A Radish Root Ferment Filtrate for Cosmetic Preservation: A Study of Efficacy of Kopraphinol

Preserving cosmetic products from microbial contamination is crucial to ensuring their safety, efficacy, and shelf life. A number of synthetic antimicrobial preservatives are available, but, since the global market demand for natural ingredients is increasing, cosmetic manufacturers are considering replacing conventional preservatives with natural alternatives. In this context, the objective of this investigation was to characterize the antimicrobial activity of the natural preservative, intended for cosmetic purposes, Kopraphinol (INCI name: Lactobacillus/Radish Root Ferment Extract Filtrate). It was tested against a panel of selected bacteria and mycetes by using conventional microbiological techniques (determination of MIC, time killing assay), and a challenge test was used to verify its potential preservative in an O/W hydrophilic cream (Cetomacrogol cream base). Kopraphinol has shown an interesting antimicrobial effectiveness, with M.I.C.s ranging from 0.78% to 6.25% for bacteria and from 1.56% to 5% for mycetes. Moreover, it fulfilled challenge test criterion A and has proven effective against microbial contamination, leading to a 3 log reduction of inoculum after 7 days for bacteria and a 2 log reduction at 14 days for fungi. The results obtained show that Kopraphinol can be considered a promising and effective candidate for the antimicrobial preservation of cosmetics and could successfully complement or even replace conventional preservatives.