Study On The Constituents, Enhancement Effect And Skin Safetyof Essential Oils From Alpinia Oxyphylla

Essential oils from plants are gaining increasing attention as potential chemical penetration enhancers. This study aimed to investigate the enhancement effect of essential oils from the fruits and leaves of Alpinia oxyphylla on skin permeation and deposition of model drug (Indomethacin). The study mainly includes chemical constituents, in vitro/in vivo permeation experiments, and skin safety test, which intend to support the application of essential oils in the field of transdermal drug delivery and cosmetics. Results are as follows:1. Essential oils from fruits and leaves were obtained through steam distillation. Major constituents of both oils were identified by gas chromatography-mass spectrometry (GC-MS). Results turned out that contents of hydrocarbon and oxygenated terpenes in fruit oil were 40.38% and 35.61%, respectively. While for leaf oil, they were 27.71% and 50.77%, respectively.2. In vitro permeation experiments were performed in Franz-type cells through excised rat skin with IND as the model drug. With the pretreatment method (2 h), the donor phase containing drug was applied, and the amount of drug passing through into the receptor phase (50% Ethanol/PBS) was analyzed by ultra performance liquid chromatography-photodiode array (UPLC-PDA). Results turned out that both oils demonstrated a significant enhancement effect on drug delivery and skin deposition (p<0.05). Particularly, at 3% concentration, enhancement ratios of fruit oil and leaf oil were 10.16 and 4.61, respectively, which were both significantly higher than that of the commonly used enhancer, Azone (2.04). It may be deduced that higher content hydrocarbon terpenes in the fruit oil contribute to the increased enhancement effect relative to the leaf oil.3. Under the same circumstances with the in vitro experiment, the in vivo penetration enhancement experiment was carried out in an in vivo rat model of drug delivery. Ultra fast liquid chromatography coupled with tandem mass spectrometry (UFLC-MS/MS) was used to analyze the plasma drug concentration of indomethacin at different intervals after the application of donor phase to examine the enhancement effect of essential oils. It was found out that both essential oils at 3% level exhibited obvious in vivo enhancement effect. At 2 h, drug plasma concentration reached maximum and gradually decreased as the time.4. The skin irritation test was carried out with rabbits. Erythema and edema scores were evaluated by a visual scoring method refered to Hygienic Standard for Cosmetics. Results indicated that both oils at certain concentrations (1%,3%, and 5%) did not cause obvious erythema or edema in rabbits. Hence, essential oils from leaves and fruits of A. oxyphylla are safe to rabbits at the concentrations tested.