Cytotoxicity, early safety screening, and antimicrobial potential of minor oxime constituents of essential oils and aromatic extracts

Abstract

Due to market and legislative expectations, there is a constant need to explore new potential antimicrobial agents for functional perfumery. In this study, we evaluated the antimicrobial activity of 53 low molecular oximes and the corresponding carbonyl compounds against Escherichia coli, Enterococcus hirae, Pseudomonas aeruginosa, Bacillus cereus, Staphylococcus aureus, Aspergillus brasiliensis, Legionella pneumophila and Candida albicans. The most potent compound was α-isomethylionone oxime, which exhibited a minimum inhibitory concentration (MIC) of 18.75 µg/mL against E. hirae. The evaluation of the MICs for bacterial and fungal strains was performed for selected compounds, for example, the MIC of 2-phenylpropionaldehyde, cis-jasmone oxime, and trans-cinnamaldehyde measured against A. brasiliensis was 37.50 µg/mL. ADME-Tox (Absorption, Distribution, Metabolism, Excretion, and Toxicity) and 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) cell viability assays were performed to assess the cytotoxicity of tested compounds. ADME-Tox indicated the safety and promising properties of selected compounds, which enables their usage as nontoxic supporting antibacterial agents. The results of the in vitro MTS assay were consistent with the ADME-Tox results. None of the compounds tested was toxic to Human Embryonic Kidney 293T (HEK293T) cells, with all cell viabilities exceeding 85%.

Figure 1

Images of HEK293T cell lines from a Nikon Eclipse TS2R microscope. (A) Control well. With added tested agents: (B) Propiophenone oxime, (C) β-ionone oxime, (D) (+)-carvone oxime, and E. norcamphor oxime. On comparison of the images, it can be stated that the tested compounds do not affect the morphology or viability of the cell line.

Figure 2

Graph showing the calculated parameters related to the biopermeability of compounds for humans: QPlogKp (predicted skin permeability, log Kp.), QPlogKhsa (prediction of binding to human serum albumin). The green area shows the normal range of values.