| Glabridin as a polyphenolic flavonoid of licorice extract has been known for its beneficial effects on the skin such as antioxidant properties,skin-lightening effect.Glabridin inhibits tyrosinase involved in melanogenesis,thereby whitening skin.But the addition of glabridin in skin care products is too low to function effectively for its poor water solubility.In this study,a positively-charged nanoemulsion as a carrier system for dermal application of glabridin was prepared by high pressure homogenization technique,which improved the solubility,stability and transdermal absorption significantly.The mechanism of transdermal absorption is innovated.On the basis of common nanotechnology,positively charged oil/water(o/w)nanoemulsions were studied,changing transmission mode which was from the passive transmission to active transmission.So that the effective components can be easily absorbed by the negatively charged skin,solving the current problem of transdermal absorption.The main results are as follows.In the first chapter,the establishments of high sensitivity,specificity,reproducibility and accuracy were good and the operation of the HPLC method is simple for the determination of glabridin.Meanwhile study the apparent oil-water distribution coefficient and the balanced solubility of glabridin.Physicochemical properties of glabridin indicated that glabridin was a suitable active ingredient for preparing oil-in-water nanoemulsion.In the second chapter,by investigating the solubility of glabridin in different oil phases and combining with the solubility of phytosphingosine in oil phase,octyldodecanol andcaprylic/capric triglycerides were selected as the oil phase of positively charged nanoemulsion.With octyldodecanol and caprylic/capric triglycerides as oil phase in 3: 1 ratio,the variety of surfactants and co-surfactants were selecte by the solubility of glabridin and the pseudo-tertiary phase diagrams.Subsequently,the encapsulated the glabridin(0.1 wt%)and the rose essential oil(0.2wt%)was kept constant,and the proposed formulation and conditions were screened via preliminary screening,then Box-Behnken experiment design further optimized the formulation.Factors such as the weight ratio of octyldodecanol/ caprylic/capric triglycerides,the concentration of phytosphingosine,the concentration of Tween80,the concentration of glycerol,the homogenisation pressur(bar)and the number of homogenisation cycles were investigated in the preliminary screening experiment.The mean droplet size,polydispersity index,zeta potential and encapsulation efficiency were selected as indicators.Response surface methodology was employed to study the effect of the weight ratio of octyldodecanol/ caprylic/capric triglycerides,the concentration of phytosphingosine and the concentration of Tween80 on droplet size,polydispersity index,zeta potential and encapsulation efficiency.The optimum formulation of positively-charged nanoemulsion was determined as follow: 9.74%octyldodecanol,10.26% caprylic/capric triglycerides,0.1% glabridin,3% glycerol,0.2% rose essential oil,5.20% Tween 80,0.58% phytosphingosine,0.1% potassium sorbate and 70.82% deionized water.The results show that the Box-Behnken surface optimization has good prediction effect and the experimental design has high reliability.Under optimum formulation conditions,the corresponding predicted response values for droplet size,polydispersity index,zeta potential and encapsulation efficiency were 131.09nm?0.128?53.24 mV and 88.56 % respectively,which showed excellent agreement with the actual values(129.00 nm,0.129,52.30 mV and 88.21%respectively),with no significant(P>0.05)differences.In the third chapter,the quality evaluation of glabridin nanoemulsion was established and the stability in vitro was investigated.The stability test showed that the positively-charged nanoemulsion was more stable.In the fourth chapter,the transdermal property of glabridin-loaded positively-charged nanoemulsion was investigated.The in vitro transdermal permeation experiments of glabridin-loaded negatively-charged nanoemulsion and glabridin-loaded positively-charged nanoemulsion were investigated by Franz diffusion cells.The results showed that compared with glabridin-loaded negatively-charged nanoemulsion,the transdermal performance of glabridin-loaded positively-charged nanoemulsion had obvious advantages and it was suitable for transdermal delivery of glabridin.In the fifth chapter,the safety of a phytosphingosine containing positively charged oil/water nanoemulsion incorporating glabridin was investigated by skin irritation test according to the technical specification for cosmetic safety(2015 edition)and national special purpose cosmetic human body safety test project.According to the skin irritation intensity classification,there was no irritation to skin.Therefore,a positively charged nanoemulsion containing glabridin has high safety... |
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