Anti-free radical activity and formulation of deformable liposomes loades with silk sericin

The purposes of this study were to investigate anti-free radical activity of sericin from Thai silk by deoxyribose assay and to formulate deformable liposomes (DL) loaded with sericin for anti-wrinkle effects by reverse phase evaporation method. Effects of the ratios of phosphatidyl choline (PC) and surfactant, types of surfactants and lipid content on DL for the most appropriate formulation were investigated. The deoxyribose assay demonstrated the capability of scavenging hydroxyl radical of sericin with IC₅₀ at 0.9 mg/ml. It was found that the formation of DL could be achieved by reverse phase evaporation method and obtained large unilamellar vesicles (LUVs). The optimum formulation comprised of 2% PC, Span 80 as surfactant and the ratio of PC:Span 80 as 85:15 by weight. Entrapment efficiency was 89.84±2.87%. Size and size distribution determined by dynamic light scattering technique was 240 nm and span 3.088. Teh formulation of serum with DL loaded with silk sericin was carried out with types of viscosity enhancers: Carbopol ultrez-10, Poloxamer 407 and chitosan (high molecular weight). The results of physical stability test by heating and cooling method for 6 cycles revealed that the appropriate viscosity enhancer was 0.5% Carbopol ultrez-10, which was mixed with DL. Afterwards, skin permeation study using newborn abdominal pig skin as skin model revealed that deformable liposomes and conventional liposomes (CL) loaded with sericin could enhance the skin penetration of sericin through pig skin as compared with sericin solution which showed no permeation. It was demonstrated that DL and CL could enhance the delivery of sericin through skin. In the formulation of DL loaded with sericin containing in serum, sericin permeated through skin slower, but the permeability coefficient was significantly higher than DL without containing in serum (P < 0.05)