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The herb, Elettariopsis triloba (Gagnep.) Loes. (syn. Amomum trilobum Gagnep. or Elettariopsis trilobum (Gagnep.), has been used ethnomedically for the treatment of rabies, inflammation and amelioration of microbial infections. We report herein the chemical constituents and antimicrobial activity of the rhizome essential oil of E. triloba from north-central Vietnam. The technique of gas chromatography (GC) and gas chromatography coupled with mass spectrometry (GC/MS) was used to analyze the oil sample while the microdilution assay was employed to determine the antimicrobial efficacy. Monoterpene compounds including camphene (23.2 %), fenchyl acetate (12.7 %), bornyl acetate (10.6 %), α-pinene (5.7 %) and limonene (5.1 %) were the main constituents of the rhizome essential oil. The essential oil displayed antimicrobial activity only towards Gram-positive bacteria of Enterococcus faecalis ATCC 299212, Staphylococcus aureus ATCC 25923 and Bacillus cereus ATCC 14579 with minimum inhibitory concentration (MIC) values of 16.0 μg/mL, 256 μg/mL and 32.0 μg/mL, respectively. The oil also inhibited the growth of the yeast, Candida albicans ATCC 10231, with a MIC value of 16.0 μg/mL. The chemical constituents and antimicrobial activity of essential oil from E. triolba were being reported for the first time and validation of the ethnomedicinal usage of the plant.

This study reported the volatile profile, the antimicrobial activity and the synergistic potential of essential oil (EO) from the Moroccan endemic Thymus atlanticus (Ball) Roussine, in combination with the antibiotics ciprofloxacin and fluconazole for the first time, to the best of our knowledge. The EO chemical composition was determined by gas chromatography coupled to mass spectrometry (GC-MS) analysis and the antimicrobial activity assessed by the disc diffusion method against three Gram positive (Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus) and three Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli and one clinical isolate, Klebsiella pneumonia). The antifungal activity was evaluated in four pathogenic yeasts (Candida albicans, C. glabrata, C. krusei and C. parapsilosis). The minimum inhibition concentration (MIC) and the synergistic effect with ciprofloxacin and fluconazole were determined by the two-fold dilution technique and checkerboard test, respectively. Twenty-one constituents were identified by GC-MS in the EO, including carvacrol (21.62%) and borneol (21.13%) as the major components. The EO exhibited a significant antimicrobial activity with inhibition zones ranging from 0.7 mm to 22 mm for P. aeruginosa and B. subtilis, respectively, and MIC values varying from 0.56 mg/mL to 4.47 mg/mL. The fractional inhibitory concentration index (FICI) values ranged from 0.25 to 0.50 for bacteria and from 0.25 to 0.28 for yeasts. The maximum synergistic effect was observed for K. pneumonia with a 256-fold gain of antibiotic MIC. Our results have suggested that EO from T. atlanticus may be used alone or in association with antibiotics as a new potential alternative to prevent and control the emergence of resistant microbial strains both in the medical field and in the food industry.

The antimicrobial activity of different essential oils (EOs) from the Lamiaceae family was evaluated on Streptococcus agalactiae, Candida albicans, and lactobacilli. S. agalactiae is the main cause of severe neonatal infections, such as sepsis, meningitis, and pneumonia. C. albicans is a primary causative agent of vulvovaginal candidiasis, a multifactorial infectious disease of the lower female reproductive tract. Lactobacilli represent the dominant bacterial species of the vaginal flora and constitute the natural defense against pathogens. On the basis of the preliminary results, the attention was focused on the EOs from Lavandula x intermedia Emeric ex Loisel. and Mentha arvensis L. By using gas ghromatography (GS) retention data and mass spectra, it was possible to identify more than 90% of the total composition of the EO samples. The minimal inhibitory concentration (MIC) and anti-biofilm activity of the two EOs were determined against all isolated strains, using the EOs by themselves or in combination with each other and with drugs (erythromycin and fluconazole). The results showed a good antimicrobial and anti-biofilm activity of both EOs and a synergistic effect, leading to the best results against all the strains, resulted using the combinations EOs/EOs and antimicrobials/EOs.

The present study describes chemical composition and antimicrobial activity of the essential oil from Origanum bilgeri, which is endemic for Turkey. The essential oil was obtained by hydrodistillation and components of the essential oil were analyzed by Gas Chromatography-Mass Spectrometry (GC-MS). The major component of O. bilgeri essential oil was carvacrol (84.8 %) and p-cymene (4.0 %), γ-terpinene (3.3 %) were the other components. Antimicrobial activity of the essential oil was investigated against standard control and resistant strains, using disc diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) methods. O. bilgeri essential oil showed very strong antimicrobial activity against all tested pathogenic bacteria except P. aeruginosa. Especially, it is important that the essential oil was more effective than antibiotics tested against methicillin-resistant Staphylococcus aureus (MRSA), vancomycin resistant Enterococcus faecalis (VRE).

The study evaluated the chemical profile, antimicrobial activity and toxicity of essential oils (EOs) of C. citratus, O. basilicum and A. rosaeodora. The EOs were extracted by hydrodistillation, the chemical profile was determined using the physicochemical parameters and the chemical composition was obtained by gas chromatography coupled to mass spectrometry (GC-MS). The toxicity assay followed the Artemia salina Leach bioassay. To perform the antimicrobial activity, the Disc Diffusion technique and the Mueller Hinton Broth Dilution (MH) technique were used. The physicochemical parameters of the EOs showed satisfactory results. The major chemical composition of the EO of A. rosaeodora presented linalool (93.60%), the EO of C. citratus exhibited geranial (43.96%) and EO of O. basilicum found methyl chavicol. All EOs in this study had LC50 between 582 mg L-1 and 282 mg L-1. The antimicrobial activity of EO C. citratus demonstrated inhibition halos for S. aureus of 25 mm and 25 mm for E. coli, EO of O. basilicum exhibited inhibition halo of 18 mm for E.coli and 20 mm for S. aureus and EO of A. rosaeodora presented 11 mm for E. coli and 15 for S. aureus. As the values of MIC and MBC found, the EO of O. basilicum presented a more effective inhibitory action against S. aureus. It was concluded that the observed biological potentials encourage the application potentials in the efficiency of the control of pathogenic microorganisms.

The present study aimed to determine the antimicrobial activity and chemical composition of leaves-extracted essential oil of Leoheo domatiophorus Chaowasku, D.T. Ngo and H.T. Le (L. domatiophorus), including antibacterial, antimycotic, antitrichomonas and antiviral effects. The essential oil was obtained using hydrodistillation, with an average yield of 0.34 ± 0.01% (v/w, dry leaves). There were 52 constituents as identified by GC/MS with available authentic standards, representing 96.74% of the entire leaves oil. The essential oil was comprised of three main components, namely viridiflorene (16.47%), (-)-δ-cadinene (15.58%) and γ-muurolene (8.00%). The oil showed good antimicrobial activities against several species: Gram-positive strains: Staphylococcus aureus (two strains) and Enterococcus faecalis, with Minimum Inhibitory Concentration (MIC) and Minimum Lethal Concentration (MLC) values from 0.25 to 1% (v/v); Gram-negative strains such as Escherichia coli (two strains), Pseudomonas aeruginosa (two strains) and Klebsiella pneumoniae, with MIC and MLC values between 2% and 8% (v/v); and finally Candida species, having MIC and MLC between 0.12 and 4% (v/v).Antitrichomonas activity of the oil was also undertaken, showing IC50, IC90 and MLC values of 0.008%, 0.016% and 0.03% (v/v), respectively, after 48h of incubation. The essential oil resultedin being completely ineffective against tested viruses, ssRNA+ (HIV-1, YFV, BVDV, Sb-1, CV-B4), ssRNA- (hRSVA2, VSV), dsRNA (Reo-1), and dsDNA (HSV-1, VV) viruses with EC50 values over 100 µg/mL. This is the first, yet comprehensive, scientific report about the chemical composition and pharmacological properties of the essential oil in L. domatiophorus.

Synergistic interaction between Chlorella vulgaris extract and Origanum elongatum essential oil against methicillin-resistant Staphylococcus aureus.

Background & Aim:The genus Salvia (commonly known as sage) is a broad genus belonging to the family Lamiaceae. This study is aimed at assessing the essential oil composition and antimicrobial activities of two Salvia species. Experimental: The chemical composition of the essential oils of Salvia officinalis L. and Salvia virgata Jacq, cultivated in Estahban (Fars, South Iran), was studied by means of GC-MSanalyses. Antimicrobial activity was tested against a panel of microorganisms including one Gram-positive (Staphylococcus epidermidis PTCC NO. 1435) and one Gram-negative (Escherichia coli) and three fungal strain (Alternaria alternata PTCC NO. 5224, Penicillium funiculosum PTCC NO. 5301 and P. funiculosum PTCC NO. 5169) using the disk diffusion and agar-well diffusion methods and the Minimum Inhibitory Concentration (MIC) technique. Results: In all, 57 compounds were identified, 42 for S. officinalis, accounting for 98.94% ofthe total oil, 29 for S. virgata (98.81%). The major components of S. officinalis essential oil were α-thujone (37.18%), 1,8-cineole (12.71%), β-thujone (9.10%) and the major components of S. virgata essential oil were caryophyllene oxide (30.23%), β-caryophyllene (22.63%), sabinene (11.82%). The antimicrobial activity of the total essential oil evaluated by the agar-well diffusion method, the results showed that the highest active against S. epidermidis and also the least active against E. coli. Inhibition of growth was tested by the disk diffusion method, the results showed that essential oil of S. officinalis and S. virgata were highest active against E. coli and P. funiculosum (PTCC NO. 5301), respectively. Also the least active against A. alternata. Recommended applications/industries: The results showed thatS. officinalis oil had higher antimicrobial activity compare to S. virgata

Antimicrobial activities of methanol extracts and essential oils of Rosmarinus officinalis, depending on location and seasonal variations

Essential oils (EOs) are chemical products produced by odoriferous glands from a variety of plants. These essential oils have many health benefits: antiseptic, anti-inflammatory and antimicrobial activities. So due to these medicinal properties, the present study was designed to analyze essential oils of Thymus zygis L. and Thymus willdenowii Boiss. for their chemical composition and biological activities. These two thyme species were collected from the region of Ifrane, Middle Atlas of Morocco. The EO was obtained by hydrodistillation, and the yields were 5.25% for T. zygis and 3.00% for T. willdenowii. The chemical composition of the EOs was analyzed by gas chromatography coupled with mass spectrometry (GC-MS), and the results showed that T. zygis EO is dominated by carvacrol (52.5%), o-cymene (23.14%), and thymol (9.68%), while the EO of T. willdenowii contains germacrene D (16.51%), carvacrol (16.19%), and geranyl acetate (8.35%) as major compounds. The antioxidant activity assessed by Diphenylpicrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays revealed that both EOs have excellent antioxidant activities; by DPPH it resulted in IC50 = 6.13 ± 0.11 for T. zygis and 6.78 ± 0.3 µg/mL for T. willdenowii, while the one by FRAP yielded EC50 = 2.46 ± 0.01 (T. zygis) and 5.17 ± 0.2 (T. willdenowii) µg/mL. The antimicrobial activity of the two essential oils was evaluated against six bacterial strains and five fungal strains by the disk diffusion method to determine the Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC) and Minimum Fungicidal Concentration (MFC). The EOs revealed variable antimicrobial activities against the different tested microbial strains and showed strong antimicrobial activities, even against strains known as multi-resistant to antibiotics (Acinetobacter baumannii) at low concentrations (2 µL/mL). T. zygis EO showed the most powerful activity against all the studied bacteria, while that of T. willdenowii recorded moderate activity when tested against Shigella dysenteriae and Salmonella Typhi. With inhibition diameters that vary between 75 mm and 84 mm for concentrations of 2 µL/mL up to 12 µL/mL, S. aureus was shown to be the most sensitive to T. zygis EO. For the antifungal activity test, T. zygis EO showed the best inhibition diameters compared to T. willdenowii EO. These results showed that T. zygis EO has more powerful antioxidant and antimicrobial activities than T. willdenowii EO, therefore, we deduce that thyme EOs are excellent antioxidants, they have strong antimicrobial properties, and may in the future represent new sources of natural antiseptics that can be used in pharmaceutical and food industry.

Artemisia judaicaL. essential oil was studied for antibacterial activity against various clinical isolates of bacteria resistant to a number of antibiotics. The antibacterial activity was evaluated against 20 multidrug resistant (MDR) of clinical origin compared to standard ATCC strains. The strains that showed resistance against the maximum number of antibiotics tested were selected for an antibacterial assay by three methods: Disc diffusion method, microatmosphere and dilution method. The obtained results demonstrated that theA. judaicaessential oil possessed an excellent inhibitory effect against all of the tested strains. The most potent results were obtained against MRSA (Methicillin ResistantStaphylococcus aureus),Staphylococcus aureusandBacillus subtilis(their MIC was 8.75 µg/ml). MIC (Minimal Inhibitory Concentration) and MBC (Minimal Bactericidal Concentration) values for essential oil against all tested strains were equal. According to GC‐MS analysis forty‐one constituents were identified, which represented 84.66 % of the total essential oil, being piperitone (73.4 %) the main compound. Copyright © 2015 John Wiley & Sons, Ltd.

The in vitro antioxidant and antimicrobial activity of the essential oil from Melaleuca alternifolia (M. alternifolia) was evaluated in this report. The antioxidant potential of the essential oil from M. alternifolia was evaluated by the DPPH (2,2-diphenyl-1-picrylhydrazyl) method, thiobarbituric acid reactive species (TBARS) assay, and the hydroxyl radical scavenging activity method. The essential oil from M. alternifolia was able to reduce DPPH with an EC50 (concentration for 50% of maximal effect) of 48.35 μg/ml, inhibit the lipid peroxidation with an IC50 (50% inhibitory concentration) of 135.9 μg/ml, and eliminate hydroxyl radicals with an EC50 of 43.71 μg/ml. Antimicrobial screening, minimum inhibitory concentration, and minimum bactericidal concentration assays showed that the essential oil from M. alternifolia inhibited strongly the growth of different types of microorganisms, including Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Penicillium italicum Wehmer, and Penicillium digitatum Sacc. Thus, the essential oil of M. alternifolia possesses antioxidant and antimicrobial activity and could be suitable for use as a natural preservative ingredient in food, agriculture, and pharmaceutical industries.

Antioxidant, antibacterial, and cytotoxic activities of Cedrus atlantica organic extracts and essential oil

Antimicrobial Activity of Some Egyptian Spice Essential Oils

Essential oils (EOs) are widely recognized for their broad-spectrum antimicrobial properties. However, their impact on the development of antimicrobial resistance (AMR), particularly in multidrug-resistant (MDR) pathogens, remains underexplored. This study investigates the inhibitory potential of selected EOs and their influence on resistance development, quorum sensing (QS), and biofilm formation. Twenty-three EOs were screened for antimicrobial activity using a microdilution assay against strains of the ESKAPE pathogens. Five EOs with varying minimum inhibitory concentrations (MICs) were selected for resistance induction studies via serial passaging of Staphylococcus aureus ATCC 6538 under sub-inhibitory EO exposure. Anti-QS activity was assessed by quantifying violacein inhibition in Chromobacterium violaceum, while biofilm inhibition was evaluated using the crystal violet assay. Twelve EOs (52%) demonstrated noteworthy antimicrobial activity (MIC ≤ 1.00 mg/mL). Origanum vulgare and Thymus vulgaris exhibited strong inhibition (MIC ≤ 1.00 mg/mL), along with significant anti-QS and biofilm suppression (≥ 70% inhibition). Resistance induction studies revealed transient MIC fluctuations (p = 0.00 – 0.02) without stable resistance development. Notably, EO exposure led to heteroresistance to conventional antibiotics, but EO efficacy was retained across passages. The findings support the potential of EOs as sustainable antimicrobial agents against MDR pathogens. Their ability to inhibit QS and biofilm formation, coupled with the absence of long-term resistance development, underscores their promise in mitigating AMR. Further mechanistic studies and clinical validation are warranted to advance EO-based therapeutics.