Antimicrobial Activity Of Essential Oils Research Articles

Antimicrobial activity of essential oils (Citrus bergamia Risso & Poiteau, Melaleuca alternifolia and Chenopodium botrys) on pathogen strains isolated in milk samples from mastitic sheep

The aim of this investigation was to study in vitro antibacterial activity of essential oils (EOs) (Citrus bergamia Risso & Poiteau, Melaleuca alternifolia and Chenopodium botrys) on pathogenic strains isolated in milk samples from mastitic sheep. The in vitro antibacterial activity showed that EOs induced higher bacterial inhibition against pathogens isolated in mastitic milk (Staphylococcus xylosus, Staphylococcus epidermidis, Streptococcus salivarius, Enterococcus faecium, Streptococcus agalactiae and Pseudomonas aeruginosa) than common antimicrobial agents used in veterinary medicine, with Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values significantly lower, excepted for P. Aeruginosa. The antibacterial activity of EOs has been attributed to the chemical composition of each phyto-complexes, constituted by monoterpenes, sesquiterpenes and their associated alcohols, identified by GC-MS analysis, with a synergic action in the bacterial cells. The results obtained confirmed in vitro antimicrobial activity of these EOs and their potential use in the treatment of sheep mastitis infection.

HOẠT TÍNH KHÁNG VI SINH VẬT CỦA TINH DẦU TỪ LÁ LOÀI TRÂM TRÁI TRẮNG (SYZYGIUM TSOONGII (MERR.) MERR. & PERRY), TRÂM BULLOCK (SYZYGIUM BULLOCKII (HANCE) MERR. & PERRY) VÀ TRÂM TÍCH LAN (SYZYGIUM ZEYLANICUM (L.) DC.) Ở HÀ TĨNH

Research on antimicrobial activity of essential oils from leaf of Syzygium tsoongii, Syzygium bullockii and Syzygium zeylanicum in Ha Tinh Province showed that essential oils from leaves of three species had antibacterial activity against three strains on the Gram (+): (Enterococus faecalis (ATCC 299212), Staphylococcus aureus (ATCC 25923), Bacillus cereus (ATCC 14579) and against Candida albicans (ATCC 10231). The essential oil from the leaves of Syzygium tsoongii and Syzygium zeylanicum had not antibacterial activity against Gram (-), while the essential oil from the leaves of Syzygium bullockii could be against 2 strains of Gram (-): Escherichia coli and Salmonella enterica strains.

Structural Characterization, Antioxidant, Antidiabetic and Antimicrobial Activities of Citrus Limettarisso, Citrus Nobilis X Citrus Deliciosa and Citrus Maxima

Background: The pharmacological properties of citrus fruits have long been recognized in traditional medicine, with recent scientific studies corroborating their potential as sources of natural bioactive compounds. Citrus limettarisso, Citrus nobilis x Citrus deliciosa, and Citrus maxima, in particular, have garnered attention for their antioxidant, antidiabetic, and antimicrobial properties. Prior research has highlighted these species' capabilities, with various studies reporting on their significant health benefits. Objective: This study aims to evaluate and compare the antioxidant, antidiabetic, and antimicrobial activities of essential oils extracted from the peels of Citrus limettarisso, Citrus nobilis x Citrus deliciosa, and Citrus maxima, thereby contributing to the understanding of their potential therapeutic applications. Methods: Essential oils were extracted from the peels of the three citrus species using hydro distillation. The antioxidant activity was assessed through Total Phenolic Content (TPC), Total Flavonoid Content (TFC), and DPPH Radical Scavenging Assay. Antiglycation potential and alpha-amylase inhibition were evaluated for antidiabetic properties, while antimicrobial activity was determined using the Agar Well Diffusion Method. Results: Citrus limettarisso showed the highest TPC (301.4474 ± 2.930402 mg GAE/100g) and significant antioxidant activity (68.26347% DPPH scavenging). Citrus maxima exhibited a high TFC (143.8727 ± 5.454545 mg CE/100g) but lower TPC (115.8333 ± 3.553444 mg GAE/100g). Citrus nobilis x Citrus deliciosa demonstrated considerable TPC (244.1667 ± 5.862774 mg GAE/100g) and TFC (50.17576 ± 0.457566 mg CE/100g). Antiglycation and alpha-amylase inhibition assays revealed Citrus limettarisso as the most potent antidiabetic agent with the highest inhibition percentages. All three species showed significant antimicrobial activity. Conclusion: The study confirms the substantial pharmacological potential of Citrus limettarisso, Citrus nobilis x Citrus deliciosa, and Citrus maxima, particularly in terms of their antioxidant and antidiabetic properties. Citrus limettarisso emerged as the most potent in most assays, underscoring its potential for therapeutic use. These findings support the use of these citrus species as natural sources of bioactive compounds for health and medical applications. It carries special importance for public health advancements.

Phytochemical profile and antimicrobial activity of essential oils from two Syzygium species against selected oral pathogens

BackgroundThe genus Syzygium (Myrtaceae) comprises several essential oil-rich species that are utilized traditionally for treating tooth infections and toothache. The current study aimed to extract essential oils (EOs) from the leaves of Syzygium samarangense and Syzygium malaccense cultivated in Egypt for the first time and screen their antimicrobial potential against oral-related pathogens.MethodsThe intended EOs were extracted using hydrodistillation (HD) by boiling fresh leaves with distilled water; supercritical fluid (SF) by extracting the dried leaves using supercritical CO2 at 40 °C and 150 bar; and the headspace (HS) in which the fresh leaves were heated in a glass vial and the vaporized aroma were analyzed. The volatile constituents were analyzed using GC/MS and identified by comparing the experimental Kovats' retention indices with the literature. The antimicrobial activity was assessed against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Candida albicans using agar diffusion, microwell dilution, and biofilm formation assays. Statistical significance (p < 0.05) was determined by applying one-way ANOVA and Duncan's post hoc test.ResultsThe yield of the extracted EOs differs between the applied methods, and the SF approach harvested the maximum (0.52–0.46%). The GC–MS analysis of SF EOs revealed a discrepancy between the two species. Since S. malaccense showed an abundance of hydrocarbons represented mainly by squalene (60.60%), S. samarangense was deemed to have oxygenated sesquiterpenes exemplified in globulol (52.09%). On the other side, the HD and HS EOs were sequentially comparable, while differed in the percentage of their majors. γ-terpinene (33.06%) pioneered the HS-derived aroma of S. malaccense, while S. samarangense was abundant with α-pinene (30.18%). Concurrently, the HD EOs of S. malaccense and S. samarangense were commonly denoted by caryophyllene oxide (8.19%-18.48%), p-cymene (16.02%- 19.50%), and γ-terpinene (12.20%-17.84). Ultimately, both species EOs exhibited broad-spectrum antimicrobial potential, although the HD EO was more potent than the SF EO. The HD EOs of both species potently inhibited the growth of E. coli (MIC 3.75 µL/mL) and suppressed C. albicans biofilm formation by 83.43 and 87.27%, respectively. The SF-EOs efficiently suppressed the biofilm formation of Gram-positive bacteria by 76.45%-82.95%.ConclusionEOs extracted from both species by different methods possessed a unique blend of volatile components with broad-spectrum antimicrobial activity. They were promoted as bioactive hits for controlling oral infections, however further investigations concerning their safety in clinical settings are needed.

Preparation, physicochemical characterisation and assessment of liquid and vapour phase antimicrobial activity of essential oil loaded lipid nanoparticles

Many essential oils have garnered attention as promising antimicrobials; however, their inherent volatility and susceptibility to degradation limit their effective utilisation. Encapsulation can address these limitations by entrapping the essential oils within protective matrices. In the current study, native Australian essential oils, Tasmanian mountain pepper (Tasmannia lanceolata) and lemon myrtle (Backhousia citriodora) and non-native thyme (Thymus vulgaris) were encapsulated in lipid nanoparticles (LNs) using high-pressure homogenisation. The morphology, size, stability and release properties of the LNs was assessed using cryo-TEM, DLS, turbiscanning and dialysis, respectively. The encapsulation efficiency of the LNs was determined using ultrafiltration and GC-FID analysis. The liquid and vapour phase antimicrobial activity and mode of action were determined using microdilution, inverted petri plate assays, and TEM, respectively. Stable spherical LNs (<200 nm size) with encapsulation efficiencies <88% and polydispersity index <0.2 were formulated. LNs generally showed higher antimicrobial activity than unencapsulated oils except for vapour phase activity which varied amongst the oils. Time-dependent cell membrane damage was confirmed using TEM. Essential oils exhibited a bi-phasic release profile from LNs characterised by initial burst release, followed by sustained release. In summary, encapsulation stabilised, promoted sustained release and enhanced the antimicrobial efficacy of the essential oils.

Antimicrobial Activity of Essential Oil of Origanum Majorana L. and Schinus Molle L. Endemic in Northern Cyprus

Antimicrobial Activity of Essential Oil of Origanum Majorana L. and Schinus Molle L. Endemic in Northern Cyprus

Essential Oils: A “Potential Green” Alternative in Pharmaceutical, Nutritional and Agricultural Sectors

In the era of modern medicine, the therapeutic use of plant-derived essential oils has been one of the fascinating fields of study for researchers around the globe. The plant-derived essential oils, which are a combination of volatile organic compounds may be used as a substitute for the treatment of pathogenic microbes. The antimicrobial properties of essential oils are extremely diverse. In microbial infections, essential oils create an electrochemical gradient across the cell wall which intervenes with ATP synthesis and can also disrupt the electron transport system (ETS) by rupturing the mitochondrial membrane. Many essential oils have antiviral properties that can effectively treat COVID-19. The purpose of the current review is to shed light on the antimicrobial efficacy of essential oils. A survey of the methods used for the determination of the interaction and mechanisms involved in the antimicrobial activities of essential oils are also reported as well and the applications of essential oils could be interesting COVID-19 therapeutic options because of their pharmacological actions. This review will attract the attention of researchers to optimize and elucidate the use of essential oils as green alternatives to treat the deadliest infectious diseases in living organisms.

Antimicrobial Activity of Essential Oils in Vapor Phase In Vitro and Its Application in Combination with Lactic Acid to Improve Chicken Breast Shelf Life.

The effect of essential oils (EOs) incorporated in their vapor phase combined with lactic acid immersion pretreatment was studied on fresh refrigerated chicken breast shelf life. Among the several EOs assayed, the in vitro results obtained from the vapor diffusion test allowed mustard, oregano, and garlic EOs to be selected due to their higher antimicrobial activity. In addition, it was possible to determine the EO minimum inhibitory concentrations against Pseudomonas aeruginosa and Escherichia coli and to identify EO binary mixtures showing synergistic or additive effects. Based on the obtained results, a ternary mixture constituted by 0.073, 0.292, and 0.146 µL/mL of headspace of mustard, oregano, and garlic, respectively, was proposed for its application to chicken breasts. The ternary mixture inhibitory action was confirmed in vitro against P. aeruginosa and E. coli. Furthermore, the presence of numerous compounds with recognized antimicrobial and antioxidant activity was found in its volatile phase through gas chromatography. When applying an EO mixture in its vapor phase in combination with 1.0% v/v of lactic acid immersion pretreatment on refrigerated chicken breast, a decrease in mesophilic microorganisms' growth rate as well as in lipid oxidation was observed. Moreover, in a preliminary sensory test, the treated chicken breast was found to be acceptable to consumers and showed no significant differences compared to untreated chicken. In conclusion, the combined use of lactic acid immersion and EOs in their vapor phase was an effective alternative to increase chicken breast shelf life.

Chemical composition, antioxidative and antimicrobial activities of essential oil of wild Artemisia annua from Ningxia, China

Artemisia annua is an essential aromatic medicinal plant endemic to China. Here, essential oil was extracted from wild A. annua from Ningxia, China. GC-MS analysis showed that A. annua essential oil was dominated by artemisia ketone, a characteristic compound accounting for 31.26%, followed by eucalyptol (14.89%), camphor (8.69%), myrcene (8.25%) and α-pinene (6.65%). The overall antioxidative potential represented by DPPH and ATBS free radical scavenging rates was weak. The essential oil exhibited good bactericidal activities against Escherichia coli and Staphylococcus aureus and fungicidal activities against Trichophyton rubrum and Epidermophyton floccosum. The minimum inhibitory and microbicidal concentrations were 0.02 mg/mL and 5.12 mg/mL for both bacteria, 0.315% and 2.5% for E. floccosum, and 0.625% and 5% for T. rubrum. The results suggest that A. annua essential oil may be an antimicrobial adjuvant to be applied in pharmaceutical and cosmetic industries.

Chemical composition and antimicrobial activity of essential oils of two wild olive subspecies Olea europaea L.var. sylvestris and the endemic olive Olea europaea subsp. lapperinie from Algeria

Two wild olive subspecies are fixed in this research: Olea europaea L.var. sylvestris and Olea europaea subsp. laperrinei despite its ecological value, the chemical composition of subsp. laperrinei oil remains unknown. The samples were harvested from the different geographical area. Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography-flame-ionization detection (GC-FID) analysis of Olea europaea L. var. sylvestris allowed the identification of 29 compounds oil with Nonanal (11.82%), theaspiranea A (9.81%), 3-hexen-1-ol,benzoate(9.31%) as a major constituents, while in the subspecies of the Saharan region 31 compounds were separated, where α-pinene (16%), β-Ocimene (12.82%), dl-Limonene (8.20%) were the main components. The results of the disc diffusion method showed that the two volatile oils have efficient antibacterial activity but, subsp. laperrinei essential oil has a higher range of inhibition, in which P. aeruginosa and B. subtilis showed an extreme sensitivity, while the K. pneumoniae bacterium shows a great resistance to the two essential oils.

Training in tools to develop quantitative microbial risk assessment of ready-to-eat food with a comparison between the Romanian and Spanish food supply chains.

The prevention and control of bacterial contamination on ready-to-eat (RTE) fresh produce is an essential task to ensure food safety. Therefore, the development of novel and effective decontamination technologies to ensure microbiological safety of fruits and vegetables has gained considerable attention and new sanitisation methods are needed. The antimicrobial activity of essential oils (EOs) is well documented, but their application in fresh produce remains a challenge due to their hydrophobic nature. Thus, nanoemulsions efficiently contribute to support the use of EOs in foods by enhancing their dispersibility, their contact area and facilitating the introduction into bacterial cells. The combination of these factors ultimately increases their antimicrobial activity. Quantitative microbial risk assessment (QMRA) is gaining more attention as an effective tool to assess and prevent potential risks associated with food-borne pathogens. In this context, the current project aims to study the effectiveness of different washing methods based on nanoemulsified EOs, comparing them against traditional methods, using a QMRA model for Escherichia coli O157:H7 on cherry tomatoes. Different simulations within a stochastic risk assessment model were implemented using the biorisk package for R, aiming to describe microbial behaviour and biological risk along the Romanian and Spanish food supply chains of RTE fresh produce. Nanoemulsions were prepared using oregano and rosemary EOs, each from Romania and Spain. The four nanoemulsions were evaluated as decontamination treatments to control the growth of E. coli O157:H7 on artificially contaminated cherry tomatoes. The decontamination treatments showed encouraging results, comparable to commonly used chlorine solutions. Therefore, oregano and rosemary nanoemulsions are promising and could be a feasible alternative for chlorine solutions in the reduction of microbiological contaminants.

Compositions and Antimicrobial Activity of Essential Oils from Artabotrys chitkokoi

Compositions and Antimicrobial Activity of Essential Oils from Artabotrys chitkokoi

Synergistic antimicrobial activity of essential oils in combination with phage endolysin against Salmonella Typhimurium in cooked ground beef

This study was designed to evaluate the antimicrobial activity of selected essential oils (AITC, carvacrol, eugenol, and thymol) in combination with Salmonella phage-encoding endolysin (LysPB32) against Salmonella Typhimurium KCCM 40253 in vitro and in cooked ground beef. The minimum inhibitory concentrations (MICs) of AITC, carvacrol, eugenol, and thymol against S. Typhimurium were determined in the absence and presence of LysPB32 using broth microdilution assay. In vitro antimicrobial susceptibility of S. Typhimurium to the essential oils in combination with LysPB32 was evaluated at 37 °C for 24 h using time-kill curve assay. The N-phenyl-1-napthylamine (NPN) uptake and relative bacterial fitness were measured to evaluate the outer membrane permeability and reproductive success. The morphological alterations of these treated S. Typhimurium cells were observed through a holotomographic 3D microscopy. The MICs of AITC, carvacrol, eugenol, and thymol against S. Typhimurium were significantly decreased from 6.0 to 2.9 mg/mL, 3.0 to 0.8 mg/mL, 2.8 to 0.7 mg/mL, and 1.4 to 0.7 mg/mL, respectively, when treated with LysPB32 (100 μg/mL). The combinations of carvacrol, eugenol, and thymol combined with LysPB32 effectively reduced the numbers of S. Typhimurium to below the detection limit (20 CFU/mL) after 12 h incubation at 37 °C, caused by membrane disruption. The relative bacterial fitness was significantly decreased in S. Typhimurium treated with carvacrol in the absence and presence of LysPB32. The combinations of carvacrol and eugenol with LysPB32 most effectively inhibited the growth of S. Typhimurium in cooked ground beef after 24 h of storage at 37 °C (>2 log reduction) and 7 days of refrigerated storage (>2 log reduction). Therefore, this study could provide the possibility of using the combinations of essential oils and phage endolysin as synergistic antimicrobials and also pave the way for designing effective food preservatives to enhance food safety and quality.

Essential oils in broiler chicken diets as antimicrobial agents: Systematic review

The search for alternative ingredient options in the animal diet that have antimicrobial activity is due to many factors, such as pathogens increasing resistance and the presence of antibiotic residues in animal products consumed by humans. Therefore, there is a rising demand for natural additives that do not interfere with animal development or human health. Here, we compare studies on the use of essential oils as antimicrobial agents in broiler chicken diets. First, 90 papers were found using the key words “broilers”, “antimicrobial”, and “essential oils”. The second step was to select the papers according to the scales of Jadad and Medeiros and Stein, where six remaining researchers were selected to describe the antimicrobial activity of essential oils in response to enteric pathogens. Essential oils (EOS) have antimicrobial activity against different pathogens, such as E. coli, S. Enteritidis, S. Heidelberg and C. perfringens, and are considered alternatives to antibiotics used in animal production. The EOs that showed the greatest effectiveness were oregano essential oil (EO), cinnamaldehyde and thymol concentrates; when used together with additives such as sodium butyrate and xylanase, there was better antimicrobial action and improved animal performance. Ginger and carvacrol EOS also demonstrated antimicrobial activities, as did thymol, cinnamaldehyde and eucalyptus EO concentrates, but studies on the specific action of plant species that produce EOS for certain pathogens are still lacking; thus, the topic lacks an ongoing study addressing the addition of EOS in the feed of poultry production.

Antioxidant and Antimicrobial Activity of Essential oil Extracted from Trachyspermum Ammi (ajwain) Seeds: an In-vitro Study

The food industry uses essential oils derived from natural sources as flavouring and preservatives. The purpose of this study is to investigate how temperature affects the essential oil extracted from Trachyspermum ammi, seeds which has the best antioxidant and antimicrobial properties, in order to find a green substitute for toxic chemically produced preservatives used in food and pharmaceutical chemistry. Trachyspermum ammi (ajwain seeds) seeds were hydrodistilled at various temperatures (60°C to 90°C). The amount of essential oil was found to decrease on increasing temperature (2.1ml, 1.5 ml and 1.0 ml at 70°C, 80°C, and 90°C respectively). Hence, 70°C was the ideal temperature for extracting the essential oil from ajwain seeds. 25 components were discovered in the essential oil extracted from ajwain seeds by GC-MS technique. The predominant ingredient was shown to be thymol (31.40%). The percentages of scavenger activity against hydrogen peroxide were 70.75%, 86.99%, and 95.28% for 70°C, 80°C, and 90°C respectively. Due to the presence of the largest concentration of thymol (67.66%), the results showed that essential oil extracted at 90°C demonstrated the highest level of antioxidant property. By using the disc diffusion method, the antimicrobial activity of an essential oil made from ajwain seeds was evaluated. MIC50 of standard essential oil of Trachyspermum ammi seeds against gram positive strain was observed 10 µL/mL of culture and 25µL/mL of culture was observed against gram negative bacteria. Essential oil extracted at 70°C showed antimicrobial activity by forming zones of inhibition with diameters including discs of 18.3 mm and 14.36 mm against S. aureus and E. coli, respectively. Essential oil extracted at 80°C produced zones of inhibition with diameters of 18.68 mm and 15.30 mm, respectively. In the case of essential oil extracted at 90°C, the zones of inhibition against S. aureus and E. coli had diameters of 18.690.3 mm and 15.38 mm, respectively. As a result, using Trachyspermum ammi essential oil as a food preservative and the temperature at which it is extracted are unaffected by an increase in extraction temperature. Hence, essential oil obtained from Trachyspermum ammi seeds can be used as green alternative of chemically synthesized toxic preservatives used in food and pharmaceutical chemistry.

Essential Oils – Anti-Microbial and Pharmacological Properties of Essential Oils

The oils that are essential are highly concentrated herbal extracts from extremely significant botanicals. Popularly these oils are used in complementary and substitute medicine. The oil is usually extracted from flowers, leaves, roots, and added parts of plants. The antimicrobial activity of essential oils and their components has been studied for a very long time. Essential oils are produced from a complex combination of unstable atoms that are delivered by the optional digestion of sweet-smelling and medicinal plants and can be produced by various techniques, including distillation or microwaves. The huge number of studies on the antimicrobial action of essential oils has permitted the logical acknowledgment of these mixtures on the control of a wide scope of microbial microorganisms. The advances made on the examination of the method of activity of essential oils against bacterial cell targets give us new points of view to battle constant and antimicrobial safe bacterial microorganisms.

Chemical composition and antimicrobial activity of essential oils from the leaves and rhizomes of Hedychium yunnanense Gagnep. (Zingiberaceae) collected in Vietnam

Hedychium yunnanense Gagnep., belonging to the Zingiberaceae family, has aroused much interest due to its non-volatile chemical constituents. Nevertheless, no data about essential oils (EOs) of this species is available. In this study, the chemical composition and antimicrobial activity of EOs from leaves and rhizomes of H. yunnanense collected in Vietnam were analyzed. The EOs of the rhizomes and leaves were obtained as yellow oils with extraction yields of 0.21 and 0.09%, respectively. Fifty-seven chemical components, accounting for 94.35-98.92%, were identified in the two EOs. The rhizomes EO mainly contains β-pinene (21.07%), 1,8-cineole (20.63%), α-pinene (8.80%) and camphene (6.35%), while the leaves EO was rich in β-pinene (45.92%), α-pinene (19.48%), and β-caryophyllene (18.26%). Both EOs exhibited more potent antimicrobial activities than the standard drug, streptomycin, as they demonstrated significantly lower minimum inhibitory concentrations against the tested bacteria and fungus. Additionally, the leaves EO may possess stronger antimicrobial activities than the rhizomes EO. The findings of the study will provide a better understanding of the chemical composition and bioactivities of H. yunnanense.

Chemical Composition and Antimicrobial Activities of Essential Oils from Meistera verrucosa

Chemical Composition and Antimicrobial Activities of Essential Oils from Meistera verrucosa

Antibacterial Activity of Essential Oils of &lt;i&gt;Thymus serpyllum&lt;/i&gt; L. and &lt;i&gt;Thymus marschallianus&lt;/i&gt; Willd.

Introduction. Plant essential oils are supposed to be applied for local treatment of infectious focuses.Aim. The aim of this study was evaluation of antimicrobial activity of essential oils of Thymus serpyllum L. and Thymus marschallianus Willd., widely distributed in the Saratov region.Materials and methods. Antimicrobial activity of the essential oils was determined by a serial dilution test at the microbial number of 5 × 105 CFU/ml against 6 strains of Staphylococcus aureus, including S. aureus FDA 209P and five clinical, 2 strains of Escherichia coli – E. coli ATCC 25922 and one clinical, two strains of Pseudomonas aeruginosa – P. aeruginosa ATCC 27835 and one clinical.Results and discussion. The bactericidal minimal inhibitory concentrations (MICs) of essential oil of T. serpyllum were determined for all strains of staphylococci (for 5 – 1097,5, for 1 – 2195 µg/ml). The bacteriostatic MICs were determined for 3 strains (for 2 – 548,75, for 1 – 1097,5 µg/ml). MICs of the T. marschallianus essential oil were bactericidal for all strains of S. aureus (120 for 5 and 480 µg/ml for 1 strain). For all test strains of gram-negative bacteria MICs of the essential oils of both species were bactericidal and amounted to 1097 and 960 µg/ml. Considering the chemical composition of the oils by thymol and its isomers, MIC50 of T. marschallianus and T. serpyllum for the test staphylococcal strains amounted 108,89 and 496,59, for the test strains of gram-negative bacteria 683,91 and 783,43 µg/ml respectively.Conclusion. According to the values of MIC50 antistaphylococcal activity of the essential oils of T. marschallianus was significantly higher than this activity of the essential oils of T. serpyllum.

In-vitro antimicrobial activity of essential oils of Tasmania

ABSTRACT Thirteen commercial Tasmanian essential oils were evaluated for their antimicrobial activity against 14 human pathogens and cosmetic contaminants including Enterococcus hirae, Kocuria rhizophila, Staphylococcus epidermidis, Propionibacterium acnes, Staphylococcus aureus, Escherichia coli, Klebsiella aerogenes, Klebsiella pneumoniae, Pluralibacter gergoviae, Pseudomonas fluorescens, Burkholderia cepacia, Pseudomonas putida, Aspergillus brasiliensis, and Aspergillus fumigatus. The antimicrobial activities of various essential oils were evaluated using the AlamarBlue Cell Viability Assay, covering a testing concentration range from 3.125 to 800 µg/mL. Essential oils were deemed active if their minimum inhibitory concentration (MIC) value was less than or equal to 800 µg/mL. The essential oils of Rosemary (Rosmarinus officinalis ct. α-pinene), Parsley Herb (Petroselinum crispum), and Bitter Fennels (Foeniculum vulgare) demonstrated significant growth inhibitory effects on one microorganism (P. fluorescens) within an MIC value of ≤ 800 µg/mL. Big Badja Gum (Eucalyptus badjensis), Blue Gum (Eucalyptus globulus), Peppermint (Mentha piperita), and Lavender (Lavandula angustifolia) essential oils inhibited the growth of two different microorganisms. Southern Rosalina (Melaleuca ericifolia), Parsley Seed (Petroselinum crispum), Smoky Tea Tree (Leptospermum glaucescens), and Kunzea (Kunzea ambigua) essential oils exhibited an MIC value of less than or equal to 800 µg/mL against 4, 5, 6, and 8 microorganisms respectively. Notably, Coastal Tea Tree (Leptospermum laevigatum) essential oil displayed the most profound antimicrobial activity, inhibiting 11 out of 15 microbial strains within an MIC range of 50–800 µg/mL. The results of the gas chromatography analysis showed that the coastal tea tree essential oil was composed primarily of monoterpenes, with smaller amounts of sesquiterpenes and their oxygenated derivatives. 35 Compounds were identified, representing 95.50% of the compounds in the coastal tea tree essential oil. The main constituents of this essential oil were α-pinene (34.83%), followed by α- and β-eudesmols (10.21% total), and limonene (9.56%).