Effect of hot or warm property on skin toxicity of essential oil as penetration enhancer and its mechanism / 中国中药杂志

To compare the effect of hot or warm property of Chinese medicine(CM) on the skin toxicity of essential oils(EOs) as penetration enhancer in vitro and in vivo, and explore the mechanism. EOs were extracted from WIM of Bichengqie(Litseae Fructus), Dingxiang(Flos Syzygii Aromatici), Huajiao(Pericarpium Zanthoxyli Bungeani), and Xiaohuixiang(Fructus Foeniculi) with warm property, and Ganjiang(Rhizoma Zingiberis), Gaoliangjiang(Rhizoma Alpiniae Officinari), Hujiao(Fructus Piperis), and Wuzhuyu(Fructus Evodiae Rutaecarpae) with hot property, respectively. Then the in vitro toxicity was evaluated by human keratinocyte cytotoxicity. In vivo skin irritation potency was also evaluated through pathological observation after topical administration. The components, especially those located in stratum corneum, were analyzed by GC-MS. The main components, namely monoterpenes and sesquiterpenes, of EOs extracted from CM with hot property,were detected for the interaction with keratino-lipid ceramide 3 by molecular simulation technology; and the interaction energy value was calculated based on the optimal conformation. It was found that the skin cell toxicity of EOs from CM with hot property was significantly higher than that of EOs from CM with warm property. However, there was no significant difference between them by in vivo skin irritation evaluation. Whether from CM with hot property or warm property, EOs showed a significant reduced toxicity compared with azone. Sesquiterpenes(33.56%±19.38%) were found to be one of the main components in EOs from CM with hot property, while almost no sesquiterpenes was found in EOs from CM with warm property. After topical administration of EOs from CM with hot property, sesquiterpenes were demonstrated to be prone to locate in stratum corneum. The results of molecular simulation also revealed that the interaction between sesquiterpenes and ceramide 3 was significantly stronger than that of monoterpenes(P<0.01). In conclusion, the location of sesquiterpenes in stratum corneum resulted in the significant difference between in vitro skin cell toxicity and in vivo skin irritation potency. The EOs from CM with hot property shall be taken into account for further development of potent penetration enhancer.

Investigation of Skin Irritation of Essential Oils from Interior-warming Medicines / 中国实验方剂学杂志

Objective:To investigate the skin irritation of essential oils(EOs) extracted from interior-warming medicines. Method:Three EOs from interior-warming medicines(Cinnamomi Cortex, Caryophylli Flos and Alpiniae Officinarum Rhizoma) were selected as research objects.The in vitro skin cytotoxicity and in vivo skin irritation of these EOs were determined and compared.Moreover, the skin irritation was also predicted by the novel skin test panels. Result:Toxicity of these three EOs to human skin fibroblasts(HSF) was significantly different, half-inhibitory concentration(IC50) values of EOs from Cinnamomi Cortex, Alpiniae Officinarum Rhizoma and Caryophylli Flos were (11.16±0.28), (53.33±1.71), (226.70±17.61) mg·L-1, respectively.However, in vivo skin irritation evaluation showed that the local toxicity of these three EOs was in the order of EO of Cinnamomi Cortex > EO of Caryophylli Flos > EO of Alpiniae Officinarum Rhizoma. The evaluation results of skin test panels for these three EOs were in accordance with the results of in vivo skin irritation evaluation. Conclusion:Toxicity of these three EOs against skin cells in vitro is inconsistent with their in vivo skin irritation. Skin test panels are expected to be able to accurately predict in vivo skin irritation of EOs instead of cytotoxicity evaluation.

New Techniques for the Evaluation of Penetration Enhancers / 中国药学杂志

Penetration enhancers (PEs) are commonly used for improving bioavailability of transdermal drug delivery formulations. In the present paper, the new techniques to investigate the penetration enhancement ability, penetration enhancement mechanism and skin safety of PEs were intensively reviewed. The trends of PE research include high throughput evaluation of penetration enhancement ability, micro-molecular research of penetration enhancement mechanism and quantitative characterization of skin safety. Emergence of new techniques provides technical support which is faster, more comprehensive and reliable for the selection and research of penetration enhancers in future.