified. The structural elucidation of the liberated sugar moiety could yield a valuable clue in revealing the reaction mechanism (Fig. 1). In the present paper, we describe the structural elucidation of the sugar moiety after cleavage of a C-glucosyl bond of puerarin by anaerobic incubation with a human intestinal bacterium, strain PUE, and a cell-free extract. Results Synthesis of [6؆,6؆-D 2 ]puerarin (8)Since puerarin (1) has only one primary alcohol at C-6 of the sugar moiety, we targeted it for labeling with deuterium. First, 1 was treated with benzaldehyde and zinc chloride to give 2. Other hydroxyl groups of 2 were acetylated with acetic anhydride in pyridine to obtain 3. Benzylidene acetal of 3 was hydrolyzed under an acidic condition to afford 4. The primary hydroxyl of 4 was oxidized to carboxylic acid with a Jones reagent to give 5. The acetyl groups of 5 were removed by alkali to give 6, then, the carboxyl group was esterified to yield 7 by a usual method. We failed the reduction of 7 to the corresponding alcohol with LiAlD 4 due to decomposition, but 8 was prepared from 7 by slow addition of CD 3 OD into the reaction mixture containing NaBD 4 . 12) In this reaction, the addition of CH 3 OH instead of CD 3 OD gave a mixture of 8 and [6Љ-H,6Љ-D]puerarin (ca. 1 : 1 ratio), because hydrogen atoms originated from CH 3 OH were also incorp...

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The methanol extracts of the leaves of Crataegus pinnatifida showed potent inhibitory activities against HIV-1 protease at a concentration of 100 micrograms/ml. The subsequent fractionation and isolation of the extract gave two active compounds. Their structures were identified as uvaol (1) and ursolic acid (2) by spectral data. These active compounds inhibit HIV-1 protease with IC50 values of 5.5 and 8.0 microM, respectively.

An HPLC-PAD-MS(n) method was employed to profile the phenolic compounds of the aerial part of Artemisia pectinata (Neopallasia pectinata), a plant with no previous reports concerning its phenolic constituents. Three isomers of trans-caffeoylquinic acid accompanied by cis-5-caffeoylquinic acid, six isomers of trans-dicaffeoylquinic acid, two isomers of methyl trans-dicaffeoylquinate (including one new isomer), a trans-caffeoylferuloylquinic acid and three flavanoids were identified unambiguously by analysis of their UV and MS(n) spectra in comparison with standard compounds that were isolated from natural sources, or synthesised, or were surrogate standards (green coffee extract). Other compounds were identified by analysis of their UV and MSn data in comparison with those reported in the literature. MS(n) experiments also suggested the presence of groups of dicaffeoylquinic acid glycosides, caffeoylquinic acid diglycosides, caffeoylquinic acid glycosides and quinic acid diglycosides.