Factorial design applied to the optimization of lipid composition of topical antiherpetic nanoemulsions containing isoflavone genistein

Abstract

Débora Fretes Argenta,1 Cristiane Bastos de Mattos,1 Fabíola Dallarosa Misturini,1 Leticia Scherer Koester,1 Valquiria Linck Bassani,1 Cláudia Maria Oliveira Simões,2 Helder Ferreira Teixeira1 1Programa de Pós-graduação em Ciências Farmacêuticas da Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; 2Programa de Pós-graduação em Farmácia da Universidade Federal de Santa Catarina, Florianópolis, Brazil Abstract: The aim of this study was to optimize topical nanoemulsions containing genistein, by means of a 23 full factorial design based on physicochemical properties and skin retention. The experimental arrangement was constructed using oil type (isopropyl myristate or castor oil), phospholipid type (distearoylphosphatidylcholine [DSPC] or dioleylphosphaditylcholine [DOPC]), and ionic cosurfactant type (oleic acid or oleylamine) as independent variables. The analysis of variance showed effect of third order for particle size, polydispersity index, and skin retention of genistein. Nanoemulsions composed of isopropyl myristate/DOPC/oleylamine showed the smallest diameter and highest genistein amount in porcine ear skin whereas the formulation composed of isopropyl myristate/DSPC/oleylamine exhibited the lowest polydispersity index. Thus, these two formulations were selected for further studies. The formulations presented positive ζ potential values (>25 mV) and genistein content close to 100% (at 1 mg/mL). The incorporation of genistein in nanoemulsions significantly increased the retention of this isoflavone in epidermis and dermis, especially when the formulation composed by isopropyl myristate/DOPC/oleylamine was used. These results were supported by confocal images. Such formulations exhibited antiherpetic activity in vitro against herpes simplex virus 1 (strain KOS) and herpes simplex virus 22 (strain 333). Taken together, the results show that the genistein-loaded nanoemulsions developed in this study are promising options in herpes treatment. Keywords: skin retention, antiherpetic activity, phospholipids, cationic nanoemulsions