Screening, fingerprinting, and identification of phenolic antioxidants in Persicaria chinensis (L.) H. Gross by liquid chromatography - electrochemical detection and liquid chromatography - tandem mass spectrometry.

Persicaria chinensis (L.) H. Gross (P. chinensis), also known as "Huotanmu" in Chinese, is a traditional ethnic herbal medicine and a functional food ingredient. In this study, liquid chromatography - electrochemical detection (LC-ECD) screening, liquid chromatography - tandem mass spectrometry (LC-MS/MS) identification, and multivariate statistical analysis were combined to clarify the antioxidant components in P. chinensis. The samples were extracted using 80 % aqueous methanol under ultrasound-assisted extraction and their in vitro antioxidant activities were evaluated. The fingerprint of P. chinensis was established using LC-ECD, while the identification of major chemical components was performed using LC-MS/MS through comparison of ion fragments. Subsequently, grey correlation analysis and partial least squares regression analysis were used to investigate the association of different compounds with antioxidant activity. P. chinensis from different sources showed excellent DPPH radical scavenging capacity, ABTS radical scavenging capacity, and ferric reducing antioxidant power. A total of 25 common peaks were obtained and identified in the LC-ECD fingerprint of P. chinensis, which were primarily comprised of tannins and flavonoids. The similarity between samples of different batches was ≥ 0.767, indicating relatively consistent quality. The comprehensive analysis results of grey relational analysis and partial least squares regression analysis indicated that tannins such as di-galloyl-HHDP-hexoside and davidiin were the major contributors to the antioxidant activity of P. chinensis. Therefore, LC-ECD can rapidly screen the potential phenolic antioxidants of P. chinensis, providing a basis for its product development, resource utilization, and quality control.