Antioxidative and antibacterial activity of indigenous edible wild fruit species from Bushbuckridge Local Municipality, South Africa

Introduction: Antimicrobial drug resistance and unwanted side effects of conventional medicines necessitate research on medicinal plants’ use as alternatives. This study investigated the antibacterial and antioxidant properties of Carissa spinarum, Diospyros mespiliformis, Euclea crispa, Ficus thonningii, Strychnos madagascariensis, and Strychnos spinosa. Methods: Hexane, acetone, and methanol leaf extracts were tested for antimicrobial activity against Klebsiella pneumoniae and Pseudomonas aeruginosa using disc diffusion and microdilution assays, and for antioxidant activity using 2,2-diphenyl-1-picryhydrazyl (DPPH) and ferric-reducing power assays. Results: Methanol yielded the highest quantities of crude. The extracts of D. mespiliformis, E. crispa, and F. thonningii showed strong antimicrobial activity against P. aeruginosa with inhibition zones up to 28 mm and minimum inhibitory concentrations (MICs) from 0.781–1.563 mg/mL. The acetone extract of D. mespiliformis also exhibited activity against K. pneumoniae (MIC: 3.125 mg/mL). The methanol extract of E. crispa displayed potent antioxidant activity, achieving a half-maximal inhibitory concentration (IC50) of 1.42 µg/mL, which was comparable to ascorbic acid at concentrations of 62.5–250 µg/mL (P > 0.05). Acetone extracts of S. spinosa and methanol extracts of C. spinarum demonstrated good ferric-reducing power; however, all the plant extracts were significantly different from ascorbic acid and butylated hydroxytoluene at 250 µg/mL (P˂0.05). Conclusion: The leaves of wild plant species exhibited significant antimicrobial and antioxidant activities, making them possible sources of novel compounds for combating infections and oxidative stress.