Antibacterial Potential Of Essential Oils Research Articles

Biopesticide potential of Anisomeles indica Kuntze leaf essential oil and its nanoemulsion against bacterial blight - Xanthomonas strains

The objective of this study was to examine the chemical composition of essential oil A. indica leaves and its nanoemulsion, and evaluation of potential for use as a biopesticide. Essential oil of A. indica extracted from fresh leaves was found to be 99.97% composed of 59 components, according to GC-MS analysis. A non-ionic surfactant Tween 80 and the essential oil of A. indica were combined to create a stable nanoemulsion using sonication method. A long durable stable nanoemulsion was obtained after thirty minutes of sonication, and it was examined using TEM (Transmission electron microscopy), DLS (Dynamic light scattering), and FTIR (Fourier transform infrared spectroscopy) analyses. To consider its practical applications, other factors such as stability, viscosity, pH, turbidity, and creaming index were also investigated. Antibacterial properties of essential oil and nanoemulsion were evaluated against bacterial blight plant pathogens Xanthomonas oryzae and Xanthomonas citri. The MIC (Minimum inhibitory concentration) was determined using the broth microdilution method, and the anti-Xanthomonas activity was assessed utilizing by agar disc diffusion method. Using the crystal violet (CV) technique, inhibition of biofilm formation and development were evaluated. Disturbance of bacterial membrane permeability was confirmed by estimating the proteins and nucleic acids (DNA, and RNA) leakage from the cell membrane. Greenhouse studies using rice/paddy plants were conducted to demonstrate the antibacterial potential of essential oil and nanoemulsion, using RNR-15048 rice cultivar by seed treatment and foliar spray groups. Results of the investigations suggest that, when the essential oil was transformed into a nanoemulsion, its antibacterial effect against bacteria was significantly increased, that might be attributed to the essential oil enhanced ability to penetrate the bacterial cells. Essential oil of A. indica and its nanoemulsion reduced rice bacterial blight disease by 84%and pathogen-virulence by 92%, and promoted the growth and development of rice/paddy seedlings. These results confirm that A. indica essential oil and its nanoemulsion possess anti-bacterial blight properties, without affecting growth and development of host plants. Essential oil of A. indica and its nanoemulsion could be used as biopesticide to control Xanthomonas induced bacterial blight diseases in crop plants either by using for seed treatment or as a foliar spray.

Antibacterial Potential of Essential Oils and Silver Nanoparticles against Multidrug-Resistant Staphylococcus pseudintermedius Isolates.

Staphylococcus pseudintermedius is an emergent zoonotic agent associated with multidrug resistance (MDR). This work aimed to describe the antibacterial activity of four essential oils (EOs) and silver nanoparticles (AgNPs) against 15 S. pseudintermedius strains isolated from pyoderma. The four EOs, namely Rosmarinus officinalis (RO), Juniperus communis (GI), Citrus sinensis (AR), and Abies alba (AB), and AgNPs were used alone and in combination to determine the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC). All strains were MDR and methicillin-resistant. Among the antibiotic cohort, only rifampicin, doxycycline, and amikacin were effective. EOs' chemical analysis revealed 124 compounds belonging to various chemical classes. Of them, 35 were found in AR, 75 in AB, 77 in GI, and 57 in RO. The monoterpenic fraction prevailed over the sesquiterpenic in all EOs. When EOs were tested alone, AB showed the lowest MIC followed by GI, AR, and RO (with values ranging from 1:128 to 1:2048). MBC increased in the following order: AB, AR, GI, and RO (with values ranging from 1:512 to 1:2048). MIC and MBC values for AgNPs were 10.74 mg/L ± 4.23 and 261.05 mg/L ± 172.74. In conclusion, EOs and AgNPs could limit the use of antibiotics or improve the efficacy of conventional therapies.

Essential Oil from the Leaves, Fruits and Twigs of Schinus terebinthifolius: Chemical Composition, Antioxidant and Antibacterial Potential.

Schinus terebinthifolius Raddi, popularly known as "Pink pepper", is a plant native to Brazil. The objective of this work was to analyze the chemical composition and the antioxidant and antibacterial potential of essential oils (EOs) from the leaves, fruits and twigs of S. terebinthifolius, aiming for their application in food safety. EOs were obtained by hydrodistillation and the chemical composition was determined by gas chromatography coupled to mass spectrometry. Phenolic compounds were quantified and antioxidant activity was evaluated using three different methods. The antibacterial activity was determined by the broth microdilution method against foodborne bacteria. In the chemical analysis, 22 compounds were identified in the leaves, 13 compounds in the fruits and 37 compounds in the twigs, revealing the presence of the main compounds germacrene D (12.04%, 15.78%, 20,41%), caryophyllene (15.97%, 3.12%, 11.73%), α-pinene (11.6%, 17.16%, 2.99%), β-pinene (5.68%, 43.34%, 5.60%) and γ-gurjunene (16,85%, 3,15%) respectively. EOs showed better antioxidant potential using the β-carotene/linoleic acid method with 40.74, 61.52 and 63.65% oxidation inhibition for leaves, fruits and twigs, respectively. The EO from the leaves showed greater antibacterial potential against Escherichia coli and Staphylococcus aureus with a minimum inhibitory concentration (MIC) of 0.62 mg mL-1, a value lower than the MIC of sodium nitrite (5.00 mg mL-1), the antimicrobial standard synthetic. The activities of pink pepper EOs suggest their potential as a biopreservative in foods.

The Antibacterial Potential of Essential Oils of Oral Care Thai Herbs against Streptococcus mutans and Solobacterium moorei—In Vitro Approach

Oral malodor, often known as halitosis, is an irritating breath odor that originates in the mouth and can cause significant psychological and social distress. Chlorhexidine, a powerful antimicrobial agent effective against bacteria and fungi, has become the standard treatment for halitosis. However, it has drawbacks including altered taste perception, dry mouth, and more noticeable dental staining. The use of natural essential oils to avoid these unwanted effects has proven to be an attractive strategy. This study aims to evaluate the potential of four essential oils consisting of Ma-kwean fruit (Zanthoxylum limonella, MK), clove bud (Syzygium aromaticum, CV), star anise fruit (Illicium verum, SA) and cinnamon bark (Cinnamomum aromaticum, CM) for the purpose of combating bad breath by assessing their antibacterial efficacy against halitosis-associated bacteria (Streptococcus mutans and Solobacterium moorei). The hydro-distillation process was used to prepare the essential oils, which were obtained as yellowish to colorless liquids with yields of 6.58 ± 0.81, 12.21 ± 2.98, 4.29 ± 0.15 and 1.26 ± 0.09% for MK, CV, SA and CM, respectively. The terpenoid compounds terpinene-4-ol (47.04%), limonene (17.19%), sabinene (13.27%) and alpha-terpineol (6.05%) were found as the main components in MK essential oil, while phenylpropanoids were identified as the primary components of other essential oils, namely trans-cinnamaldehyde (83.60%), eugenol (83.59%) and anethol (90.58%) were identified as the primary components of CM, CV and SA essential oils, respectively. For the antibacterial properties, the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values were investigated. CM essential oil exhibited the greatest capacity to inhibit growth and eradicate S. mutans, with MIC and MBC values of 0.039%, followed by CV (MIC of 0.078% and MBC of 0.156%) and MK (MIC and MBC of 0.156%), whereas the MIC of SA was 1.250% without eradication. Both CM and CV essential oils demonstrated exceptional efficacy against S. moorei, with MIC and MBC values of 0.019% and 0.033%, respectively. Furthermore, the inhibition of S. moorei biofilm formation was investigated and we discovered that the lowest effective concentration necessary to eliminate the S. moorei biofilm was one quarter of the MIC for MK, CM and CV, while that for SA essential oil was half of the MIC. These encouraging results suggest that the incorporation of MK, CM and CV essential oils into oral care products could potentially enhance their efficacy in halitosis treatment.

Antibacterial potential of essential oils extracted from three medicinal plants against some foodborne bacteria

Antibacterial potential of essential oils extracted from three medicinal plants against some foodborne bacteria

Aktivitas Antibakteri Minyak Atsiri Kulit Jeruk Limau (Citrus amblycarpa (Hassk.) Ochse) Dalam Mengendalikan Bakteri Streptococcus mutans

Dental caries is an infection disease of tooth tissue caused by Streptococcus mutans bacteria. Atsiri is essential oil is a liquid-shaped compound that is thought to have potential as an antibacterial. The purpose of this study was to determine the antibacterial potential of essential oil of limau lime in controlling Streptococcus mutans bacteria. The antibacterial test in this study used disk disfussion method with 8 treatment groups and 4 replications is 5 concentrations of atsiri oils, 1 positif disc amoxicillin antibiotic, 2 negative control with DMSO and aquades. The data obtained were analyzed with normality test, Anova test and BNT test. Isolation of atsiri’s oil of limau lime in this study using the method of steam-water distillation. 
 Streptococcus mutans bacteria were isolated from dental caries patients and tested using macroscopic, microscopic, gram staining, and biochemical methods. The study found that the atsiri oils of limau lime has antibacterial activity in vitro against Streptococcus mutans bacteria, as evidenced by the formation of an inhibit zone. Concentration as 100% with 15.38mm inhibitory zone diameter is the most effective concentration to inhibit the growth of Streptococcus mutans bacteria. The statistical analysis revealed a significant influence between the treatments at the 5% significance level.

Antibacterial potential of essential oils against planktonic and sessile cells of Escherichia coli isolated from diarrhea cases in swine

Escherichia coli is a pathogen associated with infections in piglets in the post-weaning phase, its pathogenicity is related to the animal's susceptibility to bacterial enterotoxins. The objective of the present study was to determine the EOs activity against E. coli strain, in the form planktonic and sessile. Although the Disc-Diffusion tests to determine the Minimum Inhibitory Concentration, do not fully corroborate with the other analyzes of this study, it was noticed bacteria inhibition. The EOs were prepared at 0.4%, 0.8% and 1.0% for tests. The tested EOs were effective against E. coli planktonic cells (p<0.05). As for the sessile cells, the most significant result was inhibition and 100% sessile cells at the concentration of 1.0% of Cymbopogon citratus EO. Although there was resistance in some treatments, the tested EOs demonstrated inhibition capacity, constituting promising alternatives for the control of E. coli, especially of planktonic cells.

Evaluation of the Antibacterial Potential of Essential Oil and Extract of Apium graveolens L. as an Environmentally Friendly Technology Against Helicobacter pylori

The hygiene hypothesis links the environmental and microbial exposure in early life to the prevalence of atopy, allergy, and asthma. Helicobacter pylori infection is typically acquired in childhood and the acquisition is associated with poor household hygiene. In this study, the current knowledge on the activity of essential oils and extract of Apium graveolens L. (celery seeds) and their derivatives against H. pylori was reviewed. Celery seeds were prepared at the Pharmaceutical Farm (Babol, Mazandaran) of Iran. The essential oils were extracted by a Clevenger approach and analyzed using GC-MS, and maceration method was used to prepare the extract. H. pylori bacteria were isolated by the cultivation of gastric biopsy removed from the patient who had gastric ulcer. The antibacterial activities of both essential oils and extract against H. pylori were evaluated by agar dilution method, and the corresponding MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) values were determined for each sample. The results showed that the main components in celery seed essential oils were α-pinene (20.25%), β-pinene (16.62%), and Sabinene (7.81%). Among different samples, essential oils of celery seed exhibited better effect on H. pylori with MIC value of 1.56 mg/mL and MBC value of 3.12 mg/mL. Methanol and water extracts of celery seed showed MIC values of 0.38 mg/mL and 0.78 mg/mL and MBC values of 1.56 mg/mL and 6.25 mg/ mL, respectively (P≤0.005). The results of this study indicated that all the samples had antibacterial effect against H. pylori due to antibacterial components.

Antibacterial potential of essential oils from medicinal plants for food preservation: a review

Essential oils, also called volatile or ethereal oils, are compounds naturally present in plants. Several medicinal plants are sources of these essential oils extraction, besides different secondary metabolites that are produced, such as terpenoids, alcoholic compounds, aldehydes, ketone bodies and phenols. The essential oils usage as substitutes for synthetic preservatives in food has been gaining space in research due to the interest of the populationin consuming healthier products. Moreover, the industry seeks to attend the necessities of the consumers to produce foods with less synthetic additives, but ensuring the preservation of organoleptic characteristics and shelf life. This review aims to present the antibacterial activity of essential oils from medicinal plants and its use as a food preservative.

Chemical Characterization and Antibacterial Efficacy of Essential Oils of Three Lamiaceae Species Growing in Cameroon

Essential oils (EOs) have aroused attention among the naturally-occurring therapeutic compounds with anti-infective properties. This study examined the chemical composition and the antibacterial potential of EOs from three Lamiaceae species including Ocimum gratissimum (leaves), Plecthrantus epilithicus (leaves), and Satureja robusta (leaves and flowers). EOs were obtained by hydrodistillation using a Clevenger-type apparatus, followed by characterization by gas chromatography-mass spectrometry (GC-MS) and flame ionization detector (GC/FID). The antibacterial efficacy of EOs was screened using the microdilution method, against a panel of eight foodborne bacteria isolates namely Enterobacter cloacae, Yersinia enterocolotica, Klebsiella pneumoniae, Salmonella typhi, Escherichia coli, Citrobacter freundii, Shigella flexneri, and Enterococcus faecalis. GC-MS and GC/FID analysis led to the identification of 53 components from EOs of P. epilithicus, while around forty compounds have been characterized from the EOs of O. gratissimum (43), leaves of Satureja robusta (43), and flowers of S. robusta (44). The nature of identified compounds varied according to the species. The most prevalent volatile compounds identified in the EOs of P. epilithicus were piperitenone oxide (23.65%) and two isomers piperitone oxide 2/2 (16.15%) and piperitone oxide 1/2 (7.24%). The major constituents in the EOs of leaves of O. gratissimum were elemicin (33.474%) and eugenol (30.258%). Piperitone oxide, piperitone, and germacrene D were identified as major constituents in both the EOs of leaves of S. robusta (28.3%, 15.14%, and 9.42% respectively) and flowers (45.6%, 11.55%, and 3.94% respectively). The oils displayed selective antibacterial potential, with the recorded minimal inhibitory concentration (MIC) values ranging from 0.0156 to 1% (v/v). EOs of P. epilithicus as well as that of the leaves and flowers of S. robusta acted against all studied bacteria. Most of the MIC values were below 0.25% (v/v), indicating a strong inhibitory potential of studied EOs. The present study provides a strong baseline for consideration of the EOs from O. gratissimum, S. robusta, and P. epilithicus in the control of bacterial foodborne infections.

Antibacterial potential of essential oils of Zataria multiflora and Mentha piperita, micro- and nano-formulated forms

Plant-derived essential oils (EOs) shave many usages in health and medicine, such as antibacterial agents. The aim of this study was the improvement of antibacterial activities of two EOs using nanotechnology. Antibacterial activity was investigated on four important human pathogenic bacteria using the 96-well plate microdilution method, a quantitative approach. Eleven formulations were prepared using each of the EOs. Eventually, the best nanoformulation with the smallest particle size and polydispersive indices (PDI and SPAN) was selected using each EO for further investigations. Moreover, two microemulsions with similar ingredients and the same portion in comparison with two selected nanoemulsions were also prepared. Antibacterial activity of each EO was compared with its micro- and nano-emulsions. The antibacterial efficacy of Zataria multiflora EO (ZMEO) was significantly better than Mentha piperita EO (MPEO). Besides, the antibacterial activity of nanoemulsion of ZMEO with a particle size of 129 ± 12 nm was significantly better than no- and micro-formulated forms of ZMEO. Interestingly, the efficiency of MPEO nanoemulsion (160 ± 25 nm) was also significantly better than MPEO and its micro-formulated form. Regardless of the intrinsic antibacterial property of two examined EOs, by formulating to nanoemulsion, their efficiencies were improved. Nanoemulsion of ZMEO introduced as an inexpensive, potent and green antibacterial agent.

Antibacterial Potential of Essential Oils Against Ground Beef Isolates

The objective of this study was to evaluate the antibacterial activity of different EOs against Escherichia coli, Salmonella spp., and coagulase-positive staphylococcus isolated from ground beef. The EOs had values varying from 0.78μl/mL to 100μl/mL, and the essential oil of Citrus lemon did not present any bacterial activity against the studied strains. For E. coli, the essential oil of Cinnamomum zeylanicum presented the best inhibitory activity (MIC = 0.78μl/mL to 1.56μl/mL). In Salmonella spp., the EOs of Cymbopogon citratus (MIC = 12.5μl/mL and 25.0μl/mL), C. zeylanicum (MIC = 25.0 µL/mL) and Ocimum basilicum (MIC = 6.25μl/mL, 12.5μl/mL and 50.0μl/mL) exhibited similar results. The EOs of C. zeylanicum and Eugenia caryophyllata demonstrated the lowest average values of study against coagulase-positive Staphylococcus (MIC = 3.12μl/mL, 6.25μl/mL and 12.5μl/mL). With the data obtained in the study, it can be observed the potential of EOs in the control of pathogenic food microorganisms, as well as validate future researches on the proprieties and active compounds of these products, besides the toxicity of these compounds and the possible alterations that can be caused on the food.

Chemical Composition, Antioxidant and Anti-bacterial Potential of Essential Oil of Medicinal plant Isodon rugosus

Isodon rugosus is a medicinally valuable herb containing a variety of important secondary metabolites and essential oil with important chemical constituents of pharmaceutical precursors. The active components of volatile oil of I. rugosus were analyzed using GC-MS. Anti-oxidant potential of the oil was assessed with 2, 2-diphenyl-1-picrylhydrazyl (DPPH). Anti-bacterial power of the essential oil accessed disc diffused method. A total of 19 constituents were quantified and identified with different concentrations in essential oil. Among which Caryophyllene oxide was 28.99%. Limonene oxide cis was 26.52%, (Z, E)-Farnesol was 17.34%, followed by 1-erpinen-4-ol 3.33%, o-Cymene 2.04 while the concentrations of rest of constituents were between 1.11 to 0.2%. The investigation showed that the essential oil of I. rugosus possessed significant antibacterial and antioxidant potential

Reversal of resistance in bacteria underlies synergistic effect of essential oils with conventional antibiotics.

The pervasive of bacterial resistance earnestly threaten the prevention and the treatment of infectious diseases. Therefore, scientific communities take precedence over development of new antimicrobial agents. The aim of the study was to determine antimicrobial potency of three North-African essential oils Pituranthos chloranthus, Teucruim ramosissimum and Pistacia lentiscus individually, and in combination with antibiotics, to inhibit the growth of highly resistant clinical pathogen. Bacteria clinically isolated from patients, subsequently, challenged to a panel of drugs to determine the antibiotic-resistance profiles. Drugs displaying clinically irrelevant CMI were subjected to further studies in order to rescue antibiotic actions. Singular activity of essential oils and activity when combined with an antibiotic was hence elucidated. The results obtained highlighted the occurrence of strong antibacterial potential of essential oils when administrated alone. In the interactive experiment essential oils were found highly effective in reducing the resistance of Methicillin-resistant Staphylococcus aureus to amoxicillin, tetracycline, piperacillin, ofloxacin and oxacillin and resistance of Acinetobacter baumannii to amoxicillin and to ofloxacin in interactive manner. Furthermore, the results proved synergism among essential oils and both antibiotics ofloxacin and novobiocin against the Extended-Spectrum Beta-Lactamase producing E.coli (ESBL). Time kill kinetics was performed with a combination of sub-inhibitory concentrations to confirm the efficiency and killing rate of the combination over time. Further, the hypothetical toxicity of essential oils against human keratinocytes HaCat and murine spleenocytes were examined. The chemical composition of essential oils was assessed by GC/MS analysis and the major constituents found were sabinene, limonene, terpinen-4-ol, and β-eudesmol.

Chemical composition, antibacterial activity and related mechanism of the essential oil from the leaves of Juniperus rigida Sieb. et Zucc against Klebsiella pneumoniae

Ethnopharmacological relevanceJuniperus rigida is used as Tibetan and Mongolian medicine in China for the treatment of rheumatoid arthritis, nephritis, brucellosis and other various inflammatory diseases. Aim of the studyTo evaluate antibacterial potential of essential oils from J. rigida leaves against Klebsiella pneumoniae and to examine its possible related mechanisms. The study was undertaken in order to scientifically validate the traditional use of J. rigida. Materials and methodsThe essential oil was extracted from the leaves of J. rigida by supercritical CO2 fluid extraction technology. Chemical composition of essential oils was analyzed by gas chromatography-mass spectrometry (GC–MS). The antibacterial activity was evaluated against 10 bacteria by the paper disc diffusion method. The minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values of the essential oil were estimated by agar dilution method. The antibacterial mechanism was evaluated by growth curve, the integrity of cell membrane, the SDS-PAGE of protein patterns and scanning electron microscope (SEM). Results61 components were identified from the essential oil. Caryophyllene (13.11%) and α-Caryophyllene (11.72%) were found to be the major components. The antibacterial activities of the essential oil were screened and compared against 10 bacteria. The essential oil showed good antibacterial activity against K. pneumoniae, with the biggest diameters of inhibition zones (DIZ) (16.00±0.25mm) and the lowest MIC and MBC values of 3.125mg/mL. The increase in proteins, 260nm absorbing materials of bacterial cells suspension indicated that the cytoplasmic membranes were broken by the essential oil. The SDS-PAGE of bacterial proteins demonstrated that the essential oil could damage bacterial cells through the destruction of cellular proteins. Scanning electron microscopy (SEM) showed that the essential oil damaged the morphology of cell wall and membrane. ConclusionsThe essential oil of J. rigida has potential antibacterial activities against K. pneumoniae. The antibacterial mechanism is the essential oil causing the irreversible damage to the cell wall and membrane, leading to the leakage of proteins and 260nm absorbing materials (DNA and RNA). Further phytochemical and pharmacological studies are required for proper scientific validation of the folk use of this plant species.

Composição química e eficácia do óleo essencial e do extrato etanólico de Alpinia zerumbet sobre Staphylococcus aureus

RESUMO: O presente trabalho descreve a atividade antibacteriana do óleo essencial e do extrato etanólico das folhas de Alpinia zerumbet (colônia) sobre cepas de Staphylococcus aureus isoladas de vacas com mastite subclínica e cepas padrão ATCC 29213 e ATCC 25923, por meio do método de difusão em ágar. Foram utilizados 10 tratamentos contendo diferentes concentrações do óleo essencial e do extrato etanólico (100,0; 50,0; 25,0; 12,5 e 6,3 mg.mL-1) e o grupo controle (álcool etílico a 50% e Tween a 1%). Os constituintes majoritários do óleo essencial foram p -cimeno (32,72%), 1,8-cineol (24,05%) e 4-terpineol (20,23%), sendo esses determinados por cromatografia a gás acoplada a espectrometria de massas e cromatografia a gás com detector de ionização de chama (CG-EM/DIC). No extrato etanólico foi detectado o ácido elágico e três flavonoides: rutina, quercetina e campferol, por meio de cromatografia a líquido de alta eficiência acoplada a detector de arranjo de diodo (CLAE-DAD). Todas as cepas apresentaram sensibilidade aos tratamentos com óleo essencial e extrato etanólico. A melhor resposta foi obtida com o óleo essencial de A. zerumbet que, na concentração de 100 mg.mL-1 proporcionou inibição total do crescimento bacteriano. Esses resultados sugerem o potencial antibacteriano do óleo essencial e do extrato etanólico de A. zerumbet no controle da mastite bovina.

Antibacterial potential of essential oils of the needles of Pinus halepensis against Staphylococcus aureus and Escherichia coli

Objective: To examine the in vitro antimicrobial activities of essential oil of the needles of Pinus halepensis (P. halepensis). Methods: The antibacterial activity of essential oil of the needles of P. halepensis was determined using the agar well diffusion technique and disc diffusion method against Staphylococcus aureus ATCC 25923, and Escherichia coli ATCC 25922. Results: The diameter of zones of inhibition exhibited by the essential oil was between 6 and 17 mm. The essential oils was compared favorably with gentamycin used as a standard control. The minimum inhibitory concentration determined by the agar well diffusion method was 0.52 mg/ mL for Staphylococcus aureus and 2.15 mg/mL for Escherichia coli. The minimum bactericidal concentration of the oils against the two microorganisms was 4.17 mg/mL. Conclusions: The results obtained from this study reveal that P. halepensis essential oils possess antibacterial activities and can be used as antimicrobial agents in the search for new drugs.

Control of planktonic and sessile bacterial cells by essential oils

The antibacterial potential of essential oils (EOs) from Cinnamomum cassia bark and Melaleuca alternifolia and Cymbopogon flexuosus leaves was evaluated against planktonic and sessile cells of enteropathogenic Escherichia coli (EPEC) and Listeria monocytogenes. The EOs were tested singly and in different combinations of equal percentages: mixtures of two (1:1 in v/v) and three EOs (1:1:1 in v/v/v). The minimal inhibitory concentrations (MICs) were determined against planktonic cells and the anti-biofilm activity was verified against bacterial cells adhered in the wells of polystyrene microplates. These initial tests indicated the EO of C. cassia as a potential anti-biofilm agent, and their effect was studied against sessile cells of biofilms formed on stainless steel surface under agitation and static conditions. For both bacterial species, a solution containing 2% (v/v) of C. cassia EO was effective against the biofilm formed under static conditions, because the counts obtained were below the detection level of the plate count method employed. Although the biofilm of L. monocytogenes showed a decreased number of adhered cells after formation under agitating conditions (p<0.05), it was surprisingly more resistant to the EO of C. cassia than the biofilm formed under static conditions (p<0.05). All of the EOs and combinations tested presented antibacterial activity, almost against planktonic cells; however, the EO of C. cassia showed to be the most effective as a potential agent for the production of sanitizers for biofilm control in the food industries.

Antibacterial potential of the essential oil from Sideritis montana L. (Lamiaceae)

The antibacterial potential of essential oil from Serbian Sideritis montana L. (Lamiaceae) on different bacteria was investigated. The essential oil was obtained from air dried aerial parts of the plant with 0.03% (w/w) yield by hydrodistillation for 4 h using a Clevenger-type apparatus. The essential oil analyses were performed simultaneously by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) systems. Dominant compounds class is sesquiterpene hydrocarbons. The main constituents of oil were germacrene D (37,9%) and trans-geraniol (26,1%). The antibacterial activity of the essential oil was tested towards 4 different bacteria, laboratory control strain obtained from the American Type Culture Collection (ATCC). Gram negative bacteria were represented by Escherichia coli ATCC 13706, Pseudomonas aeruginosa ATCC 27853, Salmonella enteritidis ATCC 13076 while researched Gram positive strain was Staphylococcus aureus ATCC 29213. Broth microdilution method was used to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Essential oil has been found to have antibacterial activity against all tested bacteria, with a MIC values ranging from 0.03 to 0.06 ?l/ml and MBC values from 0.06 to 0.12 ?l/ml. Reference antibiotic tetracycline was active in concentrations between 0.025 to 0.1 ?g/ml. Essential oil from Serbian S. montana has high antibacterial potential which should be studied further.

Evaluation of antimicrobial and phytochemical screening of Fennel, Juniper and Kalonji essential oils against multi drug resistant clinical isolates

ObjectiveThe inhibitory effects of essential oils including fennel, juniper and kalonji from Foeniculum Vulgare, Juniperus Osteosperma and Nigella Sativa on multi drug resistant clinical isolates were investigated. All the oils have been evaluated for phytochemical constituents, antibacterial activity and TLC bioautography assay. MethodsPreliminary phytochemical analysis was performed. The antibacterial potential of essential oils from fennel, juniper and kalonji fennel, juniper and kalonji was evaluated by agar well diffusion method against multi drug resistant clinical isolates. The antibacterial effect was investigated using the TLC-bioautographic method. ResultsPreliminary phytochemical analysis demonstrated the presence of most of the phytochemicals including saponins, cardiac glycosides, steroids, terpenoids, flavonoids and tannins. Antibacterial activity of essential oils was assessed on eight multi-drug resistant (MDR) clinical isolates from both Gram-positive and Gram-negative bacteria and two standard strains. All the oils tested showed significant to moderate antibacterial activity toward all tested strains except Acinetobacter sp and Staphylococcus aureus MRSA. The maximum zone of inhibition was found to be 25±0.12 mm for juniper oil followed by 21±0.085 mm for kalonji oil against Staphylococcus aureus 2. Thin layer chromatography and bioautography assay demonstrated well-defined growth inhibition zones against Staphylococcus aureus 2 and E. coli for juniper essential oil in correspondence with tannins observed at Rf values of 0.07 and 0.57. ConclusionsBased on the present study, the essential oils from juniper and kalonji possess antibacterial activity against several multi drug resistant pathogenic bacteria and thus can be used as a base for the development of new potent drugs and phytomedicine.