根據文獻指出，有一些防曬成分經UV照射後會產生光不穩定性，除了防曬效果降低，也會對皮膚造成敏感。而市售的高SPF值防曬產品往往都是添加了大量的防曬劑，更是會造成皮膚的負擔，並且防曬產品無法百分之百阻擋UV，而部份UV穿透至皮膚時，會造成釵h自由基的產生，而對細胞造成傷害，導致皮膚出現不良狀況，例如：乾燥、老化…等等。
本研究的第一階段是利用化學性防曬劑Parsol MCX (Ethylhexyl methoxycinnamate)、Parsol 1789 (Butyl methoxydibenzoylmethane)、Parsol SLX (Benzylidene malonate polysiloxane)、Octocrylene、以及物理性防曬劑為經Silica包覆之TiO2(Titanium dioxide)，以不同的配方比例經UV1000s儀器測定，探討防曬劑間SPF值的加乘作用。結果顯示，TiO2與Parsol MCX或TiO2與Parsol 1789搭配時都能有良好的加乘作用。當TiO2 4.8%與Parsol MCX 2%、Parsol 1789 2%三者搭配時，能以化學性防曬劑添加量低且保有理想之SPF值(SPF 36)。另外，將303種不同的中草藥以DPPH、TEAC之抗氧化測定模式尋找出具有強抗氧化力的中草藥，並且測定具抗氧化力之中草藥對超氧陰離子自由基、過氧化氫自由基、羥自由基、過氧化自由基清除能力。結果顯示，在DPPH system及TEAC system中發現由漆樹科植物之水萃取物抗氧化力最強，IC50分別為1.44ppm及1.66ppm。
本研究的第二階段是建立細胞評估模式，探討化學性以及物理性防曬劑在細胞模式下對於細胞經UV照射時的保護作用，另外探討具抗氧化力之中草藥在細胞經UV照射後，對細胞的修復、保護作用。結果顯示，在抗氧化劑對細胞保護方面，大戟科植物之乙醇萃取物及使君子科植物之萃取物對細胞有良好的保護作用。在人體試驗中，漆樹科植物之萃取物、使君子科植物之乙醇萃取物、大戟科植物之乙醇萃取物對紫外線引起的紅斑反應均有良好的抑制作用。 As previously reported, some sunscreen ingredients were unstable after UV irradiation. It reduced the efficacy of sun protection and caused the skin sensitivity. In order to reach a high SPF value, a lot of sunscreen ingredients were added to the commercial sunscreen products. However, the sunscreen products could not provide 100% protection, and some of the ingredients were absorbed into to the skin. The absorbed ingredients will produce a lot of free radicals, and damage the cells, therefore the skin will appear unhealthful, such as dryness, ageing etc.
This first stage of our study is to evaluate the synergistic effect of chemical and physical ingredients. The chemical sunscreen ingredients included Parsol MCX (Octyl methoxycinnamate), Parsol 1789 (Butyl methoxydibenzoylmethane), Parsol SLX (Benzylidene malonate polysiloxane), Octocrylene. The physical sunscreen ingredient is titanium dioxide coated with silica. The SPF values of different formulations were determined by Labsphere UV1000s. The antioxidation experiments were employed to find out the Chinese herbal medicine with strong anti-oxidant activities. Three hundreds kinds of Chinese herbs were screened by DPPH and TEAC anti-oxidant method, and their scavenge activities against the O2-, H2O2, OH․, ROO․ free radicals were performed by a BJL detector.
This second stage of our study is to establish a cellular evaluation model. The cells were irradiated with UV radiation, the repairing and protective effects of sunscreens and anti-oxidant Chinese herbal medicine were evaluated. Some of the plant extracts such as AGR、HGR、ACF、AME have potent inhibition activities on UV induced erythema.
