In vitro and in vivo evaluation of the delivery of topical formulations containing glycoalkaloids of Solanum lycocarpum fruits.

The glycoalkaloids solasonine (SN) and solamargine (SM) have been studied for their antiparasitic, antifungal, and anticancer properties, especially in vitro and in vivo against non-melanoma skin cancer. Thus, the alkaloidic extract of Solanum lycocarpum, which contains approximately 45% each of SN and SM, was used to define the best experimental conditions for in vitro and in vivo assays. The in vitro assays were performed with the Franz cell diffusion porcine skin model to evaluate the effects of different pHs and the presence of monoolein, ethoxydiglycol or ethanol penetration enhancers on the skin penetration and retention of SN and SM after 3, 6, 9 and 12h of exposure. The in vivo assay was performed on hairless mice with the formulation selected in the in vitro assays. The results showed that pH 6.5 was optimal for SM penetration. The formulation containing 5% alkaloidic extract, 5% propylene glycol, 5% monoolein and a hydroxyethyl cellulose gel base (Natrosol) (pH 6.5) was optimal for the delivery of SN and SM into the skin, and this formulation is potentially useful for the topical therapy of several skin disorders.