The essential oils yield of Cedrus atlantica, Chenopodium ambrosioides and Eucalyptus camaldulensis was different. C. ambrosioides gave a relatively higher yield (2.1 ± 0.1%), while that of C. atlantica was low (1.0 ± 0.1%) and that of E. camaldulensis was lower (0.75 ± 0.1% of dry matter). The active ingredients of the essential oils and some of their biological effects were also determined. The characterization of their chemical compositions showed that the three essences have different chemical profiles: C. atlantica was richer in sesquiterpenes (β-Himachalene (54.21%) and γ -Himachalene (15.54%)), C. ambrosioides was very rich in monoterpene peroxides and monoterpenes (α-Terpinene (53.4%), ascaridole (17.7%) and ρ-Cymene (12.1%)) and E. camaldulensis was very rich in monoterpene compounds and monoterpenols (p-cymene (35.11%), γ-Eudesmol (11.9%), L-linalool (11.51%) and piperitone (10.28%)). The in vitro measurement of antioxidant activity by the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) reduction assay showed a significant performance of the eucalyptus oil and average performance of the other two (C. atlantica and C. ambrosioides). The in vitro bio-test for their antimicrobial effects showed that the antibacterial activity differed depending on the essential oil and the concentration used, and that their bactericidal efficacy was similar or superior to that of synthetic antibiotics. The toxicity test on rats revealed that the LD₅₀ of the three essential oils was 500 mg/kg body weight, which classifies them as category four cytotoxic natural products at high doses.

This article aimed to study the antimicrobial activity, chemical composition, and acute oral toxicity of essential oils (EOs) of Mentha pulegium and Rosmarinus officinalis, two aromatic and medicinal plants widely used in the traditional Moroccan pharmacopeia. The average content of EOs was 3.2 and 2.5% for M. pulegium and R. officinalis, respectively. The chemical characterization showed a richness in some compounds identified by gas chromatography coupled with mass spectrometry (GC/MS): R(+)-Pulegone (45.48%), Menthone (14.2%), Piperitone (8.15%), and Isomenthone (7.18%) in M. pulegium and 1,8-Cineole (46.32%), Camphene (13.4%), and α-Pinene (9.52%) in R. officinalis. These metabolites showed a significant antimicrobial effect against the tested strains (bacteria and yeasts isolated from the hospital environment) compared to synthetic antibiotics that seem to be ineffective against resistant microorganisms. Based on lethal concentration LD₅₀ >5,000 mg/kg (body weight), the oil was found to be marginally safe according to OECD guidelines and can be further explored (bio-product with low risk).

The spread of microbial resistance around the world is one of the most serious threats to public health. Every year one to three antibiotics are released to the market, as each antibiotic has a limited effective lifespan after which microorganisms develop resistance. The need to identify new natural antimicrobial agents is an important research goal at the global level. The use of volatile plant extracts as antimicrobial agents represents a low risk for the development of resistance by microorganisms because these products are made up of several phytocompounds from different groups which work in synergy. The objective of this work is to test, in vitro, the antimicrobial activity of the essential oil of cedrus atlantica against six bacterial strains; Salmonella sp, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and streptococcus sp. And three strains of yeast; Candida Tropicalis, Candida Albicans, Saccharomyces Cerevisiae. With the aim of researching new effective antibacterial substance with a broad spectrum of action. The results of the quantitative analysis showed a richness in certain compounds identified by gas chromatography coupled with mass spectrometry; β-Himachalene, α-Himachalene, himachalene oxide and Limonene. The essential oil to show a significant antibacterial effect compared to the synthetic antibiotics tested Piperacillin 30 µg (PRL30) and Ampicillin 10 µg (AMP 10).