Antimicrobial, antioxidant and wound healing activities of methanol leaf extract of Bridelia micrantha (Hochst.) Baill.

Abstract

Bridelia micrantha is a medicinal plant used traditionally for the treatment of wounds. However, there are no documented scientific reports on the wound healing activities of this plant. This study was conducted to investigate the antimicrobial, antioxidant and wound healing activities of methanol leaf extract of B. micrantha (BME). The antimicrobial activity was determined using the agar well diffusion and broth dilution methods. Antioxidant activity was performed in vitro using the DPPH scavenging antioxidant activity followed by in vivo wound healing activities using the excision wound model. Preliminary phytochemical screening of BME showed the presence of saponins, tannins, flavonoids, alkaloids, triterpenes, glycosides, steroids and coumarins. BME exhibited dose-dependent antimicrobial activities. The most susceptible organism to BME was N. gonorrhoeae with mean zones of inhibition ranging from 20.50 ± 1.00 to 28.50 ± 1.00 mm. The least susceptible organism was S. typhi with mean zones of inhibition in the range of 15.50 ± 0.00 to 21.50 ± 0.00 mm. The MICs of BME against the test organisms were in the range of 1.25 to 2.5 mg/mL. Sub-inhibitory concentrations of BME potentiated the activities of ciprofloxacin and ketoconazole. BME showed a dose-dependent increase in antioxidant activity with IC50 of 0.2626 µg/mL. The BME formulated creams at concentrations of 0.625, 2.5, and 10% w/w showed a significant (p<0.0001) increase in rate of wound closure compared to the control group. Histological studies revealed marked angiogenesis, collagenation and re-epithelization in BME-treated wound tissues compared to the untreated group. The methanol leaf extract of B. micrantha possess antimicrobial, antioxidant and wound healing activities, thereby proving the folkloric use of the leaves of B. micrantha as a wound-healing agent.