Combination of electrochemical unit and ESI-MS in fragmentation of flavonoids.

Abstract

Predictive approaches on the activity of natural compounds based on the fragmentation by instrumental techniques are important for consideration of such molecules as drug candidates and defining new structures with promising properties. Since flavonoids are well-known antioxidants, their redox properties can be related to their pharmacological activity. In this work, the potential of electrochemical unit coupled to electrospray ionisation mass spectrometry (ESI-MS) was assessed for fragmentation activity relationships studies of selected flavonoids. Methodology of this research included electrochemical conversion of standards of flavonoids at different pH values and their further analysis with the use of ESI-MS. In addition, signals obtained from the blank samples were also identified and used for interpretation due to electrochemical nature of the ESI source. Half maximal inhibitory concentration (IC50 ) values of flavonoids for 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant activity assays were analysed for possible correlation with the structures of flavonoids and products of electrochemical conversion. Fragmentation activity relationships were suggested using the proposed approach and for some of the flavonoids it was not specific enough to determine the input of a particular structural feature to the activity, but for others they were in agreement with those found in the literature. Obtained results showed potential of the proposed approach for application in plant sciences as a fast pre-screening tool for newly isolated bioactive compounds.