Gambir, an official pharmacopoeic medicine in Japan, is the aqueous extract of the leaves and young twigs of Uncaria gambir ROXB. (Rubiaceae).2) The extract has been used for the treatment of diarrhea and sore throat as an astringent medicine in Southeast Asia, 3) and also for hoarseness, as an ingredient of the kampo medicine "Kyoseihatekigan."Flavan monomers, (ϩ)-catechin (1) and (ϩ)-epicatechin (2), 4) several other dimeric compounds 5) related to 1, as well as alkaloids, 6,7) have been reported to be the constituents. Our investigation on the polyphenolic contents of a manufactured gambir product led to the isolation of 1, 2, and seven dimeric flavans 3-9. Although the seven dimeric flavans were known compounds, the present study revealed that the stereostructures of four of the chalcane-flavan dimers should be revised to 6-9. Their 1 H-and 13 C-NMR spectral assignments are also shown here, since those were not reported in detail previously. 5,8) Results and DiscussionA manufactured product of gambir purchased in Japan was extracted with MeOH, and the extract was fractionated by column chromatography on Dia-ion HP-20 using aqueous MeOH. (ϩ)-Catechin (1) was crystallized from the eluate with 20% MeOH, and the mother liquor was subjected to column chromatography on a Toyopearl HW-40 to give a fraction containing both monomeric and dimeric flavans. The fraction was further chromatographed on octadecylsilyl (ODS) silica gel, Sephadex LH-20, and MCI-gel CHP-20P columns to give (ϩ)-catechin (1), (ϩ)-epicatechin (2), procyanidin B1 (3), 9,10) procyanidin B3 (4), 11) gambiriin C (5), 5) and gambiriin A1 (6). The eluate, with 40% MeOH from the column of Dia-ion HP-20, was separated in an analogous way to give gambiriin A2 (7), gambiriin B1 (8), and gambiriin B2 (9). Gambiriin A1 (6) was obtained as an amorphous powder. The dimeric molecular formula, C 30 H 28 O 12 , was indicated by the [MϩH] ϩ ion peak at m/z 581 in the electrospray-ionization (ESI)-MS. The showed a large coupling constant (7.5 Hz), indicating that the lower unit was 2,3-trans catechin. The 2,3-trans structure was also validated by the 13 C-NMR spectrum, which showed the C-2 L signal at d 82.5. The remaining set of the methine-methine-methylene protons [d: 2.56 (H-ga U ), 2.95 (Hgb U ), 4.68 (H-b U ), 4.75 (H-a U )] was attributable to the substituted propyl group in the chalcane structure. The molecular formula of 6, which was indicated by the ESI-MS, also substantiates this open-chain chalcane structure.The rotating frame nuclear Overhauser effect spectroscopy (ROESY) of 6 showed correlations of H-a U /H-2Ј L and Hb U /H-2Ј L , indicating the presence of an interflavonoid link between position C-8 L and the upper chalcane unit (C-a U ) (Fig. 2). These correlations would not be observed if the linkage occurred at C-6 L . The aliphatic protons of 6 appeared as broad signals, due to the restricted rotation around the interflavonoid linkage, which confirmed the location of the linkage at C-8 L .The assigned structure of 6 based on these data suggest...

Gambir (asen'yaku in Japanese), an aqueous extract of leaves and young twigs of Uncaria gambir Roxb., has traditionally been used as a treatment for diarrhea and dysentery as an internal medicine and for sore throat as a gargle. Although it is a pharmacopoeic medicine in Japan, the quantitative evaluation of its constituents has not yet been adopted in the Japanese pharmacopoeia. We analyzed polyphenolic constituents in 31 gambir and related products to establish evaluation methods, since gambir contains large amounts of polyphenolic constituents. The total ‰avan contents in the samples revealed using the vanillin-HCl estimation method ranged from 24 79％. Reversed-phase high performance liquid chromatography (RP-HPLC) analysis indicated that catechin was the most abundant constituent in each sample, with contents in the range of 7 76％. The catechin contents in the gambir products between theˆrst and third quartiles were 28 54％. Thus, the lower limit of the catechin content in gambir products can be set at around 20％ for quality management. Fifteen tested samples were subjected to HPLC analysis to show the presence of epicatechin (1.5％ on average) and the dimeric compounds procyanidin B1, procyanidin B3, and gambiriin A1 (ca. 1％ each). The molecular weight distributions of polymeric ‰avans in the gambir products were analyzed by gel permeation chromatography (GPC) and showed that the average degree of polymerization for each sample was 3 to 7. These results indicate that the combination of the vanillin-HCl method, RP-HPLC analysis, and GPC analysis gives valuable information for evaluating the polyphenolic proˆles of gambir products.

New Dimeric Flavans from Gambir, an Extract of Uncaria gambir -[isolation and structure determination of procyanidin dimer (I), gambirflavan D1 (II) and gambirflavan D2 (III)]. -(TANIGUCHI, S.; KURODA, K.; YOSHIKADO, N.; DOI, K.-I.; TANABE, M.; SHIBATA, T.; YOSHIDA, T.; HATANO*, T.; Heterocycles 74 (2007) 1, 595-605; Grad. Sch. Med., Dent. Pharm. Sci., Okayama Univ., Okayama 700, Japan; Eng.) -C. Cyrus 23-201

No abstract

Die direkte Trimethylsilylierung von Olivin (ungefähre Formel (Mg"‐8Fe0′2)2 SiO4) lieferte Teil‐Trimethylsilylderivate von Ortho‐ und Disilicaten, deren nicht‐silylierte Silanol‐ 122 gruppen mit dem Alkohol verestert werden, der als organisches Lösungsmittel in der Trimethylsilylierung verwendet wurde.