Metabolomic profiling, antioxidant and anti-inflammatory activities of Hypericum species growing in South Korea

Abstract

Although Hypericum species are best known as plants that produce hypericin and are used in folk medicine, their other chemical constituents are poorly understood. Polyphenolic secondary metabolites from whole plants of representative Korean Hypericum species (H. laxum Koidz., H. erectum Thunb., and H. ascyron L.) were analyzed using a ultra performance liquid chromatography-quadrupole time-of-flight/mass spectrometry (UPLC-Q-TOF/MS)-based approach combined with unsupervised principal component analysis (PCA) multivariate analysis. On the loading scatter plot, significant changes in metabolites were found between species, and three flavonol glycosides (8: Quercetin-3-O-galactoside, 12: Kaempferol-3-O-glucoside, and 13: Quercetin-3-O-rhamnoside) were evaluated as key markers among 17 isolated metabolites. The extracts of H. laxum Koidz. exhibited significant quenching effects on DPPH and ABTS radicals, with IC50 values of 10-20 μg/mL, and were slightly higher in total phenol (TP) and total flavonoid (TF) contents than other species. Additionally, antiinflammatory activity was observed by reduced nitric oxide (NO) and interleukin-6 (IL-6) production from lipopolysaccharide (LPS)-stimulated macrophages (RAW 264.7 cells). This is the first study to report the presence of bioactive metabolites and their correlating biological activities in H. laxum Koidz.