Chem. Pharm. Bull. 54(10) 1451—1454 (2006)

land of China, and the rhizomes and roots are a source of Chinese crude drug “Niu-Wei-Cai”, which has been used for treatment of bronchitis, lumbago of renal asthenia, traumatic injury, asthenia edema, and bronchial dilation agents. It is a commonly used as traditional Chinese medicine and it has been recorded in an endemic Pharmacopoeia in China. Until now, only one literature of chemical investigation was reported on the rhizomes and roots of this plant, and two neotigogenin glycosides were isolated from the rhizomes and roots of S. riparia. As a part of our ongoing analyses of Chinese medicinal plants, we have surveyed the constituents of the rhizomes and roots of S. riparia. Here we report the isolation and characterization of four new constituents, 3-Oa -L-rhamnopyranosyl-(1→2)-[a -L-rhamnopyranosyl(1→6)]-b-D-glucopyranosyl 3b ,20a-dihydroxy-5a-furost22(23)-ene 26-O-b-D-glucopyranoside, named riparoside A (1), 3-O-a-L-rhamnopyranosyl-(1→2)-[a-L-rhamnopyranosyl-(1→6)]-b-D-glucopyranosyl 3b ,16b-dihydroxy-5apregnan-20-one 16-O-[5-O-b-D-glucopyranosyl 5-hydroxy4-methyl-pentanoic acid]-ester 26-O-b-D-glucopyranoside, named riparoside B (2), sucrosyl ferulic acid ester (3), and 3methoxy-4-isopropylbenzyl alcohol gentiobioside (4) together with 4 known flavonoid derivatives, rhamnetin, luteolin, quercetin and luteoloside by analysis of their Hand C-NMR spectra and comparison with published data. The powdered rhizomes and roots of S. riparia were extracted with EtOH. After evaporation of EtOH in vacuo, the ethanolic extract suspended in water was subjected to Diaion HP-20. The first aqueous eluate was discarded and the next methanolic eluate was recovered. After removed of solvent, the resultant was repeatedly column-chromatographed on silica gel and ODS to obtain eight compounds. Four flavonoid compounds were identified as known compounds; rhamnetin, luteolin, quercetin and luteoloside by comparison of their physical and spectral data with the reported values and on the basis of the spectroscopic evidence. Other two new steroidal compounds were named as riparoside A (1) and riparoside B (2), while the remaining two compounds (3, 4) were also new. Riparoside A (1), an amorphous power, [a]D 52.5° (MeOH), had a molecular formula of C51H84O22 determined by high resolution HR-FAB-MS (m/z 1071.3802 [M Na] ) as well as its C and distortionless enhancement by polarization transfer (DEPT) NMR data. The H-NMR spectrum (in CD3OD) showed three tertiary methyl signals at d 0.81 (3H, s), 0.84 (3H, s), and 1.48 (3H, s), one secondary methyl signal at d 0.94 (3H, d, J 6.7 Hz), one olefinic proton signal at d 4.35 (1H, dd, J 7.3, 14.6 Hz), a proton signal at d 4.84 (1H, m) attached to an ester group, together with four anomeric proton signals at d 4.23 (1H, d, J 7.9 Hz), 4.38 (1H, d, J 7.9 Hz), 4.70 (1H, s) and 4.83 (1H, s). The CNMR spectrum (in CD3OD) displayed total 51 carbon signals, which were composed of 27 signals due to steroidal sapogenol moiety and 24 carbon signals due to a sugar moiety. Sugar signals were assigned to be two terminal a-Lrhamnopyranosyl (rha I, II, C-1-6: d 101.7, 102.8; 72.4, 70.7; 72.3, 72.5; 73.8, 74.0; 69.8, 70.7; 18.1, 17.8, respectively), 26-O-terminal b-D-glucopyranosyl (C-1-6: d 104.7, 75.3, 75.2, 72.3, 79.8, 62.8), and 2,6-di-O-sugar-substituted-b-Dglucopyranosyl (C-1-6 d 102.6, 79.6, 75.4, 71.7, 76.8, 67.1) moieties. The heteronuclear multiple bonds correlation (HMBC) indicated the bounding sites of two terminal rhamnopyranosyl moieties, one terminal glucopyranosyl moiety and one substituted-glucopyranosyl moiety. That is, the HMBC between rhamnopyranosyl (I) H-1 at dH 4.70 and glucopyranosyl (I) C-2 at dC 79.6; rhamnopyranosyl (II) H-1 at dH 4.83 and glucopyranosyl (I) C-6 at dC 67.1; glucopyranosyl (I) H-1 at dH 4.38 and sapogenol C-3 at dC 77.9; and glucopyranosyl (II) H-1 at dH 4.23 and sapogenol C-26 at dC 76.1 were observed. Therefore, 1 showed the presence of 3O-a -L-rhamnopyranosyl-(1→2)-[a -L-rhamnopyranosyl(1→6)]-b-D-glucopyranosyl and 26-O-b-D-glucopyranosyl moieties. Moreover, the remaining carbon signals deducted the sugar-originating signals were 27, which were composed of three methyl carbons at d 12.7, 14.2, 21.5, nine methylene carbon at d 21.6, 2 29.9, 30.7, 33.2, 34.1, 35.6, 38.2, 40.5, one hydroxymethyl carbon at d 76.1, two oxygen-bearing October 2006 1451 Chem. Pharm. Bull. 54(10) 1451—1454 (2006)