The chemical compositions of four commercial essential oils were investigated using gas chromatography (GC) and gas chromatography-mass spectrometry (GC/MS) in this study. The prostate cancer cell lines PC3 and LNCaP were used to test the antiproliferative activities of the four essential oils using crystal violet staining. p-Cymene (14.2%), limonene (11.6%), and elemol (10.8%) were identified as the main compounds in Elemi-A. Limonene (36.4%), terpinolene (11.2%), and α-phellandrene (10.3%) were the major constituents in Elemi-B. α-Pinene (22.9%) and α-thujone (14.5%) were the main compounds of Frankincense-A. α-Thujone (35.4%) was the main compound in Frankincense-B. Three essential oil samples (Elemi-A, Elemi-B, and Frankincense-A) had minimum inhibitory concentration (MIC) values under 2 mg/mL against Bacillus subtilis and displayed noteworthy antibacterial activity. Additionally, Elemi-A had MIC values under 2 mg/mL against B. cereus and Pseudomonas aeruginosa. Moreover, Elemi-B had MIC values under 2 mg/mL against P. aeuroginosa. Elemi-B and Frankincense-B had dose-dependent and significant antiproliferative effects with IC50 values of 266.7 μg/mL and 230 μg/mL, respectively, against PC3 cells. The IC50 values of Elemi-A and Frankincense-A in the PC3 cells were 821.6 and 537.7 μg/mL, respectively. Only Elemi-B displayed a dose-dependent antiproliferative effect in the LNCaP cells with an IC50 value of 235.4 μg/mL. The present study determined the chemical composition of the essential oil of Elemi of French origin for the first time. Additionally, the antiproliferative activities of four essential oils against PC3 and LNCaP cells were first reported. Elemi-B, with the lowest IC50 values in the LNCaP and PC3 cells, had promising anticancer potential.

This study aimed to determine the secondary metabolite profiles and antibacterial activity of H. perforatum L extracts against Gram-positive clinical isolates. The plant materials (Sample A and Sample B) were macerated with n-hexane, ethyl acetate and methanol (MeOH). The antibacterial activitiy of plant extracts and routinely used antibiotics were tested against Gram-positive bacteria. The secondary metabolite profiles of Sample A were determined by LC-Q-TOF-MS. The MIC values for n-hexane and ethyl acetate extracts of Sample A were lower than the susceptibility breakpoints of most broad-spectrum antibiotics (e.g. vancomycin, teicoplanin and linezolid) in a certain proportion of Gram-positive bacteria. The n-hexane extract of Sample A showed good antibacterial activity with MICs lower than the susceptibility breakpoint of teicoplanin in 58% of coagulase-negative staphylococci. The n-hexane and ethyl acetate extracts of Sample A had rich phloroglucinol constituents. The n-hexane and ethyl acetate extracts of Sample A could be alternative antibacterial agents against Gram-positive bacteria.

Essential oil composition and antibacterial activity of Calendula arvensis L. were investigated. The essential oil of aerial part was obtained through hydro-distillation using a Clevenger type apparatus with 0.38 (v/w) yield. The essential oil components were determined by GC-MS analyses. Thirty-six components were identified in the essential oil that represented 91.8 % of the oil. The major components of the essential oil were δ-cadinene (14.8 %), epi-cubebol (10.7 %), α-cadinol (8.5 %), cubenol (7.7 %), cubebol (7.2 %), 1-epi-cubenol (5.4 %) and ledene (5.1 %). Antibacterial activity of essential oil was observed against Staphylococcus aureus ATCC 29213, Bacillus cereus ATCC 14579, Pseudomonas aeruginosa ATCC 27853 and Escherichia coli ATCC 25922 by using a broth microdilution. The essential oil showed weak inhibitory activity against E. coli and B. cereus at 8 mg/mL. The oil didn‘t show any antibacterial activity against S. aureus and P. aeruginosa. These results revealed that the oil was rich in oxygenated sesquiterpenes as well as had a weak antimicrobial activity.

Background/Objectives: Essential oils of Thymbra spicata subsp. spicata are known for their rich phytochemical content and bioactive properties. This study aimed to evaluate the antimicrobial, anti-biofilm and anti-quorum sensing, as well as the cytotoxic activities of T. spicata subsp. spicata essential oils (TS-EO1 and TS-EO2) obtained from two different localities in Türkiye, along with a detailed chemical composition analysis. Methods: TS-EO1 and TS-EO2 were obtained by the hydrodistillation method and analyzed using Gas Chromatography—Mass Spectrometry (GC-MS) to determine their phytochemical profiles. Antimicrobial activities were assessed against Gram-positive and Gram-negative bacteria, and fungal strains were assessed using the broth microdilution method. Anti-biofilm and anti-quorum sensing activities were evaluated using Pseudomonas aeruginosa PAO1 and Chromobacterium violaceum ATCC 12472, respectively. Cytotoxic properties were tested on four cell lines (A549, MCF-7, U87MG, and L929) using the MTT assay. Results: Both essential oil samples were rich in carvacrol (54.3% and 54.1%), followed by p-cymene and γ-terpinene. The essential oils exhibited significant antimicrobial activity, particularly against Staphylococcus aureus (6.25 mg/mL) and Candida parapsilosis (0.20 mg/mL). Sub-MIC concentrations significantly inhibited biofilm formation and quorum sensing. Both samples showed moderate cytotoxic properties against human cancer cell lines, particularly A549 (IC50: 116.3 and 134.4 μg/mL, respectively). Conclusions: This study showed that T. spicata subsp. spicata essential oils have significant antimicrobial, anti-biofilm, and anti-quorum sensing properties against various bacteria and fungi, along with moderate cytotoxic effects, indicating their medicinal and pharmaceutical potentials. This is the first study which revealed anti-biofilm and anti-quorum sensing properties of T. spicata essential oils to our knowledge.