Evaluation of the Phenolic Profile, Antioxidant, and Anti‐Gout Effects of Three Aerial Parts of the Algerian Herb <i>Diplotaxis harra</i>

Abstract

This study investigated the phenolic profile, antioxidant capacity, and anti-gout potential of methanolic extracts obtained from flowers, leaves, and stems of Diplotaxis harra subsp. crassifolia. Total phenolic and flavonoid contents were quantified spectrophotometrically, and individual phenolics were characterized by LC-MS/MS, revealing 15 compounds in flowers, 11 in leaves, and 7 in stems, with quinic acid as the predominant constituent. Antioxidant activity was evaluated using DPPH, ABTS, CUPRAC, FRAP, phosphomolybdenum, and metal-chelation assays, in which flower extracts consistently exhibited the highest antioxidant potential. Xanthine oxidase (XO) enzyme inhibition assay revealed that the flower extract exhibited the best inhibition activity, with an IC₅₀ of 0.212 mg/mL, comparable to that of the positive control allopurinol (0.25 mg/mL). Consistently, molecular docking showed that gentisic and protocatechuic acids, most phenolics in the extract, bind XO with more favorable energies than allopurinol through extensive hydrogen-bonding and hydrophobic interactions at key active site residues. Overall, this initial organ-specific evaluation of D. harra provides strong support for its flower extracts as promising candidates for standardized anti-gout preparations and as scaffolds for future XO inhibitor development.