Development of propidium iodide as a fluorescence probe for the on-line screening of non-specific DNA-intercalators in Fufang Banbianlian Injection

• Propidium iodide probe was developed into an on-line screening method for the first time.
• HPLC−DAD−MSn−DNA−PI−FLD system was established for screening active compounds.
• PI was able to identify non-specific DNA intercalators from complex samples.
• 38 of the identified compounds are DNA intercalation active in Fufang Banbianlian Injection.

Fufang Banbianlian Injection (FBI) has been widely used as an anti-inflammatory and anti-tumor prescription. To understand the relationships between its bioactive ingredients and pharmacological efficacies, our previous study has been successfully identified some DNA-binding compounds in FBI using an established on-line screening system, in which 4′,6-diamidino-2-phenylindole (DAPI) was developed as a probe. However, DAPI can be only used to screen ATT-specific DNA minor groove binders, leaving the potential active intercalators unknown in FBI. As a continuation of our studies on FBI, here we present a sensitive analytical method for rapid identification and evaluation of DNA-intercalators using propidium iodide (PI) as a fluorescent probe. We have firstly established the technique of high-performance liquid chromatography−diode-array detector−multistage mass spectrometry−deoxyribonucleic acid−propidium iodide−fluorescence detector (HPLC−DAD−MSn−DNA−PI−FLD) system. As a result, 38 of 58 previously identified compounds in FBI were DNA-intercalation active. Interestingly, all previously reported DNA-binders also showed intercalative activities, suggesting they are dual-mode DNA-binders. Quantitative study showed that flavonoid glycosides and chlorogenic acids were the main active compounds in FBI, and displayed similar DNA-binding ability using either DAPI or PI. In addition, 13 active compounds were used to establish the structure-activity relationships. In this study, PI was developed into an on-line method for identifying DNA-intercalators for the first time, and thus it will be a useful high-throughput screening technique for other related samples.