Hydroalcoholic gel with Argentine propolis: the potential for antimicrobial and antioxidant activities, stability evaluation, and in vitro phenolic release

Abstract

Propolis has been used in ethnobotany and traditional practices and is currently considered a source of phytotherapeutics. The aim of this study was to develop an antibiotic and antioxidant hydrogel containing Argentine propolis extract and evaluate its stability for one year in different conditions. A fingerprint by HPLC-DAD of propolis extract showed the presence of caffeic, coumaric, ferulic and cinnamic acids, caffeic acid phenethyl ester (CAPE) and flavonoids such as pinobanksin, apigenin, kaempferol, pinocembrin, chrysin, and galangin. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of propolis extract on clinical isolates (Gram-negative and Gram-positive) from the skin and soft tissue infections were between 25–100 μgGAE/ml and 50–200 μgGAE/ml, respectively. The concentration of propolis extract required to scavenge 50% of free radicals was 2 μgGAE/ml. The hydrogel with extract kept its chemical, physical and microbiological stability, and its biological properties over 1year of storage, mainly at 4 °C and at room temperature and light-protected. In addition, topical formulation showed good results in the release assay of active principle by using Franz’s cell. These studies suggest that the topical formulation could be used as an antioxidant and antibacterial topical apitherapeutic product.