Phytochemical Profiling and Antioxidant Properties of Ziziphus lotus (L.) Fruits Supported by Xanthine Oxidase Inhibition and Molecular Docking

Abstract

<i>Ziziphus lotus</i> (L.) Lam., an extremophyte shrub native to the Mediterranean basin, yields underexplored fruits as a source of therapeutic agents. This study combined in vitro and in silico approaches to evaluate the antioxidant potential of <i>Z. lotus</i> fruits and predict their potential to inhibit xanthine oxidase (XO), a key enzyme in reactive oxygen species generation and oxidative stress-related pathologies. The ethyl acetate extract from the hydroalcoholic macerate was enriched in total phenolics (281.33 ± 1.5 μg GAE/mg) and flavonoids (127.26 ± 5.89 μg RE/mg) and displayed remarkable effects against the ABTS^•+ radical cation (IC₅₀ = 18.49 ± 1.47 μg/mL) and phenanthroline reducing power (A_0.5 = 8.38 ± 0.69 μg/mL), together with measurable xanthine oxidase inhibition (IC₅₀ = 170.4 ± 5.90 μg/mL). The compounds tentatively identified by full-scan UHPLC-QtoF-HRMS were docked against XO (PDB ID: 3NVY), with phytosphingosine (-8.5 kcal/mol) and rutin (-8.3 kcal/mol) exhibiting the strongest binding affinities, forming favorable predicted interactions with critical catalytic residues, followed by 6‴-feruloylspinosin, 3',5'-di-C-β-glucopyranosylphloretin and hexadecasphinganine (ranging from -7.8 to -7.6 kcal/mol). Predictive structure-activity relationships were also observed. These results provide insights into the antioxidant potential of <i>Z. lotus</i> phytochemicals and highlight the value of this extremophile plant as sustainable resource for phytotherapy and the management of oxidative stress-related diseases.