Antimicrobial activity of oleuropine and thyme extracts against selected pathogenic microorganisms and their potential uses as natural preservatives

Abstract

Introduction: Currently, there is an increasing desire for food, cosmetic, and pharmaceutical products with fewer synthetic chemicals, and longer shelf life. Thus, there is an urgent need to develop these products with self-preservation and /or protection from microbial growth using natural substances. The purpose of this study was to confirm the antimicrobial activity of Oleuropein and thyme oil (pharmacopeial grade). In addition, we combined oleuropein and thyme oil at different concentrations to determine their antimicrobial synergistic effects and the potential to use them as natural preservatives in food, cosmetic, and pharmaceutical preparations. Methods: Oleuropine and thyme oil were evaluated for their activity against human pathogenic microorganisms such as Candida albicans (ATCC 10231) Aspergillus niger (ATCC 16404), Escherichia coli (ATCC 8739), Pseudomonas aeruginosa (ATCC 9027), Staphylococcus aureus (ATCC 6538). The antimicrobial activity of the extracts was performed by antimicrobial preservative tests used for topical formulations according to the United States Pharmacopeia (USP). Results: The efficiency of Oleuropine against the microbes tested showed an optimum concentration of 0.6%. Whereas thyme oil at a concentration of 0.1% v/v. showed that it was effective against the three bacteria only The antimicrobial activity of oleuropine (0.4 w/v %) and thyme oil (0.1 v/v % ) showed synergistic activity against all pathogenic microorganisms tested. Conclusion: The combination can be considered very promising for use as antimicrobial natural preservatives in food, cosmetic, and pharmaceutical products. In addition, it can be of great significance in the treatment of infectious diseases such as superficial skin infections caused by pathogenic microorganisms.