Chemical profiling of Houttuynia cordata Thunb. by UPLC-Q-TOF-MS and analysis of its antioxidant activity in C2C12 cells

Houttuynia cordata Thunb. ("Yu-Xing-Cao"), a traditional Chinese medicinal herb, has long been used to treat various diseases. However, detailed information regarding the chemical constituents of H. cordata aqueous extract is lacking, and the molecular basis of its beneficial effects on muscle is unknown. To investigate these points, in this study, we used ultra-performance liquid chromatography coupled with quadrupole-time-of-flight-mass spectrometry (UPLC-Q-TOF-MS) in positive and negative ion modes to profile and identify the major constituents of H. cordata water extract. A total of 63 peaks were identified based on mass and fragmentation characteristics, including 29 organic acids and their glycosides, 17 flavonoids, 7 volatiles, 4 pyrimidine and purine derivatives, 2 alkaloids, 2 amino acids, 1 isovanillin, and 1 coumarin. The total flavonoid and polyphenol contents of the extract were 4.77 and 139.15 mg/mL, respectively, by ultraviolet spectrophotometry. The cytoprotective activity of H. cordata aqueous extract was evaluated using C2C12 cells treated with tumor necrosis factor (TNF)-α to induce oxidative challenge. The TNF-α induced decrease in cell viability was reversed by treatment for 48 h with the extract; moreover, superoxide dismutase activity was increased while reactive oxygen species level was decreased. These results provide molecular-level evidence for the antioxidant effect of H. cordata extract and highlight its therapeutic potential for the treatment of muscle injury or diseases caused by oxidative stress.