Protective effects of azarole polyphenolic extracts against oxidative damage using in vitro biomolecular and cellular models

• Tunisian azarole polyphenols exhibit antioxidant capacity and inhibited cholesterol oxidation.
• Polyphenols protected liposomes and rat homogenate liver against lipid peroxidation.
• Evaluation of cytotoxic effect of azarole extracts using normal and cancer cells.
• Azarole extracts modified melanin production in melanoma cells.

The antioxidant activity of the different polyphenolic extracts prepared from Tunisian azarole, Crataegus azarolus and Crataegus monogyna (Rosaceae family) leaves, fruit peel, pulp and syrup was evaluated using cholesterol, liposome and rat liver-homogenate oxidation assays and cytotoxic activity in differentiated Caco-2, undifferentiated Caco-2, and B16F10 melanoma cells. Protective effects were observed against thermal-cholesterol degradation at 140 °C for 1 h, which depended on the concentration and the type of the extract. Moreover, the pre-treatment with the phenolic extracts preserved liposomes and rat liver-homogenate from oxidative induced damage by Cu2+ and Fe2+ at 37 °C for 24 h and 2 h, respectively. Azarole phenolics inhibited the oxidation of polyunsaturated fatty acids (PUFA) and limited the production of oxidized compounds. Furthermore, within tested concentrations (0.24-4.8 mg/mL), all extracts did not show any toxic effect on differentiated Caco-2 cells; while, they were found cytotoxic to cancer Caco-2 cells, except, extracts of pulp and syrup of C. monogyna. Using B16F10 melanoma cell model, only azarole pulp and syrup extracts were found toxic and induced the production of melanin in a dose-dependent manner.