Preparation and characterisation of organic UV filters based on combined PHB/liposomes with natural phenolic compounds.

In this study preparation and characterization of new UV-protecting systems based on liposomes/polyhydroxybutyrate (PHB) with encapsulated coffee extracts are presented. Green and roasted coffee extracts with high phenolics content, high antioxidant activity and sun protection factor (SPF) value 40-50 were used as model organic UV filters and encapsulated into liposomes and PHB-liposomes. Particle size and colloid stability was observed by dynamic light scattering and zeta-potential. Toxicity of particles was tested by MTT and LDH assay on HaCaT cell line. All prepared samples showed moderate or high encapsulation efficiency. Addition of PHB up to 50 % of lecithin led to increased size and stability. As optimal addition of 20 % PHB into liposome particles was found leading to optimum size and processing of particles, to high UV-protective effect as well as to increased colloid stability and SPF value during long-term storage. Significant differences in cell viability were found in cytotoxicity studies after exposure of keratinocytes to liposomes with different PHB content. Newly fabricated PHB-liposome particles with coffee extract were not found as toxic for HaCaT cells and in LDH test up to 12 %. These particles can act as active carriers for organic sunscreen components in combination with UV-protective effect of PHB.