Natural rubber latex membranes incorporated with three different types of propolis: Physical-chemistry and antimicrobial behaviours

Natural Rubber Latex (NRL) is a biocompatible material with demonstrated capacity to induce vascularisation and tissue regeneration. Propolis is a complex resinous product prepared by Apis mellifera with the aim of protecting beehives against infectious microorganisms. It is flora-dependent and its antimicrobial activity can vary according to its geographical origin. This study compares the incorporation of three different types of propolis into an NRL membrane aiming at optimal controlled release of propolis potential antimicrobial compounds towards Candida albicans whilst keeping NRL mechanical characteristics desirable for wound healing bandage purposes. The propolis samples were classified as red, green and poplar propolis according to their chemical composition determined by ultra-high performance liquid chromatography coupled in series with both UV spectrophotometry and high-resolution mass spectrometry. The Minimum Inhibitory Concentrations (MIC) towards C. albicans were determined before their incorporation into NRL membranes. The release of NRL-propolis components in Simulated Body Fluid (SBF) was monitored by UV–Vis spectroscopy. The antimicrobial activity and the effects of the materials released on mouse fibroblasts were assessed. FTIR analyses were carried out in order to verify the formation of new chemical bonds that might prevent the release of propolis components from the NRL membrane. The mechanical characteristics of the NRL membranes remained adequate after the incorporation of the three types of propolis investigated whilst allowing the release of the red, and poplar propolis most active compounds against C. albicans. At 30 and 50% the released materials (eluates) from the NRL membranes incorporated with red and poplar propolis types were not toxic to fibroblast cells. These results suggest that red and poplar propolis can be incorporated into NRL membranes for the preparation of wound healing dressing.