A new neolignan and a new biphenylpropanoid from the leaves of Cupressus funebris Endl.

• A new neolignan and a new biphenylpropanoid isolated from the leaves of Cupressus funebris Endl. The type of biphenylepoxypropanes are rarely found in natural sources, we are fortunate to have obtained a pair of enantiomers and analyzed them by circular chromatography. The antioxidant experiments showed that due to the difference of the stereochemistry, the antioxidant activity of cis is significantly stronger than that of trans. A new neolignan, (-)-(7 S , 8 R)-3‑methoxy-4', 7-epoxy-8, 5'-neolignane-5, 9, 3', 9′-tetraol (1) and a new biphenylpropanoid, 1, 2-epoxy-1-(3', 4'-dihydroxyphenyl-)-3-(2'', 3'', 5''-trihydroxyphenyl-) propane (2), together with eight known compounds (3-10), were isolated from the 95% EtOH extract of the leaves of Cupressus funebris Endl. Their structures were determined by spectroscopic methods including NMR, circular dichroism (CD) spectra and comparison of the NMR data with reported in references. The antioxidant activities of all compounds were evaluated by DPPH, ABTS, and FRAP methods. Compounds 2 (IC 50 : 33.98 ± 0.11 μM), 3 (IC 50 : 32.97 ± 0.63 μM), 8 (IC 50 : 32.07 ± 1.57 μM), and 9 (IC 50 : 33.30 ± 2.29 μM) showed stronger DPPH free radical scavenging activity than l -ascorbic acid (IC 50 : 64.31 ± 1.32 μM). Except for 4 , the other compounds showed ABTS radical scavenging abilities comparable to l -ascorbic acid (54.91 ± 1.18 μM) with the IC 50 ranged from 24.42 ± 1.78 μM to 138.70 ± 13.58 μM. Compound 3 (0.72 ± 0.02 mmol/g) showed the same ferric reducing antioxidant power (FRAP) as l -ascorbic acid (0.83±0.02 mmol/g). [ABSTRACT FROM AUTHOR]