Antioxidant activity and identification of bioactive compounds from leaves of Anthocephalus cadamba by ultra-performance liquid chromatography/electrospray ionization quadrupole time of flight mass spectrometry

Objective:To evaluate the antioxidant potential of different extract/fractions of Anthocephalus cadamba（A.cadamba）（Roxb.） Miq.（Rubiaceae） and study the tentative identification of their active constituents.Methods:The extract/fractions were screened for antioxidant activity using various in vitro assays viz.DPPH assay,ABTS assay,superoxide anion radical scavenging assay, reducing power assay and plasmid DNA nicking assay.Total phenolic content of extract/fractions was determined by colorimetric method.An ultra-performance LC-electrospray-quadrupoletime of flight mass spectrometry method was used to analyse the active constituents of extract/ fractions of A.cadamba.Results:The ethyl acetate fraction was found to be most active fraction in all the assays as compared to other extract/fractions.The IC50 value of ethyl acetate fraction （ETAC fraction） was 21.24μg/mL,1.12μg/mL,9.68μg/mL and S7.81μg/mL in DPPH assay, ABTS assay,reducing power assay and superoxide scavenging assay respectively.All the extract/ fractions also showed the potential to protect the plasmid DNA（pBR322） against the attack of hydroxyl radicals generated by Fenton’s reagent.The bioactive compounds were identified by UPLC-ESI-QTOF-MS,by comparing the mass andλmax with literature values.Conclusions:The potential of the extract/fractions to scavenge different free radicals in different systems indicated that they may be useful therapeutic agents for treating radical-related pathologic damage.