# Optimizing Antibacterial Essential Oil Blends from Helichrysum plicatum, Petroselinum crispum, and Origanum vulgare for Dairy Preservation: Mixture Design and In Silico Analysis

## TL;DR

This study finds that a blend of three essential oils can effectively inhibit bacteria in dairy products, offering a natural preservation solution.

## Contribution

The study introduces an optimized essential oil blend and validates its antibacterial properties using both experimental and computational methods.

## Key findings

- A 16:16:68 ratio of H. plicatum, P. crispum, and O. vulgare oils showed optimal antibacterial efficacy against L. monocytogenes and E. coli.
- Key compounds like carvacrol and α-pinene exhibited good drug-likeness and stable binding to bacterial enzymes.
- The essential oil blend is proposed as a natural antimicrobial for dairy preservation.

## Abstract

This study demonstrates the potential of Helicrisum plicatum (H. plicatum), Petroselinum crispum (P. crispum) and Origanum vulgare (O. vulgare) essential oils and their combination against four strains of two bacterial species, Listeria monocytogenes (L. monocytogenes) and Escherichia coli (E. coli), isolated from milk. GC/MS and GC/FID analyses of H. plicatum essential oil revealed α-pinene (27.61%), γ-curcumene (20.7%) and neryl acetate (5.88%) as the main compounds present in H plicatum essential oil. The main components of the essential oil of P. crispum were α-pinene (17.34%), 1,3,8-p-menthatriene (23.66%), β-phellandrene (10.41%) and myristicin (12.7%). In O. vulgare essential oil, carvacrol (58.3%), o-cymene (15.4%) and thymol (6.0%) were predominant compounds. Subsequently, an augmented simplex-centroid mixture design was applied to optimize the antibacterial efficacy of EO formulations against L. monocytogenes and E. coli. The simultaneous optimization all responses indicates that the optimal antimicrobial formulation was achieved using a ternary mixture of H. plicatum, P. crispum, and O. vulgare in a 16:16:68 (v/v/v) ratio. In parallel, an in silico study of four main essential oil components evaluated their drug-likeness, pharmacokinetic and toxicity properties, and binding to bacterial targets. These major compounds satisfy the main standards for drug-like molecules, with simulations pointing to good oral absorption, an acceptable safety profile, and stable binding to key enzymes in E. coli and L. monocytogenes, which supports their antibacterial potential. Overall, these combined experimental and computational results point to oregano, parsley, and immortelle essential oils as promising natural antimicrobial options for improving the preservation of dairy products.