In vitro evaluation of antibacterial activity of a plant extract-loaded wound dressing

Abstract

This study reports the in vitro efficacy of a mixture of plant extracts used as antibacterial agents loaded in a dressing to prevent infection in a wound. These natural compounds were extracted from avocado and mango.A mixture of equal proportions of petroleum ether extract from avocado kernels and methanolic extract from mango kernels was effective on the majority of 36 bacterial strains and presented excellent results against S. aureus. The Minimal Inhibitory Concentrations (MIC) measured on Staphylococcus aureus (ATCC 6538) were 0.019 mg/mL for the mixture compared to 0.039 mg/mL for the avocado or mango extract alone. This mixture was incorporated into a wound dressing composed of non-woven fabric and a gel. This gel consists of a plasticizer (starch/glycerin) and an absorbent (CMC/PCD) and is designed to have swelling properties and entrap plant extract. A formulation containing equal proportions of CMC and PCD enabled us to obtain 800% of swelling and a good adhesion of the gel to the non-woven fabric.The final dressing containing the mixture of avocado and mango extracts presented excellent antibacterial activity against S. aureus. Microbiological tests demonstrated that a wound dressing loaded with avocado/mango seed extract induced additional bacterial reduction of 3 Log10 and 2 Log10 against S. aureus and P. aeruginosa respectively but no additional bacterial reduction of C. albicans compared to the control.Our study demonstrated the scope for interest in plant species extracts provided by agricultural co-products in developing a new antibacterial wound dressing.