تاريخ مجلس الدراسات العليا

2021-02-14

اسم الطالب

فرح مهدي عبدعلي السعيدي

ملخص الرسالة

The depletion of the ozone layer has increased the risk of sun damage from harmful UV rays. Prolong exposure to sun rays could lead to melanomas of the skin. Sunscreen agents block UV rays, reduce the likelihood of sunburns, and prevent premature aging of the skin. However, the lack of reliable databases and analytical methods had made the evaluation of the effect of sunscreen agents unavailable and thus the comparison between them was made difficult.Therefore, the aim of this research project was to evaluate the effect of different formulations and formulation ingredients (e.g., cream, lotion, and gel) on the performance of SPF using UV spectrophometry and to investigate the employability of FTIR spectroscopy as a user friendly and quick method to evaluate the sunscreen concentration, type, and application time on light transmittence. Three formulations of sunscreens were prepared; cream, lotion and gel using organic sunscreen agents Oxybenzone (Benzophenone-3) and octyl methoxycinnamate, inorganic agents (TiO2 and ZnO) and mixed formula of the two organic agents. UV spectroscopy method was used to evaluate the SPF value for each formula. The Oxybenzone three formulas showed low and similar SPF values ranging from 5-7. The octyl methoxycinnamate formulas showed better SPF values, both the cream and gel octyl methoxycinammate 10% gave SPF= 23, while the 10% lotion demonstrated an SPF value of 17. Mixing the two organic sunscreen agents did not improve the SPF value, but reduced it to 17-18. The prepared formulas of TiO2 and ZnO gave too low values of the SPF. The effect of sunscreen agent, concetration, type and application time was studied using FTIR transmission through the Strat-M® membrane. After 2 hours of topical application of sunscreen formualtions, using the maximum allowed concentrations, the FTIR spectra at wavenumber 805 cm-1 demonstrated a significant reduction of transmission from 96.55% to 60.09%, 57.59%, 32.02%, 37.1% for Oxybenzone (Benzophenone-3), octyl methoxycinnamate, TiO2, and ZnO respectively (P<0.05). A significant reduction in transmission was observed (p<0.05) with increasing sunscreens concentrations after 2 hours of application. Nevertheless, the upper limit concentration showed no appreciable change from the middle concentration and hence it is cost effective to emply the midlle concnetration. Inorganic sunscreens showed a higher protection level than organic. Fixed-dose combinations of the sunscreens showed enhanced effect yet not synergistic. However, using combinations allowed lower concentrations of sunscreens to be used and hence avoidance of adverse events particularly for organic sunscreens. In conclusion, the use of FTIR spectroscopy with synthetic skin is a quick, user-friendly technique that enables the assessment of the effect of sunscreens in blocking radiation penetration and transmission.