Antimicrobial Activity Of Essential Oils Research Articles

In vitro Antimicrobial Activity of Essential Oil Extracted from Leaves of Leoheo domatiophorus Chaowasku, D.T. Ngo and H.T. Le in Vietnam.

The present study aimed to determine the antimicrobial activity and chemical composition of leaves-extracted essential oil of Leoheo domatiophorus Chaowasku, D.T. Ngo and H.T. Le (L. domatiophorus), including antibacterial, antimycotic, antitrichomonas and antiviral effects. The essential oil was obtained using hydrodistillation, with an average yield of 0.34 ± 0.01% (v/w, dry leaves). There were 52 constituents as identified by GC/MS with available authentic standards, representing 96.74% of the entire leaves oil. The essential oil was comprised of three main components, namely viridiflorene (16.47%), (-)-δ-cadinene (15.58%) and γ-muurolene (8.00%). The oil showed good antimicrobial activities against several species: Gram-positive strains: Staphylococcus aureus (two strains) and Enterococcus faecalis, with Minimum Inhibitory Concentration (MIC) and Minimum Lethal Concentration (MLC) values from 0.25 to 1% (v/v); Gram-negative strains such as Escherichia coli (two strains), Pseudomonas aeruginosa (two strains) and Klebsiella pneumoniae, with MIC and MLC values between 2% and 8% (v/v); and finally Candida species, having MIC and MLC between 0.12 and 4% (v/v).Antitrichomonas activity of the oil was also undertaken, showing IC50, IC90 and MLC values of 0.008%, 0.016% and 0.03% (v/v), respectively, after 48h of incubation. The essential oil resultedin being completely ineffective against tested viruses, ssRNA+ (HIV-1, YFV, BVDV, Sb-1, CV-B4), ssRNA- (hRSVA2, VSV), dsRNA (Reo-1), and dsDNA (HSV-1, VV) viruses with EC50 values over 100 µg/mL. This is the first, yet comprehensive, scientific report about the chemical composition and pharmacological properties of the essential oil in L. domatiophorus.

Composition and antimicrobial activity of essential oil of yarrow (Achillea millefolium L.)

The medicinal plant yarrow (Achillea millefolium L.) belongs to the Asteracea family. It is being used in the pharmacological, food, and cosmetic industry. The economic importance of yarrow resides in its essential oil (EO). This plant is used in traditional medicine as the EO has properties which range from antibacterial, antifungal, anti-inflammatory, anti-oxidant and antitumor activities. The objective of this study was to identify chemical components and EO content of yarrow, as well as its antimicrobial activity against some micro-organisms in vitro. The fresh leaves were collected in a morning in October (2018) at the UNIPAR Medicinal Plants Garden, Umuarama-Paraná State, Brazil. The EO was obtained by hydrodistillation of the modified Clevenger type. After that, the content (m/m%) was calculated. The chemical composition of the EO was identified by gas chromatography/mass spectrometry (GC/MS). The minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC) and minimal fungicidal concentration (MFC) were determined by a microdilution method in 96-well microtitre plates and effect of EO was assessed on four micro-organisms (Candida albicans, Staphylococcus epidermidis, Escherechia coli and Klebsiella pneumoniae). The EO content (yield) in the plant shoots was 0.4% (four grams of EO kg-1 of plant fresh shoots) and presented 20 chemical compounds such as α-farnesene (31.66%), followed by chamazulene (17.17%), β-caryophyllene (10.27%) and sabinene (8.77%). The majority class was hydrocarbon sesquiterpene with 74.29%. The antimicrobial activity tests showed that the EO had low antimicrobial activity against the analyzed species with MIC for all species above 1.5 mg mL-1. It was concluded that the EO content was 0.4%. The major component was α-farnesene (31.66%) and EO presented low MIC.

Chemical Compositions, Mosquito Larvicidal and Antimicrobial Activities of Essential Oils from Five Species of Cinnamomum Growing Wild in North Central Vietnam

Members of the genus Cinnamomum (Lauraceae) have aromatic volatiles in their leaves and bark and some species are commercially important herbs and spices. In this work, the essential oils from five species of Cinnamomum (C. damhaensis, C. longipetiolatum, C. ovatum, C. polyadelphum and C. tonkinense) growing wild in north central Vietnam were obtained by hydrodistillation, analyzed by gas chromatography and screened for antimicrobial and mosquito larvicidal activity. The leaf essential oil of C. tonkinense, rich in β-phellandrene (23.1%) and linalool (32.2%), showed excellent antimicrobial activity (MIC of 32 μg/mL against Enterococcus faecalis and Candida albicans) and larvicidal activity (24 h LC50 of 17.4 μg/mL on Aedes aegypti and 14.1 μg/mL against Culex quinquefasciatus). Cinnamomum polyadelphum leaf essential oil also showed notable antimicrobial activity against Gram-positive bacteria and mosquito larvicidal activity, attributable to relatively high concentrations of neral (11.7%) and geranial (16.6%). Thus, members of the genus Cinnamomum from Vietnam have shown promise as antimicrobial agents and as potential vector control agents for mosquitoes.

Antibacterial activity of Centaurea pumilio L. root and aerial part extracts against some multidrug resistant bacteria

BackgroundIn the context of searching for potent, safe, natural antimicrobial agents to combate the global antimicrobial resistance (AMR) phenomenon, the current study evaluates for the first time ever, the broad-spectrum antimicrobial activity of essential oil (EO) and extracts from the rare wild plant Centaurea pumilio L.. It has tremendous ethnomedicinal values; its dried root is used as a fattening agent, a treatment for bad breath and diabetes, and screened for schistosomicidal activity.MethodsC. pumilio EO was extracted by hydrodistillation using a Clevenger apparatus. Chemical constituents of aerial part were extracted using a sequential solvent/solvent procedure employing four solvents with increasing polarities in the following order: petroleum ether, chloroform, ethyl acetate, and n-butanol. The chemical constituents were identified by GC-MS. Fifty-two microbial strains were used; twenty-six multidrug resistant (MDR), sixteen clinical, and ten reference strains. The identification of the microbial strains was performed by MALDI-TOF-MS. The antimicrobial activity of the EO and the aerial part and the root extracts was assessed through disc diffusion assay. A minimum inhibitory concentration (MIC) of the EO and extracts was determined using the broth micro-dilution method.ResultsThe growth of reference and clinical strains was inhibited by EO, methanol, chloroform, and ethyl acetate aerial part extracts and chloroform root extract. The MDR strains growth, however, was inhibited only by EO and chloroform aerial part extract. GC-MS identified for the first time eighteen constituents from aerial part EO and chloroform extract each. EO showed antimicrobial activity against the reference, clinical, and MDR strains with MIC values of 31.25–125, 31.25–125, and 62.50–250 μg/mL, respectively. Methanol aerial part extract exhibited high antimicrobial activities with MIC values of 62.50–250 μg/mL against reference and clinical strains. Chloroform root extract displayed strong antimicrobial activity against reference and clinical strains recording MIC values of 62.50–250 μg/mL and 62.50–125 μg/mL, respectively. The chloroform aerial part extract demonstrated potent antimicrobial activity against the reference, clinical, and MDR strains with 31.25, 31.25, and 15.62 μg/mL MIC values, respectively.ConclusionsPresent data unravel the C. pumilio pharmacological magnitude to discover eco-friendly potent antimicrobial agents to fight AMR phenomenon.

Antimicrobial Activity and Chemical Constituents of Essential Oil from the Leaves of Alpinia globosa and Alpinia tonkinensis

This paper reports the chemical constituents and the antimicrobial activity of essential oils hydrodisitlled from the leaves of Alpinia globosa Hour (syn. Amomum globosum Lour.) and Alpinia tonkinensis Gagnep. The essential oils were analysed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC/MS) techniques. The minimum inhibitory concentration (MIC) values were measured by the microdilution broth susceptibility assay. The absolute yields of the essential oils were 0.16 % (v/w, ± 0.01) and 0.21 % (v/w, ± 0.02), respectively for A. globosa and A. tonkinensis, calculated on a dry weight basis. The major constituents of A. biglobosa were β-pinene (12.1 %), α-gurjunene (10.5 %) and (Z)-13-docosenamide (9.0 %). The compounds occurring in higher amount in A. tonkinensis includes β-pinene (33.5 %), (E)-β-ocimene (9.6 %), γ-terpinene (9.2 %) and α-pinene (8.4 %). The essential oil of A. tonkinensis inhibited the growth of Saccharomyces cerevisiae (ATCC 16404) with MIC value of 25.0 μg/mL. In addition, both essential oils displayed antimicrobial activity against Escherichia coli (ATCC 25922), Staphylococcus aureus subsp. aureus (ATCC 11632) and Fusarium oxysporum (ATCC 48112) with MIC value of 50.0 μg/mL. The chemical constituents and antimicrobial activity of the studied essential oils were being reported for the first time.

Chemical Composition and Antimicrobial Activity of Essential Oil from Aerial Part (Leaves and Fruit) of Eucalyptus gomphocephala DC

The objective of this study was to investigate the species identification, chemical composition and the antimicrobial activity of tuart (Eucalyptus gomphocephala DC) fruits and leaves. The essential oil content was 0.34 % and 0.23 % in the fruits and leaves, respectively. The main essential oil constituents of tuart fruits were 1,8-cineole (46.69 %), p-cymene (8.99 %), baeckeol (8.57 %), α-pinene (5.21 %), and globulol (4.25 %). The main essential oil constituents of tuart leaves were 1,8-cineole (24.25 %), p-cymene (20.70 %), α-pinene (14.15%), β-pinene (8.17 %), γ-terpinene (6.90 %), methyleugenol (6.78 %), α-terpineol (4.75 %), and limonene (3.80 %). The antimicrobial activity of essential oil was examined against Gram-positive bacteria Staphylococcus aureus, Bacillus subtilis, Kocuria rhizophila; Gram-negative bacteria Escherichia coli, Pseudomonas aeruginosa, Salmonella abony; yeast Saccharomyces cerevisiae, Candida albicans; and fungal strain Aspergillus brasiliensis according to the agar well diffusion method. The leaf essential oil showed higher antimicrobial activity against almost all strains of the microorganisms tested, with Salmonela abony being the most sensitive microorganism by having zone of inhibition 28.6 mm, followed by Escherichia coli (27.9 mm), Bacillus subtilis (26.2 mm) and Pseudomonas aeruginosa (25.8 mm). The tuart fruit essential oil had lower activity against tested microorganisms. Aspergillus brasiliensi was the most resistant microorganism to the inhibitory activity of the fruit and leaf essential oil in this study. Thus, tuart fruits and leaves essential oil have the potential to be used as a new source for the pharmaceutical and cosmetic products.

Antimicrobial Activity of Essential Oils against Staphylococcus and Malassezia Strains Isolated from Canine Dermatitis.

Staphylococcus spp. bacteria are the most frequently involved agents in canine cutaneous infections. Treatment of these infections is based on antibiotic therapy, that often is not effective because of the antibiotic-resistance of the bacterial strains. Cutaneous staphylococcal infections are often complicated by Malassezia yeasts, that may be resistant to the conventional antifungal drugs. The present investigation was aimed to evaluate the in vitro antimicrobial activity of some essential oils (EOs) in view of a potential cutaneous application. In detail, EOs obtained from lemon verbena (Aloysia triphylla L’Hèr. Britton), cinnamon (Cinnamomum zeylanicum J. Presl), myrrh (Commiphora myrrha (Nees) Engl. var. molmol), lemongrass (Cymbopogon citratus (DC.) Stapf), litsea (Litsea cubeba (Lour.) Pers.), lemon balm (Melissa officinalis L.), oregano (Origanum vulgare L.), savory (Satureja montana L.), and thyme (Thymus vulgaris L.) were assayed against Staphylococcus spp. and Malassezia pachydermatis strains previously isolated from dogs with dermatitis. All EOs were tested by agar disk diffusion and minimum inhibitory concentration methods to verify the antistaphylococcal activity, and by a microdilution method to evaluate the activity against M. pachydermatis. O. vulgare, T. vulgaris, and S. montana showed the best antibacterial activity against all the selected strains, with MICs ranging from 0.29 to 0.58 mg/mL, from 0.58 to 1.16 mg/mL, and from 0.56 to 1.12 mg/mL, respectively, whereas A. triphylla (1.03 mg/mL) and S. montana (1.8 mg/mL) were the most active against M. pachydermatis. After a proper in vivo evaluation, O. vulgare, T. vulgaris, and S. montana EOs could be a promising treatment to combat canine cutaneous mixed infections.

Comparative antioxidant, anticancer and antimicrobial activities of essential oils from Semen Platycladi by different extraction methods

Semen Platycladi is a highly valued seed tonic from the Cupressaceae Platycladus orientalis (L.) Franco, which contains abundant essential oils exhibiting antioxidant, antimicrobial, sedative and hypnotic potency. The study was formulated to estimate the potential antioxidant, anticancer and antibacterial activities of its essential oils as well as its correlation with chemical constituents. The comparison of three isolation methods including steam distillation extraction, heating reflux extraction, and Soxhlet extraction of ethanol was carried out to isolate essential oils whose chemical composition were identified and evaluated by Gas Chromatography-Mass Spectrometer. It turned out that the yield of essential oils obtained through heating reflux extraction and Soxhlet extraction was almost 40 % higher than those extracted by steam distillation extraction in nearly one-quarter of a time used by the steam distillation extraction. A total of 76 compounds were identified, including ten alkanes, 14 alkenes, 13 alcohols, one aldehyde ketone, three ethers, one acid, 17 esters, five aromatic compounds, and 12 others. The essential oils extracted by steam distillation extraction were proved to have the best antioxidant and antimicrobial activity although with the lowest yield. Scanning electron microscopic observation displayed that the of S. aureus revealed serious disruption of cell membranes resulting in the loss of cell viability. Therefore, it’s vital to adopt a proper method to obtain the target ingredients recommended as nutraceuticals and/or phytomedicines.

The Antimicrobial Activity of Essential Oils and Extraction of Medicinal Plants Galium Verum, Echinacea, Garlic, Turmeric, Corn Silk, Raspberry, Red John’s Wort, St. John’s Wort and Ginger and Use as Adjuvant Therapy in the Treatment of Cancer of the Lymphatic System

The Antimicrobial Activity of Essential Oils and Extraction of Medicinal Plants Galium Verum, Echinacea, Garlic, Turmeric, Corn Silk, Raspberry, Red John’s Wort, St. John’s Wort and Ginger and Use as Adjuvant Therapy in the Treatment of Cancer of the Lymphatic System

Gas chromatography–mass spectrometry profile and antimicrobial activities of Ballota bullata Pomel and B. nigra L. subsp. uncinata (Fiori & Bég.): A comparative analysis

This study was carried out to compare for the first time, the chemical composition and antimicrobial activities of essential oils from two Ballota species growing wild in different regions of Tunisia. The volatile oils obtained by hydro-distillation of Ballota bullata Pomel and Ballota nigra L. subsp. uncinata (Fiori & Bég.) Patzak were analyzed by gas chromatography (GC) and gas chromatography mass spectrometry (GC/MS) to investigate the variations in chemical profiles. The results showed a significant difference in terms of essential oil yields and characteristic aroma. Valerianol (18.3%), α-muurolol (7.9%) and spathulenol (7.1%) were identified as the major odorants in B. bullata, while B. nigra subsp. uncinata oil was mainly composed of hexadecanoic acid (31.8%) and linoleic acid (17.9%). In addition, oxygenated sesquiterpenes were found to be the principal constituents of B. bullata essential oil (42.1%), whereas long chain oxygenated hydrocarbons form the main class in B. nigra (49.7%). Moreover, the antimicrobial activities were tested in vitro against five bacteria: Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica, Staphylococcus aureus and Bacillus subtilis and the yeast Candida albicans. B. bullata essential oil showed stronger antibacterial effects comparing to B. nigra oil. Consequently, B. bullata essential oil holds promising antimicrobial potential, confirming its traditional medical use.

Repellent, Insecticidal and Antimicrobial Activities of Leaf Essential Oils from Three Eucalyptus Species.

Developing effective and eco-friendly antimicrobials and pesticides has become a highly important issue. The repellent, insecticidal and antimicrobial activity of essential oils (EOs) isolated by hydrodistillation from dried leaves of the three Eucalyptus species (E. cloeziana, E. umbellata and E. benthamii) were investigated. During GC/MS analysis, α-pinene (47.36 %), 1,8-cineol (38.53 %) and α-pinene (35.31 %) were identified as major components of E. cloeziana, E. umbellata and E. benthamii, respectively. The EOs from E. cloeziana exhibited the longest effective protection time (465 min, at 50.0 % w/w) for humans among the EOs studied. The effective protection time was 30 min and 300 min at concentrations of 12.5 % (w/w) and 25.0 % (w/w), respectively. Fumigating insecticidal activity of EOs from three Eucalyptus species was tested by airtight fumigation in conical flask, which indicated that essential oils had a highly and rapidly insecticidal activity on Culex pipiens quinquefasciatus. The antimicrobial activity of EOs was evaluated by using disc diffusion and agar dilution methods. There was no significant difference in the antibacterial activity of EOs from E. cloeziana and E. umbellate and they had the same MICs (20 mL/L) on Staphylococcus aureus, Salmonella typhi, Bacillus subtilis and Escherichia coli. E. benthamii had the worst microbial inhibitory effect among the three Eucalyptus essential oils and the MIC value for the test species is 40 mL/L except for Rhodotorula Harrison (10 mL/L).

Application of Essential Oils as Green Corrosion Inhibitors

This review reports the application of essential oils (EOs) as a green corrosion/biocorrosion inhibitor. The topics discussed are: (i) sources and composition of EOs, (ii) adsorption mechanism, (iii) anticorrosion effects of EOs on metal surfaces, (iv) electrochemical investigations, (v) antimicrobial activity of EOs on corrosion-producing bacteria and algae, (vi) synergetic effects of EOs, and (vii) economical aspect and application of inhibitors. Various aspects of biofilms are discussed to identify microbiologically influenced corrosion (MIC) and the characterization of microorganisms causing MIC. The studies indicate that EOs have the potential as eco-friendly corrosion inhibitors in both aggressive chemicals and biofilm environments.

Comparison of Yield Chemical Composition and Biological Activities of Essential Oils Obtained from Thymus pallidus and Thymus satureioides Coss. Grown in Wild and Cultivated Conditions in Morocco

Thymus pallidus and Thymus satureioides are two endemic Moroccan species of thyme that belong to the Lamiaceae family. They are exploited intensively from the wild for their essential oils (EOs) which are characterized by numerous therapeutic properties. In order to ensure the conservation and sustainable use of these species, the effect of cultivation on yield, chemical composition, antioxidant and antimicrobial activities of EOs were investigated over the course of three years. A slight decrease of EOs yield was obtained by steam distillation from cultivated thymes. As well as the yield, the scanning electron microscopy analysis of the leaves has also showed a decrease in the gland density. The gas chromatography/mass spectrometry (GC/MS) and GC/Flame Ionization Detector (GC/FID) analyses of EOs led to the identification of 32 compounds representing more than 98.4 % of the total oils. The major compounds of wild T. pallidus EOs were γ-terpinene (20.23-21.49 %), borneol (12.33-12.39 %) and α-phellandrene (11.63-12.58 %). Whereas EOs obtained from cultivated plants were dominated by γ-terpinene (17.27-17.32 %), borneol (12.39-8.3 %), camphene (10.67-10.97 %) and α-phellandrene (10.57-10.71 %). Carvacrol (26.07-26.18 %) and borneol (17.25-20.67 %) were the main chemical constituents in both wild and cultivated T. satureioides EOs. Regarding the antioxidant activity, the EOs of cultivated thymes were not highly affected by cultivation. Despite some chemical variability, our results show that cultivation also did not affect the antimicrobial activity of the essential oils of both species. These results imply that the cultivation process could be a promising alternative to ensure the sustainable use of the two endemic thyme species in threat.

Inhibition of Listeria monocytogenes by natural antimicrobial

The aim of the study was to evaluate antimicrobial activity of essential oil from plants as natural antimicrobial to inhibit Listeria monocytogenes. A total of 6 essential oil extracted from galangal (Alpinia galanga), ginger (Zingiber officinale), lemongrass (Cymbopogon citratus), orange skin (Citrus sinensis), rosemary (Rosmarinus officinalis) and turmeric (Curcuma longa). By using Minimum Inhibitory Concentration (MIC), the highest and lowest antimicrobial activity of essential oil to inhibit the growth of L. monocytogenes was found on lemongrass oil (0.32 % ± 0.12 %) and turmeric (7.46 % ± 2.79%), respectively. By using disc diffusion assay, the highest antimicrobial activity to against L. monocytogenes was shown by lemongrass oil (7.46 ± 2.79 mm). There is no antimicrobial activity observed in orange peel oil. Out of the essential oil tested, lemongrass oil showed the most promising natural antimicrobial to inhibit L. monocytogenes.

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

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

Investigation on Antimicrobial Activities of Essential Oil and Extract from Fresh Peel of Citrus hystrix DC. (shauk-nu)

Investigation on Antimicrobial Activities of Essential Oil and Extract from Fresh Peel of Citrus hystrix DC. (shauk-nu)

In Vitro Susceptibility of Multidrug Resistant Strains of Salmonella to Essential Oils

Antimicrobial resistance has become a global threat to public health. There is a critical need to find new antimicrobial substances from natural sources. The aim of this study was to investigate the antimicrobial activity of essential oils (EOs) obtained from Origanum vulgare, Thymus serpyllum, Thymus vulgaris, and Melaleuca alternifolia against multidrug resistant strains of Salmonella isolated from samples of diverse animal origin. The strains were biochemically identified, serotyped, and characterized for their antimicrobial resistance profiles. The antimicrobial activity of the EOs against the strains was evaluated using the Kirby-Bauer diffusion method, followed by determination of the minimal inhibitory concentration and minimum bactericidal concentrations. The EOs of T. serpyllum and O. vulgare, which contain carvacrol as the main compound, show excellent antimicrobial activity.

Bioproducts from forest biomass: Essential oils and hydrolates from wastes of Cupressus lusitanica Mill. and Cistus ladanifer L.

Unattended forest wastes are, among others, a potential source of wildfires, as well as a growth media for forest pests. As a way of lowering the detrimental effect of these wastes, it is important to convert these under-valued resources into a value-generating market forest wastes use. Essential oils (EOs) and hydrolates (Hs) from Cupressus lusitanica and Cistus ladanifer waste products, resulting from forest landscaping in Portugal, were evaluated for chemical composition and biological activity. Essential oils and Hs were obtained by steam-distillation (SD) and hydrodistillation (HD). Essential oils and Hs volatiles were analysed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC–MS). The antimicrobial activity of EOs was studied by disk agar diffusion method against Escherichia coli, Staphylococcus aureus and Candida albicans. Antioxidant activity of EOs and Hs was evaluated by 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) free radical, superoxide anion radical formation, xanthine oxidase and chelating metal ions assays. Anti-inflammatory activity of Hs was assessed by albumin denaturation assay. Monoterpene hydrocarbons and oxygen-containing monoterpenes dominated C. lusitanica EO (SD, 82–86 %, HD, 80–85 %) and Hs volatiles (SD, 93–94 %; HD 64–81 %), respectively. α-Pinene (14–36 %), limonene (8–21 %), δ-3-carene (8–19 %) and sabinene (6–18 %) were the main EO constituents. Hydrolates volatiles were dominated by cis-3-hexen-1-ol (0.1–13 %), camphor (1–11 %), umbellulone (t-48 %), p-cymene-8-ol (11–16 %) and terpinen-4-ol (21–31 %). C. ladanifer EOs were dominated by monoterpene hydrocarbons (SD, 48–80 % and HD, 29 %) and Hs by oxygen-containing monoterpenes (SD, 38–43 %, HD, 39 %). The EO major constituents were α-pinene (13–28 %) and camphene (5–25 %), whereas 2,6,6-trimethyl cyclohexanone (2–12 %) and trans-pinocarveol (5–13 %) dominated the Hs volatiles. This study reports for the first time the chemical composition of the hydrolate volatiles of these two species and their anti-inflammatory properties. Among the studied biological activities, the EOs showed the best antioxidant properties while Hs demonstrated higher anti-inflammatory activity.

Synergistic effect of Cordia curassavica Jacq. essential oils association against the phytopathogen Xanthomonas campestris pv. campestris.

The increased use of pesticides applied to treat diseases caused by bacteria has caused serious environmental problems. There are few fungicides/bactericides for the treatment of plant diseases caused by Xanthomonas campestris pv. campestris (Xcc), and only two natural products with general bactericidal/fungicidal use are available on the market. Thus, this study evaluated the antimicrobial activity of essential oils (EOs), and their combinations, from five distinct genotypes of Cordia curassavica (Jacq.) Roem. & Schult (Syn. Varronia curassavica Jacq.) (CCUR) against Xcc. GC/MS chemical analysis revealed α-pinene, sabinene, (E)-caryophyllene, ar-curcumene, β-sesquiphellandrene, 7-cyclodecen-1-one, and ar-Turmerone as the major compounds of the five EOs of CCUR. All EOs showed growth inhibition of Xcc with minimum inhibitory concentration between 500 and 1000μgmL-1. The associations between two EOs from different CCUR genotypes showed that 70% of the total combinations had an additive effect. However, the combinations between CCUR-002 × (-302, -202) and CCUR-302 × (-601) showed a synergistic effect, with mean fractional inhibitory concentration FIC50 values of 0.28, 0.42, and 0.40, respectively. This study demonstrates that combinations of C. curassavica EOs have antimicrobial activity and a potential to be used in the control of black rot. Graphical abstract.

Lignin Nanoparticles: Green Synthesis in a γ-Valerolactone/Water Binary Solvent and Application to Enhance Antimicrobial Activity of Essential Oils

Lignin nanoparticles (LNPs), as a special aggregate of renewable and biodegradable lignin available in abundant amounts, are a perfect building-block material because of their advantages, including...