Chemical constituents from Canarium album Raeusch and their anti-influenza A virus activities

Two new dyhydrophaseic acid glucoside isomers, (1′S, 3′R, 5′S, 8′R, 2Z, 4E)-dihydrophaseic acid-3′-O-β-d-glucopyranoside (2) and (1′R, 3′S, 5′R, 8′R, 2Z, 4E)-dihydrophaseic acid-3′-O-β-d-glucopyranoside (4), together with 10 known compounds [myo-inositol (1), 3,4-dihydroxybenzoic acid (3), 3-O-galloyl quinic acid (5), ellagic acid (6), gallic acid (7), ethyl gallate (8), scopoletin (9), ellagic acid-4-O-β-d-glucopyranoside (10), ellagic acid-4-O-α-l-rhamnopyranoside (11), and isocorilagin (12)] were isolated from the chloroform extract of Canarium album Raeusch fruits by repeated chromatography on macroporous adsorption resin, silica gel, Sephadex LH-20, Toyopearl HW-40F, and reverse-phase C18 columns, etc. Their structures and absolute configurations were determined by comprehensive analysis of 1D- and 2D-nuclear magnetic resonance (NMR), high-resolution electron spray ionization mass spectrometry (HR-ESI–MS), ESI–MS, optical rotation, circular dichroism spectra, and comparison of NMR data with data of known compounds. Bioassay of their anti-influenza virus A activities showed that compounds 9 and 12 displayed a significant inhibitory effect with IC₅₀ values of 22.9 ± 3.7 and 5.42 ± 0.97 μg/ml, respectively.