Evaluation of antioxidant and antibacterial activities of extracts of Celtis philippensis Blanco (Ulmaceae) on multidrug resistant wound pathogens

Background: Antimicrobial resistance among wound pathogens is increasing, creating the need to search for new and effective agents, especially among medicinal plants used to treat wounds traditionally. There is a worldwide search for medicinal plants with good antibacterial and antioxidant activities to treat infected wounds.

Objectives: Celtis philippensis used locally to treat infections was evaluated for its antioxidant and antibacterial activities against multidrug resistant (MDR) pathogens from infected wounds from three Nigerian hospitals.

Methods: Methanol extract of C. philippensis stem was tested at 20 and 10mg/ml on 32 wound pathogens comprising of Staphylococcus aureus (14), Pseudomonas aeruginosa (10) and Klebsiella pneumoniae (8). Agar diffusion methods was used to determine antibiogram and susceptibility to extracts while agar dilution method was used to determine minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC). The antioxidant potential was evaluated by four methods: catalase activity, lipid peroxidation inhibition, hydrogen peroxide radical scavenging activity and DPPH radical scavenging activity. Statistical analysis was done using ANOVA.

Results: Antibiogram showed that the test organisms were MDR bacteria. The extract was active on all the tested pathogens with zones of inhibition of between 13-35mm. The MIC and MBC values ranged between 0.625- 5mg/ml for all the test organisms and MIC index indicated bactericidal activity. The methanol extract showed good antioxidant activity (lipid peroxidation inhibition and catalase activity) comparable with ascorbic acid standard.

Conclusion: Antioxidant and antibacterial activities of Celtis philippensis justified its folkloric use in treating infections. Moreover, good activity on multidrug resistant wound pathogens highlights its potentials as a source of antimicrobial agents to treat wounds infected with MDR pathogens.