Four New Steroidal Saponins from the Roots of Dracaena cambodiana with NO Production Inhibition Activity in LPS Activated RAW 264.7 Cells

Abstract

Seven steroidal saponins including three new 16,23-cyclocholestanes (1-3) and one new pregane (4) were isolated from the roots of Dracaena cambodiana Pierre ex Gagnep. Their chemical structures were elucidated to be (23R,25R)-26-O-β-D-glucopyranosyl-16,23-cyclocholesta-5,17(20)-dien-22-one-3β,16α,26-triol-3-O-α-L-rhamnopyranosyl-(1→2)-[α-L-rhamnopyranosyl-(1→3)]-β-D-glucopyranoside (1), (23R,25R)-26-O-β-D-glucopyranosyl-16,23-cyclocholesta-5,17,20(22)-trien-3β,22,26-triol-3-O-α-L-rhamnopyranosyl-(1→3)-β-D-glucopyranoside (2), (23R,25R)-16,23-cyclocholesta-5,16,20(22)-trien-3β,22,26-triol-3-O-α-L-rhamnopyranosyl-(1→3)-β-D-glucopyranoside (3), 3β-[(O-α-L-rhamnopyranosyl-(1→3)-[α-L-rhamnopyranosyl-(1→2)]-β-D-gluco-pyranosyl)oxy]-pregna-5,17(20)-diene-16-one-20-carboxylic acid 4''''-O-β-D-glucopyranosylisopentyl ester (4), cambodianoside A (5), diosbulbiside C (6), and diosbulbiside D (7), by IR, HR-ESI-MS, 1D and 2D NMR spectra. Compounds 1 and 4-7 inhibited nitric oxide (NO) production in lipopolysaccharide activated RAW 264.7 cells with IC₅₀ values ranging from 19.03±1.84 to 67.92±3.81 μM, whereas compounds 2 and 3 were inactive with IC₅₀ values over 100 μM.

Keywords: Asparagaceae; Dracaena cambodiana; cambodianoside G−J; nitric oxide inhibition activity; steroidal saponin.