New compounds from the aerial parts of Calligonum mongolicum

Abstract Previously undescribed compounds, (R)-4-(4-hydroxyphenyl)-2-butanol 2-O-(6-O-galloyl)-β-D-glucopyranoside (1) and (E)-5-(4-hydroxyphenyl)pent-2-enoic acid (2), together with 20 known compounds (3-22) were isolated from the aerial parts of Calligonum mongolicum. Compound 3 was obtained from a natural source for the first time, and all of the compounds (1-22) were reported for the first time in this plant. The structural elucidation of compounds 1 and 2 were performed mainly by HRFABMS, HREIMS, 1H and 13C NMR, 1H–1H COSY, HMQC, and HMBC spectroscopy. Some of the enzyme inhibitory activities of the isolated compounds were estimated, and catechin (7) showed ten times higher phenoloxidase inhibitory activity (IC50 9.1 μM) than epicatechin (8) (IC50 148.3 μM). Compounds 7 and 8 have a common molecular structure, except for their stereochemistry, and this result was supported by a reproducibility test using pure guaranteed authentic samples.