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Abstract

Background:The high mortality rate due to infectious diseases has recently been associated with the development of resistance to antibiotics by several strains of microorganisms worldwide. One of the pathophysiological conditions of mammalian tissues in response to infectious organisms is oxidative stress. Natural extracts or their chemical constituents as antioxidants are known to be very effective at preventing the destructive processes caused by oxidative stress. The main aim of the current study was to evaluate in vitro antibacterial, antioxidant, and cytotoxic effects of ethanolic root extracts of Kedrostis capensis A. Meeuse (Cucurbitaceae) and Trachyandra asperata Kunth. (Xanthorrhoeaceae). Materials and Methods: The assessments of antibacterial and antioxidant effects were performed using well diffusion method and 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical scavenging activity assay, respectively, while cytotoxic potentials were evaluated by employing the brine shrimp toxicity model. Results: K. capensis extract possessed bactericidal activity against Escherichia coli and Staphylococcus aureus and bacteriostatic activity against Pseudomonas aeruginosa with minimum inhibition concentration (MIC) values ranging from 62.5 to 500 µm/mL and minimum bactericidal concentration (MBC) values varying from 125 to 1000 µm/mL, while T. asperata extract was only bacteriostatic against S. aureus with MIC value of 500 µm/mL and MBC value greater than 1000 µm/mL. Both K. capensis and T. asperata extracts scavenged DPPH free radicals in a concentration-dependent manner with the half maximal inhibitory concentration (IC 50 ) values of 113.68 ± 0.11 µg/mL and 134.63 ± 0.27 µg/mL, respectively. K. capensis extract exhibited a relatively higher toxicity potential with 50% lethality concentration (LC 50 ) value of 102.37 ± 0.19 µg/mL, while T. asperata was non-toxic with lower LC 50 value of 522.75 ± 0.35 µg/mL. Obtained results suggest that K. capensis and T. asperata ethanolic root extracts possess bioactive secondary metabolites with antibacterial, antioxidant, and cytotoxicity properties with potential pharmaceutical applications.