Bioactive Constituents from Chinese Natural Medicines. XVII. Constituents with Radical Scavenging Effect and New Glucosyloxybenzyl 2-Isobutylmalates from Gymnadenia conopsea

Abstract

The methanol-eluted fraction of the methanolic extract from the tubers of Gymnadenia conopsea was found to show radical scavenging activities for DPPH and super oxide anion ( . O 2 ؊ ) radicals. Three new glucosyloxybenzyl 2-isobutylmalates, gymnosides VIII, IX, and X, were isolated from this natural medicine together with 58 known constituents. The stereostructures of gymnosides were elucidated on the basis of chemical and physicochemical evidence. In addition, the phenanthrene and dihydrostilbene constituents showed radical scavenging activities and suggested the following structural requirements on radical scavenging activities; a) phenanthrenes: 1) dihydrogenation at the 9,10-positions enhances the activities, 2) the 1 or 3-p-hydroxybenzyl group enhances the activities; b) dihydrostilbenes: 1) methylation of the 3-position reduces the activities, 2) the 2-and/or 6-p-hydroxybenzyl groups enhance the activities.

Bioactive Constituents from Chinese Natural Medicines. XXXII. Aminopeptidase N and Aldose Reductase Inhibitors from Sinocrassula indica: Structures of Sinocrassosides B4, B5, C1, and D1-D3

“…The 1 H-(DMSO-d 6 , Table 1) and 13 C-NMR (Table 2) C 169.3). On the basis of this evidence, the structure of sinocrassoside D 3 was determined (6).…”

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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.

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“…(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.…”

“…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.…”

“…[1][2][3] Acid hydrolysis of 1a with 1.0 M HCl liberated quercetin (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) August 7, 2008 Jϭ8. 2 Table 1) and 13 …”