On-line Screening and Identification of Free Radical Scavenging Compounds in Water Extract of Tea by High Performance Liquid Chromatography-Mass Spectrometry-2,2-Diphenyl-1-Picrylhydrazyl

Abstract

A new method based on the HPLC on-line scavenging diphenyl-1-picrylhydrazyl (DPPH*) radical activity and ESI-TOF/MS for the rapid screening and identification of radical scavengers from water extract of tea was developed. Water extract of tea was separated by HPLC. The outlet of HPLC flow cell was connected to a split valve in order to divert a flow to ESI-TOF/MS for on-line rapid identification of the antioxidants in water extract of tea, and another stream react post-column with the DPPH solution for on-line screening the antioxidants in water extract of tea. The results showed that eleven compounds in tea have scavenging radical activity, and all the eleven compounds including theanine, theogallin, gallocatechin grade, theophyline, tryptophan, epigallocatechin, epigallocatechin-3-gallate, table catechole, gallate, gallocatechin-3-gallate and catechin gallate were identified by ESI-TOF/MS according to literatures and data base. The method has also been used for several other natural products successfully. This method is reliable, efficient and it is a powerful tool for rapid screening and identification of free radical scavenging compounds in complex natural products.