Cupressus sempervirens Essential Oil: Exploring the Antibacterial Multitarget Mechanisms, Chemcomputational Toxicity Prediction, and Safety Assessment in Zebrafish Embryos

Abstract

Nowadays, increasing interest has recently been given to the exploration of new food preservatives to avoid foodborne outbreaks or food spoilage. Likewise, new compounds that substitute the commonly used synthetic food preservatives are required to restrain the rising problem of microbial resistance. Accordingly, the present study was conducted to examine the chemical composition and the mechanism(s) of action of the Cupressus sempervirens essential oil (CSEO) against Salmonella enterica Typhimuriumand Staphyloccocus aureus. The gas chromatography analysis revealed α-pinene (38.47%) and δ-3-carene (25.14%) are the major components of the CSEO. By using computational methods, such as quantitative structure-activity relationship (QSAR), we revealed that many CSEO components had no toxic effects. Moreover, findings indicated that α-pinene, δ-3-carene and borneol, a minor compound of CSEO, could inhibit the AcrB-TolC and MepR efflux pump activity of S. enterica Typhimurium and S. aureus, respectively. In addition, our molecular docking predictions indicated the high affinity of these three compounds with active sites of bacterial DNA and RNA polymerases, pointing to plausible impairments of the pathogenic bacteria cell replication processes. As well, the safety profile was developed through the zebrafish model. The in vivo toxicological evaluation of (CSEO) exhibited a concentration-dependent manner, with a lethal concentration (LC₅₀) equal to 6.6 µg/mL.

Keywords: Cupressus sempervirens essential oil; antibacterial activity; computational toxicology; membrane permeability; molecular docking; replication and transcription inhibition; zebrafish.

Figure 1

The embryotoxicity of different concentrations of (CSEO) in embryonic zebrafish mortality. All tests were performed in triplicate; Values with a different letter (a–g) are significantly different (p < 0.05).

Figure 2

AcrB efflux pump receptor of S. enterica Typhimurium complexed with α-pinene (A), δ-3-carene (B), and borneol (C).

Figure 2

AcrB efflux pump receptor of S. enterica Typhimurium complexed with α-pinene (A), δ-3-carene (B), and borneol (C).

Figure 3

MepR receptor of S. aureus complexed with α-pinene (A), δ-3-carene (B), and borneol (C).

Figure 3

MepR receptor of S. aureus complexed with α-pinene (A), δ-3-carene (B), and borneol (C).

Figure 4

α-Pinene complexed with DNA polymerase enzyme (A), RNA polymerase (B), topoisomerase II (C) of S. aureus.

Figure 4

α-Pinene complexed with DNA polymerase enzyme (A), RNA polymerase (B), topoisomerase II (C) of S. aureus.

Figure 5

α-Pinene complexed with DNA polymerase enzyme (A), RNA polymerase (B), topoisomerase II (C) of S. enterica Typhimurium.

Figure 5

α-Pinene complexed with DNA polymerase enzyme (A), RNA polymerase (B), topoisomerase II (C) of S. enterica Typhimurium.

Figure 6

δ-3-Carene complexed with DNA polymerase enzyme (A), RNA polymerase (B), topoisomerase II (C) of S. aureus.

Figure 6

δ-3-Carene complexed with DNA polymerase enzyme (A), RNA polymerase (B), topoisomerase II (C) of S. aureus.

Figure 7

δ-3-carene complexed with DNA polymerase enzyme (A), RNA polymerase (B), topoisomerase II (C) of S. enterica Typhimurium.

Figure 7

δ-3-carene complexed with DNA polymerase enzyme (A), RNA polymerase (B), topoisomerase II (C) of S. enterica Typhimurium.

Figure 8

Borneol complexed with DNA polymerase enzyme (A), RNA polymerase (B), topoisomerase II (C) of S.aureus.

Figure 8

Borneol complexed with DNA polymerase enzyme (A), RNA polymerase (B), topoisomerase II (C) of S.aureus.

Figure 9

Borneol complexed with DNA polymerase enzyme (A), RNA polymerase (B), topoisomerase II (C) of S. enterica Typhimurium.

Figure 9

Borneol complexed with DNA polymerase enzyme (A), RNA polymerase (B), topoisomerase II (C) of S. enterica Typhimurium.