Iridoid constituents from the male flower ofEucommia ulmoidesand their promotion proliferation on ESF-1

Four new iridoids (1, 2, 12, and 13), together with nine known iridoids (3-11), were isolated from the male flowers of Eucommia ulmoides Oliver and were characterized as 3β-methoxyartselawnin C (1), 6β-hydroxyl-1β,3β-dimethoxyartsclaenin III (2), 3,4-dihydro-3β-ethoxyasperuloside (12) and 3,4-dihydro-3β-ethoxydesacetylasperuloside (13) by extensive analyses of their 1D and 2D NMR spectroscopy and mass spectra. All of the isolated compounds were assayed for the promoting proliferation of skin fibroblasts cell (ESF-1) and compounds 4 and 7 (5 μM) significantly stimulated the proliferation of ESF-1 cells.