Chem. Pharm. Bull. 54(2) 234—236 (2006)

plant, the rhizomes of which have been used for the treatment of enteritis and bacillary dysentery in China and Korea. Several flavonol glycosides, lignans, monoterpenes, tannins, and triterpenenes have been isolated as chemical constituents of this plant. A previous bioactivity-guided investigation for the aerial parts of this plant demonstrated that flavonol glycosides possess hepatoprotective activity in primary cultures of rat hepatocytes injured by H2O2. 1) Thus, the aerial parts of R. podophylla were recollected and reinvestigated to search for other active compounds. From EtOAcand n-BuOH-soluble extracts, three new acetylated flavonol glycosides (1—3), along with eleven known compounds, were isolated and characterized. Compound 1 was obtained as a dark yellow powder and gave a quasimolecular ion [M H] at m/z 461.1091 in high resolution fast atom bombardment mass spectroscopy (HR-FAB-MS), consistent with an elemental formula of C22H20O11. The H-NMR spectrum of 1 showed two broad singlet proton signals at d 6.15 (1H, br s, H-6) and 6.38 (1H, br s, H-8), and two doublet proton signals at d 6.88 (2H, d, J 8.8 Hz, H-3 , 5 ) and 8.05 (2H, d, J 8.8 Hz, H-2 , 6 ), assignable to a kaempferol moiety. An anomeric proton appeared at d 5.51 (1H, br s, H-1 ) along with other glycosidic protons in the range of d 3.61 to 4.15. In addition to these proton signals, a methyl proton signal was observed at d 1.90 due to the presence of an acetyl group. These data suggested that compound 1 contained an acetylated sugar. By comparison of Hand C-NMR data of a sugar in 1 with those in the literature, the sugar of 1 proved to be 5 -acetyl-arabinofuranoside and the position of an acetyl group was confirmed by the HMBC correlations from H2-5 (d 3.78, 4.02) to a carbonyl group (d 169.4). The position of sugar attachment to the aglycone was found to be the C-3 position through an ether linkage based on the observed J correlations between H-1 (d 5.51) and C-3 (d 133.2) in the heteronuclear multiple-bond correlation spectroscopy (HMBC) data. The stereochemistry of the sugar in 1 was determined to be L configuration by GC analysis of acid hydrolysate. Therefore, the structure of compound 1 was elucidated as kaempferol-3-O-a-L5 -acetyl-arabinofuranoside. A molecular formula of C22H20O11 of compound 2 was deduced from its HR-FAB-MS (Found at m/z 461.1081 [M H] , Calcd for C22H21O11 461.1084). The Hand CNMR spectral data of 2 were similar to those of 1, and permitted the assignment of the aglycone and sugar moiety in 2 except for the position of an acetyl group in the sugar. The signal of C-2 appeared to move upfield and that of C-3 was observed in the downfield region when compared to those of 1 in the C-NMR spectrum. This observation suggested the location of an acetyl group on the C-3 of sugar, which was ascertained by the cross peak between d 4.71 (H-3 ) and 170.0 (C O) in the HMBC data. Based on the above data, the structure of compound 2 was determined as kaempferol 3-O-a-L-3 -acetyl-arabinofuranoside. Compound 3 displayed a sodiated ion at m/z 541.0957 [M Na] corresponding to a molecular formula of C24H22O13Na in the HR-FAB-MS. The signals belonging to a quercetin skeleton were observed at d 6.18 (1H, br s, H-6), 6.37 (1H, br s, H-8), d 6.84 (1H, d, J 8.7 Hz, H-5 ), 7.38 (1H, d, J 8.7 Hz, H-6 ), and 7.39 (1H, br s, H-2 ) in the HNMR spectrum. Also, two methyl proton peaks appeared at d 1.92 and 2.09 suggesting that two acetyl groups were present in 3. When the chemical shifts of this compound were compared to those of an arabinofuranoside in the literature, two signals at d 63.3 (C-5 ) and 79.6 (C-3 ) appeared to be shifted downfield. These findings suggested that two acetyl groups were attached to C-3 and 5 . Furthermore, the HMBC data confirmed these substitutions by observation of long range correlations between d 4.66 (H-3 ) and 170.2 (C O) as well as d 3.89 and 4.11 (H2-5 ) and d 170.0 (C O). These data enabled us to assign the structure of 3 as quercetin 3-O-a-L-3 ,5 -diacetyl-arabinofuranoside. Other isolates were elucidated as kaempferol, quercetin, myricetin-3-O-a-L-arabinofuranoside, quercetin-3-O-b-D234 Notes Chem. Pharm. Bull. 54(2) 234—236 (2006) Vol. 54, No. 2