Four new phenolic compounds from the tender leaves of Eucommia ulmoides Oliv. and their anti-inflammatory activities

Four new phenolic compounds, 2-{[3-(3,4-dihydroxyphenyl)propanoyl]oxy}propanoic acid (1), 2-{[3-(3,4- dihydroxyphenyl)propanoyl]oxy}propanoic acid methyl (2), (±)3-{2-[1-(3? ,4? -dihydroxy-phenyl)ethyl]-4,5- dihydroxyphenyl}propanoic acid methyl (3), and (±)3-{2-[1-(3? ,4? -dihydroxy-phenyl)ethyl]-4,5-dihydroxyphenyl}propanoic acid (4), together with five known compounds, methyl 3-(3,4-dihydroxyphenyl)-propanoate (5), 3,4-dihydroxybenzenepropionic acid (6), caffeic acid (7), protocatechuic acid (8), and 1,3-trans-5,6-dihydroxy-3-(3? ,4? -dihydroxyphenyl)indan-1-methyl (9)were isolated from the tender leaves of Eucommia ulmoides Oliv. Compound 9 was isolated from Eucommiaceae for the first time. The structures of the new compounds were elucidated from the spectra of 1D NMR and 2D NMR, and MS data. Compounds 1-9 were tested to determine their inhibitory effect on LPS-induced NO production in macrophage RAW264.7 cells. Modest inhibitory activities were observed for compounds 2-5 and 9, with IC50 values ranging from 8.3 to 31.0 ?M. This research enriches the current chemical information regarding the leaves of Eucommia ulmoides Oliv. and provides a reference for further research on its anti-inflammatory effects.