Major Compounds Of Essential Oil Research Articles

Ethnobotanical and Bioactive Characteristics of some Sideritis L. Taxa and Major Essential Oil Compounds

Ethnobotanical and Bioactive Characteristics of some Sideritis L. Taxa and Major Essential Oil Compounds

Essential Oils from Different Parts of Magnolia laevifolia: Chemical Constituents and Insecticidal Activities against Liposcelis bostrychophila.

Many synthetic pesticides were used to control a severe storage pest, booklouse (Liposcelis bostrychophila). However, considering the environmental impact, plant secondary metabolites were acceptable alternatives. An endemic plant, Magnolia laevifolia, has a significant and unique odour, so its essential oil (EO) could be an option for bio-pesticide development. This study extracted EOs from leaves, flowers, carpels and seeds of M. laevifolia. The common and major compound of EOs was isocapnell-9-en-8-one, which was present at 17.7 to 91.6 % in these four parts. We found no regular pattern in the composition of EO in terms of parts and collection time according to principal component analysis. The contact and repellent activities of EOs against the booklouse were then conducted. Leaves and flowers' EOs collected in the flowering stage had the best contact toxicity. The percent repellency values of the EOs from different parts of M. laevifolia reached above 80 % after 2 and 4 h exposure at 63.17 nL/cm2, with the same levels as DEET (p<0.05). It was shown that parts of plants and collecting time could influence the insecticidal activities of M. laevifolia EOs against booklouse, but collecting time played a significant decisive role in the contact test.

Cinnamaldehyde for the Treatment of Microbial Infections: Evidence Obtained from Experimental Models.

Cinnamaldehyde (CNM) is a cyclic terpene alcohol found as the major compound of essential oils from some plants of the genus Cinnamomum (Lauraceae). CNM has several reported pharmacological activities, including antimicrobial, antivirulence, antioxidant, and immunomodulatory effects. These properties make CNM an attractive lead molecule for the development of anti-infective agents. In this descriptive review, we discuss the application of CNM in experimental models of microbial infection using invertebrate and vertebrate organisms. CNM (pure or in formulations) has been successfully applied in the treatment of infections caused by a range of bacterial (such as Cronobacter sakazakii, Escherichia coli, Listeria monocytogenes, Mycobacterium tuberculosis, Pseudomonas aeruginosa, Salmonella enterica, Staphylococcus aureus, Streptococcus agalactiae, Vibrio cholerae) and fungal (such as Aspergillus fumigatus, Candida albicans and Cryptococcus neoformans) pathogens. All these experimental evidence-based findings have promoted the use of cinnamaldehyde as the leading molecule for developing new anti- infective drugs.

Variation in Yield, Chemical Composition and Biological Activities of Essential Oil of Three Curcuma Species: A Comparative Evaluation of Hydrodistillation and Solvent-Free Microwave Extraction Methods.

The essential oils of three medicinally important Curcuma species (Curcuma alismatifolia, Curcuma aromatica and Curcuma xanthorrhiza) were extracted using conventional hydro-distillation (HD) and solvent free microwave extraction (SFME) methods. The volatile compounds from the rhizome essential oils were subsequently analysed by GC-MS. The isolation of essential oils of each species was carried out following the six principles of green extraction and comparison was made between their chemical composition, antioxidant, anti-tyrosinase and anticancer activities. SFME was found to be more efficient than HD in terms of energy savings, extraction time, oil yield, water consumption and waste production. Though the major compounds of essential oils of both the species were qualitatively similar, there was a significant difference in terms of quantity. The essential oils extracted through HD and SFME methods were dominated by hydrocarbon and oxygenated compounds, respectively. The essential oils of all Curcuma species exhibited strong antioxidant activity, where SFME was significantly better than HD with lower IC50 values. The anti-tyrosinase and anticancer properties of SFME-extracted oils were relatively better than that of HD. Further, among the three Curcuma species, C. alismatifolia essential oil showed the highest rates of inhibition in DPPH and ABTS assay, significantly reduced the tyrosinase activity and exhibited significant selective cytotoxicity against MCF7 and PC3 cells. The current results suggested that the SFME method, being advanced, green and fast, could be a better alternative for production of essential oils with better antioxidant, anti-tyrosinase and anticancer activities for application in food, health and cosmetic industries.

Comparative chemical composition and pesticidal evaluation of Acorus calamus accessions collected from different geographical locations

The objectives of the present study were to investigate the phytochemical composition of essential oils (EO) from rhizomes of Acorus calamus collected from Jorhat, Assam; Munsyari and Pantnagar, Uttarakhand, India. EOs were studied for different pesticidal activities viz; nematicidal, insecticidal, and herbicidal activity. To study the synergistic effect of EOs on pesticidal activity, four combinations of EOs were prepared. Phenylpropanoids with β-asarone as the main compound were identified in all collections with varying percentages. Its contribution was found to be 85.8% in Munsyari EOs followed by 74.3% in Pantnagar and 62.6% in Assam collections. All EOs exhibited dose-dependent in vitro nematicidal activity against Meloidogyne incognita in terms of immobility and inhibition of egg hatching. The activity was observed as maximum in the EO combination of all three collections (1:1:1) whereas minimum in the Assam collections. In insecticidal activity against Lipaphis erysimi and Selepa celtis, maximum mortality was observed in Munsyari collections. The oils were assessed for sprout inhibition activity in terms of seed germination inhibition, coleoptile growth of the shoot and root against Raphanus raphanistrum. Maximum seed germination inhibition, % shoot, and root growth inhibition were found in all collections EO combinations. To predict the possible mode of action and the structure-activity relationship between major compounds of EOs and biological activities, in silico molecular docking and ADME/Tox studies were performed. The docking results revealed the mode of action of proteins of insects, nematodes, and weeds and were found in support of in vitro experiments. The study may be helpful for the development of herbal-based pesticides after proper clinical trials.

Chemical Profile and Cytotoxicity Evaluation of Aerial Parts of Marrubium vulgare L. From Different Locations in Turkey.

Marrubium vulgare L. (Lamiaceae) is used for respiratory and gastrointestinal system disorders in folk medicine. According to European Pharmacopoeia criteria, standardization of the plant is defined by its marrubiin content. In present study, phenolics, marrubiin and essential oil compositions of M. vulgare from different locations in Turkey were analyzed quantitatively by UPLC, GC and GC/MS. Besides, their cytotoxic potentials were evaluated. In the samples, forsythoside B (77-400 mg/100 g dw), arenarioside (forsythoside F) (0-241 mg/100 g dw), verbascoside (acteoside) (171-416 mg/100 g dw) and apigenin-7-O-glucoside (0-17 mg/100 g dw) were determined in different ranges. Marrubiin contents (0.58-1.46 %) of some samples were two times higher than European Pharmacopoeia standards (0.7 %). β-Caryophyllene (7.24-20.34 %), (Z)-β-farnesene (1.58-34.85 %), germacrene D (9.8-13.37 %), bicyclogermacrene (1.71-8.63 %) and β-bisabolene (0-16.68 %) were detected as major compounds in essential oils. The sample from the west of Aegean Region showed cytotoxicity against human neuroblastoma (SH-SY5Y) cell lines (IC50 : 59.80 μg/mL) although it has no effect on non-cancerous NIH-3T3cell lines. This is the first report on phenolic profiles of M. vulgare populations from Turkey. Their potential as marrubiin source for pharmaceutical industry should be considered.

The biochar-based nanocomposites influence the quantity, quality and antioxidant activity of essential oil in dill seeds under salt stress

The essential oil content and composition of medicinal plants may be influenced by eco-friendly products for nutrient availability under abiotic stresses. This research was conducted to determine the effects of biochar (30 g kg−1 soil) and biochar-based nanocomposites (BNCs) of iron (30 g BNC-FeO kg−1 soil), zinc (30 g BNC-ZnO kg−1 soil), and their combined form (15 + 15 g) on dill (Anethum graveolens L.) under salinity levels (non-saline, 6 and 12 dS m−1). Application of biochar, particularly BNCs increased iron and zinc content and decreased sodium accumulation in leaf tissues. The seed essential oil content increased under high salinity. Salinity changed the values of major compounds in essential oil and induced the formation of compounds such as alpha,2-dimethylstyrene, cuminyl alcohol, p-cymene, and linalool. Biochar treatments especially BNCs with a higher production of monoterpenes increased the levels of limonene, carvone, apiol, and dillapioll. All extracts showed a considerable DPPH-inhibitory effect with application of BNCs under salinity. The maximum antioxidant activity was observed under high level of salinity with application of the combined form. Therefore, the combined form of nanocomposite was the best treatment to improve the content of basic commercial monoterpenes and consequently antioxidant activity of essential oil in salt-stressed dill plants.

Determination of Chemical Compounds and Investigation of Biological Properties of Matricaria chamomilla Essential Oils, Honey, and Their Mixture.

This exploratory investigation aimed to determine the chemical composition and evaluate some biological properties, such as antioxidant, anti-inflammatory, antidiabetic, and antimicrobial activities, of Matricaria chamomilla L. essential oils (EOs). EOs of M. chamomilla were obtained by hydrodistillation and phytochemical screening was performed by gas chromatography–mass spectrophotometry (GC-MS). The antimicrobial activities were tested against different pathogenic strains of microorganisms by using disc diffusion assay, the minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) methods. The antidiabetic activity was performed in vitro using the enzyme inhibition test. The antioxidant activity of EOs was tested using the free radical scavenging ability (DPPH method), ferrous ion chelating (FIC) ability, and β-carotene bleaching assay. The anti-inflammatory effects were tested in vivo using the carrageenan-induced paw edema method and in vitro using the inhibition of the lipoxygenase test. The analysis of the phytochemical composition by GC-MS revealed that camphor (16.42%) was the major compound of EOs, followed by 3-carene (9.95%), β-myrcene (8.01%), and chamazulene (6.54%). MCEO, honey, and their mixture exhibited antioxidant activity against the DPPH assay (IC50 ranging from 533.89 ± 15.05 µg/mL to 1945.38 ± 12.71 µg/mL). The mixture exhibited the best radical scavenging activity, with an IC50 of 533.89 ± 15.05 µg/mL. As antidiabetic effect, EO presented the best values against α-glucosidase (265.57 ± 0.03 μg/mL) and α-amylase (121.44 ± 0.05 μg/mL). The EOs and honey mixture at a dose of 100 mg/kg exhibited a high anti-inflammatory effect, with 63.75% edema inhibition after 3 h. The impact of EOs on the studied species showed an excellent antimicrobial (Staphylococcus aureus ATCC 29213 (22.97 ± 0.16 mm)), antifungal (Aspergillus niger (18.13 ± 0.18 mm)) and anti-yeast (Candida albicans (21.07 ± 0.24 mm) effect against all the tested strains. The results obtained indicate that the EOs of M. chamomilla could be a potential drug target against diabetes, inflammation and microbial infections; however, further investigations to assess their bioactive molecules individually and in combination are greatly required.

Seasonal changes in rosemary species: A chemotaxonomic assessment of two varieties based on essential oil compounds, antioxidant and antibacterial activities.

Rosemary (Rosmarinus officinalis L.) is a popular herb in cooking, traditional healing, and aromatherapy. This study was conducted to evaluate the effects of meteorological conditions plant growth stage and genetic factors on the yield, quantitative and qualitative composition, on the antioxidant and antimicrobial activities of rosemary essential oil from two Tunisian locations (El Fahs and Matmata) during two successive years. The composition of the essential oils obtained by hydrodistilation from rosemary plants were carried out annually using GC and GC/MS. Results showed the the main constituents were camphor (18.2–28.1%), 1,8-cineole (6.4–18.0%), α-pinene (9.7–13.5%), borneol (4.4–9.5%), and camphene (5.1–8.7%). The principal component and heatmapper analyses showed group segregation of the two studied varities based on major essential oil compounds. Additionally, in vitro antimicrobial and antioxidant activities showed that rosemary essential oils had an important ability in scavenging DPPH, as well as a higher bactericidal effect. The seasonal variation, growth stage and genetic pools seemed to be a factors of significant variation of the composition, antimicrobial and the antioxidant activities of the rosemary essential oils. These finding would be taken to use the chemotaxonomy tools to develop a program for Rosmary protection conservation and identification based on essential oil composition.

Chemical and antibacterial properties of Baccharis dracunculifolia DC essential oils from different regions of Brazil

ABSTRACT This study aimed to evaluate the chemical and antibacterial properties of the essential oil of B. dracunculifolia from three regions of Brazil: Midwest, Southeast and South region. The major compounds of essential oil from Midwest region were (E)-nerolidol (28.15%) and spathulenol (17.68%), both oxygenated sesquiterpenes. And the major compounds of essential oils from Southeast and South regions were (E)-nerolidol (12.75–13.95%), bicyclogermacrene (10.76–14.21%) and limonene (10.49–19.36%). The three essential oils showed antibacterial activity for both Gram-positive and Gram-negative bacteria tested, with MIC values from 0.03 to 0.15 mg/mL and MBC values from 0.05 to 0.30 mg/mL. The B. dracunculifolia essential oil from the Midwest region of Brazil presented higher values of oxygenated sesquiterpenes and was more effective on all tested bacterial strains, with lower and statistically significant MBC values, compared to the oils from the Southeast and South regions of Brazil

Potential Action Mechanism and Inhibition Efficacy of Morinda citrifolia Essential Oil and Octanoic Acid against Stagonosporopsis cucurbitacearum Infestations.

The use of plant-based products has been shown to efficiently inhibit fungi-mediated diseases in agricultural crops. Here, we extracted and evaluated the composition of noni, Morinda citrifolia L., essential oil and assessed its activities against Stagonosporopsis cucurbitacearum in Cucumis melo L. Using in silico molecular approaches, potential interactions between the essential oil major components and S. cucurbitacearum tyrosine–tRNA ligase were predicted. Finally, we also measured the potential interference of plant physiology (the stomatal conductance and net photosynthesis) mediated by the application of the M. citrifolia essential oil. Chromatographic analysis revealed that octanoic acid (75.8%), hexanoic acid (12.8%), and isobutyl pent-4-enyl carbonate (3.1%) were the major essential oil compounds. Octanoic acid and noni essential oil, when used as preventive measures, reduce fungal mycelial growth at a concentration of 5 mg/mL without causing significant damage to the treated leaves, which reinforces their efficacies as preventive tools against S. cucurbitacearum. Molecular docking analyses predicted very stable interactions between the major essential oil constituents and S. cucurbitacearum tyrosine–tRNA ligase, suggesting the interference of these plant-based molecules upon enzyme activation. Octanoic acid and M. citrifolia essential oil at concentrations of 20 mg/mL decreased the stomatal conductance and net photosynthesis rate of melon plants, resulting in robust phytotoxicity. Collectively, our findings indicated that despite the phytotoxicity risks at higher concentrations, M. citrifolia essential oil and octanoic acid, have potential as alternative tools for the integrative management of S. cucurbitacearum.

Chemical diversity of essential oils of rhizomes of six species of Zingiberaceae family

In this study, the essential oils from the rhizomes of six species belonging to the Zingiberaceae family, including Zingiber zerumbet, Curcuma pierreana, Globba macrocarpa, Alpinia conchigera, Stahlianthus campanulatus and Amomum sp., collected in Binh Chau-Phuoc Buu Nature Reserve were isolated using hydrodistillation, and their constituents were identified via Gas Chromatography-Mass Spectrometry. A total of 91 constituents have been identified from essential oils. These compounds were classified into 4 clusters by Agglomerative Hierarchical Clustering (AHC) and Principal Component Analysis (PCA) analysis. The principal constituents of the essential oils isolated from four species, C. pierreana, S. campanulatus, A. conchigera, and Z. zerumbet contained camphene (18.82%), α-copaene (11.75%), p-xylene (21.86%), and α-santalene (17.91%), which were significantly different from those in previous reports. Furthermore, this study revealed the chemical constituents of essential oils of G. macrocarpa and Amomum sp. for the first time. Accordingly, artemisia triene (22.21%), β-pinene (13.57%), 4,6,8-trimethylazulene (11.1%), 2-tert-butylquinoline (9.86%), β-patchoulene (7.06%), α-elemene (6.93%), and β-ocimene (6.0%) were the major compounds in essential oils of G. macrocarpa rhizomes whereas the oil of Amomum sp. was found to be rich in 2-carene (21.82%), fenchyl acetate (14.26%), 3-carene (8.28%), bornyl acetate (7.7%), and D-limonene (7.13%).

Molecular Modeling Approaches Can Reveal the Molecular Interactions Established between a Biofilm and the Bioactive Compounds of the Essential Oil of Piper divaricatum.

Molecular modeling approaches are used in a versatile way to investigate the properties of diverse organic and inorganic structures such as proteins, biomolecules, nanomaterials, functionalized nanoparticles, and membranes. However, more detailed studies are needed to understand the molecular nature of interactions established in gelatin biofilms impregnated with bioactive compounds. Because of this, we used computational methods to evaluate how the major compounds of Piper divaricatum essential oil can interact with the gelatin biofilm structure. For this, we used as inspiration the paper published, where various properties of the essential oil impregnated gelatin biofilm P. divaricatum are reported. After our computer simulations, we related our molecular observations to biofilm’s structural and mechanical properties. Our results suggest that the major compounds of the essential oil were able to interrupt intermolecular interactions between the chains of the biofilm matrix. However, the compounds also established interactions with the amino acid residues of these chains. Our molecular analyses also explain changes in the structural and mechanical properties of the essential oil-impregnated biofilm. These results can support the planning of functional packaging impregnated with bioactive compounds that can protect food against microorganisms harmful to human health.

Untargeted Metabolomics Approach of Cross-Adaptation in Salmonella Enterica Induced by Major Compounds of Essential Oils.

Cross-adaptation phenomena in bacterial populations, induced by sublethal doses of antibacterial solutions, are a major problem in the field of food safety. In this regard, essential oils and their major compounds appear as an effective alternative to common sanitizers in food industry environments. The present study aimed to evaluate the untargeted metabolomics perturbations of Salmonella enterica serovar Enteritidis that has been previously exposed to the sublethal doses of the major components of essential oils: cinnamaldehyde, citral, and linalool (CIN, CIT, and LIN, respectively). Cinnamaldehyde appeared to be the most efficient compound in the assays evaluating the inhibitory effects [0.06% (v/v) as MBC]. Also, preliminary tests exhibited a phenotype of adaptation in planktonic and sessile cells of S. Enteritidis when exposed to sublethal doses of linalool, resulting in tolerance to previously lethal concentrations of citral. A metabolomics approach on S. Enteritidis provided an important insight into the phenomenon of cross-adaptation induced by sublethal doses of major compounds of some essential oils. In addition, according to the results obtained, when single molecules were used, many pathways may be involved in bacterial tolerance, which could be different from the findings revealed in previous studies regarding the use of phytocomplex of essential oils. Orthogonal projection to latent structures (OPLS) proved to be an interesting predictive model to demonstrate the adaptation events in pathogenic bacteria because of the global engagement to prevent and control foodborne outbreaks.

Physiological reaction and chemical composition of Stachys schtschegleevii Sosn. essential oil under water deficit.

Stachys schtschegleevii Sosn. is an endemic medicinal plant belonging to the Lamiaceae family and mainly grown in North-western Iran. Drought stress is an important factor in reducing the yield of medicinal herbs. Water-stress tolerance involves subtle changes in cellular biochemistry. It appears to be the result of the accumulation of compatible solutes and of chemical compositions that can be rapidly induced by osmotic stress. For this purpose, the effect of different irrigation regimes (well-watered and irrigation after depletion of 40% and 70% of field capacity (FC)) were studied in S. schtschegleevii. The experiment was conducted in a randomized complete block design in three replications. The results showed that water-deficit had negative effects on shoot dry matter, relative water content, and photosynthetic pigments of the exposed plants. The essential oil (EO) content under water-deficit had an increasing trend. Water-deficit significantly increased total phenol content, proline, H2O2, and malondialdehyde contents. Linalool, β-pinene oxide, α-campholenal and germacrene-D were the major compounds of essential oils (EOs) affected by water-deficit stress. Finally, although water deficiency reduces the shoot dry matter yield of the S. schtschegleevii, the accumulation of EO increased as a plant response to water-deficit stress.

A comparative phytochemical profiling of essential oils isolated from three hemp (Cannabis sativa L.) cultivars grown in central-northern Morocco

Hemp known botanically as Cannabis sativa L. (CS) is an important industrial crop. A huge literature was devoted to its biology owing to its numerous health-healing properties and biotechnological applications. However, little is known about essential oil (CSEO) chemical composition in the cultivars grown in Morocco. In this research work, we aimed at investigating CSEO chemical composition of three cultivars namely: ‘Beldiya’, ‘Mexicana’, and ‘Critical Plus’. CSEOs were isolated from dried inflorescences using hydrodistillation and then subjected to chemical analysis using GC-MS. Our results showed that CSEOs yield and chemical composition varied significantly among cultivars. ‘Critical Plus’ showed the greatest record of CSEO yield (0.688%), while ‘Mexicana’ had the lowest value (0.330%). However, ‘Critical Plus’ presented the smallest values for the most of major compounds. Chemical composition showed an important phytochemical richness especially terpenoids. The most abundant compounds found in CSEOs were the following: β-caryophellene (13.39–25.32%), β-myercene (10.03–20.09), α-humulene (4.88–8.73%), caryophellene oxide (1.46–6.07%), decane (1.41–4.46%), and α-pinene (1.91–3.66%). The highest records of these compounds were reported in ‘Beldiya’ (β-caryophellene, caryophellene oxide, and decane) and ‘Mexicana’ (β-myercene, α-humulene, and α-pinene). Principal component analysis allowed a good separation of the three investigated cultivars based on their essential oil major compounds. It could be concluded that, the studied cultivars were caryophellene chemotypes, the local cultivar ‘Beldiya’ along with ‘Mexicana’ performed better in terms of essential oil yield and major phytochemicals over ‘Critical Plus’.

Pharmacognostic Evaluation of Trachyspermum Ammi (Ajwain Seeds) Seed Extract for Vulvovaginal Candidiasis (VVC)

Introduction: In recent years, people are more health-conscious and avoiding the use of synthetic drugs, which are not only harmful to them but also to the environment as they are manmade. So, there is an urgent need for naturally available biologically active compounds which are environment friendly and has tremendous health benefits for the welfare of human being. Trachyspermum Ammi, commonly known as ‘Ajwain,’ is a plant native to India. It has been shown to have antifungal, antioxidant, antimicrobial, antinociceptive, cytotoxic, hypolipidemic, antihypertensive, antispasmodic, broncho-dilating, antilithiasis, diuretic, abortifacient, antitussive, nematicidal, Anthelmintic and antifilarial properties. Furthermore, studies reveal the presence of a variety of phytochemical constituents, including carbohydrates, glycosides, saponins, phenolic compounds, volatile oil (thymol, -terpinene, para-cymene, and- and -pinene), protein, fat, fibre, and mineral matter containing calcium, phosphorous, iron, and nicotinic acid. Methods: TLC of essential oil of Trachyspermum ammi, was performed and revealed the presence of. Thymol. GC-FID &amp; GC-MS analysis of essential oil shows the presence of 31 compounds. The most existing major compounds in essential oil were Thymol (33.40 %), γ-Terpinene (16.58 %), β-Pinene (13.82 %), 2-Pinene (6.02 %), 3-Cyclohexene-1-carboxaldehyde, 1,3,4-tri-methyl (5.35 %), p-Cymene (3.85 %), Linalool (2.89 %) and α-Thujene (2.44 %). Results: Antimicrobial activity of essential oil showed against Staphylococcus aureus and E. coli, it was proven by using cup well method by observing zone of inhibition to the microbial strains at different concentrations of essential oil. The minimum inhibitory concentration was also observed. Conclusion: It was confirmed that essential oil shows the antimicrobial activity as well as shows effect to fungal strains. In conclusion, the presence of numerous essential oil ingredients, and the results of experimental studies showed that Trachyspermum ammi essential oil possessed antioxidant, antibacterial, and antifungal action. Vulvovaginal candidiasis can be treated with this essential oil.

Inhibition of biofilm produced by methicillin-resistant Staphylococcus aureus (MRSA) by thymoquinone.

Multidrug resistance is a leading public health challenge that is causing a significant increase in mortality and morbidity. If antimicrobial resistance (AMR) remains unsolved, it may cause 10 million deaths every year. Along with a public health concern, it is also a financial concern that would cause 2-3.5% reduction in Gross Domestic Product (GDP) and a 100 trillion USD loss to the world. One of the ways to combat AMR is to discover new antibiotics. This study was aimed to evaluate the antibiofilm and antibacterial potencies of essential oil of Nigella sativa. Standard microbiological guidelines (CLSI) were used for the identification and antibiogram of selected strains of MRSA. Moreover, a time-kill assay of MRSA against Thymoquinone extracted from Nigella Sativa was also performed. Five strains, including four MRSA strains from implants related infections and one standard strain ATCC 25923, were examined. GC-MS identified components of essential oil of Nigella Sativa. Thymoquinone and p-cymene, major compounds of essential oil, were subjected to antibacterial and antibiofilm activities. Thymoquinone revealed strong inhibitory activities against MRSA strains. Zone inhibition measured 22 to 44 mm, and MIC values ranged from 26 to 43 Ul/mL. Thymoquinone also exhibited strong antibiofilm activity against biofilm producer MDR strains of Staphylococcus aureus.

Morphological and metabolomics impact of sublethal doses of natural compounds and its nanoemulsions in Bacillus cereus

Microbiological safety in food industry are always a concern regarding sublethal tolerance in bacteria for common and natural sanitizers. Natural bacteriocins, such as nisin (NIS), may negatively interfere in the efficiency of major compounds of essential oils against foodborne pathogenic bacteria. However, nanoemulsioned forms increase the bactericidal potential of natural compounds acting synergistically. In this study, cinnamaldehyde (CIN), citral (CIT), and linalool (LIN) were evaluated independently, associated with NIS, and in nanoemulsions (NEs) against Bacillus cereus using untargeted-metabolomics. Results revealed morphological changes in the structure of B. cereus treated with NEs of CIN and CIT, both NIS-associated. In addition, sensibility tests and UHPLC-QTOF-MS analyses indicated that NIS might react together with CIT reducing the bactericidal efficiency, while the nanoemulsion of CIT effect was enhanced by NIS in nanoemulsioned forms. This study highlights the importance of prudent administration of natural compounds as antimicrobial agents to prevent sublethal tolerance in pathogenic bacteria.

A new green insecticide for stored wheat grains: Efficiency against Rhyzopertha dominica and risk assessment

This work evidenced the insecticidal activity of encapsulated Mentha spicata essential oil (EO) against Rhyzopertha dominica in presence of stored wheat grain and evaluated the residual EO amount in wheat grains after treatment. EO distribution in the different fractions recovered after grain milling was also determined. The mortality rate against R. dominica reached more than 90% and was dependent on the amount of EO released from the encapsulation matrix. The quantification of the two major compounds of EO, (R)-limonene and (R)-carvone, showed that wheat grains contained different amount depending on the storage conditions. When wheat grains were stored in open jars, the EO residual amount in grains was especially low (1.98 mg/kg) compared to amount in closed jar (51.6 mg/kg). The flour resulting from milling contained lower amount of EO compounds in comparison with the bran fractions. The contact of wheat grains with EO clearly modified the native aromatic profile of the wheat flour as the most represented compounds were those belonging to the EO. In the native flour, ten volatile compounds, mainly alcohols and aldehydes due to oxidation of lipids were identified, which represented only 14% of the aromatic profile when the wheat grains were treated by EO. However, when the storage condition of grains mimics the silos conditions, the level of (R)-carvone, the major component of spearmint EO is found around 3 mg/kg of flour which was far below its currently use in bakery products.