UPLC/Q-TOF-MS profiling of phenolics from Canarium pimela leaves and its vasorelaxant and antioxidant activities

Canarium pimela K.D. Koenig, Burseraceae, have a long history of use in the Chinese traditional medicine treatment of various ailments including hypertension, and our research team has reported the anti-hypertensive activity and delineated the mechanism involved in the action. The following research aims to evaluate the vasorelaxant and antioxidant activities of ethanol extract from C. pimela leaves and to analyze its chemical composition by ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) that may correlate with their pharmacological activities. The results showed that pre-incubation of aortic rings with the extract (0.3, 1, 3, 10, 30 and 100   mg/l) significantly inhibited the contractile response of the rings to norepinephrine-induced contraction ( p   <   0.01or p   <   0.05). Crude ethanol extract and refined ethanol extract showed a highest inhibitory effect against 2,2dipheyl-2-picrylhydrazyl hydrate scavenging activity (IC 50 of crude ethanol extract   =   15.42   ±   0.14   μg/ml and IC 50 of refined ethanol extract   =   5.72   ±   0.31   μg/ml) and 2,2′-azinobis (3-ethyl-benzothiazoline-6-sulphonic acid ammonium salt) (ABTS (IC 50 of crude ethanol extract   =   3.24   ±   0.18   μg/ml and IC 50 of refined ethanol extract   =   1.88   ±   0.07   μg/ml) scavenging activity, which was considerably higher than that reported for butylated hydroxytoluene and lower of that measured for ascorbic acid. Moreover, its chemical composition was analyzed by UPLC/Q-TOF-MS. Sixteen compounds including nine flavonoids, four tannins, two phenolic acids and one dianthrone were identified for the first time as constituents of this species. And of this, six major phenolic components were simultaneous quantitative analysis by HPLC-UV, chlorogenic acid is the major compounds in C. pimela leaves. These results indicate that the phenolic-rich extract of C. pimela leaves is a promising natural pharmaceutical for combating hypertension and oxidative stress.