Abstract
To date, no study has focused on Uvaria macrophylla leaves with various traditional efficiencies. This paper therefore applied a database affinity ultra-high-performance liquid chromatography with quadrupole Orbitrap tandem mass spectrometry (UHPLC-Q-Orbitrap-MS/MS) strategy to analyze the lyophilized aqueous extract of U. macrophylla leaves. Through database comparison and MS fragment elucidation, this study has putatively identified 41 constituents belonging to flavonoid, phenolic acid, steroid, and saccharide natural product classifications. Significantly, four groups of isomers (liquiritigenin vs. isoliquiritigenin vs. pinocembrin; oroxylin A vs. wogonin vs. galangin 3-methyl ether; isoquercitrin vs. hyperoside; protocatechuic acid vs. 2,5-dihydroxybenzoic acid) have been successfully distinguished from each other. All of 41 constituents were then subjected to a quantitative analysis based on linear regression equation established by the above UHPLC-Q-Orbitrap-MS/MS strategy and an ABTS+•-scavenging antioxidant assay. Finally, the chemical content was multiplied by the corresponding ABTS+•-scavenging percentage to calculate the antioxidant contribution. It was shown that the chemical contents of 41 constituents varied from 0.003 ± 0.000 to 14.418 ± 1.041 mg/g, and gallic acid showed the highest antioxidant contribution. Gallic acid is considered as a suitable antioxidant quality-marker (Q-marker) of U. macrophylla leaves. These findings have scientific implications for the resource development and quality control of U. macrophylla leaves.