On-line screening and identification of radical scavenging compounds extracted from Flos Lonicerae by LC-DAD-TOF-MS

Flos Lonicerae is commonly used in traditional Chinese medicine. The ethanolic extracts prepared from Flos Lonicerae were used for the rapid evaluation of free radical scavenging activity by using the extracts to clear on-line 2,2'-diphenyl-1-picrylhydrazyl (DPPH center dot) free radical with LC serving as the separating tool of bioactive compounds, two diode array detectors (DAD) and a time-of-flight mass spectrometer (TOF-MS) as qualitation tools. The LC-DPPH on-line method of Flos Lonicerae extracts revealed the presence of four radical scavenging compounds, which were simultaneously identified as chlorogenic acid, rutin, and two isomers of isochlorogenic acid by high-resolution TOF-MS. To the best of our knowledge, it is original to demonstrate the rapid and successful use of LC-DPPH-DAD-TOF-MS to directly and simultaneously screen and identify the anti-free radical compounds in the extracts of Flos Lonicerae without any purification. The present method provides a useful improvement on the reducing of workload