Green manure (Crotalaria juncea L.) enhances Origanum vulgare L. biomass accumulation, essential oil yield, and phytochemical properties.

Green manure (GM) may reduce the use of chemical fertilizers, been an ecologically appropriate strategy to cultivation of medicinal plants. Crotalaria juncea, is one of the most used because it adapts to different climatic and high nitrogen content. Origanum vulgare. is widely used in cooking, pharmaceutical, cosmetic industries and food products. The objectives of this study were to evaluate the GM on biomass, essential oil (EO), phenolic and antioxidant. The experiment consisted: control; 150, 300, 450, and 600 g (Sh= leaves+steam) more 200 g roots (R); 600 g aerial part; 200 g roots; and soil with 300 g cattle manure per pot. The highest dry weights were observed in the presence of GM and cattle manure (90 days). The control had an EO production 75% lower in relation to the dose of 450 g GM (Sh+R). Principal component analysis showed that GM and cattle manure positively influenced the dry weight, content, yield, and EO constituents, and total flavonoids. The GM contributed to the accumulation of the major EO compounds (trans-sabinene hydrate, thymol, terpinen-4-ol). The GM management may be beneficial for cultivating, because it can increase the production of biomass and the active components, in addition to being an inexpensive resource.

Synergistic effects of thyme and oregano essential oil combinations for enhanced functional properties of sericin/pectin film.

This work aimed to assess the synergistic antibacterial effects of thyme and oregano essential oils in various ratios (thyme:oregano; 10:0, 8:2, 6:4, 4:6, 2:8, 10:0). We hypothesized that the synergistic combination of thyme and oregano essential oils can be effectively incorporated into sericin/pectin film to enhance its functional properties. Among the combinations tested, the mixture of thyme/oregano essential oil (TOE) at an 8:2 ratio exhibited the most potent synergistic activity against P. aeruginosa and S. aureus, with fractional inhibitory concentration index (FICindex) of 0.9. In this combination, thymol constituting 51.83 % of TOE (8:2), was the predominant component. TOE at an 8:2 ratio was selected to incorporate into sericin/pectin film. Different concentrations of TOE (0.8 %, 1.2 % and 1.6 %) were applied to evaluate their impact on film properties compared to a film without essential oil (control). It was found that increasing TOE concentration (control; 0 %) to 1.6 % reduced film moisture content (from 21.53 % to 16.91 %), decreased yellowness (from 18.24 to 15.92), diminished gloss (from 63.79 to 11.18), lowered swelling index (from 1.24 to 0.98), and reduced tensile strength (from 9.70 to 4.14 MPa). However, the addition of TOE showed higher film total phenolic content (8.59-31.53 mg gallic acid/g dry sample) and increased antioxidant activity (0.99-3.68 µmol Trolox /g dry sample). Moreover, the film with 1.2 % and 1.6 % of thyme/oregano essential oil exhibited inhibitory effects against all tested bacteria. Therefore, the thyme/oregano essential oil combination can provide the desirable physicochemical properties of the sericin/pectin film, as well as its antibacterial and antioxidant activities, making it a promising alternative for food packaging material applications.

Exploring the phytoconstituents, antimicrobial potency, and cytotoxic effects of essential oil from Origanum punonense from Palestine.

BACKGROUND: Origanum punonense Danin is one of the old traditional medicinal plants Bedouins utilize in the Dead Sea region to treat a variety of illnesses, those caused by infections. The current study aimed to identify the phytochemical components of O. punonense essential oil (EO) and determine its antiproliferative and antimicrobial effects. METHODS: Gas chromatography and mass spectrometry were employed to detect the phytochemical constituents of O. punonense EO. Broth microdilution assay was utilized to determine the antimicrobial effects against various microbial species, including those causing diabetic foot infections. RESULTS: This study revealed that O. punonense EO contains 44 phytochemical compounds, of which 41 compounds were detectable and amounted to 99.78% of the total oil. The main chemical components of the oil were carvacrol (57.4%), p-cymene (6.66%), carvone (5.35%), pinene (4.9%), and terpinene (2.96%). The antiproliferative activity of different concentrations of O. punonense EO was noted in all of the investigated cell lines, with the best activity at the concentration of 500 µg/mL. The greatest antibacterial activity was against Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Proteus vulgaris, with MIC values of 1.56 µL/mL. In addition, and the O. punonense EO showed strong antifungal activity against Candida albicans with a MIC value of 0.8 µL/mL. In addition, the O. punonense EO showed potent antibacterial activity against all MRSA samples obtained from the diabetic foot with a MIC value of 3.13 µL/mL. The O. punonense EO demonstrated potent activity against Carbapenem-resistant Enterobacterales, Citrobacter freundii, and K. pneumoniae, with MICs value of 6.25 µL/mL. CONCLUSION: The potent antiproliferative and broad antimicrobial activity of O. punonense EO makes it an effective strategy for treating infections, especially in immunocompromised patients with chronic comorbidities such as cancer and diabetes mellitus.

Supercritical CO2 extraction of naringenin from Mexican oregano (Lippia graveolens): its antioxidant capacity under simulated gastrointestinal digestion.

A supercritical CO2 method was optimized to recover naringenin-rich extract from Mexican oregano (Lippia graveolens), a flavanone with high antioxidant and anti-inflammatory activity. The effect of the extraction parameters like pressure, temperature, and co-solvent on naringenin concentration was evaluated. We used response surface methodology to optimize the naringenin extraction from oregano; the chemical composition by UPLC-MS of the optimized extract and the effect of simulated gastrointestinal digestion on its antioxidant capacity and total phenolic content were also evaluated. The optimum conditions were 58.4 °C and 12.46% co-solvent (ethanol), with a pressure of 166 bar, obtaining a naringenin content of 46.59 mg/g extract. Also, supercritical optimized extracts yielded high quantities of cirsimaritin, quercetin, phloridzin, apigenin, and luteolin. The results indicated that the naringenin-rich extract obtained at optimized conditions had higher total phenolic content, antioxidant capacity by TEAC and ORAC, and flavonoid content, compared with the methanolic extract, and the simulated gastrointestinal digestion reduced all these values.

Antifungal effects of carvacrol, the main volatile compound in Origanum vulgare L. essential oil, against Aspergillus flavus in postharvest wheat.

Plant volatile organic compounds (VOCs) with antimicrobial activity could potentially be extremely useful fumigants to prevent and control the fungal decay of agricultural products postharvest. In this study, antifungal effects of volatile compounds in essential oils extracted from Origanum vulgare L. against Aspergillus flavus growth were investigated using transcriptomic and biochemical analyses. Carvacrol was identified as the major volatile constituent of the Origanum vulgare L. essential oil, accounting for 66.01 % of the total content. The minimum inhibitory concentrations of carvacrol were 0.071 and 0.18 µL/mL in gas-phase fumigation and liquid contact, respectively. Fumigation with 0.60 µL/mL of carvacrol could completely inhibit A. flavus proliferation in wheat grains with 20 % moisture, showing its potential as a biofumigant. Scanning electron microscopy revealed that carvacrol treatment caused morphological deformation of A. flavus mycelia, and the resulting increased electrolyte leakage indicates damage to the plasma membrane. Confocal laser scanning microscopy confirmed that the carvacrol treatment caused a decrease in mitochondrial membrane potential, reactive oxygen species accumulation, and DNA damage. Transcriptome analysis revealed that differentially expressed genes were mainly associated with fatty acid degradation, autophagy, peroxisomes, the tricarboxylic acid cycle, oxidative phosphorylation, and DNA replication in A. flavus mycelia exposed to carvacrol. Biochemical analyses of hydrogen peroxide and superoxide anion content, and catalase, superoxide dismutase, and glutathione S-transferase activities showed that carvacrol induced oxidative stress in A. flavus, which agreed with the transcriptome results. In summary, this study provides an experimental basis for the use of carvacrol as a promising biofumigant for the prevention of A. flavus contamination during postharvest grain storage.

Cytotoxic Effect Induced by Sicilian Oregano Essential Oil in Human Breast Cancer Cells.

Origanum vulgare L. is an aromatic plant that exerts antibacterial, antioxidant, anti-inflammatory, and antitumor activities, mainly due to its essential oil (EO) content. In this study, we investigated the possible mechanism underlying the in vitro antitumor activity of EO extracted by hydrodistillation of dried flowers and leaves of Origanum vulgare L. grown in Sicily (Italy) in MDA-MB-231 and MCF-7 breast cancer cell lines. Gas chromatography-mass spectrometry analysis of Oregano essential oil (OEO) composition highlighted the presence of twenty-six major phytocompounds, such as p-cymene, γ-terpinene, and thymoquinone p-acetanisole. OEO possesses strong antioxidant capacity, as demonstrated by the DPPH test. Our studies provided evidence that OEO reduces the viability of both MCF-7 and MDA-MB-231 cells. The cytotoxic effect of OEO on breast cancer cells was partially counteracted by the addition of z-VAD-fmk, a general caspase inhibitor. Caspases and mitochondrial dysfunction appeared to be involved in the OEO-induced death mechanism. Western blotting analysis showed that OEO-induced activation of pro-caspases-9 and -3 and fragmentation of PARP decreased the levels of Bcl-2 and Bcl-xL while increasing those of Bax and VDAC. In addition, fluorescence microscopy and cytofluorimetric analysis showed that OEO induces a loss of mitochondrial membrane potential in both cell lines. Furthermore, we tested the effects of p-cymene, γ-terpinene, thymoquinone, and p-acetanisole, which are the main components of OEO. Our findings highlighted that the effect of OEO on MDA-MB-231 and MCF-7 cells appears to be mainly due to the combination of different constituents of OEO, providing evidence of the potential use of OEO for breast cancer treatment.

Use of Nile tilapia (Oreocromis niloticus) processing residues in the production of pâtés with the addition of oregano (Origanum vulgare) essential oil.

The effect of the use of Nilo tilapia filleting residues in the production of pâtés with the addition of oregano essential oil stored for 90 days at 4 °C was evaluated. For that, 5 treatments were performed as follows: TSA-control treatment; TES with the addition of sodium erythorbate; and formulation TOE1 with 600 ppm oregano essential oil; TOE2 with 1000 ppm essential oil; and TOE3 with 1400 ppm essential oil. The pâtés showed adequate technological and physicochemical characteristics and microbiological counts within the legislation standards. No significant differences were observed in the luminosity of the pâté formulations during storage, and the addition of oil contributed to the increase in a* values and stability of b* values. Regarding the lipid and protein oxidation, TOE3 showed lower values at the end of the shelf-life. The addition of essential oil did not affect the hardness and cohesiveness of the products. The fatty acids in greater amounts in the samples were linoleic, oleic, palmitic, and stearic acids. The analysis of biogenic amines indicated that only the treatments with the highest amounts of sodium erythorbate (TES and TOE1) showed losses of spermidine. It was observed that decreasing the inclusion of sodium erythorbate and increasing the inclusion of oregano essential oil resulted in a drop in cadaverine values. A total of 46 volatile compounds were detected in the samples with the highest amount of free fatty acids and all the formulations were well accepted sensorially.

Phytochemical analysis and biological activities of essential oils extracted from Origanum grossii and Thymus pallidus: in vitro and in silico analysis.

The study aimed at investigating the phytochemical composition, antioxidant and antibacterial activities of essential oils (EOs) of Origanum grossii and Thymus pallidus. The selection of these plants for the study was driven by a comprehensive survey conducted in the Ribat Elkheir region of Morocco, where these plants are widely utilized. The results reflect the valorization of these plants based on the findings of the regional survey. The GC-MS phytochemical analysis revealed that the main constituents of the essential oil were carvacrol and thymol for O. grossii and T. pallidus respectively. Quantitative assays demonstrated that O. grossii exhibited higher levels of polyphenols (0.136 mg AGE/mg EO) and flavonoids (0.207 mg QE/mg EO) compared to T. pallidus. The DPPH assay indicated that O. grossii EOs possessed approximately twice the antiradical activity of T. pallidus, with IC50 values of approximately 0.073 mg/mL and 0.131 mg/mL, respectively. The antibacterial activity tests showed that both essential oils exhibited significant inhibition zones ranging from 26 to 42 mm against all tested bacterial strains. The MIC values varied among the bacteria, generally falling within the range of 0.31 to 2.44 µg/mL, demonstrating the potency of the EOs to serve as antibacterial. Molecular docking revealed that O. grossii and T. pallidus essential oils interact with antibacterial and antioxidant proteins (1AJ6 and 6QME). Key compounds in O. grossii include p-cymene, eucalyptol, and carvacrol, while T. pallidus contains potent chemicals like p-cymene, ɤ-maaliene, valencene, α-terpinene, caryophyllene, himachalene, and thymol. Notably, the most potent chemicals in Origanum grossii are p-cymene, eucalyptol, and carvacrol, while the most potent chemicals in Thymus pallidus are p-cymene, α-terpinene, and thymol. These findings suggest that these plant EOs could be used to develop new natural products with antibacterial and antioxidant activity.

Development of a novel cryostructured composite coating of xanthan-bovine collagen-oregano essential oil spraying applied for the preservation of commercial biscuits marketed in Mexico.

Cryostructured gels, better known as cryogels, are a very important emerging class of biomaterials that have diverse applications in food preservation. This work shows a novel alternative to prepare a cryostructured composite coating made from a blend of xanthan, bovine collagen, and oregano essential oil. The composite coating was suitably applied onto the surface of preservative-free biscuits which were stored for 15 days at 25 ± 2°C and 52% ± 1% relative humidity. The evaluation focused mainly on the changes in the physicochemical, textural, and microbiological characteristics of the biscuits. It was found that the coated samples significantly (p < 0.05) decreased moisture absorption, water activity, and fungal growth. However, the composite coating minimally impacted the quality of biscuits in terms of color, texture profile, and surface microstructure. Overall, the cryostructured composite coating constitutes an advance in technological strategies aimed at the preservation of baked products. This will allow, in the future, the development of novel coatings on bakery products to generate new trends in the conservation of their properties and extension of shelf life. This could be achieved through the implementation of new technologies in the food industry, with the aim of making them more environmentally friendly and contributing to the generation of less plastic waste. PRACTICAL APPLICATION: The study and application of cryogels, as innovative systems in the food industry, allow to expand and diversify the materials that can function as coatings to maintain some quality characteristics, in this case in bakery products, so it is important to analyze their effects and consider them to improve conservation processes.

The role of γ-aminobutyric acid and salicylic acid in heat stress tolerance under salinity conditions in Origanum vulgare L.

Origanum vulgare L., a medicinal and aromatic herb, has been used for hundreds of years. This plant contains valuable chemical compounds that can be used as medicine for treatment. On the other hand, a gradual increase in the planet's average temperature could negatively affect the growth and the composition of the O. vulgare. For this reason, in this study, the effect of two protective compounds, namely salicylic acid (SA) and gamma-aminobutyric acid (GABA), on temperature and salinity stress conditions was investigated. Oregano plants were grown at 23/12°C temperature as control and 27/16°C heat stress in the greenhouse (16/8 h photoperiod) for one months. The plants were treated with GABA and SA and subjected to salt stress for 30 days. Subsequently, the plant's physiological, biochemical, and phytochemical characteristics were examined. The results showed that all studied traits (in control and treated samples) were significantly different at 27°C, from 23°C. In addition, the highest amount of thymol and carvacrol were detected from plants grown at 27°C. In regards to salinity, stressed- plants had less damage to membrane stability and H2O2 level, when treated with GABA or SA. This study revealed that both SA and GABA compounds had an exellent protective effect on temperature and salt stress on O. vulgare. Based on enzyme-pigment evaluations and secondary metabolites, SA showed a better protective effect on temperature effects and GABA in a saline environment. In general, using these compounds can provide better conditions for the growth and preservation of O. vulgare chemical compounds. However, it certainly requires more experiments to find the signal pathways involved in these processes.

Multi-functional konjac glucomannan/chitosan bilayer films reinforced with oregano essential oil loaded ß-cyclodextrin and anthocyanins for cheese preservation.

In this work, a multifunctional bilayer film was prepared by solvent casting method. Elderberry anthocyanins (EA) were incorporated into konjac glucomannan (KGM) film as the inner indicator layer (KEA). ß-cyclodextrin (ß-CD) loaded with oregano essential oil (OEO) inclusion complexes (ß-CD@OEO) was prepared and incorporated into chitosan (CS) film as the outer hydrophobic and antibacterial layer (CS-ß-CD@OEO). The impacts of ß-CD@OEO on the morphological, mechanical, thermal, water vapor permeability and water resistance properties, pH sensitivity, antioxidant, and antibacterial activities of bilayer films were thoroughly evaluated. The incorporation of ß-CD@OEO into bilayer films can significantly improve the mechanical properties (tensile strength (TS): 65.71 MPa and elongation at break (EB): 16.81 %), thermal stability, and water resistance (Water contact angle (WCA): 88.15°, water vapor permeability (WVP): 3.53 g mm/m2 day kPa). In addition, the KEA/CS-ß-CD@OEO bilayer films showed color variations in acid-base environments, which could be used as pH-responsive indicators. The KEA/CS-ß-CD@OEO bilayer films also presented controlled release of OEO, good antioxidant, and antimicrobial activity, which exhibited good potential for the preservation of cheese. To sum up, KEA/CS-ß-CD@OEO bilayer films have potential applications in the field of food packaging industry.

Antimicrobial and Antibiofilm Efficacy and Mechanism of Oregano Essential Oil Against Shigella flexneri.

The aim of this study was to assess the antimicrobial activity of oregano essential oil (OEO) against Shigella flexneri and eradication efficacy of OEO on biofilm. The results showed that the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of OEO against S. flexneri were 0.02% (v/v) and 0.04% (v/v), respectively. OEO effectively killed S. flexneri in Luria-Bertani (LB) broth and contaminated minced pork (the initial population of S. flexneri was about 7.0 log CFU/mL or 7.2 log CFU/g), and after treatment with OEO at 2 MIC in LB broth or at 15 MIC in minced pork, the population of S. flexneri decreased to an undetectable level after 2 or 9 h, respectively. OEO increased intracellular reactive oxygen species concentration, destroyed cell membrane, changed cell morphology, decreased intracellular ATP concentration, caused cell membrane depolarization, and destroyed proteins or inhibited proteins synthesis of S. flexneri. In addition, OEO effectively eradicated the biofilm of S. flexneri by effectively inactivating S. flexneri in mature biofilm, destroying the three-dimensional structure, and reducing exopolysaccharide biomass of S. flexneri. In conclusion, OEO exerts its antimicrobial action effectively and also has a valid scavenging effect on the biofilm of S. flexneri. These findings suggest that OEO has the potential to be used as a natural antibacterial and antibiofilm material in the control of S. flexneri in meat product supply chain, thereby preventing meat-associated infections.

Are polar extracts and essential oil from Origanum vulgare Linn. (oregano) an alternative against itraconazole-resistant dermatophytes from veterinary cases?

Although the conventional therapy against dermatophytosis is based on antifungal drugs and environmental disinfection, the emergence of itraconazole(ITZ)-resistant dermatophytes has encouraged the search for active compounds, such as Origanum vulgare L. (oregano) essential oil (EO). However, little is known about its effect in polar extracts or the mechanism of action of these extracts and EO. We investigated the antifungal activity of four polar extracts and one EO from oregano against ITZ-susceptible and ITZ-resistant dermatophytes and their action mechanism. Polar extracts were prepared as infusions at 10 (INF10) and 60 (INF60) minutes, decoction (DEC) and hydroalcoholic extract (HAE); EO was purchased. All extracts and itraconazole were tested against Microsporum gypseum, M. canis, M. nanum, Trichophyton mentagrophytes and T. verrucosum isolated from cats, dogs and cattle (n = 28), and humans (n = 2) (M38-A2, CLSI). Among polar extract, DEC stood out as antifungal, followed by INF10 and INF60; HAE was little active. For EO, all isolates were susceptible, including ITZ-resistant dermatophytes. EO was selected for action mechanism assays, and acted in cell wall and plasmatic membrane by complexing with fungal ergosterol. By chromatographic analysis, 4-hydroxibenzoic acid was the most prevalent compound in all polar extracts, followed by syringic acid and caffeic acid; luteolin was present only in HAE. For EO, carvacrol was the major compound (73.9%); followed by γ-terpinene (3.6%) and thymol (3.0%). These findings showed that the extract type of oregano has influenced the antifungal action on dermatophytes, highlight EO and DEC, that are promising as antifungal agent, including against ITZ-resistant dermatophytes.

Nanoencapsulation of oregano essential oil using cellulose nanocrystals extracted from hazelnut shell to enhance shelf life of fruits: Case study: Pears.

This study aimed to investigate the potential application of cellulose nanocrystals (CNCs) extracted from an agricultural waste for encapsulation of oregano essential oil (OEO) and subsequently their use for coating to improve the shelf life of pears as a model. By hydrolyzing hazelnut shell cellulose under the optimum conditions, high crystalline CNCs with a zeta potential of -67.8 ± 4.4 mV and a diameter of 157 ± 10 nm were produced. Different concentrations of OEO (10-50 % w/w) were incorporated into CNCs and characterized using FTIR, XRD, SEM and TEM. OEO containing 50 % CNC with the highest EE and LC was selected for coating. Pears were coated with gluten containing 0.5, 1.5 and 2 % encapsulated OEO (EOEO) and pure OEO and stored for 28 days. Physicochemical, microbial and sensory properties of the pears were examined. Microbial analysis showed that EOEO2% was more effective in controlling microbial growth than controls and pure OEO, and a 1.09 Log reduction in bacterial count was recorded on day 28 of storage when compared to control. It was concluded that CNCs produced from an agricultural waste and loaded on an essential oil could be used to extend the shelf life of pear and potentially other fruits.

Essential Oil Composition and Antioxidant Activity of Oregano and Marjoram as Affected by Different Light-Emitting Diodes.

Oregano and marjoram are important aromatic spices in the food industry, as well as medicinal plants with remarkable antioxidant properties. Despite their popularity, little is known about treatments that would influence the antioxidant capacity of essential oils. In this study, different spectra of LED light, namely blue, red, white, blue-red, and natural ambient light as a control, were applied to assess the essential oil content, composition, flavonoid, phenolic, and antioxidant capacity of oregano and marjoram. GC-MS analysis revealed thymol, terpinen-4-ol, sabinene, linalool, p-cymene, and γ-terpinene as the main compounds. In oregano, the thymol content ranged from 11.91% to 48.26%, while in marjoram it varied from 17.47% to 35.06% in different samples. In oregano and marjoram, the highest phenolic contents were in blue (61.26 mg of tannic acid E/g of DW) and in white (65.18 mg of TAE/g of DW) light, respectively, while blue-red illumination caused the highest increase in total flavonoids. The antioxidant activity of oregano and marjoram extract was evaluated using two food model systems, including DPPH and ß-carotene bleaching. The highest antioxidant capacity was obtained in control light in oregano and blue-red light in marjoram. The results provide information on how to improve the desired essential oil profile and antioxidant capacity of extracts for industrial producers.

Emulsions containing composite (clove, oregano, and cinnamon) essential oils: Phase inversion preparation, physicochemical properties and antibacterial mechanism.

Natural essential oils (EOs), especially those combining different individual EOs (also termed composite EOs) with enhanced performance, are becoming healthy, market-sought food preservatives/additives. This study aims to provide insights into the challenge regarding EOs processing due to their low solubility and the elusive mechanism under the enhanced bio-reactivity of composite EOs. A unique oil/water interacting network was created by phase-inversion processing, which enhances EO solubilization and emulsification to form composite EO formulations (EOFs) containing ordinary cinnamon, oregano and clove EOs. These EOFs mainly contained cinnamaldehyde, carvacrol and eugenol and exhibited excellent post-storage stability. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability of EOFs (at 15.880 µL/mL) was > 88%, and the Ferric reducing antioxidant power (FRAP) was 1.8 mM FeSO4·7H2O. The minimum inhibitory concentration (MIC) of EOFs against E. coli and S. aureus was ∼7.940 µL/mL. The EOFs could cause quick deterioration of bacterial structures, demonstrating high efficacy in bacteria-killing and anti-biofilm formation.

Anti-inflammatory activity of essential oils from Tunisian aromatic and medicinal plants and their major constituents in THP-1 macrophages.

In this study, the capacity of eight essential oils (EOs), sage (Salvia officinalis), coriander (Coriandrum sativum), rosemary (Rosmarinus officinalis), black cumin (Nigella sativa), prickly juniper (Juniperus oxycedrus), geranium (Pelargonium graveolens), oregano (Origanum vulgare) and wormwood (Artemisia herba-alba), on the inhibition of NF-κB activation was screened at concentrations up to 0.25 µL/mL using THP-1 human macrophages bearing a NF-κB reporter. This screening selected coriander, geranium, and wormwood EOs as the most active, which later evidenced the ability to decrease over 50 % IL-6, IL-1ß, TNF-α and COX-2 mRNA expression in LPS-stimulated THP-1 macrophages. The chemical composition of selected EOs was performed by gas chromatography-mass spectrometry (GC-MS). The two major constituents (>50 % of each EO) were tested at the same concentrations presented in each EO. It was demonstrated that the major compound or the binary mixtures of the two major compounds could explain the anti-inflammatory effects reported for the crude EOs. Additionally, the selected EOs also inhibit>50 % caspase-1 activity. However, this effect could not be attributed to the major components (except for ß-citronellol/geranium oil, 40 %/65 % caspase-1 inhibition), suggesting, in addition to potential synergistic effects, the presence of minor compounds with caspase-1 inhibitory activity. These results demonstrated the potential use of the EOs obtained from Tunisian flora as valuable sources of anti-inflammatory agents providing beneficial health effects by reducing the levels of inflammatory mediators involved in the genesis of several diseases.

Microbiological Studies on the Influence of Essential Oils from Several Origanum Species on Respiratory Pathogens.

Essential oils (EOs) with established and well-known activities against human pathogens might become new therapeutics in multidrug-resistant bacterial infections, including respiratory tract infections. The aim of this study was to evaluate the antimicrobial activity of EOs obtained from several samples of Origanum vulgare, O. syriacum, and O. majorana cultivated in Poland. EOs were analyzed by GC-MS and tested against four bacterial strains: Staphylococcus aureus (MRSA), Haemophilus influenzae, Haemophilus parainfluenzae, and Pseudomonas aeruginosa. Chemical analyses showed that the Eos were characterized by a high diversity in composition. Based on the chemical data, four chemotypes of Origanum EOs were confirmed. These were carvacrol, terpineol/sabinene hydrate, caryophyllene oxide, and thymol chemotypes. Thin-layer chromatography-bioautography confirmed the presence of biologically active antibacterial components in all tested EOs. The highest number of active spots were found among EOs with cis-sabinene hydrate as the major compound. On the other hand, the largest spots of inhibition were characteristic to EOs of the carvacrol chemotype. Minimal inhibitory concentrations (MICs) were evaluated for the most active EOs: O. vulgare 'Hirtum', O. vulgare 'Margarita', O. vulgare 'Hot & Spicy', O. majorana, and O. syriacum (I) and (II); it was shown that both Haemophilus strains were the most sensitive with an MIC value of 0.15 mg/mL for all EOs. O. majorana EO was also the most active in the MIC assay and had the highest inhibitory rate in the anti-biofilm assay against all strains. The most characteristic components present in this EO were the trans-sabinene hydrate and terpinen-4-ol. The strain with the least sensitivity was the MRSA with an MIC of 0.6 mg/mL for all EOs except for O. majorana, where the MIC value reached 0.3 mg/mL. Scanning electron microscopy performed on the Haemophilus influenzae and Haemophilus parainfluenzae biofilms showed a visible decrease in the appearance of bacterial clusters under the influence of O. majorana EO.

Essential oil composition and antimicrobial potential of aromatic plants grown in the mid-hill conditions of the Western Himalayas.

Essential oils are highly concentrated natural extracts obtained from plants, rich in bioactive constituents with antimicrobial properties, but the distinctive climate of the Western Himalayan region influences the same. Aromatic and medicinal plants, viz., Origanum majorana, Origanum vulgare, Cymbopogon winterianus, Pelargonium graveolens, and Nepeta cataria were grown in the foothills of the Western Himalayan condition and evaluated for essential oil content, composition, and their effect on some of the most common pathogenic microorganisms. The essential oil content (%) was 0.77, 0.45, 1.37, 0.15 and 0.17% in O. majorana, O. vulgare, C. winterianus, P. graveolens, and N. cataria, respectively. The major essential oil constituents of the isolated oils were terpinen-4-ol, thymol, citronellal, citronellol, and nepetalactone, contributing 41.24%, 31.81%, 43.13%, 43.35% and 91.43% in O. majorana, O. vulgare, C. winterianus, P. graveolens, and N. cataria, respectively. Well-diffusion assay revealed that the essential oil of O. majorana and O. vulgare was active against both the tested Gram-positive, viz., Bacillus subtilis MTCC 121, Micrococcus luteus MTCC 2470, and Staphylococcus aureus MTCC 96; and Gram-negative, viz., Escherichia coli MTCC 43, Klebsiella pneumoniae MTCC 109, and Pseudomonas aeruginosa MTCC 2453 bacteria, while the essential oil of C. winterianus, P. graveolens, and N. cataria showed activity against only some Gram-positive bacteria. Minimum inhibitory concentration (v/v) values indicated the highest efficacy of O. majorana essential oil against B. subtilis (0.5%), M. luteus (1%), and S. aureus (1%), while O. vulgare was most efficient to E. coli (2%) and K. pneumoniae (2%). C. winterianus essential oil did not inhibit any bacterial strains. M. luteus was susceptible to the essential oil of P. graveolens (1%) and N. cataria (0.5%) at low concentrations. Present findings showed the association between the chemical constituents' profile of isolated essential oils from the Himalayan region and their antimicrobial activity, indicating their perspective to be utilized as antibacterial means.

Modulatory effect of Origanum vulgare essential oil and carvacrol on Malassezia spp. virulence factors.

Malassezia sympodialis and Malassezia furfur are recognized as an important part of the human and animals healthy skin microbiota, but also as an opportunistic fungus due to their association with a broad spectrum of skin and systemic infections. Human skin infections associated with Malassezia spp. are often chronic, recurrent, and topical or oral azole treatments are challenging with not always successful outcomes. A wide inter and intraspecies antifungal susceptibility variability that may suggest a combination of wild-type strains and resistant mutants was reported. The essential oils are complex hydrophobic mixtures of different compounds extracted from plants by distillation and have demonstrated antimicrobial activity. In this study, toxicity in the larvae model and the ability of Origanum vulgare essential oil (OVEO) and carvacrol to inhibit virulence factors such as hydrophobicity, adherence, and biofilm formation of M. sympodialis and M. furfur was evaluated. We have demonstrated the antifungal activity of OVEO and carvacrol against both species. Carvacrol was more active and less toxic than OVEO at low concentrations (< 1 mg/ml). Malassezia sympodialis showed a significant decrease in adherence and its ability to form biofilms when OVEO or carvacrol is present. Both Malassezia species showed reduced hydrophobicity in the presence of carvacrol. Further studies will have to be carried out to understand how these substances act, but the inhibition of some virulence factors could represent a new target to overcome the problem of drug resistance.

The work reports the research on the effect of the Origanum vulgare essential oil and carvacrol, against virulence factors such as hydrophobicity, adherence, and biofilm formation of two species of Malassezia. The inhibition of virulence factors could represent a new target to overcome the drug resistance reported.