Effects of ultraviolet radiation on the kinetics of in vitro percutaneous absorption of lavender oil

https://doi.org/10.1016/j.ijpharm.2009.07.037Get rights and content

Abstract

The purpose of the present study is to investigate the influence of ultraviolet radiation on the rat skin absorption of lavender essential oil. The pure oil was extracted from Lavandula angustifolia by steam distillation. The chemical composition of lavender oil showed that terpenes are major compounds. In vitro, the essential oil was applied onto the rat skin. The amount of the compounds was determined using gas chromatography. Similarly, the amount of these compounds was analyzed for the skin exposed to ultraviolet radiation (UVAI) after 4, 8, 12 and 24 h. Our study demonstrated that the penetration profiles showed a cycle of charge–discharge (4 h/4 h, respectively). Our data point to the presence of reversible change in stratum corneum behavior. Interestingly, the ultraviolet radiation altered the cycle (charge–discharge) for terpenes (low lipophilicity) and increased the charge time. However, for terpenes (high lipophilicity), the ultraviolet radiation decreased the charge amplitude.

Introduction

The absorption of auxiliary ingredients from pharmaceutical formulations is one of the least explored processes (Cal et al., 2001, Cal and Sznitowska, 2003). This is also true for percutaneous penetration enhancers, a special kind of excipients which penetrate into the skin and the promote diffusion of drugs as a consequence of the changes in the structure of stratum corneum, a barrier layer of the skin (Cal and Sznitowska, 2003). Terpenes are absorption promoters frequently used in numerous studies, but the kinetics of their transdermal absorption has not been well-documented yet, in spite of the fact that terpenes are used in cosmetic and dermatological products not only for their promoting effect but also as fragrances or active substances (Williams and Barry, 1991). They are considered as nontoxic; however, they are well-known sensitizers and, due to a very broad biological activity, other side effects cannot be excluded (Schempp et al., 2002). Therefore, their penetration through the skin should be controlled.

The mechanism of the changes in the stratum corneum (SC) is a subject of most publications on terpenes and skin (Williams and Barry, 1991, Buck, 2004). Alone, or in mixtures, terpenes promote the percutaneous penetration of lipophilic as well as hydrophilic drugs. The range of Log P values for terpenes is wide, from 1 up to 6, and the linear relationship between Log P and the enhancement effect towards penetration of model drugs was reported (El-Kattan et al., 2001). There are only few published studies on absorption of terpenes into the skin. In addition, the skin is constantly exposed to pro-oxidant environmental stresses which can influence the percutaneous absorption of many compounds such as terpenes. Indeed, the skin is constantly exposed to the ultraviolet radiation including exposure to the sun, the use of sun-tanning devices and during a phototherapy meeting (Tzaneva et al., 2001, Herrling et al., 2006; Mantena and Katiyar, 2006). Terpenes are major constituents of essential oils such as lavender oil obtained from Lavandula angustifolia (Cal et al., 2001, Cavanagh and Wilkinson, 2002). It is used for its sedative and spasmolytic effects (Kim and Lee, 2002).

The purpose of the present study was to determine the in vitro percutaneous absorption kinetic of main components of lavender oil and the influence of ultraviolet radiation on its kinetics.

Section snippets

Essential oil extraction

Dried plants of L. angustifolia (3 kg) were coarsely cut and extracted by ultrasound assisted steam distillation. The extraction duration was 3 h. The yield was 3.40% optimized for a relative pressure of 0.4 bar. The essential oil obtained is a pale-yellow liquid with a slightly camphoraceous odor.

Skin penetration studies

In vitro skin permeation experiments were carried out using cell diffusion. The dorsal skin of Wistar rat (180–200 g) was shaved by an electric clipper a night before of experiment and then the excised

Chemical composition of lavender oil

The chemical identification and the quantitative estimation of lavender oil showed that it contained five main components: linalool (25.18%), linalyl acetate (21.71%), 1,8-cineol (14.12%), camphor (11.15%) and carvacrol (2.34%) (Table 1).

In vitro percutaneous absorption of lavender oil

The percutaneous absorption of lavender oil was studied by the determination of its main components quantities that was accumulated during the times of exposition, and the system was protected against evaporation. During different times, no terpenes were

Discussion

The present study was undertaken in order to investigate the influence of ultraviolet radiation on rat skin absorption kinetic of lavender essential oil. Firstly, we have determined the chemical composition of lavender oil. Our results showed that terpenics compounds were main constituents of the essential oil: linalool (25.18%), Linalyl acetate (21.71%), 1,8-cineol (14.12%), camphor (11.15%) and carvacrol (2.34%). The chemical composition analysis of essential oil for the same specie carried

View full text