During the course of our studies on bioactive constituents from Chinese natural medicines, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] we found that the methanolic extract of the whole plant of Sinocrassula indica (Crassulaceae) inhibited the increase of serum glucose levels in both sucrose-and glucose-loaded rats.2) From the methanolic extract, 15 acylated flavonol glycosides, sinocrassosides A 1 -A 12 and B 1 -B 3 (7-21), were isolated together with 11 flavonoids (22-32), 2 megastigmanes (33, 34), Lphenylalanine, and guanosine [1][2][3] and several fravonoid constituents were found to show hepatoprotective effects on Dgalactosamine-induced cytotoxicity in primary cultured mouse hepatocytes.1) As a continuing study on the constituents from S. indica, we additionally isolated six new flavonol glycosides, sinocrassosides B 4 (1), B 5 (2), C 1 (3), D 1 (4), D 2 (5), and D 3 (6). This paper deals with the isolation and structure elucidation of 1-6 as well as aminopeptidase N and aldose reductase inhibitory activities of the isolated compounds.The methanolic extract from the dried whole plant of S. indica (7.7% from the dried plant) was partitioned into an EtOAc-H 2 O (1 : 1, v/v) mixture to furnish an EtOAc-soluble fraction (2.5%) and an aqueous phase. The aqueous phase was further extracted with n-BuOH to give an n-BuOH-soluble fraction (1.7%) and an H 2 O-soluble fraction (3.4%), which was described previously.2) From the EtOAc-and nBuOH-soluble fractions, 1 (0.0068%), 2 (0.0007%), 3 (0.0027%), 4 (0.0006%), 5 (0.0074%), and 6 (0.0010%), were purified using normal-and reversed-phase silica gel chromatographies and finally HPLC. (28), together with L-rhamnose and D-glucose, which were identified by HPLC analysis. [1][2][3][4][5][6][7][9][10][11][12][13] The 1 H-(DMSO-d 6 , Table 1) and 13 C-NMR (Table 2) spectra 1a, which were assigned by various NMR experiments, showed signals assignable to meta-coupled aromatic protons [d 6.47, 6.83 (1H each, both d, Jϭ1.8 Hz,6,] and orthoand meta-coupled ABC-type protons [d 6.85 (1H, d, 1438 Vol. 56, No. 10 Bioactive Constituents from Chinese Natural Medicines. XXXII. Yamashina-ku, Kyoto 607-8412, Japan: and b Pharmaceutical Research and Technology Institute, Kinki University; 3-4-1 Kowakae, Higashi-osaka, Osaka 577-8502, Japan. Received June 7, 2008; accepted July 22, 2008; published online August 7, 2008 From the methanolic extract of the whole plant of Sinocrassula indica (Crassulaceae), six new flavonol glycosides, sinocrassosides B 4 (1), B 5 (2), C 1 (3), D 1 (4), D 2 (5), and D 3 (6), were isolated together with 30 compounds. The structures of 1-6 were elucidated on the basis of chemical and physicochemical evidence. In addition, several constituents were found to show inhibitory effects on aminopeptidase N and aldose reductase.
