Formulation and skin permeation behaviour of a commercial standardised bilberry extract
Vaccinium myrtillus L. (bilberry) is a member of the Ericaceae family. The fruit extracts are used for the treatment of diarrhoea, mouth and throat inflammation, and as a symptomatic treatment of problems related to varicose veins, such as painful and heavy legs . The main characteristic and pharmacologically active constituents of the berries are anthocyanins. Their content in the fresh fruit is approximately 0.1–0.5%, while concentrated bilberry extracts are usually standardized up to 25–36% anthocyanins [2,3]. These pigments display a remarkable number of biochemical and pharmacological activities and many of their pharmacological properties have been correlated to the scavenging ability of oxygen-generated free radicals and to the inhibition of lipid peroxidation [1,4,5]. Recently, a cytoprotective effect against oxidative damage has also been demonstrated . The aim of the present study was to prepare several formulations with a commercial standardized extract containing 36% anthocyanins (Indena S.p.A., Milan, Italy) and evaluate both stability and skin permeability using the stripping test method . Some conventional preparations such as an anphyphil cream and two gels (natrosol and sepigel) were prepared, in addition liposomes, ethosomes and microemulsions were developed. The best skin permeation was obtained with ethosomes and microemulsions, with 15% of anthocyanin permeation. Recently, cyanidin-3-O-β-glucopyranoside, one of the main anthocyanins of bilberry extract, showed anti-proliferative activity against human melanoma cells , and anthocyanins were able to prevent skin cancer in rodents . Thus, ethosomes and microemulsions will be useful as delivery strategies that are able to substantially improve the therapeutic applicability of such antitumour compounds.
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