ANTIMICROBIAL AND WOUND HEALING PROPERTIES OF KIGELIA AFRICANA AND STROPHANTHUS HISPIDUS
Christian Agyare, Anita Serwaa Dwobeng, Yaw Duah Boakye, Kwesi Boadu Mensah, Patrick George Ayande and Martin Adarkwa-Yiadom
Pharmaceutics Department, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
Objectives: To investigate the antimicrobial and antioxidant properties of methanol leaf and stem bark extracts of Kigelia africana and methanol leaf and root extracts of Strophanthus hispidus and to determine wound healing properties of the extracts.
Methods: The antimicrobial activities of the methanol extracts were determined against two Gram-positive and two Gram-negative bacteria and a fungus using agar diffusion and micro-dilution methods. The antioxidant activities were determined using 1,1-diphenyl-2-picryl-hydrazyl (DPPH) method. The influence of the extracts on rate of wound closure was investigated using the excision wound model and histopathological investigation of both treated and untreated wound tissues performed. Phytochemical screening and HPLC finger-printing of the plant materials and extracts were performed, respectively.
Results: The MICs of leaf extract of K. africana against the test organisms were between 2.5 to 7.5 mg/mL and that of stem bark extract were from 2.25 to 7.5 mg/mL. The leaf extract of S. hispidus had MIC range of 2.5 to 7.5 mg/mL and 2.5 to 10 mg/mL for root extract. The IC50 of leaf and stem bark extracts of K. africana were 56.9 and 13.7 µg/mL respectively and leaf and root of S. hispidus were 49.8 and 45.1 µg/mL respectively. K. africana extracts (7.5% w/w) showed significant (p<0.05) wound contraction at day 7 with 72% of wound closure whiles significant wound contractions were observed on day 11 for stem bark of K. africana (p<0.05) and S. hispidus leaf extract (p<0.05) and the root extract (p<0.05) with wound closures of 91, 92 and 90%, respectively. Histopathological examination of the treated wound tissues showed profuse angiogenesis, enhanced collagenation and re-epithelialization compared with the untreated wound tissues. The extracts were found to contain alkaloids, saponins, tannins, flavonoids, carbohydrates and sapogenetic glycosides. The HPLC finger-printing of the extracts were developed for identification and quality control purposes.
Conclusions: The leaf, stem bark and root extracts of K. africana and S. hispidus exhibited antimicrobial, antioxidant and enhanced wound healing properties and these may justify the medicinal uses of these plants for treatment of microbial infections and wounds.