Rapid screening and identification of compounds with DNA-binding activity from Folium Citri Reticulatae using on-line HPLC–DAD–MSn coupled with a post column fluorescence detection system

Abstract To study the interactions between natural compounds and deoxyribonucleic acid (DNA), a method has been established combining a high-performance liquid chromatography–diode array detector–multi-stage mass spectrometer with a fluorescence detector (HPLC–DAD–MS n –FLD). The FLD was used to monitor fluorescence intensity of the ethidium bromide–DNA (EB–DNA) complex when a compound separated by HPLC was introduced. This novel method was used to simultaneously obtain the HPLC fingerprint, UV spectra, MS n fragments and DNA-binding activity profile of various components in Folium Citri Reticulatae . As a result, 35 compounds were identified, of which 25 were found in the extract of Folium Citri Reticulatae for the first time, and 33 compounds showed DNA-binding activities, with the most active being feruloylhexaric and p -coumaroylhexaric acids. In addition, the precision, stability and reproducibility of this method were validated by two positive controls, quercetin and hesperidin. This new on-line method is accurate, precise and reliable for further high-throughput screening of DNA-binding compounds from food samples and other complex matrices.