Phytochemical constituents, chemotaxonomic significance and anti-arthritic effect of Eucommia ulmoides Oliver staminate flowers

Phytochemical investigation of Eucommia ulmoides Oliver staminate flowers provided twenty-seven compounds, including 11 triterpenes (1-11), 4 fatty acids (12-15), 1 coumarin (16), 1 chromone (17), 7 flavonoids (18-24) and 3 cyclopeptide alkaloids (25-27). Compounds 4-6, 8-9, 11-15, 17 and 25-27 were reported for the first time in the genus Eucommia. Their structures were determined by nuclear magnetic resonance, mass spectroscopy, optical rotation, circular dichroism spectroscopy analyses and comparison with literature data. The anti-arthritic activity of these compounds was also evaluated in this study. The result showed 1, 2, 4, 9 and 14 could significantly inhibit proliferation of fibroblast-like synovial cells from rats with IC50 values ranging from 11.83 to 50.12 μM. Furthermore, the chemotaxonomic significance of the isolated compounds has also been discussed. 12 and 25-27 might possess chemotaxonomic value for staminate flowers.