DPPH RADICAL SCAVENGING ACTIVITY OF SELECTED FLAVONOIDS: EXPERIMENTAL EVALUATION OF ORIENTIN, BREVISCAPINE AND VITEXIN

Abstract

Oxidative stress involves reactive oxygen species and other reactive species and flavonoids are widely studied for their ability to neutralize radicals. In this study, we compared the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity of orientin, breviscapine and vitexin at concentrations of 1,2,5,10,25, and 50 µg/mL. Absorbance was measured at 517 nm and a sample-specific blank correction was applied before calculating percentage radical-scavenging activity (% RSA). The DPPH control showed an absorbance of 0.8897. All three compounds showed an increase in % RSA in a concentration-dependent manner. Orientin rose from 13.50 ± 0.02% at 1 µg/mL to 74.86 ± 0.30% at 50 µg/mL and passed the 50% response between 10 and 25 µg/mL. Linear interpolation between the experimental concentrations yielded an estimated IC₅₀ of 21.3 µg/mL. Breviscapine rose from 13.51 ± 0.35% to 63.03 ± 0.35% across the same concentration range giving an interpolated IC₅₀ of 29.3 µg/mL. Vitexin rose from 12.62 ± 0.26%, to 49.33 ± 0.32% and did not reach 50% RSA at the highest tested concentration; therefore Vitexin IC₅₀ was reported as >50 µg/mL. Under the present experimental conditions the relative DPPH radical-scavenging activity was orientin > breviscapine > vitexin. The findings provide an experimental comparison of the three compounds while the limited concentration range and triplicate design warrant cautious interpretation of IC₅₀ estimates.