Antimicrobial Properties Of Essential Oils Research Articles

Antimicrobial Properties of Essential Oils of the Monarda Genus Plants Cultivated in Belarus

Antimicrobial Properties of Essential Oils of the Monarda Genus Plants Cultivated in Belarus

Variation in the Antimicrobial Activity of Essential Oils from Cultivars of Lavandula angustifolia and L. × intermedia

The antimicrobial properties of essential oil from Lavandula sp. raise hopes related to its use in phytotherapy. This study aimed to evaluate the antimicrobial activity of essential oils from cultivars of L. angustifolia (‘Hidcote Blue Strain’, ‘Hidcote Blue’) and L. × intermedia (‘Phenomenal’, ‘Grosso’) grown in central-eastern Poland, that is, at the border of the northern lavender cultivation range. The chemical composition of the essential oils was determined by GC/MS. Essential oil concentrations (20, 10, 5, 2.5, 1.25, 0.6, 0.3, 0.16, 0.08, and 0.04 mg/mL) were tested to determine the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) or minimum fungicidal concentration (MFC) towards ten strains of Gram-positive bacteria, five Gram-negative bacteria, and eight yeasts in vitro culture. Essential oils from the Lavendula cultivars showed antimicrobial activity against all microorganisms analysed. The yeasts were characterised by higher sensitivity to lavender oil compared to bacteria, while Gram-positive bacteria were more sensitive than Gram-negative bacteria. The lowest MIC values for bacteria and fungi were obtained for ‘Grosso’. Furthermore, the ‘Grosso’ oil showed the highest fungicidal activity, while the highest bactericidal activity was found in ‘Hidcote Blue’ and ‘Grosso’. Using Staphylococcus aureus as an example, it was shown that different bacterial strains of the same species show varying sensitivity to the essential oil. A higher oil content was noted for the cultivars L. × intermedia, especially for the ‘Phenomenal’. Linalyl acetate and linalool were the main components of the essential oil in all cultivars. However, in the ‘Grosso’ oil, a high content of terpinen-4-ol (18.08%) was also recorded. An analysis of the relationships between the content of the main components in the analysed essential oils and the antimicrobial activity of essential oils suggested that linalool and terpinen-4-ol were compounds potentially responsible for antimicrobial activity. The obtained results allow us to conclude that essential oil with significant antimicrobial activity can be obtained from Lavandula sp. plants harvested in the northern part of the cultivation range.

Antimicrobial action of Oregano, Thyme, Clove, Cinnamon and Black pepper essential oils free and encapsulated against foodborne pathogens

The antimicrobial properties of essential oils from spice and medicinal plants have aroused interest for their potential as an alternative to the use of chemical preservatives in foods. In this work, we studied the bacteriostatic and bactericidal effects of Oregano, Thyme, Clove, Cinnamon and Black-pepper essential oils (EOs) against strains of Staphylococcus aureus, Listeria sp, Escherichia coli and Salmonella sp. that contaminate food and cause Foodborne Diseases (FBD). The study was carried out with free EOs and in blends, to study the potential synergistic effect between them. Moreover, microcapsules containing oregano, thyme and clove EO were developed with different wall materials obtained by complex coacervation between three different polymers (chitosan, gelatin, and Arabic gum). Among the free EOs, cinnamon EO stood out in inhibiting the growth of all bacteria tested. The best combination was Oregano + Thyme, presenting a synergistic effect against the bacteria tested with a considerable reduction in the initial Minimum Inhibitory Concentration (MIC). Encapsulation positively influenced the inhibitory power of the oils by resulting in MICs lower or close to those of the oil in the free form. Given the above, we can conclude that the tested EOs perform well in inhibiting these pathogens and that their effect is potentiated when tested in combination.

Chemical Composition and Antimicrobial Properties of Essential Oils Obtained from the Resin of Picea orientalis L.

This study aims to evaluate the chemical composition and antimicrobial (antibacterial and antifungal) properties of the essential oil subtracted from the oleoresins, which were obtained from the stem of the Picea orientalis naturally grown in Turkey. The essential oil of the resin was obtained through the hydrodistillation method in a Clevenger type device, and it was analyzed with GC-MS/FID. The structure of 74 compounds that were found in the essential oil was elucidated by comparing with literature data and the database in the appliance. Limonene (53.40%), β-pinene (20.74%) and α-pinene (14.51%) were determined to be the major components. The highest class of compounds in resin essential oils was identified as monoterpene hydrocarbons. The antimicrobial activity of the essential oil was investigated with the agar well diffusion method against 25 microorganisms, including 13 gram-negative, 7 gram-positive bacteria and 5 yeast-molds. As the results of the analysis, the highest antibacterial activity was recorded against S. typhimurium from gram-negative bacteria with inhibition zone ranging as (13.70±0.10-9.70±0.10 mm) and S. aureus from gram-positive bacteria with inhibition zone ranging as (9.30±0.10-6.80±0.10 mm). Additionally, the highest antifungal activity was obtained against C. albicans from yeast-molds with inhibition zone ranging as (10.10±0.10-6.10±0.10 mm).

Standardization of in-vitro methods for determination of antimicrobial properties of essential oils

Essential oils (EOs) have been recognized as well tolerated substances with great commercial value that finds applications in traditional medicine. This study systematically reviews various methods published from 2016 to 2020 that were employed to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of essential oils. The main question was, ‘What are the most reliable in-vitro methods to determine MIC and MBC of EOs’? The reported outputs of the search terms for the colony-forming unit (CFU), MIC, MBC, and the zone of inhibition (ZOI) were used to assess the methods.121 studies reported ‘Antibacterial’, 90 ‘Antifungal’, 110 ‘Antimicrobial’, 71 ‘ZOI’, 17 ‘CFU’, and 35 ‘MIC and MBC’. Forty-seven studies were selected according to the criteria for analysis in this review. This review indicated that each study requires its appropriate method. The antimicrobial efficacy of herbal extracts or EOs was not comparable to those of the antibiotics. The use of standard microbial strains is essential when clinical strains are included in the research. Based on the contents and analysis of the published articles, it is clear that designing antimicrobial experiments using EOs would produce more reliable results than those of the extracts. Based on the literature review and our experience, we suggest parameters to consider while determining antimicrobial properties of essential oils.

Antimicrobial effects of essential oils from Tanacetum vulgare L. and Salvia officinalis L., growing in Slovakia

Possible antimicrobial properties of essential oils isolated from Tanacetum vulgare L., and Salvia officinalis L., harvested from five different locations in Slovakia, were examined using the disc agar diffusion method and by the microdilution method. GC/MS analysis of the essential oil from Tanacetum vulgare L. resulted in the identification of 16 compounds constituting 82.1% of the total oil. Gram-positive bacteria, mainly Bacillus subtilis, were more susceptible to essential oils from both plants than were gramnegative species. Tested essential oils posses also anti-yeast activity. The shares of the constituents in the essential oils as well as their antimicrobial activity differed in dependence on the locality.

Characterization and Antimicrobial Properties of Essential Oils from Four Wild Taxa of Lamiaceae Family Growing in Apulia

Four taxa of the Lamiaceae family growing in Apulia (Clinopodium suaveolens, Satureja montana subsp. montana, Thymbra capitata, and Salvia fruticosa subsp. thomasii) that had not been previously studied for their potential use in the food sector, were analyzed for their essential oils (EOs) composition and antioxidant and antimicrobial properties against some microorganisms, isolated from bread and bakery products, including molds (Aspergillus niger, Penicillium roqueforti) and spore-forming bacteria (Bacillus amyloliquefaciens and Bacillus subtilis). Two different sites were considered for each plant species, and the strongest antimicrobial EOs, which were active against all of the microorganisms tested, were those from one S. montana subsp. montana sample (Sm2) and both T. capitata EOs (Tc1 and Tc2) with Minimal Inhibitory Concentration (MIC) values ranging between 0.093% and 0.375% (v/v) against molds, while higher values were registered for bacteria (0.75–1%). In particular, the biological activity of EOs from T. capitata and S. montana subsp. montana was maybe due to the high amount of thymol and carvacrol, which were also responsible for the highest antioxidant activity. S. fruticosa subsp. thomasii EOs had different chemical profiles but showed only a slight antibacterial effect and no antifungal activity. C. suaveolens showed no significant changes between EOs with an interesting antifungal activity (MIC 0.093%÷0.187% v/v), which may be due to the presence of pulegone. These plant species can be considered as promising sources of bioactive compounds to be exploited as biopreservatives in bread and bakery products mainly considering the low concentration needed to inhibit microorganism’s growth.

Electrochemical biotesting technique as applied to comparative assessment of antimicrobial properties of essential oils

A biotesting technique is described that provides for periodic (every 2 hours) recording of changes in pH, redox potential, and electrical conductivity of a liquid culture medium incubated in the presence and in the absence of viable test microorganisms (TM) and test samples (TS). The results of a comparative analysis using this technique of antibiotic activity against Staphylococcus aureus of different concentrations of «essential oils» obtained from 10 types of plant raw materials are presented. Based on this, we can conclude the following. Using the presented methodology, it is possible to assess the effect on the dynamics of the vital activity of TM of samples of various pharmaceutical, cosmetic, food, feed and other products, much more quickly, objectively and informatively than using standard visual methods of microbiological testing. The initial antibiotic activity of TS in most cases was greater than their prolonged antibiotic activity. At the same time, the mid-term (in terms of the time of interaction of TS with TM) antibiotic activity of TS was usually intermediate in value between their initial and prolonged biological activity.

Antimicrobial potential of eucalyptus oil and lemongrass oil alone and in combination against clinical bacteria in planktonic and biofilm mode

The use of natural substances has been trending from past few years. In recent years, the synthetic products obtained from plants have gained immense importance. Essential oils and volatile products obtained from plants are the source of food flavoring, aroma products and fragrance industries. Their use is also common to cure different ailments such as cancer, skin problems and nosocomial infections. Vast research has shown the antimicrobial properties of essential oils obtained from plants. Essential oils of lemongrass and eucalyptus have antiviral, antibacterial, antioxidant and insecticidal characteristics. Lemongrass and eucalyptus oils shows their antibacterial activity towards Gram positive bacteria such as Staphylococcus aureus, Bacillus subtilis and Gram-negative bacteria such as Escherichia coli and Klebsiella pneumonia. Combination of these oils also depicts high antimicrobial activity against different strains of bacteria. This review highlights the use of essential oils of lemongrass and eucalyptus for their in vitro antimicrobial properties against different bacteria in planktonic and biofilm mode. Mode of action by which the oil shows its inhibitory activity will be discussed. Susceptibility shown by different bacteria towards these essential oils and their components will be described

Antimicrobial Activity of Selected Essential Oils against Selected Pathogenic Bacteria: In Vitro Study.

The worldwide problem of infectious diseases has appeared in recent years, and antimicrobial agents are crucial in reducing disease emergence. Nevertheless, the development and distribution of multidrug-resistant (MDR) strains in pathogenic bacteria, such as Escherichia coli, Staphylococcus aureus, Salmonella Typhi and Citrobacter koseri, has become a major society health hazard. Essential oils could serve as a promising tool as a natural drug in fighting the problem with these bacteria. The current study aimed to investigate the antimicrobial effectiveness of tea tree (Melaleuca alternifolia (Maiden and Betche) Cheel), rosemary (Rosmarinus officinalis L.), eucalyptus (Eucalyptus obliqua L’Hér.), and lavender (Lavandula angustifolia Mill) essential oils. The antimicrobial properties of essential oils were screened against four pathogenic bacteria, E. coli, S. aureus, S. Tyhpi, and C. koseri, and two reference bacterial strains, while for the testing, the agar well diffusion method was used. Gas chromatography (GC) and gas chromatography–mass spectrometric (GC–MSD) analyses were performed on essential oils. The obtained results showed that M. alternifolia essential oil is the richest in terpinen-4-ol, R. officinalis and E. oblique essential oils in 1,8-cineole, and L. angustifolia essential oil in α-terpinyl acetate. In addition, the main bioactive compounds present in the essential oil of tea tree are rich in α-pinene (18.38%), limonene (7.55%) and γ-terpinene (14.01%). The essential oil of rosemary is rich in α-pinene (8.38%) and limonene (11.86%); eucalyptus essential oil has significant concentrations of α-pinene (12.60%), p-cymene (3.24%), limonene (3.87%), and γ-terpinene (7.37%), while the essential oil of lavender is rich in linalool (10.71%), linalool acetate (9.60%), α-terpinyl acetate (10.93%), and carbitol (13.05%) bioactive compounds, respectively. The obtained results from the in vitro study revealed that most of the essential oils exhibited antimicrobial properties. Among the tested essential oils, tea tree was discovered to demonstrate the strongest antimicrobial activity. The recorded MIC of S. Typhi was 6.2 mg/mL, 3.4 mg/mL of C. koseri, 3.1 mg/mL of E. coli, and 2.7 mg/mL of E. coli ATCC 25922, compared to M. alternifolia. Similarly, only S. aureus ATCC 25923 showed antimicrobial activity towards R. officinalis (1.4 mg/mL), E. oblique (2.9 mg/mL), and L. angustifolia (2.1 mg/mL). Based on the obtained results, it is possible to conclude that tea tree essential oil might be used as an ecological antimicrobial in treating infectious diseases caused by the tested pathogens.

Antimicrobial activity of essential plant oils and their major components

Development of bactericides and fungicides in terms of isolation and identification of substances is an important area of research. Presently, under the concept of integrated pest management, all possible plant pest and disease control methods are integrated to minimize the excessive use of synthetic chemicals and also the incidence of disease.The potential of various essential oils against Gram-positive and Gram-negative bacteria and fungi is being actively investigated in various laboratories across the world. Rice the most important crop, suffers from huge yield losses due to blast and blight diseases. Most of the labs have focussed to use transgenic approaches, the use of environmentally friendly natural products, as disease control strategies. In this context, we propose to evaluate the antimicrobial properties of essential oils and their ability to control diseases of rice. Seven Essential oils from seven different plants were selected for the study. The antimicrobial activity was assessed in terms of their antibacterial activity towards non-pathogenic bacteria and pathogenic drug resistant bacteria by means of their ability to sensitize the drug resistant bacteria in plasmid curing and, ß-lactamase inhibition and as antifungal agents. In conclusion, out of the seven essential oils used, lemongrass, palm rosa and eucalyptus were found to be good antimicrobial agents.

Essential Oils as Natural Fungicides to Control Rhizopus stolonifer-Induced Spoiled of Strawberries

Strawberry is a highly desirable fruit with a unique taste and a good source of bioactive compounds beneficial to human health. However, it has a short post-harvest shelf life, mainly due to the soft rot caused by Rhizopus stolonifer. This study aimed to evaluate the antimicrobial properties of essential oils (EOs) of Mentha piperita, Cymbopogon martinii, Cinnamomum camphora, and Mentha spicata using spore germination and micro-well dilution assays, and to test the effects of the vapor-phase application of M. spicata and C. martini on the incidence and severity of soft rot in strawberry artificially inoculated with R. stolonifer. In in vitro tests, C. martinii and M. spicata EOs were the most effective, inhibiting more than 95% of the spore germination. Additionally, in the microwell dilution test, these EOs had the lowest minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) (5 and 10 μg/mL, respectively), and for the microwell dilution test, the lowest MIC (5 μg/mL and 10 μg/mL, respectively) and MFC (10 μg/mL for both). High in vivo inhibitory effects of M. spicata and C. martinii EOs were observed at 10% concentration, with 100 and 78% reduction, respectively, in the R. stolonifer-induced spoilage. Our results suggest that C. martinii and M. spicata EOs can be used as efficient natural fungicides and can be an alternative to synthetic fungicides for preserving fresh strawberries from soft rot.

Antimicrobial potentials of essential oils extracted from West African aromatic plants on common skin infections

During the last decade, the advent of multi-drug resistant pathogens responsible for skin infections tends to make conventional treatments obsolete. Even though many studies have reported the antimicrobial properties of essential oils (EOs), the inconsistent use of various susceptibility testing methods has made information on antimicrobial potential of many EO varieties fragmentary. Using a single method approach, the objective of this work was to assess and to compare the antibacterial and antifungal properties, against skin pathogens, of EOs extracted from West African aromatic plants.Twenty-three plant samples collected in Benin and Burkina Faso were screened against 20 bacterial and fungal isolates obtained from skin lesions. Activity was evaluated by the determination of minimal inhibitory concentrations (MICs), with readings facilitated by the use of resazurin, a blue dye metabolized into pink resorufin by viable cells.Following this screening, nine EOs were found particularly active with MICs lower than 0.35% v/v. Gas Chromatography-Mass Spectrometry (GC/MS) analysis was used to determine the phytochemical profile of these active EOs which were found exceptionally rich in oxygenated monoterpenes, especially aldehydes, alcohols or phenols and their derivatives.Through this study, we demonstrated that several West African EOs have a significant antimicrobial potential which could, however, be considerably impacted by plant growing or harvesting place due to phytochemical composition variation. These EOs, even if their antimicrobial effects appeared lower than those of conventional antibiotics, constitute easily available mixtures of active compounds and could nevertheless be considered, in the context of increasing multidrug resistance, as complementary or alternative therapies in common skin infections management.

Biological preservation of mayonnaise with Lactobacillus plantarum LBRZ12, dill, and basil essential oils

In this study, different variants of egg-free mayonnaise containing free and immobilized Lactobacillus plantarum LBRZ12 cells and essential oils taken from basil and dill were prepared. The composition and antimicrobial properties of essential oils were investigated. The main constituents of basil oil were methyl chavicol (36.81%), methyl eugenol (20.40%), β-linanool (14.35%), eugenol (10.55%), and L(-)-carvone (39.05%), whereas dill oil contained mostly d-limonene (21.11%) and α-phellandrene (22.68%). The essential oils exhibited strong antimicrobial activity against all test-microorganisms. The mayonnaise variants were kept refrigerated for 40 days and changes in pH, concentration of viable cells of lactobacilli, microbiological, and organoleptic characteristics were monitored. The pH decreased from 6.5 to 4.5 over the period of storage. The number of undesired microflora in mayonnaise preserved with lactobacilli and essential oils decreased significantly (0 after the 20th day) indicating their effectiveness as biological preservatives. The mayonnaise variants demonstrated pleasant organoleptic characteristics, thus meet customers’ requirements.

An In Vitro Study on the Antimicrobial Properties of Essential Oil Modified Resin Composite against Oral Pathogens.

Modifying the composition of dental restorative materials with antimicrobial agents might induce their antibacterial potential against cariogenic bacteria, e.g., S. mutans and L. acidophilus, as well as antifungal effect on C. albicans that are major oral pathogens. Essential oils (EOs) are widely known for antimicrobial activity and are successfully used in dental industry. The study aimed at evaluating antibacterial and antifungal activity of EOs and composite resin material (CR) modified with EO against oral pathogens. Ten EOs (i.e., anise, cinnamon, citronella, clove, geranium, lavender, limette, mint, rosemary thyme) were tested using agar diffusion method. Cinnamon and thyme EOs showed significantly highest antibacterial activity against S. mutans and L. acidophilus among all tested EOs. Anise and limette EOs showed no antibacterial activity against S. mutans. All tested EOs exhibited antifungal activity against C. albicans, whereas cinnamon EO showed significantly highest and limette EO significantly lowest activity. Next, 1, 2 or 5 µL of cinnamon EO was introduced into 2 g of CR and microbiologically tested. The modified CR showed higher antimicrobial activity in comparison to unmodified one. CR containing 2 µL of EO showed the best antimicrobial properties against S. mutans and C. albicans, while CR modified with 1 µL of EO showed the best antimicrobial properties against L. acidophilus.

Chemical composition and antimicrobial activity of essential oils obtained from leaves and flowers of Salvia hydrangea DC. ex Benth.

The majority of essential oils obtained from vascular plants have been demonstrated to be effective in treating fungal and bacterial infections. Among others, Salvia hydrangea is an endemic half-shrub belonging to the Lamiaceae family that has been widely used from ancient times in Iranian traditional medicine. The aim of this study was to compare the composition and antimicrobial properties of essential oils obtained from leaves or flowers of this plant, collected from the Daran region of Iran during June 2018. The oils were obtained using Clevenger apparatus, their composition was evaluated by means of gas chromatography/mass spectrometry (GC/MS) and the antimicrobial properties were assayed by measuring inhibition halos, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The yield of leaf oil was ~ 0.25% and that of flower oil was ~ 0.28%. Oil composition was affected by the part of the plants used: the most abundant bioactives contained in leaf essential oil were (+)-spathulenol (16.07%), 1,8-cineole (13.96%), trans-caryophyllene (9.58%), β-pinene (8.91%) and β-eudesmol (5.33%) and those in flower essential oil were caryophyllene oxide (35.47%), 1,8-cineole (9.54%), trans-caryophyllene (6.36%), β-eudesmol (4.11%), caryophyllenol-II (3.46%) and camphor (3.33%). Both the oils showed a significant inhibitory and lethal effect on the Gram-negative bacteria Pseudomonas aeruginosa (MIC ~ 16 µg/mL), Shigella dysenteriae and Klebsiella pneumoniae (MIC ~ 62 µg/mL). Therefore, the essential oils obtained from both leaves and flowers of S. hydrangea may have potential application as bactericidal agents against some bacteria.

Synergistic antioxidant and antimicrobial activities of essential oils of some selected medicinal plants in combination and with synthetic compounds

Regardless of the well-known antioxidant and antimicrobial properties of essential oils, requirement of their large doses is the major bottleneck in using them as food preservatives. In the present study, possible synergistic interactions on antioxidant and antibacterial capacity of essential oils from six selected medicinal plants namely Callistemon lanceolatus (Sm.) Sweet, Ocimum gratissimum L., Cymbopogon winterianus Jowitt ex Bor. (Citronella java), Cymbopogon flexuosus (Nees ex Steud.) W. Watson, Mentha longifolia (L.) L., and Vitex negundo L., in combination as well as with synthetic antioxidant and antibiotics were evaluated. Antibacterial synergistic effect was determined against three Gram positive (Staphylococcus aureus, Micrococcus luteus and Bacillus subtilis) and two Gram negative (Escherichia coli and Klebsiella pneumoniae) bacteria using broth dilution method. Antioxidant combination effect was evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging method. The types of interactions in different binary combinations were determined by calculating the fractional inhibitory concentration indexes (FICI). Synergistic interactions were observed between essential oil combinations showing enhanced antioxidant and antibacterial activity. Further it was observed that essential oils not only enhanced the antioxidant and antibacterial efficacy of synthetic compounds but also resulted in significant reduction of their active doses due to synergy.

Odoriferous Therapy: A Review Identifying Essential Oils against Pathogens of the Respiratory Tract.

This review explores the body of scientific information available on the antimicrobial properties of essential oils against pathogens responsible for respiratory infections and critically compares this to what is recommended in the Layman's aroma-therapeutic literature. Essential oils are predominantly indicated for the treatment of respiratory infections caused by bacteria or viruses (total 79.0 %), the efficacy of which has not been confirmed through clinical trials. When used in combination, they are often blended for presumed holistic synergistic effects. Of the essential oils recommended, all show some degree of antioxidant activity, 50.0 % demonstrate anti-inflammatory effects and 83.3 % of the essential oils showed antihistaminic activity. Of the essential oils reviewed, 43.8 % are considered non-toxic while the remaining essential oils are considered slightly to moderately toxic (43.7 %) or the toxicity is unknown (12.5 %). Recommendations are made for further research into essential oil combinations.

Correlation between chemical composition and antimicrobial properties of essential oils against most common food pathogens and spoilers: In-vitro efficacy and predictive modelling

Using disk diffusion assay and broth microdilution, we evaluated the antimicrobial activity of 38 commercially available essential oils (EOs) against 24 food pathogens and spoilers. These including E. coli O157: H7 (3 types), Listeria (3 types), Bacillus (2 types), Salmonella enterica (2 types), Staphylococcus aureus (3 types), Clostridium tyrobutiricum, Pseudomonas aeruginosa, Brochotrix thermosphacta, Campylobacter jejuni, Carnobacterium divergens, Aspergillus (2 types), and Penicillium (4 types). Correlation between EOs’ chemical composition and antimicrobial properties was studied using R software. Moreover, statistical models representing the relationship were generated using Design Expert®. The predictive models identified the chemical attributes of EOs that drive their antimicrobial properties while providing an understanding of their interactions. Thyme (Aldrich, Novotaste), cinnamon (Aliksir, BSA), garlic (Novotaste), Mexican garlic blend N & A (Novotaste), and oregano (BSA) were the strongest antimicrobial. The most sensitive pathogens were P. solitum (MIC of 19.53 ppm) and L. monocytogenes (MIC of 39 ppm). The correlation analysis showed that phenols and aldehydes had the strongest positive effects on the antimicrobial properties followed by the sulfur containing compounds and the esters; while the effects of monoterpenes and ketones were negative. Different sensitivity of food pathogens to chemical families was observed. For instance, phenols and aldehydes exhibited a linear inhibitory effect on L. monocytogenes (LM1045, MIC), while sesquiterpene and ester showed a significant effect on S. aureus (ATCC 6538, MIC). The developed predictive models are expected to predict the antimicrobial properties based on the chemical families of essential oils.

Anty-microbial, and anty-biofilm-forming properties of Origanum vulgare L. essential oils on Staphylococcus aureus and its antioxidant action

Essential oils (EOs) have been widely used in folk and traditional medicine, cooking, cosmetology and other sectors of the economy. The antimicrobial properties of essential oils determine the relevance of the study of their effectiveness against antibiotic-resistant biofuel clinical isolates. Our research was aimed to determine the antimicrobial and antibiofilm properties of essential oil of Origanum vulgare L. on clinical isolates of bacteria of the genus Staphylococcus and its antioxidant effect. The raw materials of Origanum vulgare L. for large-scale essential oil isolation were donated by established growers in Slovakia (Agrokarpaty, Ltd.). EOs were obtained by the large-scale distillation apparatus specifically designed for the aromatic and medicinal plants. Calendula Co., in Nova Lubovna, Slovakia. The analysis of EOs was carried out using a gas chromatograph Varian 3090. Antimicrobial activity of EOs was determined using well agar diffusion method. Quantification of biofilm formation was carried out using a microtiter plate assay and the spectrophotometric method. Biofilm formation was quantified by measuring optical density at 550 nm. Biochemical analysis of O. vulgare essential oil showed a high content of carvacrol and thymol (72%). All strains of Staphylococcus aureus were sensitive to this essential oil. At the same time, the lowest indicators of growth retardation zones were characteristic of S. aureus MRSA clinic biofilm creation. We have determined the antibio­film effect of O. vulgare essential oil on S. aureus isolates. The study showed the degradation of the biofilm under the influence of essential oil decreased with decreasing concentration. At the same time, even with the action of essential oil, the concentration of 0.01% showed a 42% decrease in the process of biofilm formation. At the highest concentration of 0.10%, a destruction of the biofilm by 78% was found. The study of the influence of essential oils on the formed biofilm showed that 0.1% solution of oil causes degradation of the biofilm by 73.2%; 0.05% – by 58% and 0.01% – by 51.5%. O. vulgare essential oil also showed high antioxidant properties. The neutralization rate of free radicals was 83%. The revealed antimicrobial properties of O. vulgare essential oil make it promising to be used as an antistatic agent, including as a component that contributes to the disintegration of biofilm in the treatment of boils, carbuncles, panari­tiums, phlegmon, wound suppuration, inhalation for respiratory diseases, as a component of rinses in inflammatory periodontal diseases.