Nanoemulsion as a carrier to improve the topical anti-inflammatory activity of stem bark extract of Rapanea ferruginea

Abstract

The aim of this study was to develop nanoemulsion containing soft extract of stem bark of Rapanea ferruginea to improve the topical delivery and anti-inflammatory activity. The extract of R. ferruginea stem bark was incorporated into the oily phase of the nanoemulsion by the method of phase inversion at low energy. The developed nanoemulsion had an average droplet size of 47.88±8.20 nm and a polydispersibility index of 0.228. Uniformity of size, spherical shape of droplet, and absence of clusters were confirmed by transmission electronic microscopy. The zeta potential was −34.7±1.15 mV. The nanoemulsion showed a moderate degree of skin irritation in the agarose overlay assay in vitro. The content of the extract markers, myrsinoic acids A and B, was 54.10±0.08 and 53.03 μg/g in the formulation, respectively. The formulation demonstrated pseudoplastic and thixotropic rheological behavior. In vitro release of chemical markers was controlled by diffusion mechanism. An extract-loaded nanoemulsion showed a topical anti-inflammatory activity in a croton oil-induced edema ear model, with a decrease in tumor necrosis factor release and myeloperoxidase activity. The nanoemulsion was 160% more efficient than the conventional cream containing 0.13% of the extract. The nanoemulsion showed suitable properties as a carrier for topical use of R. ferruginea extract and the approach for improving the topical anti-inflammatory activity.

Keywords:

• nanotechnology
• nanoemulsion
• Rapanea ferruginea
• anti-inflammatory
• phytomedicine

Acknowledgments

The authors wish to thank FAPESC (Fundação de Amparo à Pesquisa e Inovação no Estado de Santa Catarina – Edital PRONEM (06/2012) FAPESC/CNPq, grant number 2708/2012) and CNPq (Conselho Nacional de Ciência e Tecnologia) for their financial support; CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior) by master student grants in Pharmaceutical Science sponsored J Dal Mas.

Disclosure

The authors declare that the current article is based on the Master thesis submitted to the Universidade do Vale do Itajai by Juarana Dal Mas under advisor of Dr Tania Mari Bellé Bresolin and Dr Ruth Meri Lucinda-Silva.