Preparation Of Egcg Nano-Ethosomes And Its Improved Effect On Anti-Ultraviolet Radition

(-)-Epigallocatechin gallate (EGCG) as one of ester catechins, which is a bioactive molecule, has been shown to possess varieties of health functions such as antioxidant, anti-ultraviolet radiation and protection against skin cancer, etc. However, the stability of EGCG under human pH environment is poor to cause a low bioavailability. Therefore, how to enhance bioavailabllity of EGCG is a hot issue at present. The ethosome is a novel carrier for enhanced delivery in skin, which has been reported to have productive advantages, such as high entrapping capacity and excellent skin permeation. It is potential to improve stability and bioavailabllity of drugs, if drugs are entrapped by ethosomes.In the present study, preparation method of nano-ethosomes entrapping EGCG was investigated and its improved effect on anti-ultraviolet radiation was checked.(1) The conditions of preparing nano-EGCG ethosomes were investigated. By a combination of injecting and ultrasonic emulsificating, nano-ethosomes entrapping EGCG were successfully prepared. The optimum parameters for the preparation were obtained by the orthogonal test. The results showed that2%phospholipids and30%ethanol for formation of ethosomes,0.1%K9and1.0%Tween-80as stabilizers, and0.25%EGCG as drug under ultrasonic processing for2min could yield excellent ethosomes with mean size62.8nm, zeta potential-42.8mV and PDI (polydisperant index)0.097. The entrapping efficiency of the nano-ethosomes was more than90%.(2) Skin permeation experiments were conducted by cnfocal laser scanning microscope (CLSM) using rodmine B as a fluorescence probe. The results showed that in terms of the transdermal depth of ethosomes, the EGCG nano-ethosomes could permeate deeper than the EGCG hydroethanolic solution, and the EGCG transdermal quantity by ethosomes was obviously greater than that of the hydroethanolic solution. The transdermal delivery in vitro was studied by measurating the amount of EGCG in or through skin. For the EGCG nano-ethosomes the EGCG amount could reach40.13μg·cm-2and289.8μg·cm-2at8h and24h transdermal penetration while those of the EGCG hydroethanolic solution were only18.26μg·cm-2and35.67μg·cm-2.(3) The anti-ultraviolet-B (UVB) irradiation was tested by animal erxperiment with nude mice. After the mice were given UVB irradiation with a total dose of625mJ/cm2, the skin tissue change was obsvered by light microscope and TEM. The results demonstrated that EGCG nano-ethosomes could attenuate UVB-induced skin damage, and its effect was clearly better than EGCG hydroethanolic solution.