Simultaneous quantification of hydroxycinnamate derivatives and antioxidant activity of <i>Ziziphus oxyphylla</i> Edgew. leaf methanolic extract

The present study quantified hydroxycinnamate (HCIN) derivatives from the methanolic extract of <i>Ziziphus oxyphylla</i> Edgew. (<i>Z. oxyphylla</i>) leaves and evaluated the antioxidant activity. An accurate and reproducible high-performance liquid chromatography (HPLC) method for the simultaneous determination of chlorogenic acid, caffeic acid, and ferulic acid was developed, with a retention time of 4.36, 7.01, and 9.38 min, respectively. The extract exhibited a notable <i>in vitro</i> antioxidant activity, with IC₅₀ values of 220.91 ± 0.14, 254.28 ± 0.24, 241.96 ± 0.03, 190.17 ± 1.56, and 211.10 ± 0.10 µg/mL in DPPH radical, reducing power, H₂O₂ scavenging, phosphomolybdenum, and thiobarbituric acid (TBA) assays, respectively. <i>In vivo</i>, extract dose (500 mg/kg) significantly enhanced catalase (CAT: 0.18 ± 0.03 U/mg protein) and superoxide dismutase (SOD: 4.1 ± 0.3 U/mg protein) activities, while reducing thiobarbituric acid reactive species (TBARS: 0.39 ± 0.02 nmol/mg protein) compared to silymarin (0.33 ± 0.04 nmol/mg protein) at 200 mg/kg. Therefore, the <i>Z. oxyphylla</i> leaf extract, enriched with HCIN, demonstrated strong antioxidant potential, thereby validating its traditional ethnopharmacological applications.