Antimicrobial Activity Of Essential Oils Research Articles

Chemical Composition and In-Vitro Antimicrobial Screening of Leaf Essential Oil of Plectranthus gerardianus Benth., and Isolation of the Major Constituents of the Oil

Background: The Lamiaceae (Labiatae) family is one of the most diverse and widespread plant families in terms of ethnomedicine and its medicinal value is based on the concentration of the volatile oil present in it. This family is important for flavor, fragrance and medicinal properties. Many plants belonging to this family have indigenous value. Methods: The essential oil of Plectranthus gerardianus Benth. (Lamiaceae) was analyzed by GC and GC-MS analyses, while the major components were isolated and confirmed by NMR spectroscopy. Results: The oil was found to be rich in oxygenated monoterpenes, which contribute around 62% of the total oil. The major components identified were fenchone (22.90%) and carvenone oxide (16.75%), besides other mono and sesquiterpenoids. The in-vitro antimicrobial activity of essential oil was tested against three gram-negative bacteria including Pasteurella multocida, Escherichia coli, and Salmonella enterica, two gram-positive bacteria namely Staphylococcus aureus and Bacillus subtilis and two fungi namely Candida albicans and Aspergillus flavus. The antimicrobial activity of the oil was also compared to the antimicrobial activity of leaf essential oil of another Himalayan plant namely Nepetacoerulescens. Conclusion: The oil showed in-vitro antimicrobial activity against all the microbial strains and can lessen the ever-growing demand for potentially hazardous antibiotics for treatment.

Thymus vulgaris Essential Oil and Hydro-Alcoholic Solutions to Counteract Wooden Artwork Microbial Colonization

Aromatic plants represent a source of natural products with medicinal properties, and are also utilized in the food and pharmaceutical industries. Recently, the need for eco-compatible and non-toxic products, safe for both the environment and human health, have been proposed for the sustainable conservation of historic–artistic artifacts. In this study, in order to counteract microbial colonization (Aspergillus sp., Streptomyces sp., Micrococcus sp.) on wooden artwork surfaces, Thymus vulgaris L. (Lamiaceae) essential oil (EO) and hydro-alcoholic (HA) solutions were applied in a polyphasic approach. The antimicrobial activities of EO and HA solutions were preliminarily assessed by agar disc diffusion (ADD) and well plate diffusion (WPD) in vitro methods, defining the specific concentration useful for bacterial and fungal genera, identified by optical microscopies, in vitro cultures (nutrient or Sabouraud agar), and DNA base molecular biology investigations. Specifically, the microbial patina was directly removed by a hydro-alcoholic solution (while evaluating the potential colorimetric change of the artwork’s surface) combined with exposure to EO volatile compounds, performed in a dedicated “clean chamber”. This study proposes, for the first time, the combined use of two plant extracts to counteract microbial development on wooden artworks, providing supplementary information on these products as bio-agents.

Biological activities of Pituranthos scoparius essential oil from Algeria

The essential oil from aerial parts of Pituranthos scoparius obtained by hydrodistillation was analyzed by GC, GC/MS and 13C NMR and evaluated for antimicrobial and antioxidant activities. The yields were showed a very high variability ranging from 0.16 to 0.99%. Sixty two components were identified and the results indicated that the essential oil was rich in hydrocarbons monoterpenes and phenylpropanoid compounds. 6-Methoxyelemicine (0.1- 47.0%), sabinene (1.4-35.5%), limonene (0.6-24.0%), myristicine (0.2-18.9%), α-pinene (3.1- 14.7%) and dill apiole (0.0-10.6%) were the major compounds. The essential oils were tested against Staphylococcus aureus, Bacillus cereus, Escherichia coli, Klebsiella pneumonia, Candida albicans, Fusarium oxysporum, Aspergillus fumigatus and Aspergillus flavus and the minimum inhibitory concentration was determined. The tested oils have been shown to possess inhibitory action in the range from 2 to 3 µL/mL against Aspergillus fumigatus, Staphylococcus aureus and Candida albicans. The antimicrobial activity of essential oil from P. Scoparius well be due probably to the presence of synergy between myristicine and terpinen-4-ol. The antioxidant activity was evaluated through DPPH assay. All samples exhibited weak scavenging activity against DPPH, compared to standard antioxidant tested. Essential oil with IC50 of the order of 23.65±0.77 and 25.95±2.13 mg/mL could be attributed probably to the presence of limonene and germacrene D in larger amounts.

Chemical Analysis and Antioxidant and Antimicrobial Activity of Essential oils from Artemisia negrei L. against Drug-Resistant Microbes

BackgroundArtemisia negrei L. (A. negrei) is a medicinal and aromatic plant belonging to the family Asteraceae that is more widespread in the folded Middle Atlas Mountains, Morocco. Materials and Methods This study was run to investigate the phytochemical composition and antioxidant, antibacterial, and antifungal activities of Artemisia negrei L. essential oil. This oil was extracted from the fresh plant material by using the Clevenger apparatus. The phytochemical composition was characterized by GC-MS. The antioxidant activity was evaluated using different methods including DPPH, β-carotene bleaching, and total antioxidant capacity. The antibacterial activity was tested vs. multidrug-resistant bacteria including both Gram-negative and Gram-positive using inhibition zones in agar media and minimum inhibitory concentration (MIC) bioassays. The antifungal activity was conducted on Candida albicans, Aspergillus niger, Aspergillus flavus, and Fusarium oxysporum using a solid medium assay. Results The chromatographic characterization of essential oils of A. negrei revealed the presence of 34 compounds constituting 99.91% of the total essential oil. The latter was found to have promising antioxidant activity by all bioassays used such as DPPH, β-carotene bleaching, and total antioxidant capacity. The results obtained showed that our plant oils had potent antibacterial activity towards Gram-negative (E. coli 57, E. coli 97, K. pneumonia, and P. aeruginosa) and Gram-positive (S. aureus), so that the maximum inhibition zones and MIC values were around 18–37 mm and 3.25 to 12.5 mg/mL, respectively. The oil also showed antifungal activity towards Candida albicans, Fusarium oxysporum, and Aspergillus Niger except for flavus species. Conclusion The findings obtained in the work showed that A. negrei can serve as a valuable source of natural compounds that can be used as a new weapon to fight radical damage and resistant microbes.

Chemical Composition and Antioxidant, Anti-inflammatory and Antimicrobial Activities of the Essential Oil and its Major Component (Carlina oxide) of Carlina hispanica Roots from Western Algeria

The purpose of this work was to study the chemical composition and in vitro antioxidant, antimicrobial and anti-inflammatory activities of essential oil and carlina oxide isolated to Carlina hispanica roots. The in vitro combinatory effect of carlina oxide with BHT, EDTA and diclofenac to reduce their minimum effective dose and minimize their side effects was also tested. The essential oil obtained from the roots has been studied using GC and GC/MS. Antioxidant activity was assessed using radical scavenging activity (DPPH), the β-carotene bleaching test using the BHT as a positive control, and the ferrous Iron chelating using EDTA as a positive control. The activity of anti-inflammatory was assessed by the protein denaturation method using the diclofenac as a positive control. The antimicrobial activity was evaluated against six microbial strains using the Disc Diffusion Assay and the microplate method to determine the MIC. The essential oil of C. hispanica was represented mainly by an acetylenic compound carlina oxide (81.1 %) which was isolated and identified by spectroscopic 1H NMR, 13C NMR and IR methods. The results of the biological activities showed that both essential oil and carlina oxide had an interesting antioxidant and anti-inflammatory power. Likewise, the combinations of positive controls with carlina oxide showed better activities with a substantial reduction in inhibitory concentrations and dose of the antioxidants and anti-inflammatories synthetics. Further studies are needed to provide these positive control combinations with carlina oxide in the pharmaceutical industry. Keyworlds: Carlina hispanica, essential oil, carlina oxide, biological activities.

Chemical Compositions of Essential Oils and Antimicrobial Activity of the Leaves and Rhizomes of Zingiber magang and Zingiber tamii from Vietnam

The compositions and antimicrobial activity of essential oils from the leaves and rhizomes of Zingiber magang N.S. Lý & Škornièk sp. nov. and Zingiber tamii N.S. Lý & Škornièk. sp. nov. from Vietnam were reported. The essential oils from Z. magang were obtained in yields of 0.12 % (leaf) and 0.18 % (rhizome), while Z. tamii afforded essential oils with yields of 0.15 % and 0.20 %, respectively, for the leaf and rhizome. The leaf essential oil of Z. magang consists of β-pinene (12.3 %) and (E)-nerolidol (10.3 %), while α-selinene (10.5 %), caryophyllene oxide (9.7 %), and neo-intermedeol (7.5 %) were found in the rhizome essential oil. However, the compositions of essential oils from the leaf and rhizome of Z. tamii comprised mainly of β-pinene (53.8 % and 55.4 %), and sabinene (12.3 % and 12.5 %), respectively. The rhizome essential oil of Z. magang displayed promising antimicrobial activity against Enterococcus faecalis ATCC 299212 and Staphylococcus aureus ATCC 25923 with the Minimum inhibitory concentration (MIC) values of 9.99 μg/mL and 9.67 μg/mL, respectively. In addition, essential oil from the leaf of Z. tamii was the most active against Escherichia coli ATCC 25922 (MIC 44.38 μg/mL) and Candida albicans ATCC 10231 (MIC, 45.62 μg/mL). This is the first report on the chemical compositions and antimicrobial activity of essential oils of Z. magang and Z. tamii.

Investigation into the Chemical Compositions and Antimicrobial Activity of Essential Oil from the Rhizomes of Boesenbergia quangngaiensis N.S. Lý from Vietnam

Essential oils from the rhizomes of Boesenbergia quangngaiensis N.S. Lý were obtained by hydrodistillation and the chemical components were determined by gas chromatography (GC) and gas chromatography coupled with mass spectrometry (GC/MS). In addition, the microdilution broth assay was used to test the antimicrobial activity of essential oils. The yield of the B. quangngaiensis rhizome essential oils was 0.16 % (w/w). The major components identified from the rhizome essential oil of B. quangngaiensis were cis-β-elemene (18.4 %), zerumbone (11.4 %) and myrtenyl acetate (10.6 %). The antimicrobial activity test indicated that B. quangngaiensis rhizome essential oil displayed good activity against Pseudomonas aeruginosa ATCC 27853 with a Minimum inhibitory concentration (MIC) value of 7.68 μg/mL and IC50 value of 16.0 μg/mL. Also, the essential oil inhibited the growth of other tested bacteria and yeast, except Escherichia coli ATCC 25922 and Salmonella enterica ATCC 13076, with MIC value of about 30 μg/mL. The chemical components and antimicrobial activity of the B. quangngaiensis rhizome essential oil were reported for the first time.

Determination of Antimicrobial and Antioxidant Activities and Chemical Components of Volatile Oils of Atropa belladonna L. Growing in Turkey

In this study; the essential oils were obtained from the flowers and leaves of Atropa belladonna L. plants through the hydrodistillation method in a Clevenger type device. The chemical composition of volatile oils was determined by analyzing with the GC-MS/MS instrument. The antioxidant activity of the obtained volatile oils was determined according to total antioxidant content (TAC), free radical scavenging (ABTS) capacity, free radical scavenging (DPPH) amounts, total flavonoid content (TFC), total phenolic content (TPC), and ferric reducing antioxidant power (FRAP) capacity methods. Antimicrobial activities of essential oils were determined through the agar-disc diffusion method. As for the results; volatile oil yields of the A. belladonna were determined as 0.37 % in leaves and 1.57 % in flowers. The highest percentage of chemical compounds in essential oils of the A. belladonna plant were determined as (43.75 %) aldehydes in leaves and as (39.96 %) fatty acids in flowers. In addition, the main constituents found in volatile oils were eicosane (35.92 %) in the leaves and hexadecenoic acid (18.84 %) in the flowers of the A. belladonna. The highest amounts of antioxidant for the test specimens were found as 1.37-1.48 mg QE/100 mL in TFC, as 13.25-21.91 mg AA/100 mL in ABTS, as 51.49-62.87 mg GA/100 mL in TPC, and as 4.71-7.97 mg FeSO4/100 mL in FRAP capacity. As the results of the antimicrobial activities, it was determined that only the leaves of A. belladonna show antimicrobial activity against the mold-yeast and gram-positive and gram-negative bacteria microorganisms among the 17 bacteria and 6 yeast-mold types used in the study.

Antibacterial Activity of Essential Oils of Origanum bilgeri, Origanum onites, Satureja spicigera Leaves Against Agricultural Plant Pathogenic Bacteria

Natural products have gained a great interest to fight against pathogens recently. In this study, essential oils of Origanum bilgeri, Origanum onites and Satureja spicigera leaves were obtained by steam distillation using Clevenger type apparatus and compounds were identified by gas chromatography-mass spectrometry (GC/MS) analysis. Antimicrobial activities of essential oils were carried out using the Clavibacter michiganensis subsp. michiganensis (Cmm), Xanthomonas axonopodis pv. vesicatoria (Xav) and Pseudomonas syringae pv. tomato (Pst). O. bilgeri essential oil has a significant effect on (100 %) all pathogens with dose dependence. O. onites essential oil has a great effect against Cmm and Xav bacteria with the dose of 7.5 μL. The S. spicigera essential oil has an inhibition effect on Cmm at a 7.5 μL dose. Moreover, this essential oil inhibited the Xav at 94 % at 10 μL. Consequently, the corresponding essential oils could be a natural pesticide candidate for the agricultural industry.

ANTIBACTERIAL ACTIVITY OF ESSENTIAL OILS AGAINST PATHOGENS OF IMPORTANCE IN CAPRINE AND OVINE MASTITIS

ABSTRACT Mastitis is an important infirmity that affects dairy goats and sheep flocks. Antimicrobials are widely used in mastitis therapy; however, the phenomenon of bacterial resistance has sparked interest in therapeutic alternatives, especially the research on essential oils from several plant species. Therefore, this study aimed to evaluate the antimicrobial activity of essential oils against pathogens of importance in caprine and ovine mastitis. The essential oils were obtained by hydrodistillation and the chemical composition was analyzed by gas chromatography coupled to mass spectrometry (GC-MS). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) tests were performed to evaluate the antimicrobial activity of the essential oils (EO) of four plants. Fifteen bacterial isolates, previously identified as Staphylococcus spp. and Staphylococcus aureus, were used. The following plant species were used against the 15 bacterial isolates: Lippia origanoides “alecrim pimenta,” Lippia alba “erva cidreira,” Cymbopogon citratus “capim-santo,” and Ocimum basilicum “manjericão.” The first three essential oils presented antimicrobial activity against 100% of the isolates (15/15), with MICs of 560 µg mL-1, 1,173 µg mL-1, and 1,280 µg mL-1, and MBCs of 613 µg mL-1, 1,226 µg mL-1, and 1,333 µg mL-1, respectively. Nevertheless, the essential oil of O. basilicum, which was also tested, exerted no activity against any of the isolates. Carvacrol, citral, geraniol, and estragole were some of the major compounds found. These results can aid other studies that aim to use these essential oils as potential products for subsequent use in the treatment of mastitis in small ruminants.

Antimicrobial activity of essential oils and natural plant extracts against Listeria monocytogenes in a dry-cured ham-based model.

Listeria monocytogenes is a widespread common contaminant in food production facilities during preparation, storage, and distribution, and minimally processed ready-to-eat products are considered at high risk of contamination by this bacterium. Increased antibiotic resistance has led researchers to search for plant-based natural alternatives to control pathogenic microorganisms. Among these products, essential oils and plant extracts have previously shown antimicrobial activity and are possible alternatives to manage food pathogens. In this study, commercial essential oils (cinnamon, clove, oregano, ginger, and thyme) and plant extracts (pomegranate, acorn, olive, strawberry tree, and dog rose) were tested against L. monocytogenes in a dry-cured ham-based model. Essential oils and plant extracts were screened by agar diffusion and minimum inhibitory concentration for anti-L. monocytogenes activity. Cinnamon, pomegranate, and strawberry trees returned the strongest results and were therefore evaluated in a dry-cured ham-based medium assay with water activity of 0.93 or 0.95. The 10% essential oil of cinnamon was capable of completely inhibiting bacterial growth, while strawberry tree and pomegranate extract also showed antilisterial activity (P > 0.05). Water activity influenced the bacterial count of L. monocytogenes in a dry-cured ham-based medium. There was a reduction in L. monocytogenes with the application of cinnamon essential oil but, because of the negative sensory impact of this particular compound in meat products, we suggest the use of pomegranate or strawberry tree for the biocontrol of Listeria in ready-to-eat products. © 2021 Society of Chemical Industry.

Efficiency of Basil Essential Oil Antimicrobial Agents under Different Shading Treatments and Harvest Times

The aim of this study was to determine the antimicrobial activity of essential oils obtained from sweet basil (Ocimum basilicum L. cv. ‘Genovese’) cultivated in the open field under different shading conditions (red, blue, and pearl nets with a shade index of 50% and full sunlight exposure (control plants)), harvested at different times. The antimicrobial activity of basil essential oils (BEOs) obtained from all samples was determined for four microorganisms, while determinations for an additional five microorganisms included samples from non-shaded plants, plants grown under red and pearl nets, and second harvest of plants grown under blue net. Basil essential oil exhibited antimicrobial activity surpassing the activity of relevant commercial antibiotics regardless of growing conditions in the case of B. cereus, K. pneumoniae and C. albicans, while superior antimicrobial activity was exhibited in the case of essential oils from plants grown under blue nets in the case of S. aureus, E. coli and P. vulgaris. The influence of the application of colored shading nets was highly significant (p < 0.01) in the cases of all analyzed microorganisms except C. albicans and P. aeruginosa, while the influence of harvest time was proven in the cases of all microorganisms except K. pneumoniae. ANOVA proved that antimicrobial activities are highly dependent on the methods of plant production, shading treatment, and harvest time. Obtained results are discussed in relation to previously determined composition and yield of essential oils from basil grown under shade nets and harvested in different periods.

Effect of the Distillation Time on the Chemical Composition, Antioxidant Potential and Antimicrobial Activity of Essential Oils from Different Cannabis sativa L. Cultivars.

Within the unavoidable variability of various origins in the characteristics of essential oils, the aim of this study was to evaluate the effect of the distillation time on the chemical composition and biological activity of Cannabis sativa essential oils (EOs). The dry inflorescences came from Carmagnola, Kompolti, Futura 75, Gran Sasso Kush and Carmagnola Lemon varieties from Abruzzo region (Central Italy), the last two being new cultivar here described for the first time. EOs were collected at 2 h and 4 h of distillation; GC/MS technique was applied to characterize their volatile fraction. The EOs were evaluated for total polyphenol content (TPC), antioxidant capacity (AOC) and antimicrobial activity against food-borne pathogens and spoilage bacteria. The time of distillation particularly influenced EOs chemical composition, extracting more or less terpenic components, but generally enriching with minor sesquiterpenes and cannabidiol. A logical response in ratio of time was observed for antioxidant potential, being the essential oils at 4 h of distillation more active than those distilled for 2 h, and particularly Futura 75. Conversely, except for Futura 75, the effect of time on the antimicrobial activity was variable and requires further investigations; nevertheless, the inhibitory activity of all EOs against Pseudomonas fluorescens P34 was an interesting result.

Chemical Profile, Antioxidant Capacity, and Antimicrobial Activity of Essential Oils Extracted from Three Different Varieties (Moldoveanca 4, Vis Magic 10, and Alba 7) of Lavandula angustifolia.

Chemical composition, antioxidant capacity, and antimicrobial activity of lavender essential oils (LEOs) extracted from three different varieties of Lavandula angustifolia Mill. (1-Moldoveanca 4, 2-Vis magic 10, and 3-Alba 7) have been determined. These plants previously patented in the Republic of Moldova were cultivated in an organic agriculture system in the northeastern part of Romania and then harvested in 3 consecutive years (2017–2019) to obtain the essential oils. From the inflorescences in the complete flowering stage, the LEOs were extracted by hydrodistillation. Then, their composition was analyzed by gas chromatography coupled with mass spectrometry (GC-MS) and by Fourier Transformed Infrared spectroscopy (FT-IR). The major identified constituents are as follows: linalool (1: 32.19–46.83%; 2: 29.93–30.97%; 3: 31.97–33.77%), linalyl acetate (1: 17.70–35.18%; 2: 27.55–37.13%; 3: 28.03–35.32%), and terpinen-4-ol (1: 3.63–7.70%; 2: 3.06–7.16%; 3: 3.10–6.53%). The antioxidant capacity as determined by ABTS and DPPH assays indicates inhibition, with the highest activity obtained for LEO var. Alba 7 from 2019. The in vitro antimicrobial activities of the LEOs and combinations were investigated as well, by using the disk diffusion method and minimum inhibitory concentration (MIC) against the Gram-positive bacterial strain Staphylococcus aureus (ATCC 6538), Gram-negative Pseudomonas aeruginosa (ATCC 27858), Escherichia coli (ATCC 25922), the yeast Candida albicans (ATCC 10231), and clinical isolates. Our results have shown that LEOs obtained from the three studied varieties of L. angustifolia manifest significant bactericidal effects against tested microorganisms (Staphylococcus aureus and Escherichia coli), and antifungal effects against Candida albicans. The mixture of LEOs (Var. Alba 7) and geranium, respectively, in tea tree EOs, in different ratios, showed a significant enhancement of the antibacterial effect against all the studied strains, except Pseudomonas aeruginosa.

The Leaf Essential Oil of Acorus macrospadiceus (Yam.) F. N. Wei & Y. K. Li from Vietnam: Chemical Composition and Antimicrobial Activity

In the present communication, the composition and antimicrobial activity of essential oil from the leaves of Acorus macrospadiceus (Yam.) F. N. Wei & Y. K. Li from Vietnam were reported. The yield of the essential oil was 0.25 % (w/w). The main constituents of the essential oil were β-caryophyllene (31.1 %), α-selinene (12.6 %), α-asarone (12.0 %) and α-humulene (8.0 %). The essential oil displayed anti-candidal activity against Candida albicans ATCC 10231 with a minimum inhibitory concentration (MIC) value of 8.67 μg/ mL. In addition, the essential oil exhibited a broad spectrum of antimicrobial activity against the other tested microorganisms with MIC in the range 17.33 μg/mL (Enterococcus faecalis ATCC 299212) to 100.33 μg/mL (Escherichia coli ATCC 25922). The antimicrobial activities of A. macrospadiceus are being reported for the first time.

Chemical Compositions of Essential Oils and Antimicrobial Activity of Alpinia kwangsiensis from Vietnam

This paper reports the chemical compounds and antimicrobial activity of essential oils isolated from the leaves, stem, and rhizomes of Alpinia kwangsiensis T. L. Wu and S. J. Chen (Zingiberaceae). The essential oils were separately isolated using hydrodistillation of the pulverized samples (2 kg each) materials in an all- glass Clevenger-type apparatus and characterized by GC-FID and GC/MS. The yields of the essential oils were 0.16, 0.11 %, and 0.21 % (w/w), respectively, calculated on a dry weight basis. The main constituents of the essential oils (percentages, respectively) were 1,8-cineole (16.9 %, 14.3 % and 5.8 %), terpinene-4-ol (16.0 %, 13.6 % and 14.3 %), (E)-methyl cinnamate (9.4 %, 15.4 % and 4.6 %) and β-pinene (7.6 %, 9.9.% and 3.1 %). The study found out that the rhizome essential oil was the most active against Enterococcus faecalis ATCC 299212 with a minimum inhibitory concentration (MIC) value of 1.60 μg/mL, while the leaf oil displayed pronounce activity towards Bacillus cereus ATCC 14579 (MIC 3.20 μg/mL). All the essential oils inhibited the growth of Staphylococcus aureus ATCC 25923 and Candida albicans ATCC 10231, with MIC value of 6.40 μg/mL. Therefore, the essential oils obtained from A. kwangisensis may have potential applications as antimicrobial agents.

Chemical composition and antimicrobial activity of essential oils from \(\textit{Angelica sinensis}\) (Oliv.) diels cultivated in Hung Yen province of Vietnam

Essential oils from roots, flowers, fruits, and leaves plus stems of Angelica sinensis cultivated in Vietnam were obtained by hydrodistillation and were analyzed using GC/MS-FID. In total, 36, 30, 33, and 27 compounds were found accounting for 98.7%, 98.8%, 99.2%, and 100% of the oils compositions, respectively. (Z)-Ligustilide (49.4%, 29.6%, 25.8%, 28.9%) and γ-terpinene (20.6%, 38.5%, 35.5%, 44.2%) were the main components of the respective essential oils. Especially, dictyopterene C (10.8%) was found to be one of the main components of fruit oil. Among the A. sinensis essential oil samples tested, the fruit oil revealed the strongest antimicrobial activity against bacteria Escherichia coli and yeast Candida albicans with median inhibitory concentration values of 0.97 and 0.15 mg/mL, respectively.

Chemical Composition and Antimicrobial Activity of Essential oil from Scales of Moroccan Juniperus phoenicea

Abstract-The essential oil of Juniperus phoenicea was obtained by hydrodistillation method using a Clevenger-type apparatus with a yield of 1.9 % and was analyzed by gas chromatography coupled to a mass spectrometer (GC-MS). Twelve volatile compounds were identified representing 99,85% of the total oil composition, while the α-pinene (78,31%), β-Myrcene (11,92%) and limonene (3,96%) were the major compounds. This essential oil was evaluated as an antibacterial and antifungal agent. The result showed that the oil presents a high biological activity as an antibacterial agent against the three tested strains Escherichia coli, Staphylococcus aureus and Pseudomonas aeroginos. It's also active as an antifungal agent against the Candida albicans with a zone inhibition of 28 mm. Keywords: Medicinal plant, Juniperus, phoenicea, Essential oil, Chemical composition, Antimicrobial activity.

Antimicrobial Activity and Chemical Composition of Essential Oils against Pathogenic Microorganisms of Freshwater Fish.

Antimicrobials are widely applied in aquaculture for treatment of infectious diseases in fish. The increased antimicrobial resistance of fish pathogens to conventional antimicrobial treatment highlights the need for research on the antibacterial properties of natural products—in this case, essential oils (EOs). The aim of the present study was to detect the antimicrobial activity of the essential oils on pathogenic microorganisms found in freshwater fish. Freshwater fish isolates of Aerococcus spp., Aeromonas spp., Enterococcus spp., Escherichia spp., Pseudomonas spp., Shewanella spp., Yersinia spp., and Vagococcus spp. were tested for antimicrobial resistance and antimicrobial activity against 14 commercially available essential oils. Antimicrobial resistance was identified in Pseudomonas spp. isolates against cefepime and ciprofloxacin; while all Aeromonas, Enterococcus, and Yersinia isolates were fully susceptible. All tested EOs revealed antimicrobial activity against the tested freshwater fish isolates at different extents. Cinnamomum camphora exhibited strong antimicrobial activity against Aeromonas spp. (3.12 μL/mL), Enterococcus spp. (0.78–1.56 μL/mL), and Pseudomonas spp. with the MIC method. EOs of Gaultheria procumbens and Litsea cubeba showed strong antibacterial activity against Yersinia spp. and Vacococcus spp. (6.25 μL/mL). The study shows the antimicrobial activity of EOs against the most relevant freshwater fish pathogens and indicates the application opportunities in aquaculture.

Insecticidal, antimicrobial and antioxidant activities of essential oil from Lavandula latifolia L. and its deterrent effects on Euphoria leucographa

Lavandula latifolia L. is a medicinal plant has fungicidal, antibacterial and antioxidant properties. The aim of this study was to determine the chemical composition, antioxidant and antimicrobial activities of essential oil (EO) of L. latifolia L. extracted by hydrodistillation method. A total of 22 constituents were identified in L. latifolia L. using Gas chromatography–mass spectrometry analysis. The compounds such as, gamma-terpinene (26.8 %), camphor (13.8 %), 1,8-cineole (10.2 %), lavandulol (9.3 %), terpinen-4-ol (9.1 %), linalool (8.9 %), b-elemene (3.2 %), b-pinene (3.1 %), 1,4-cineole (3.07 %), camphene (2.32 %), a-terpineol (2.3 %), and a-copaene (2.2 %) were determined. The antifungal activity of this EO against five phytopathogenic fungi revealed their broad-spectrum and strong antifungal properties. Notably, the EO showed potent activity on Trichophyton mentagrophytes (31 ± 1 mm) and the minimum inhibitory concentration value was 0.125 ± 0.05 μg/mL. The oil, analyzed for its DPPH (1,1-diphenyl-2-picrylhydrazyl) and ABTS [2,2_-azinobis-(3-ethylbenzothiazoline-6- sulphonic acid)] free radical scavenging activity. Hydrodistilled EO had higher ABTS scavenging capacity than DPPH free radical scavenging power. Essential oil was used to test pesticide activity against Euphoria leucographa (Order: Coleoptera; Family: Scarabaeidae) infected in custard apple (Annona muricata) fruit. Results indicated that the spike lavender EO had contact toxicity on E. leucographa upon topical treatment. The effective concentration at 50 % (EC50) value of EC of L. latifolia L. was 0.37 % revealed considerable fumigant activity mainly due to the presence of fragrant compounds. Interestingly, custard apple (A. muricata) treated with EO effectively controlled the growth of T. mentagrophytes. Overall, antifungal and insecticidal properties of lavender EO, as a natural choice to preserve the harvested fruits thereby protecting the industrial crops.