Evaluation of Antimicrobial and Wound Healing Potential of Justicia flava and Lannea welwitschii

Microbial infections of various types of wounds are a challenge to the treatment of wounds and wound healing. The aim of the study is to determine the antimicrobial, antioxidant, and in vivo wound healing properties of methanol leaf extracts of Justicia flava and Lannea welwitschii. The antimicrobial activity was investigated using agar well diffusion and microdilution methods. The free radical scavenging activity of the methanol leaf extracts was performed using 1,1-diphenyl-2-picryl-hydrazyl (DPPH). The rate of wound contraction was determined using excision model. The test organisms used were Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 4853, Bacillus subtilis NTCC 10073, Staphylococcus aureus ATCC 25923, and clinical strains of Candida albicans. The MICs of methanol leaf extract of J. flava against test organisms were E. coli (7.5 mg/mL); P. aeruginosa (7.5 mg/mL); S. aureus (5 mg/mL); B. subtilis (7.5 mg/mL); and C. albicans (5 mg/mL). The MICs of methanol leaf extract of L. welwitschii against test organisms were E. coli (5 mg/mL); P. aeruginosa (10 mg/mL); S. aureus (5 mg/mL); B. subtilis (2.5 mg/mL); and C. albicans (2.5 mg/mL). The MBC/MFC of the extract was between 10 and 50 mg/mL. The IC(50) of the reference antioxidant, α-tocopherol, was 1.5 μg/mL and the methanol leaf extracts of J. flava and L. welwitschii had IC(50) of 65.3 μg/mL and 81.8 μg/mL, respectively. The methanol leaf extracts of J. flava and L. welwitschii gave a significant reduction in wound size as compared to the untreated. The rates of wound closure after the application of the extracts (7.5% w/w) were compared to the untreated wounds. On the 9th day, J. flava extract had a percentage wound closure of 99% (P < 0.01) and that of L. welwitschii exhibited wound closure of 95% (P < 0.05) on the 13th day compared to the untreated wounds. The two extracts significantly (P < 0.01) increased the tensile strength of wounds compared to the untreated wounds. The extracts treated wound tissues showed improved angiogenesis, collagenation, and reepithelialization compared to the untreated wound tissues. The preliminary phytochemical screening of J. flava and L. welwitschii leaf extracts revealed the presence of tannins, alkaloids, flavonoids, and glycosides. The above results indicate that methanol leaf extracts of J. flava and L. welwitschii possess antimicrobial and wound healing properties which may justify the traditional uses of J. flava and L. welwitschii in the treatment of wounds and infections.