In vitro analysis of the anticancer and antimicrobial potentials and phytochemical profiles of leaf extracts from five Vachellia species.

The prevalence of antimicrobial resistance and cancer is on the rise, and these ailments create difficulties in therapeutic management and patient compliance. Hence, this necessitates the discovery of novel, less toxic, bioactive compounds from natural sources. This study aimed to investigate the phytochemical composition of leaf extracts from Vachellia karroo, Vachellia kosiensis, Vachellia Farnesiana, Vachellia sieberiana, and Vachellia xanthophloea using Fourier Transform Infrared Spectroscopy (FTIR) and Gas Chromatography-Mass Spectrometry (GC-MS), as well as their cytotoxic activity and antimicrobial properties. Cytotoxicity was assessed in human breast adenocarcinoma (MCF-7) and colorectal carcinoma (HCT116) cell lines, as well as in normal human lung fibroblast cells (MRC5), to determine selectivity. Antimicrobial activity was evaluated against Staphylococcus aureus, Escherichia coli, and Candida albicans. The FTIR analysis indicated the presence of functional groups representing phenols, carboxylic groups, hydroxy groups, alcohols and benzene rings. GC-MS was performed on five species of Vachellia and confirmed 51 volatile compounds, including phytol, germanicol, and supraene. Among all the extracts, V. karroo and V. xanthophloea presented the most cytotoxic activity with IC₅₀ = 9.61 ± 1.00 and 9.82 ± 0.96 μg/mL against the MCF-7 cells and 3.51 ± 1.05 and 10.20 ± 0.96 μg/mL against the HCT116 cells. In addition, all the extracts show lower cytotoxicity to MRC-5 normal cells (IC₅₀ > 20 μg/mL), thus indicating good selectivity with camptothecin used as a positive control. V. karroo showed cytotoxic activity with IC₅₀ values of 9.61 ± 1.00 and 3.51 ± 1.05 μg/mL against MCF-7 and HCT116 cells, while camptothecin exhibited IC₅₀ values of 5.52 ± 0.70, 6.52 ± 0.76 and 4.60 ± 0.56 μg/mL against MRC-5, MCF-7 and HCT116 cells. The extracts showed IC₅₀ values of >20 μg/mL against MRC-5 cells, suggesting non-toxicity. As mentioned earlier, the extracts also showed a great range of antibacterial activity against S. aureus, E. coli and C. albicans. V. karroo showed minimum inhibitory concentrations (MICs) of 1.25, 2.50 and 5.00 mg/mL against S. aureus, E. coli and C. albicans, respectively and V. kosiensis with MIC values of 0.31, 1.25 and > 10.00, respectively. This study revealed the presence of several diverse and significant phytochemicals in the leaves. The bioactivities and low toxicity towards normal cells are indicative of the potential for cancer and associated bacterial co-infection treatment.