Antioxidant and protein anti-denaturation properties of an Algerian Opuntia ficus-indica aqueous extract: complementary in vitro and exploratory in silico analyses

Opuntia ficus-indica (L.) Mill. is a source of hydrophilic phenolic constituents with potential redox and protein-stabilising properties. The present study evaluated the antioxidant and protein anti-denaturation activities of a previously characterised aqueous extract and explored the molecular behaviour of selected phenolic constituents. The extract exhibited moderate antioxidant activity, with IC₅₀ values of 142.3 ± 1.4 µg/mL for DPPH and 78.6 ± 0.8 µg/mL for ABTS, and A₀.₅ values of 73.9 ± 1.1 and 88.4 ± 1.3 µg/mL in the CUPRAC and ferricyanide assays, respectively. BSA thermal denaturation was inhibited in a concentration-dependent manner, with an IC₅₀ of 412.6 ± 4.3 µg/mL. Among the investigated phenolics, catechin showed the most favourable docking behaviour, with scores reaching − 8.1 kcal·mol⁻¹, while 300-ns molecular dynamics simulations indicated preservation of the overall conformational stability of selected catechin- and epicatechin-containing complexes. ADMET calculations provided complementary preliminary pharmacokinetic and toxicity predictions. Collectively, the results demonstrate moderate chemical antioxidant and protein anti-denaturation activities of the aqueous extract, while the computational findings provide testable molecular hypotheses requiring direct enzymatic and cellular validation.