Online HPLC-Guided Screening of Chemical Composition and Bioactivity in Capparis ovata subsp. canescens

The present study evaluated the biological activities and online HPLC-DAD profiles of five extracts of Capparis ovata subsp. canescens prepared with ethyl acetate (EA), dichloromethane (DCM), ethanol, 70% ethanol/water, and water. Online HPLC-DAD with post-column antioxidant detection was used to profile tentatively annotated antioxidant-responsive metabolites at 280, 595, 517, 734, and 450 nm. Antioxidant activity was assessed using DPPH, ABTS, FRAP, CUPRAC, phosphomolybdenum (PBD), and metal-chelating assays. Eight antioxidant-responsive markers-catechin, cinnamic acid, caffeic acid, γ-tocopherol, apigenin, quercetin-3-O-hexoside, myristoleic acid, and kaempferol-3-O-rutinoside-were tentatively annotated from their chromatographic behavior, UV-DAD characteristics, and post-column antioxidant responses. Ethanol and ethanol/water extracts showed the strongest DPPH (82.35-82.97 mg TE/g), ABTS (93.68-122.00 mg TE/g), FRAP (98.46-116.84 mg TE/g), and CUPRAC (155.43-205.02 mg TE/g) activities. In the PBD assay, EA, ethanol, and DCM showed the highest activities (2.11-2.39 mmol TE/g), with EA displaying the highest numerical value (2.39 ± 0.10 mmol TE/g). These findings support further investigation of C. ovata as a source of antioxidant and enzyme-inhibitory constituents, while structural confirmation and dose-response studies remain necessary.