Influence of herbal extracts in physicochemical properties and stability of antibacterial gels

Abstract

The use of plants to treat diseases and heal wounds is a custom that dates back thousands of years and is a legacy of ancient civilizations. Although a significant proportion of the planet's plant biodiversity is found on theAmerican continent, there are very few pharmaceutical products developed from it. This work aimed to develop and characterize topical formulations (gels and emulgels), including a combination of plant extracts with recognized antibacterial activity. Hydroalcoholic extracts of Lippia turbinata Griseb. and Lippia alba (Mill.) N. E. Brown were obtained by leaching. The excipients used were Carbopol® 934 and 940, Sepigel® 305, sodium carboxymethylcellulose, methylcellulose, propylene glycol, and ethanol. The finished product was characterized by properties: organoleptic characteristics, extensibility, pH, texture profile, permeation performance, and microbiological quality. Then, they were subjected to stability studies in different conditions of temperature and humidity. They had a characteristic smell of plant species, color brown, without the presence of lumps, and with good extensibility. The gels had an in vitro permeation of porcine skin of up to 30% and low retention in the epithelium (<15%). They did not present microbial contamination and were stable for six months. Of the gels formulated, the gel with Sepigel® 4% (w/w) presented a better appearance. These results demonstrate the feasibility of transporting non-hydro soluble extracts in a gel formulation. All formulations are appropriate to preserve the antibacterial effect of original extracts. They maintain stability over time without the use of antimicrobial preservatives.