Wound Healing, Anti-inflammatory and Antibacterial Activities of 80% Methanol Leaf Extract of Vernonia leopoldi (Sch. Bip. Ex Walp.) Vatke in Mice

Abstract

The leaf of Vernonia leopoldi (Sch. Bip. Ex Walp.) Vatke has been used traditionally for the treatment of wounds. However, literature is scanty on experimental wound healing activity of the plant. The objective of this study was to investigate the wound healing activity of the 80% methanol extract of V. leopoldi leaves in mice. Wound healing activity was investigated using excision and incision wound models. The extract was studied for wound healing activity by formulating a topical ointment using two concentrations (5% and 10% w/w). Simple ointment base (negative control) and 0.2% nitrofurazone (w/v) ointment (positive control) were used for comparison of wound healing activity. The wound contraction, period of epithelialization and tensile strength were evaluated. In addition, anti-inflammatory activity was tested at doses of 100, 200 and 400 mg/kg using carrageenan hind paw oedema model. In vitro antibacterial activity was also assessed using agar well diffusion technique at concentrations of 50 - 500 µg/µl against both Gram- positive and Gram-negative bacteria that are associated with wound infections. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the extract were determined. Treatment of wound with ointment containing 5% and 10% (w/w) methanol extract exhibited significantly increased (p < 0.05) wound contraction rate, shorter epithelialization time, and higher skin breaking strength as well as increased collagen deposition, fibroblast proliferation and vascularization as evidenced by histopathological analysis. The 10% (w/w) extract ointment showed better wound healing activity than the 5% ointment and its effect was comparable to that of nitrofurazone. The extract also produced dose-dependent significant reductions (p < 0.01 - 0.001) of inflammation as compared to the control. The extract also displayed better antibacterial activity on Gram-positive than Gram-negative organisms. From the results, it can be concluded that the 80% methanol extract of V. leopoldi is endowed with wound healing, anti-inflammatory and antibacterial activities.