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

Abstract

• Four new phenolic compounds were isolated from the tender leaves of Eucommia ulmoides Oliv. • Compound 9 was isolated from Eucommiaceae for the first time. • Modest inhibitory activities were observed for compounds 2–5 and 9, with IC 50 values ranging from 8.3 to 31.0 μM. 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 IC 50 values ranging from 8.3 to 31.0 μM. 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.