Chemical constituents of Aeschynanthus bracteatus and their weak anti-inflammatory activities

Chemical examination of the EtOAc extract from the aerial parts of Aeschynanthus bracteatus led to isolation of four phenylethanol glycosides, aeschynanthosides A-D (1-4), and 55 known constituents, including 8 phenylethanoids, 23 phenols, 5 lignans, 7 flavonoids, 9 terpenoids, and 4 others. Their structures were elucidated mainly by detailed spectroscopic studies and comparison with published data. All 59 compounds were isolated for the first time from an Aeschynanthus species. The isolates were also tested for inhibitory activities against LPS-induced NO production in RAW 264.7 macrophages. Aeschynanthoside D (4) and naringenin (41), within the concentration arrange tested (50-100 microg/mL), showed very weak dose-dependent effects with the inhibition rate of 24.2%, 35.4%, 66.0%, and 9.5%, 40.1%, 65.0%, respectively, relative to positive controls.