Melaleuca alternifolia essential oil (tea tree oil) is widely used as an ingredient in skin care products because of its recognized biological activities. The European Scientific Committee on Consumer Products constantly promotes research and collection of data on both skin distribution and systemic exposure to tea tree oil components after the application of topical formulations. This study quantitatively evaluates permeation, skin layer distribution (stratum corneum, epidermis, and dermis), and release into the surrounding environment of bioactive tea tree oil markers (i.e., α-pinene, β-pinene, α-terpinene, 1,8-cineole, γ-terpinene, 4-terpineol, α-terpineol) when a 5% tea tree oil formulation is applied at a finite dosing regimen. Permeation kinetics were studied in vitro on pig ear skin using conventional static glass Franz diffusion cells and cells ad hoc modified to monitor the release of markers into the atmosphere. Formulation, receiving phases, and skin layers were analyzed using a fully automatic and solvent-free method based on headspace solid-phase microextraction/gas chromatography-mass spectrometry. This approach affords, for the first time, to quantify tea tree oil markers in the different skin layers while avoiding using solvents and overcoming the existing methods based on solvent extraction. The skin layers contained less than 1% of each tea tree oil marker in total. Only oxygenated terpenes significantly permeated across the skin, while hydrocarbons were only absorbed at trace level. Substantial amounts of markers were released into the atmosphere.

中文翻译：

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互叶白千层精油：使用无溶剂分析方法评估局部制剂的皮肤渗透和分布

互叶白千层精油（茶树油）因其公认的生物活性而被广泛用作护肤产品的成分。欧洲消费品科学委员会不断促进有关皮肤分布和应用局部制剂后茶树油成分全身暴露的研究和数据收集。本研究定量评估了生物活性茶树油标记物（即 α-蒎烯、β-蒎烯、α-萜品烯、1,8-桉树油、γ-萜品烯、4-萜品醇、α-萜品醇），当以有限剂量方案应用 5% 茶树油制剂时。使用传统的静态玻璃 Franz 扩散池和经过特别改造以监测标记物释放到大气中的细胞，对猪耳朵皮肤的渗透动力学进行了体外研究。使用基于顶空固相微萃取/气相色谱-质谱法的全自动无溶剂方法分析配方、接收相和表层。这种方法首次能够量化不同表皮层中的茶树油标记，同时避免使用溶剂并克服现有的基于溶剂提取的方法。表皮层中每种茶树油标记物的含量总计不到 1%。只有含氧萜烯显着渗透到皮肤中，而碳氢化合物仅被微量吸收。大量标记物被释放到大气中。