Evaluation of the Antioxidant and Cytotoxic Activities on Cancer Cell Line of Extracts of Parasitic Plants Harvested in Tunisia

Weeds thrive in agricultural environments. However, in certain areas of the world, they are consumed by humans as food, and they can represent a source of valuable active ingredients of ethnomedical interest. In this study, three North African parasitic plants of the Orobanchaceae family, Cistanche violacea, Orobanche crenata and Orobanche lavandulacea, normally considered as weeds, were studied to compare their biological activities. The antioxidant activity of hexane, ethyl acetate, acetone, methanol, and water extracts obtained by sequential maceration was estimated by DPPH, ABTS and FRAP assays. The metabolic profi les of aqueous extracts were studied by 1H NMR spectroscopy. The oils extracted using hexane as solvent were analyzed by GC-FID and HPLC-DAD to characterize the fatty acid profi le. The cytotoxic effect of the oil from the parasitic plants was also studied on B16F10 melanoma cancer cells. All extracts showed antioxidant activity and differences between extracts obtained using different solvents as well as for different plants have been highlighted. The highest total phenolic content was determined in O. crenata acetone extract (3.53±0.20 mmol GAE/g) and in O. lavandulacea methanol extract (2.29±0.02 mmol GAE/g). 1H NMR spectroscopy revealed the presence of amino acids, organic acids and carbohydrates. The major fatty acids in the oils were 18:2 n-6, 16:0, 18:1 n-9, and 18:3 n-3. O. lavandulacea revealed to be a highly cytotoxic species for B16F10 melanoma cells. These data suggest that, despite the extreme climate conditions and the damage that can result, the studied desert parasitic plants can represent a novel and precious source of metabolites, with promising biological activities.