Introduction

The current trends in cosmetic preservation leave the formulator with much narrower varieties of options, only facing a fast shrinking pool of compounds of interest. The personal care industry continues to seek natural, affordable mild yet effective preservative systems.
As the development and registration of complete new synthetic preservatives molecules are generally considered as unattractive and cumbersome in terms of cost, time and consumer perception, the research objective was to boldly optimize the use of already authorized compounds, by means of revealing synergistic effects between hand-picked compounds, to be exploited to generate superior preservation efficacy.
Research methods focused on a series of tests to assess antimicrobial activity of evaluated substances, such as minimum inhibitory concentration (MIC), Challenge Test for Cosmetics according to Pharmacopoeia protocols (EP, USP), as well as other aspects evaluated by clinical and applicative studies performed using various representative cosmetic formulas.