Phytochemical Screening and Antioxidant and Cytotoxic Effects of Acacia macrostachya

Acacia macrostachya is used in Burkina Faso folk medicine for the treatment of inflammation and cancer. The purpose of this study was to evaluate the antioxidant and cytotoxic effects of this plant. The cytotoxic effects of root (dichloromethane B1 and methanol B2) and stem (dichloromethane B3 and methanol B4) bark extracts of A. macrostachya were assessed on chronic K562 and acute U937 myeloid leukemia cancer cells using trypan blue, Hoechst, and MitoTracker Red staining methods. The antioxidant content of extracts was evaluated using DPPH (2,2-diphenyl-1-picryl-hydrazyl) and FRAP (ferric reducing antioxidant power) methods. The root bark extracts B1 and B2 of A. macrostachya demonstrated higher cytotoxicity with IC₅₀ values in a low µg/mL range on both U937 and K562 cells, while the stem bark B4 extract selectively affected U937 cells. Overall, healthy proliferating peripheral blood mononuclear cells (pPBMCs) were not or barely impacted in the range of concentrations cytotoxic to cancer cells. In addition, A. macrostachya exhibited significant antioxidant content with 646.06 and 428.08 µg ET/mg of extract for the B4 and B2 extracts, respectively. Phytochemical screening showed the presence of flavonoids, tannins, alkaloids, and terpenoids/steroids. The results of this study highlight the interest of A. macrostachya extracts for the isolation of anticancer molecules.