Compounds from Vernonia arborea Buch.-Ham. Inhibit Microbes that Impair Wound Healing

Aims: To identify the antimicrobial potency of the leaf fractions of Vernonia arborea against selected wound microbes viz., Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae and Stenotrophomonas maltophilia.

Background: Wound healing is often delayed due to the presence of polymicrobial load, that have to be abolished to facilitate the healing process. A major class of antimicrobial phytocompound reported to occur in Vernonia arborea species include sesquiterpenes. Reports on the wound healing potency of V. arborea in wound models of Wistar rats however did not report antimicrobial activity of the aqueous or methanolic extracts.

Methodology: The column fractions of the hexane leaf extract were tested against the selected strains by agar well diffusion assay and the zone of inhibition confirmed with TLC bioautography at specific Rf. The minimum inhibitory concentration (MIC) of the bioactive fractions was identified using resazurin microtiter assay (REMA) and the minimum bactericidal concentration (MBC) was determined. HPTLC quantification was also performed.

Results: Out of the 30 pooled fractions, six showed antimicrobial potency against all the five tested wound microbes. The minimum inhibitory concentrations of these fractions were determined, ranging from 15.62 µg/mL to 500 µg/mL for the different microbes. Quantitative High-Performance Thin Layer Chromatography (HPTLC) revealed two compounds (a and b) in the bioactive fraction10 with yields of 633 mg (63%) and 97 mg (9.7%) per gram of the extract.

Conclusion: The findings suggest the potential use of the bioactive compound in chronic infectious wound management therapy.