Boosting the Antimicrobial Activity of Highly Diluted Aqueous Alcoholic Sanitizers by Fortification with Essential Oil Components: I- Carvacrol

Abstract

The current study aims at developing alcoholic-based sanitizing formula against some pathogenic bacteria based on highly diluted (< 70.0%) aqueous isopropanol solution which is fortified with small amount of an essential oil component like carvacrol. This phenolic compound can act as antimicrobial booster for the compensation of alcohol reduction in the sanitizer. The solubility behavior of carvacrol in the aqueous alcoholic solution containing different ratios of isopropanol and water was investigated using the Gibbs’ phase diagram. Based on that, a selected formula containing 1.0% carvacrol dissolved in the highest possible dilution of isopropanol (45.0%) was chosen for testing its antimicrobial activity against some gram positive and negative pathogenic bacteria in comparison to the standard 70.0% alcohol formula without carvacrol. Results indicated that a 45.0% aqueous isopropanol solution can hold up to 5.0% carvacrol at maximum in a physically stable and homogenous sanitizing formula. Antimicrobial evaluation of the developed diluted aqueous isopropanol fortified with 1.0% carvacrol showed the same inhibition against the tested pathogenic bacteria as the standard 70.0% alcohol sanitizer without carvacrol. In conclusion, 45.0% diluted isopropanol fortified with a minimum of 1.0% up to 5.0% carvacrol (in case of intensive sanitization) can possibly be used as sanitizer for protection against some pathogenic bacteria. The practical significance of this study is the production of diluted alcoholic sanitizing formula for decontamination of surfaces against some pathogenic bacteria with the advantage of increasing alcohol dilution in order to spare the absolute alcohol reserve for more quantitative production of the sanitizer.