Lipoxygenase Inhibitory and Antioxidant Activities of Isolated Compounds from Moutan Cortex

Phytochemical investigation on the ethyl acetate and n-butanol fractions of Moutan Cortex resulted in the isolation and characterization of a new monoterpene glycoside (3) and twenty known monoterpene glycosides (1, 2, 4-21). The structure of 3 was determined by spectroscopic data interpretation and physico-chemical properties. Compounds 1 and 8 presented a remarkable inhibitory activity against lipoxygenase-1 (LOX-1) with IC∧50 values of 45.2 and 37.5 μM, respectively. Compounds 9, 10, 13, 18, 19, and 21 showed significant 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging effect with IC∧50 values of 9.8, 25.5, 6.4, 15.2, 18.7, and 23.7 μM, respectively. Benzoylpaeoniflorin (8), which exhibited the highest inhibitory effect with an IC∧50 value of 37.5±0.7 μM, was further analyzed the inhibition kinetics by Lineweaver-Burk plots. Results indicated that 8 is a non-competitive inhibitor, and the kinetic parameter values were estimated to be (31.04 μM, Ki), (0.29 μM/min, V∧m), and (48.50 μM, K∧m).