Saponins of pericarps of sapindus mukurossi and solubilization of mono desmosides by bis desmosides
Kimata, H.; Nakashima, T.; Kokubun, S.; Nakayama, K.; Mitoma, Y.; Kitahara, T.; Yata, N.; Tanaka, O.
Chemical and Pharmaceutical Bulletin 31(6): 1998-2005
ISSN/ISBN: 0009-2363 Accession: 006362980
From pericarps of Sapindus mukurossi (Japanese folk medicine: Enmei-hi), saponins of hederagenin (1), 2-7, 9, 11 and 12 were isolated along with sapindosides A (10) and B (8), both of which have already been isolated from this crude drug. Saponins 7 and 9 were identified as .alpha.-L-arabinopyranosyl(1 .fwdarw. 3)-.alpha.-L-rhamnopyranosyl(1 .fwdarw. 2)-.alpha.-L-arabinopyranoside and .alpha.-L-arabinofuranosyl,(1 .fwdarw. 3)-.alpha.-L-rhamnopyranosyl(1 .fwdarw. 2)-.alpha.-L-arabinopyranoside of 1, respectively, both of which were recently isolated from Lecaniodiscus cupanoides by Sandberg et al. New saponins named mukurozi-saponins E1 (11) and G (12) were proved to be the mono-acetate of 8 and the di-acetate of 7, respectively. By means of mass and 13C NMR spectroscopy, the locations of the acetyl groups of 11 and 12 were established at the 4-hydroxyl group of the xylosyl unit of 8 and at the 3,4-hydroxyl groups of the terminal arabinosyl unit of 7, respectively. The other new saponins, named mukurozi-saponins X (6), Y1 (5) and Y2 (4), were revealed to be .beta.-sophorosyl esters of 10, 8 and 7, respectively, by comparison of the mass and 13C NMR spectra with those of the .beta.-sophorosyl ester of 1 (13), which was synthesized from 1 as a reference compound for the study of the anomalous glycosylation shifts. Studies on the structures of the remaining saponins, 2 and 3, are in progress. The water solubilities of the monodesmosides, 7-9, which cause remarkable enhancement of the absorption of sodium ampicillin from rat intestine and rectum, were greatly increased by the bisdesmosides, 4-6.