Chemical composition and evaluation of protective effect of Ziziphus spina-christi L. against iron-induced oxidative DNA damage in Tetrahymena pyriformis

Ziziphus spina-christi has been traditionally used as a folk medicine for a variety of therapeutic benefits. However, there is no well-documented information regarding the protective role of this plant against toxicity induced by the overdose of trace metals, including iron. This work aimed to investigate the major components, as well as the antioxidant profile of aqueous extracts from different Z. spina-christi plant parts (seed, pulp, and almond), and to assess the protective effect of seed extract against iron-induced oxidative DNA damage using Tetrahymena pyriformis as a cellular model. Cells were incubated with iron (II) chloride (FeCl2) FeCl2 (1000 μM) in the absence or presence of seed extract. Lipid peroxidation and reactive oxygen species production were measured using biochemical assays. Intracellular iron accumulation was evaluated through Perl’s Prussian blue staining and ferrozine assay. The DNA damage was evaluated by pulsed-field gel electrophoresis, PCR, and restriction enzyme digestion of metallothionein (MT) gene. HPLC–DAD analysis revealed 21 different phenolic compounds; most of them were identified in the seed extract, while the almond extract exhibited a weak phenolic composition. Accordingly, seed extract showed important in vitro antioxidant activities. Pre-treatment with seed extract significantly reduced the impact of FeCl2, by attenuating MTT reduction, preventing iron accumulation, modulated antioxidant enzyme activity, reduced lipid peroxidation and significantly inhibited DNA damage. Collectively, data showed that Ziziphus spina-christi seed might act as an iron chelator agent with antioxidant properties offering effective protection against cytotoxicity and oxidative DNA damage induced by iron (II) chloride overload.