PDF(Pubmed)
Abstract：
Chamazulene (CA) is an intensely blue molecule with a wealth of biological properties. In cosmetics, chamazulene is exploited as a natural coloring and soothing agent. CA is unstable and tends to spontaneously degrade, accelerated by light. We studied the photodegradation of CA upon controlled exposure to UVB-UVA irradiation by multiple techniques, including GC-MS, UHPLC-PDA-ESI-MS/MS and by direct infusion in ESI-MSn, which were matched to in silico mass spectral simulations to identify degradation products. Seven byproducts formed upon UVA exposure for 3 h at 70 mW/cm2 (blue-to-green color change) were identified, including CA dimers and CA benzenoid, which were not found on extended 6 h irradiation (green-to-yellow fading). Photostability tests with reduced irradiance conducted in various solvents in the presence/absence of air indicated highest degradation in acetonitrile in the presence of oxygen, suggesting a photo-oxidative mechanism. Testing in the presence of antioxidants (tocopherol, ascorbyl palmitate, hydroxytyrosol, bakuchiol, γ-terpinene, TEMPO and their combinations) indicated the highest protection by tocopherol and TEMPO. Sunscreens ethylhexyl methoxycinnamate and particularly Tinosorb® S (but not octocrylene) showed good CA photoprotection. Thermal stability tests indicated no degradation of CA in acetonitrile at 50 °C in the dark for 50 days; however, accelerated degradation occurred in the presence of ascorbyl palmitate.
摘要：
Chamazulene（CA）是一种强烈的蓝色分子，具有丰富的生物学特性。在化妆品中，恰莫曲烯被用作天然的着色和舒缓剂。CA是不稳定的，倾向于自发降解，光加速。我们通过多种技术研究了在受控暴露于UVB-UVA照射下CA的光降解，包括GC-MS，UHPLC-PDA-ESI-MS/MS和直接输注ESI-MSn，将其与计算机质谱模拟进行匹配，以识别降解产物。鉴定了在70mW/cm2下暴露于UVA3小时后形成的7种副产物(蓝色至绿色变化),包括CA二聚体和CA苯型，在延长6小时的照射（绿色至黄色褪色）中未发现。在存在/不存在空气的情况下，在各种溶剂中进行的辐照度降低的光稳定性测试表明，在氧气存在下，在乙腈中的降解最高。提示了光氧化机制。在抗氧化剂（生育酚，抗坏血酸棕榈酸酯，羟基酪醇，bakuchiol,γ-萜品烯,TEMPO及其组合）表明生育酚和TEMPO具有最高的保护作用。防晒剂甲氧基肉桂酸乙基己酯,特别是Tinosorb®S(但不是辛炔)显示出良好的CA光保护。热稳定性测试表明CA在乙腈中在50°C下在黑暗中50天没有降解；但是，在抗坏血酸棕榈酸酯存在下发生加速降解。
