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1.  Bactericidal and antioxidant properties of essential oils from the fruits Dennettia tripetala G. Baker 
Background
The antibacterial and antioxidant properties of the essential oils (EOs) of unripe and ripe fruits of Dennettia tripetala and their potential for the management of infectious and oxidative-stress diseases were investigated in-vitro in this study.
Method
Essential oil obtained from the fruit in Clevenger modified apparatus, was characterized by high resolution GC-MS, while antioxidant and antibacterial properties were tested by spectrophotometric and agar diffusion methods respectively.
Results
The EO demonstrated strong antibacterial properties when subjected to multi –drug resistant bacterial strains: Enterococcus faecium (ATCC19434), Escherichia coli (ATCC 700728), Staphylococcus aureus (NCINB 50080), Listeria ivanovii (ATCC 19119), Enterobacter cloacae (ATCC13047) and four previously confirmed multi resistant bacterial isolates from our laboratory stock culture. The unripe fruit oil (UFO) demonstrated greater activity than the ripe fruit oil (RFO) against most of the tested bacteria with minimum inhibition concentrations (MIC) ranging between 0.05–0.20 mg/mL while that of the ripe fruit oil (RFO) ranged from 0.10–0.20 mg/mL. The IC50 for RFO (0.62 ± 0.12 mg/mL) showed that it has higher antioxidant strength than UFO and vitamin C (0.87 ± 0.23 and 3.39 ± 0.12 mg/mL) but a lower activity compared to β-carotene (0.32 ± 0.22 mg/mL) in scavenging 2, 2-diphenyl-1-picrylhydrazyl radicals (DPPH•). The EOs also demonstrated strong ability in scavenging three other different radicals (ABTS, lipid peroxide and nitric oxide radicals) in concentration dependant -manner.
Conclusion
Findings from this study suggest that apart from the local uses of the plant extracts, the EO has strong bioactive compounds, noteworthy antibacterial, antiradical properties and may be good candidates in the search for lead constituents for the synthesis of novel potent antibiotics.
doi:10.1186/s12906-016-1459-4
PMCID: PMC5126994  PMID: 27894288
Dennettia tripetala; Essential oils; Antibacterial; Antioxidant; Methyl phenyl formate
2.  GC and GC/MS Analysis of Essential Oil Composition of the Endemic Soqotraen Leucas virgata Balf.f. and Its Antimicrobial and Antioxidant Activities 
Leucas virgata Balf.f. (Lamiaceae) was collected from the Island Soqotra (Yemen) and its essential oil was obtained by hydrodistillation. The chemical composition of the oil was investigated by GC and GC-MS. Moreover, the essential oil was evaluated for its antimicrobial activity against two Gram-positive bacteria, two Gram-negative bacteria, and one yeast species by using broth micro-dilution assay for minimum inhibitory concentrations (MIC) and antioxidant activity by measuring the scavenging activity of the DPPH radical. The investigation led to the identification of 43 constituents, representing 93.9% of the total oil. The essential oil of L. virgata was characterized by a high content of oxygenated monoterpenes (50.8%). Camphor (20.5%) exo-fenchol (3.4%), fenchon (5.4%), and borneol (3.1%) were identified as the main components. Oxygenated sesquiterpenes were found as the second major group of compounds (21.0%). β-Eudesmol (6.1%) and caryophyllene oxide (5.1%) were the major compounds among oxygenated sesquiterpenes. The results of the antimicrobial assay showed that the oil exhibited a great antibacterial activity against the tested S. aureus, B. subtilis, and E. coli. No activity was found against P. aeruginosa and C. albicans. Moreover, the DPPH-radical scavenging assay exhibited only a moderate antioxidant activity (31%) for the oil at the highest concentration tested (1 mg/mL).
doi:10.3390/ijms141123129
PMCID: PMC3856109  PMID: 24284402
Leucas virgata; Soqotra; essential oil; antimicrobial; antioxidant
3.  Chemical composition, antioxidant and antibacterial properties of Bene (Pistacia atlantica subsp. mutica) hull essential oil 
Journal of Food Science and Technology  2015;52(10):6784-6790.
The tree Pistacia atlantica subsp. mutica, namely Bene, is widely distributed in Iranian mountains. Recent studies revealed that the oil of Bene was stable, even more stable than sesame oil, with antioxidant properties. This can give versatile applications for the oil. The volatile composition of this oil has not chemically been investigated so far. In this study, sixty three compounds were identified in the essential oil (EO) of Bene hull. The major components were determined to be α-pinene (20.8 %), camphene (8.4 %), β-myrcene (8.2 %) and limonene (8 %). Antioxidant activities of the essential oil from Bene hull were evaluated by using 2,2′- diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging, ferric reducing antioxidant power (FRAP), β-carotene bleaching test, thiobarbituric acid reactive species (TBARS) and Rancimat assays. The Bene essential oil exhibited significant antioxidant activities in FRAP and TBARS assays as compared with positive controls. In addition, the oil was evaluated for its antimicrobial activity against both Gram positive (Staphylococcus aureus) and Gram negative (Escherichia coli) bacteria. It showed significant antibacterial activities against S. aureus and E. coli with minimum inhibitory concentration (MIC) values of 6 and 12.5 μg/mL, respectively.
doi:10.1007/s13197-015-1789-0
PMCID: PMC4573120  PMID: 26396430
Pistachio; FRAP; Antioxidant activity; Antibacterial activity; Rancimat
4.  Effect of Various Essential Oils Isolated from Douglas Fir Needles upon Sheep and Deer Rumen Microbial Activity 
Applied Microbiology  1967;15(4):777-784.
The effects of essential oils isolated from Douglas fir needles on sheep and deer rumen microbial activity were tested by use of an anaerobic manometric technique. Rumen microorganisms were obtained from a sheep which had been fed mainly on alfalfa hay and dried range grass. One deer used in this study had access to Douglas fir trees the year around, whereas the other deer had no access to Douglas fir. All of the monoterpene hydrocarbons isolated from Douglas fir needles—α-pinene, β-pinene, limonene, myrcene, camphene, Δ3-carene, and terpinolene—promoted only slightly or had no effect on deer rumen microbial activity, whereas all of them promoted activity in sheep rumen microbes, except Δ3-carene and terpinolene, which inhibited activity. Of the oxygenated monoterpenes, all monoterpene alcohols—α-terpineol, terpinen-4-ol, linalool, citronellol, and fenchyl alcohol—strongly inhibited the rumen microbial activity of both sheep and deer. Monoterpene esters (bornyl acetate) produced mild inhibition for both sheep and deer microbes, and citronellyl acetate inhibited rumen microbial activity in sheep, whereas it promoted activity in both deer. Monoterpene aldehyde (citronellal) inhibited the activity of rumen microbes from both sheep and deer having no access to Douglas fir from the Hopland Field Station, whereas they produced no effect upon the deer having access to Douglas fir from the Masonite forest. Rumen microbial activity for sheep and deer was promoted slightly with aliphatic ester (ethyl-n-caproate). There was a marked difference between sheep and deer rumen microbes as affected by addition of the various essential oils. The monoterpene hydrocarbons promoted activity more on sheep rumen microbes than on deer, and the monoterpene alcohols inhibited sheep rumen microbial activity more than that of deer. Furthermore, the deer rumen microbes from Hopland Field Station were affected more than the deer from Masonite forest.
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PMCID: PMC547062  PMID: 6049303
5.  In-vitro assessment of antioxidant and antimicrobial activities of methanol extracts and essential oil of Thymus hirtus sp. algeriensis 
Background
Owing to the complexity of the antioxidant materials and their mechanism of actions, it is obvious that no single testing method is capable of providing a comprehensive picture of the antioxidant profile. The essential oil of the Thymus specie may still possess other important activities in traditional medicine, it can be used in the treatment of fever and cough. This essential oil may also have an anticancer activity.
Methods
The essential oils aerial parts hydrodistilled from Thymus hirtus sp. algeriensis, were characterised by GC/MS analysis and the methanolic extracts were chemically characterized by HPLC method. The essence of thyme was evaluated for its antioxidant and antibacterial activity.
Result
The Terpinen-4-ol are the principal class of metabolites (33.34%) among which 1.8-cineole (19.96%) and camphor (19.20%) predominate. In this study, quantitative values of antioxidant activity of crude methanolic extracts of Thymus hirtus sp. algeriensis were investigated. The essential oils was screened for their antibacterial activity against six common pathogenic microorganisms (Escherichia coli, Pseudomonas aeruginosa, Salmonella enteridis, Staphylococcus aureus, Bacillus subtilis and Listeria monocytogenes) by well diffusion method and agar dilution method (MIC). All the essences were found to inhibit the growth of both gram (+) and gram (−) bacteria organisms tested. These activities were correlated with the presence of phenolic compounds in active fractions. HPLC confirmed presence of phenolic compounds in methanol extracts.
Conclusion
Methanol extracts and essential oils from aerial parts of Thymus hirtus sp. algeriensis, were examined for their potential as antioxidants. The technique for measuring antioxidant activity, which was developed using DPPH, ABTS and β-carotene bleaching, produced results as found in established literatures. The present results indicate clearly that methanol extracts and essential oils from Thymus hirtus sp. algeriensis possess antioxidant properties and could serve as free radical inhibitors or scavengers, acting possibly as primary antioxidants, also their essential oil have an antibacterial effect.
doi:10.1186/1476-511X-13-114
PMCID: PMC4115217  PMID: 25022197
Radical scavenging effect; Phenolic compounds; Essential oil; Antioxidant activity; Antibacterial activity
6.  Antibacterial and Antioxidant Properties of the Leaves and Stem Essential Oils of Jatropha gossypifolia L. 
BioMed Research International  2016;2016:9392716.
Antibacterial and antioxidant properties of the leaves and stem essential oils (EOs) of Jatropha gossypifolia and their efficacies against infectious and oxidative stress diseases were studied in vitro. The EOs obtained using Clevenger modified apparatus were characterized by high resolution GC-MS, while their antioxidant and antibacterial properties were examined by spectrophotometric and agar diffusion techniques, respectively. The EOs exhibited strong antibacterial activity against Escherichia coli, Enterococcus faecium, and Staphylococcus aureus. The stem essential oil (SEO) was more active than the leaf essential oil (LEO) against test bacteria with minimum inhibition concentration (MIC) ranging from 0.025 to 0.05 mg/mL and the LEO from 0.05 to 0.10 mg/mL. The SEO was bactericidal at 0.025 and 0.05 mg/mL against S. aureus and E. faecium, respectively, and the LEO was bacteriostatic against the three bacteria at 0.05 and 0.10 mg/mL. The SEO IC50 (0.07 mg/mL) showed that the antiradical strength was superior to LEO (0.32 mg/mL) and β-carotene (1.62 mg/mL) in scavenging 2, 2-diphenyl-1-picrylhydrazyl radicals (DPPH•). The oils effectively reduced three other oxidants to neutral molecules in concentration dependent manner. Findings from this study suggest that, apart from the traditional uses of the plant extracts, the EOs have strong bioactive compounds with noteworthy antibacterial and antiradical properties and may be good candidates in the search for lead compounds for the synthesis of novel potent antibiotics.
doi:10.1155/2016/9392716
PMCID: PMC5098104  PMID: 27843951
7.  Antioxidant and Free Radical Scavenging Capacity of Seed and Shell Essential Oils Extracted from Abrus precatorius (L) 
Antioxidants  2014;3(2):278-287.
Essential oils from plants have been proven safe as natural antioxidants, and few are already marketed as digestive enhancers as well as in prevention of several degenerative diseases. This study evaluated the antioxidant capacity of seed and shell essential oils of Abrus precatorius (L), a herb used for ethno-medicinal practices in Nigeria. The essential oils were obtained by hydro-distillation. The ability of the oils to act as hydrogen/electrons donor or scavenger of radicals were determined by in-vitro antioxidant assays using 2,2-diphenyl-2-picryl-hydrazyl free radical (DPPH.) scavenging; 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging; lipid peroxide and nitric oxide radicals scavenging assays. The IC50 of the seed and shell oils (2.10 mg/mL and 1.20 mg/mL respectively) showed that antioxidant activity is higher than that for the standard drugs (3.20 mg/mL and 3.40 mg/mL) for the nitric oxide scavenging assay. The lipid peroxidation radical activity of the oils were similar to vitamin C, weak DPPH and ABTS radical scavenging activities were discovered in comparison to vitamin C and rutin. Generally, in the four antioxidant assays, a significant correlation existed between concentrations of the oils and percentage inhibition of free radicals and lipid peroxidation. The composition of A. precatorius essential oils reported earlier may account for their antioxidant capacity.
doi:10.3390/antiox3020278
PMCID: PMC4665479  PMID: 26784871
Abrus precatorius; essential oils; DPPH; ABTS; lipid peroxidation; nitric oxide
8.  Biochemical Activities of Iranian Cymbopogon olivieri (Boiss) Bor. Essential Oil 
Cymbopogon olivieri essential oil from aerial parts was analyzed by gas chromotography and gas chromatography-mass spectrometry and led to the identification of 38 compounds. Piperitone (72.8%), 4-carene (11.8%) and β-himachalene (7.6%) were found as the major components of the oil. The antimicrobial activity was achieved using disc-diffusion and microbroth dilution assays and microbicidal kinetics of oil was screened against different microorganisms. The possible antioxidant activity of oil was evaluated by diphenylpicrylhydrazyl free-radical scavenging system. The oil had excellent antimicrobial activity against Bacillus cereus, Staphylococcus epidermidis and Streptococcus pneumoniae. The oil exhibited inhibitory effect against Bacillus subtilis and fungi. Dvalues of oil were 12.5, 10 and 2.4 min for Escherichia coli, Staphylococcus aureus and Candida albicans, respectively. The IC50 value of Cymbopogon olivieri oil was 35 mg/ml and its antioxidant activity was lower than that of butylated hydroxytoluene. Cymbopogon olivieri oil possesses compounds with antimicrobial properties that can be used as antimicrobial agents.
doi:10.4103/0250-474X.107071
PMCID: PMC3630732  PMID: 23626392
Antimicrobial activity; antioxidant activity; Cymbopogon olivieri; diphenylpicrylhydrazyl; piperitone
9.  Evaluation of Synergistic Antibacterial and Antioxidant Efficacy of Essential Oils of Spices and Herbs in Combination 
PLoS ONE  2015;10(7):e0131321.
The present study was carried out to evaluate the possible synergistic interactions on antibacterial and antioxidant efficacy of essential oils of some selected spices and herbs [bay leaf, black pepper, coriander (seed and leaf), cumin, garlic, ginger, mustard, onion and turmeric] in combination. Antibacterial combination effect was evaluated against six important food-borne bacteria (Bacillus cereus, Listeria monocytogenes, Micrococcus luteus, Staphylococcus aureus, Escherichia coli and Salmonella typhimurium) using microbroth dilution, checkerboard titration and time-kill methods. Antioxidant combination effect was assessed by DPPH free radical scavenging method. Total phenolic content was measured by Folin-Ciocalteu method. Bioactivity –guided fractionation of active essential oils for isolation of bioactive compounds was done using TLC-bioautography assay and chemical characterization (qualitative and quantitative) of bioactive compounds was performed using DART-MS and HPLC analyses. Cytotoxic potential was evaluated by brine shrimp lethality assay as well as MTT assay using human normal colon cell line. Results showed that among the possible combinations tested only coriander/cumin seed oil combination showed synergistic interactions both in antibacterial (FICI : 0.25-0.50) and antioxidant (CI : 0.79) activities. A high positive correlation between total phenolic content and antibacterial activity against most of the studied bacteria (R2 = 0.688 – 0.917) as well as antioxidant capacity (R2 = 0.828) was also observed. TLC-bioautography-guided screening and subsequent combination studies revealed that two compounds corresponding to Rf values 0.35 from coriander seed oil and 0.53 from cumin seed oil exhibited both synergistic antibacterial and antioxidant activities. The bioactive compound corresponding to Rf 0.35 from coriander seed oil was identified as linalool (68.69%) and the bioactive compound corresponding to Rf 0.53 from cumin seed oil was identified as p-coumaric acid (7.14%) by DART-MS and HPLC analyses. The coriander/cumin seed oil combination did not show any cytotoxic effect both in brine shrimp lethality as well as human normal colon cell line assays. The LC50 in brine shrimp lethality assay was found to be 4945.30 μg/ml and IC50 in human normal colon cell line was > 1000 μg/ml. The results provide evidence that coriander/cumin seed oil combination might indeed be used as a potential source of safe and effective natural antimicrobial and antioxidant agents in pharmaceutical and food industries.
doi:10.1371/journal.pone.0131321
PMCID: PMC4488432  PMID: 26132146
10.  Health-promoting value and food applications of black cumin essential oil: an overview 
Journal of Food Science and Technology  2015;52(10):6136-6142.
Black cumin (Nigella sativa L.) seeds and its essential oil have been widely used in functional foods, nutraceuticals and pharmaceutical products. Analysis of Nigella sativa essential oil using GC and GC-MS resulted in the identification of many bioactive compounds representing ca. 85 % of the total content. The main compounds included p-cymene, thymoquinone, α-thujene, longifolene, β-pinene, α-pinene and carvacrol. Nigella sativa essential oil exhibited different biological activities including antifungal, antibacterial and antioxidant potentials. Nigella sativa essential oil showed complete inhibition zones against different Gram-negative and Gram-positive bacteria including Penicillium citrinum Bacillus cereus, Bacillus subtilis, Staphylococcus aureus and Pseudomonas aeruginosa. The essential oil showed stronger antioxidant potential in comparison with synthetic antioxidants (i.e., BHA and BHT) in a rapeseed oil model system. The oil exhibited also stronger radical scavenging activity against DPPH·radical in comparison with synthetic antioxidants. The diversity of applications to which Nigella sativa essential oil can be put gives this oil industrial importance.
doi:10.1007/s13197-015-1785-4
PMCID: PMC4573164  PMID: 26396361
Nigella sativa; Functional properties; Novel food thymoquinone; Longifolene
11.  Asteraceae Artemisia campestris and Artemisia herba-alba Essential Oils Trigger Apoptosis and Cell Cycle Arrest in Leishmania infantum Promastigotes 
We report the chemical composition and anti-Leishmania and antioxidant activity of Artemisia campestris L. and Artemisia herba-alba Asso. essential oils (EOs). Our results showed that these extracts exhibit different antioxidant activities according to the used assay. The radical scavenging effects determined by DPPH assay were of IC50 = 3.3 mg/mL and IC50 = 9.1 mg/mL for Artemisia campestris and Artemisia herba-alba essential oils, respectively. However, antioxidant effects of both essential oils, determined by ferric-reducing antioxidant power (FRAP) assay, were in the same range (2.3 and 2.97 mg eq EDTA/g EO, resp.), while the Artemisia herba-alba essential oil showed highest chelating activity of Fe2+ ions (27.48 mM Fe2+). Interestingly, we showed that both EOs possess dose-dependent activity against Leishmania infantum promastigotes with IC50 values of 68 μg/mL and 44 μg/mL for A. herba-alba and A. campestris, respectively. We reported, for the first time, that antileishmanial activity of both EOs was mediated by cell apoptosis induction and cell cycle arrest at the sub-G0/G1 phase. All our results showed that EOs from A. herba-alba and A. campestris plants are promising candidates as anti-Leishmania medicinal products.
doi:10.1155/2016/9147096
PMCID: PMC5078739  PMID: 27807464
12.  Antioxidant, antimicrobial and antiproliferative activities of Anthemis palestina essential oil 
Background
Anthemis palestina (Asteraceae) extends across the Mediterranean region, southwest Asia and eastern Africa. Although traditionally used for several applications, in vitro investigation of biological functions associated with Anthemis palestina essential oil had never been reported.
Methods
The air-dried flowers of Anthemis palestina were subjected to hydrodistillation to yield the oil. The antioxidant activity of the hydrodistilled oil was characterized using various in vitro model systems such as DPPH, ferric-reducing antioxidant power and hydroxyl radical scavenging activity. Antibacterial activity was tested against six bacterial species, representing both Gram positive and Gram negative bacteria. Antifungal activity was evaluated using three Candida species. The minimum inhibitory concentration (MIC) for each examined microorganism was determined using the microdilution method. The oil’s antiproliferative effects against eight human cancer cell lines were also studied and the lethal doses that resulted in 50% reduction of cell viability (LD50) were determined.
Results
The results indicate that the essential oil of Anthemis palestina exhibited substantial antioxidant activities as demonstrated with DPPH, ferric reducing antioxidant power, and hydroxyl radical scavenging activity. In addition, a broad-spectrum antibacterial activity of the oil was revealed with better susceptibility of Gram positive bacteria towards the oil. The MIC values ranged between 6–75 μg/ml. Besides, the oil demonstrated a moderate inhibitory effect on the three Candida species examined; with MIC values ranging between 48–95 μg/ml. Potent cytotoxic activities, especially against HeLa cell line; with LD50 of 32 μg/ml, BJAB cell line; with LD50 of 57 μg/ml, and Caco-2 cell line; with LD50 of 61 μg/ml, were observed.
Conclusion
The results obtained indicate high potential of Anthemis palestina essential oil as bioactive oil, for nutraceutical and medical applications, possessing antioxidant, antimicrobial and antiproliferative activities.
doi:10.1186/1472-6882-14-297
PMCID: PMC4133619  PMID: 25112895
Anthemis palestina; Essential (volatile) oil; Antioxidant; Antimicrobial; Antiproliferative
13.  Dual Bioactivities of Essential Oil Extracted from the Leaves of Artemisia argyi as an Antimelanogenic versus Antioxidant Agent and Chemical Composition Analysis by GC/MS 
The study was aimed at investigating the antimelanogenic and antioxidant properties of essential oil when extracted from the leaves of Artemisia argyi, then analyzing the chemical composition of the essential oil. The inhibitory effect of the essential oil on melanogenesis was evaluated by a mushroom tyrosinase activity assay and B16F10 melanoma cell model. The antioxidant capacity of the essential oil was assayed by spectrophotometric analysis, and the volatile chemical composition of the essential oil was analyzed with gas chromatography-mass spectrometry (GC/MS). The results revealed that the essential oil significantly inhibits mushroom tyrosinase activity (IC50 = 19.16 mg/mL), down-regulates B16F10 intracellular tyrosinase activity and decreases the amount of melanin content in a dose-dependent pattern. Furthermore, the essential oil significantly scavenged 2,2-diphenyl-1-picryl-hydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzthiazoline- 6-sulphonic acid) ABTS radicals, showed an apparent reduction power as compared with metal-ion chelating activities. The chemicals constituents in the essential oil are ether (23.66%), alcohols (16.72%), sesquiterpenes (15.21%), esters (11.78%), monoterpenes (11.63%), ketones (6.09%), aromatic compounds (5.01%), and account for a 90.10% analysis of its chemical composition. It is predicted that eucalyptol and the other constituents, except for alcohols, in the essential oil may contribute to its antioxidant activities. The results indicated that essential oil extracted from A. argyi leaves decreased melanin production in B16F10 cells and showed potent antioxidant activity. The essential oil can thereby be applied as an inhibitor of melanogenesis and could also act as a natural antioxidant in skin care products.
doi:10.3390/ijms131114679
PMCID: PMC3509604  PMID: 23203088
Artemisia argyi; essential oil; tyrosinase; melanin; antioxidant
14.  Composition, antimicrobial, antioxidant, and antiproliferative activity of Origanum dictamnus (dittany) essential oil 
Microbial Ecology in Health and Disease  2015;26:10.3402/mehd.v26.26543.
Background
Nowadays, there has been an increased interest in essential oils from various plant origins as potential antimicrobial, antioxidant, and antiproliferative agents. This trend can be mainly attributed to the rising number and severity of food poisoning outbreaks worldwide along with the recent negative consumer perception against artificial food additives and the demand for novel functional foods with possible health benefits. Origanum dictamnus (dittany) is an aromatic, tender perennial plant that only grows wild on the mountainsides and gorges of the island of Crete in Greece.
Objective
The aim of the present study was to investigate the antimicrobial, antioxidant, and antiproliferative properties of O. dictamnus essential oil and its main components and assess its commercial potential in the food industry.
Design
O. dictamnus essential oil was initially analyzed by gas chromatography–mass spectrometry (GC–MS) to determine semi-quantitative chemical composition of the essential oils. Subsequently, the antimicrobial properties were assayed and the minimum inhibitory and non-inhibitory concentration values were determined. The antioxidant activity and cytotoxic action against the hepatoma adenocarcinoma cell line HepG2 of the essential oil and its main components were further evaluated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and by the sulforhodamine B (SRB) assay, respectively.
Results
The main constituents of O. dictamnus essential oil identified by GC–MS analysis were carvacrol (52.2%), γ-terpinene (8.4%), p-cymene (6.1%), linalool (1.4%), and caryophyllene (1.3%). O. dictamnus essential oil and its main components were effective against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Listeria monocytogenes, Salmonella Enteritidis, Salmonella typhimurium, Saccharomyces cerevisiae, and Aspergillus niger. In addition, the estimated IC50 value for the DPPH radical scavenging activity for O. dictamnus essential oil was 0.045±0.0042% (v/v) and was mainly attributed to carvacrol. The EC50 value for the essential oil in the 72h SRB assay in HepG2 cells was estimated to be 0.0069±0.00014% (v/v). Among the individual constituents tested, carvacrol was the most bioactive compound and accounted for the observed antiproliferative activity of the essential oil.
Conclusions
The results revealed that O. dictamnus essential oil is a noteworthy growth inhibitor against the microbes studied. It also possesses significant antioxidant activity and demonstrated excellent cytotoxicity against HepG2 cells. Taken together, O. dictamnus essential oil may represent an effective and inexpensive source of potent natural antimicrobial agents with health-promoting properties, which may be incorporated in food systems.
doi:10.3402/mehd.v26.26543
PMCID: PMC4424236  PMID: 25952773
O. dictamnus essential oil; antimicrobial; antioxidant; antiproliferative; GC–MS analysis
15.  Comparative evaluation of antioxidant and insecticidal properties of essential oils from five Moroccan aromatic herbs 
This study describes the antioxidant and insecticidal activities of essential oils (EOs) of Mentha suaveolens subsp. timija, Thymus satureioides, Achillea ageratum, Cotula cinerea and Salvia officinalis widely used in Morocco as flavorings, food additives and preservatives. Sixty seven components were identified accounting for more than 95.0 % of the total oils. M. suaveolens subsp. timija oil had as main components menthone and pulegone. A. ageratum oil was particularly rich in artemisyl acetate and yomogi alcohol. The essential oil of T. satureioides was characterized by high contents of carvacrol and borneol. C. cinerea oil contained trans-thujone and cis-verbenyl acetate as major constituents, whereas S. officinalis oil was characterized by trans-thujone and camphor. Antioxidant activities were examined by means of 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), reducing power, β-carotene/linoleic acid bleaching and ABTS radical tests. In all assays, the highest antioxidant potency was observed in T. satureioides EO with IC50 values ranging from 0.15 ± 0.36 μg mL-1 to 0.23 ± 0.67 μg mL−1 across the four assays. The in vitro evaluation of the insecticidal activity showed that M. suaveolens subsp. timija EO present the highest insecticidal efficiency against adults of Tribolium castaneum with LD50 and LD90 values of 0.17 μL cm−2 and 0.26 μL cm−2, respectively and LT50, LT90 values ranged from 44.19 h to 2.98 h and 98.14 h to 6.02 h, respectively. Our data support the possible use of T. satureioides oil as potential antioxidant agent, while M. suaveolens subsp. timija oil can be developed as a new natural bio-insecticide.
doi:10.1007/s13197-014-1284-z
PMCID: PMC4375224  PMID: 25829614
Mentha suaveolens subsp. timija; Thymus satureioides; Achillea ageratum; Cotula cinerea; Salvia officinalis; Essential oils
16.  Chemical composition, antioxidant activity and in vitro antibacterial activity of Achillea wilhelmsii C. Koch essential oil on methicillin-susceptible and methicillin-resistant Staphylococcus aureus spp. 
3 Biotech  2014;5(1):39-44.
The present study investigated the chemical composition of the essential oil (EO) from aerial parts (flowering stage) of Achillea wilhelmsii C. Koch by GC–MS. In addition, the antioxidant activity of the EO as well as its antimicrobial activity against methicillin-susceptible and methicillin-resistant Staphylococcus aureus (MRSA) strains was tested. Antioxidant activity was measured by the ability of the EO to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals while the antimicrobial activity was assessed by the disc-diffusion method. In total, 52 compounds were recognized, accounting for 97.33 % of the EO. The main compounds in the EO were carvacrol (22.49 %), dihydrocarvone (13.23 %), linalool (12 %), 1,8-cineol (11.42 %), camphene (8.31 %), thymol (5.28 %), camphor (3.71 %), pulegone (2.82 %) α-terpineol (2.11 %), bornyl acetate (1.14 %), and farganol (1.01 %). The EC50 value of the EO was 0.01 and 0.08 mg/mL for the antioxidant and DPPH-scavenging ability, respectively. A. wilhelmsii EO affected methicillin-sensitive Staphylococcus aureus (MSSA) and MRSA, but the impact was more effective on MSSA.
doi:10.1007/s13205-014-0197-x
PMCID: PMC4327754
Achillea wilhelmsii; Antioxidant activity; Essential oil (EO); GC–MS; MRSA; MSSA; Staphylococcus aureus
17.  Chemical Composition, Antioxidant, Anti-Inflammatory and Anti-Proliferative Activities of Essential Oils of Plants from Burkina Faso 
PLoS ONE  2014;9(3):e92122.
This research highlights the chemical composition, antioxidant, anti-inflammatory and anti-proliferative activities of essential oils from leaves of Ocimum basilicum, Ocimum americanum, Hyptis spicigera, Lippia multiflora, Ageratum conyzoides, Eucalyptus camaldulensis and Zingiber officinale. Essential oils were analyzed by gas chromatography–mass spectrometry and gas chromatography–flame ionization detector. Major constituents were α-terpineol (59.78%) and β-caryophyllene (10.54%) for Ocimum basilicum; 1, 8-cineol (31.22%), camphor (12.730%), α-pinene (6.87%) and trans α-bergamotene (5.32%) for Ocimum americanum; β-caryophyllene (21%), α-pinene (20.11%), sabinene (10.26%), β-pinene (9.22%) and α-phellandrene (7.03%) for Hyptis spicigera; p-cymene (25.27%), β-caryophyllene (12.70%), thymol (11.88), γ-terpinene (9.17%) and thymyle acetate (7.64%) for Lippia multiflora; precocene (82.10%)for Ageratum conyzoides; eucalyptol (59.55%), α-pinene (9.17%) and limonene (8.76%) for Eucalyptus camaldulensis; arcurcumene (16.67%), camphene (12.70%), zingiberene (8.40%), β-bisabolene (7.83%) and β-sesquiphellandrène (5.34%) for Zingiber officinale. Antioxidant activities were examined using 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) methods. O. basilicum and L. multiflora exhibited the highest antioxidant activity in DPPH and ABTS tests, respectively. Anti-inflammatory properties were evaluated by measuring the inhibition of lipoxygenase activity and essential oil of Z. officinale was the most active. Anti-proliferative effect was assayed by the measurement of MTT on LNCaP and PC-3 prostate cancer cell lines, and SF-763 and SF-767 glioblastoma cell lines. Essential oils from A. conyzoides and L. multiflora were the most active on LNCaP and PC-3 cell lines, respectively. The SF-767 glioblastoma cell line was the most sensitive to O. basilicum and L. multiflora EOs while essential oil of A. conyzoides showed the highest activity on SF-763 cells. Altogether these results justify the use of these plants in traditional medicine in Burkina Faso and open a new field of investigation in the characterization of the molecules involved in anti-proliferative processes.
doi:10.1371/journal.pone.0092122
PMCID: PMC3963878  PMID: 24662935
18.  Chemical composition, anthelmintic, antibacterial and antioxidant effects of Thymus bovei essential oil 
Background
It has been recently recognized that oxidative stress, helminth and microbial infections are the cause of much illness found in the underdeveloped, developing and developed countries. The present study was undertaken to identify the chemical composition, and to assess anthelmintic, antimicrobial and antioxidant effects of Thymus bovei essential oil.
Methods
The chemical composition of the essential oil was analyzed using gas chromatography mass spectrometry (GC-MS). Antimicrobial activity was tested against the selected strains from American Type Culture Collection (ATCC) and clinical isolates such as Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Methicillin Resistant Staphylococcus aureus, Candida albicans using MIC assay. The anthelmintic assay was carried out on adult earthworm (Pheretima posthuma), while antioxidant activity was analyzed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging method.
Results
Trans-geraniol (35.38 %), α-citral (20.37 %) and β-citral (14.76 %) were the major compounds comprising 70.51 % of the essential oil. Our results showed that T. bovei essential oil exhibited strong anthelmintic activity, even higher than piperazine citrate, the used reference standard, with potential antioxidant activity almost equal to the Trolox standard. Furthermore, T. bovei essential oil had powerful antibacterial and antifungal activities against the studied pathogens.
Conclusion
Essential oil of T. bovei exerted excellent antioxidant, antimicrobial, and anthelmintic activities. Moreover, this study found that T. bovei volatile oil contains active substances that could potentially be used as natural preservatives in food and pharmaceutical industries, these substances could also be employed for developing new anthelmintic, antimicrobial and antioxidant agents.
doi:10.1186/s12906-016-1408-2
PMCID: PMC5080681  PMID: 27782845
Thymus bovei; Essential oil; Antioxidant; Anthelmintic; Antimicrobial
19.  Antioxidant and antibacterial activities of the leaf essential oil and its constituents furanodienone and curzerenone from Lindera pulcherrima (Nees.) Benth. ex hook. f. 
Pharmacognosy Research  2012;4(2):80-84.
Background:
Lindera pulcherrima (Nees.) Benth. ex Hook. f. (Family: Lauraceae), an evergreen shrub, is an important medicinal plant distributed in temperate Himalayan regions. The leaves and bark are used as spice in cold, fever, and cough.
Materials and Methods:
In this study, the terpenoid composition, antioxidant, and antibacterial activities of the leaf essential oil and its major constituents are being analyzed.
Conclusion:
The in vitro antioxidant activity showed a potent free radical scavenging activity for the essential oil as evidenced by a low IC50 value for DPPH radical followed by furanodienone (0.087 ± 0.03 and 1.164 ± 0.58 mg/ml respectively) and the inhibition of lipid peroxidation for the oil and furanodienone also followed the same order (IC50 0.74 ± 0.13 and 2.12 ± 0.49 mg/ml, respectively). The oil and the constituents were also tested against three Gram negative (Escherichia coli, Salmonella enterica enterica, and (Pasturella multocida) and one Gram positive (Staphylococcus aureus) bacteria. The essential oil was effective against S. aureus (IZ = 19.0 ± 0.34; MIC 3.90 μl/ml) while furanodienone showed potent activity against E. coli and S. enterica enterica (IZ = 18.0 ± 0.14 and 16.0 ± 0.10 respectively). On the other hand, curzerenone was found to be slightly effective against E. coli (IZ = 10.8 ± 0.52). The MIC value of the essential oil was least against S. aureus (MIC = 3.90 μl/ml) and that of furanodienone against E. coli (MIC = 3.90 μl/ml).
doi:10.4103/0974-8490.94721
PMCID: PMC3326761  PMID: 22518079
Antibacterial; antioxidant; curzerenone; furanodienone; lauraceae; lindera
20.  Chemical Composition and Antioxidant Properties of Juniper Berry (Juniperus communis L.) Essential Oil. Action of the Essential Oil on the Antioxidant Protection of Saccharomyces cerevisiae Model Organism 
Antioxidants  2014;3(1):81-98.
The essential oil of juniper berries (Juniperus communis L., Cupressaceae) is traditionally used for medicinal and flavoring purposes. As elucidated by gas chromatography/flame ionization detector (GC/FID) and gas chromatography/mass spectrometry (GC/MS methods), the juniper berry oil from Bulgaria is largely comprised of monoterpene hydrocarbons such as α-pinene (51.4%), myrcene (8.3%), sabinene (5.8%), limonene (5.1%) and β-pinene (5.0%). The antioxidant capacity of the essential oil was evaluated in vitro by 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging, 2,2-azino-bis-3-ethylbenzothiazoline-6 sulfonic acid (ABTS) radical cation scavenging, hydroxyl radical (ОН•) scavenging and chelating capacity, superoxide radical (•O2−) scavenging and xanthine oxidase inhibitory effects, hydrogen peroxide scavenging. The antioxidant activity of the oil attributable to electron transfer made juniper berry essential oil a strong antioxidant, whereas the antioxidant activity attributable to hydrogen atom transfer was lower. Lipid peroxidation inhibition by the essential oil in both stages, i.e., hydroperoxide formation and malondialdehyde formation, was less efficient than the inhibition by butylated hydroxytoluene (BHT). In vivo studies confirmed these effects of the oil which created the possibility of blocking the oxidation processes in yeast cells by increasing activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx).
doi:10.3390/antiox3010081
PMCID: PMC4665443  PMID: 26784665
juniper essential oil; Juniperus communis; GC/MS; antioxidant; Saccharomyces cerevisiae; antioxidant enzymes
21.  Antioxidative Properties and Inhibition of Key Enzymes Relevant to Type-2 Diabetes and Hypertension by Essential Oils from Black Pepper 
The antioxidant properties and effect of essential oil of black pepper (Piper guineense) seeds on α-amylase, α-glucosidase (key enzymes linked to type-2 diabetes), and angiotensin-I converting enzyme (ACE) (key enzyme linked to hypertension) were assessed. The essential oil was obtained by hydrodistillation and dried with anhydrous Na2SO4, and the phenolic content, radical [1,1-diphenyl-2 picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) and nitric oxide (NO)] scavenging abilities as well as the ferric reducing antioxidant property (FRAP) and Fe2+-chelating ability of the essential oil were investigated. Furthermore, the effect on α-amylase, α-glucosidase, and ACE enzyme activities was also investigated. The characterization of the constituents was done using GC. The essential oil scavenged DPPH∗, NO∗, and ABTS∗ and chelated Fe2+. α-Pinene, β-pinene, cis-ocimene, myrcene, allo-ocimene, and 1,8-cineole were among the constituents identified by GC. The essential oil inhibited α-amylase, α-glucosidase, and ACE enzyme activities in concentration-dependent manners, though exhibiting a stronger inhibition of α-glucosidase than α-amylase activities. Conclusively, the phenolic content, antioxidant activity, and inhibition of α-amylase, α-glucosidase, and angiotensin-1 converting enzyme activities by the essential oil extract of black pepper could be part of the mechanism by which the essential oil could manage and/or prevent type-2 diabetes and hypertension.
doi:10.1155/2013/926047
PMCID: PMC3856121  PMID: 24348547
22.  Comparative chemical profiling, cholinesterase inhibitions and anti-radicals properties of essential oils from Polygonum hydropiper L: A Preliminary anti- Alzheimer’s study 
Background
Cholinesterase inhibition is a vital target for the development of novel and mechanism based inhibitors, owing to their role in the breakdown of acetylcholine (ACh) neurotransmitter to treat various neurological disorders including Alzheimer’s disease (AD). Similarly, free radicals are implicated in the progression of various diseases like neurodegenerative disorders. Due to lipid solubility and potential to easily cross blood brain barrier, this study was designed to investigate the anticholinesterase and antioxidant potentials of the standardized essential oils from the leaves and flowers of Polygonum hydropiper.
Methods
Essential oils from the leaves (Ph.LO) and flowers (Ph.FO) of P. hdropiper were isolated using Clevenger apparatus. Oil samples were analyzed by GC-MS to identify major components and to attribute the antioxidant and anticholinesterase activity to specific components. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory potentials of the samples were determined following Ellman’s assay. Antioxidant assays were performed using 1,1-diphenyl,2-picrylhydrazyl (DPPH), 2,2-azinobis[3-ethylbenzthiazoline]-6-sulfonic acid (ABTS) and hydrogen peroxide (H2O2) free radical scavenging assays.
Results
In the GC-MS analysis 141 and 122 compounds were indentified in Ph.LO and Ph.FO respectively. Caryophylene oxide (41.42 %) was the major component in Ph.FO while decahydronaphthalene (38.29 %) was prominent in Ph.LO. In AChE inhibition, Ph.LO and Ph.FO exhibited 87.00** and 79.66***% inhibitions at 1000 μg/ml with IC50 of 120 and 220 μg/ml respectively. The IC50 value for galanthamine was 15 μg/ml. In BChE inhibitory assay, Ph.LO and Ph.FO caused 82.66*** (IC50 130 μg/ml) and 77.50***% (IC50 225 μg/ml) inhibitions respectively at 1000 μg/ml concentration. In DPPH free radical scavenging assay, Ph.LO and Ph.FO exhibited IC50 of 20 and 200 μg/ml respectively. The calculated IC50s were 180 & 60 μg/ml for Ph.LO, and 45 & 50 μg/ml for Ph.FO in scavenging of ABTS and H2O2 free radicals respectively.
Conclusions
In the current study, essential oils from leaves and flowers of P. hydropiper exhibited dose dependent anticholinesterase and antioxidant activities. Leaves essential oil were more effective and can be subjected to further in-vitro and in-vivo anti-Alzheimer’s studies.
Electronic supplementary material
The online version of this article (doi:10.1186/s12944-015-0145-8) contains supplementary material, which is available to authorized users.
doi:10.1186/s12944-015-0145-8
PMCID: PMC4632677  PMID: 26530857
Polygonum hydropiper; Essential oils; GC-MS; Anticholinesterase and antioxidant
23.  Enhancement of the antibiotic activity of erythromycin by volatile compounds of Lippia alba (Mill.) N.E. Brown against Staphylococcus aureus 
Pharmacognosy Magazine  2011;7(28):334-337.
Background:
Lippia alba (Mill.) N.E. Brown, popularly known as “erva-cidreira,” is commonly found in northeastern Brazil. The leaves tea is used to treat digestive disturbances, nausea, cough, and bronchitis.
Objective:
This work reports the chemical composition and erythromycin-modifying activity by gaseous contact against Staphylococcus aureus.
Materials and Methods:
The leaves of L. alba were subjected to hydrodistillation, and the essential oil extracted was examined with respect to the chemical composition, by gas chromatography-mass spectrometry (GC-MS), and the essential oil extracted was evaluated for antibacterial and antibiotic-modifying activity by gaseous contact.
Results:
The overall yield of essential oil obtained by hydrodistillation was 0.52%. The GC-MS analysis has led to the identification of the main components: geranial (31.4%) and neral (29.5%). It was verified that the essential oil interfered with erythromycin antibiotic activity against S. aureus ATCC 25923 was enhanced (221.4%) in the presence of 12% essential oil. The 3% essential oil increased the effect against S. aureus ATCC 25923 (41.6%) and S. aureus ATCC 6538 (58.3%). Conclusion: The essential oil of L. alba influences the activity of erythromycin and may be used as an adjuvant in antibiotic therapy against respiratory tract bacterial pathogens.
Conclusion:
The essential oil of L. alba influences the activity of erythromycin and may be used as an adjuvant in antibiotic therapy against respiratory tract bacterial pathogens.
doi:10.4103/0973-1296.90415
PMCID: PMC3261068  PMID: 22262937
Chemical composition; erythromycin; essential oil; Lippia alba; modulatory activity
24.  Chemical Composition, Antioxidant and Antimicrobial Activities of Thymus capitata Essential Oil with Its Preservative Effect against Listeria monocytogenes Inoculated in Minced Beef Meat 
The chemical composition, antioxidant and antimicrobial activities, and the preservative effect of Thymus capitata essential oil against Listeria monocytogenes inoculated in minced beef meat were evaluated. The essential oil extracted was chemically analyzed by gas chromatography-mass spectrometry. Nineteen components were identified, of which carvacrol represented (88.89%) of the oil. The antioxidant activity was assessed in vitro by using both the DPPH and the ABTS assays. The findings showed that the essential oil exhibited high antioxidant activity, which was comparable to the reference standards (BHT and ascorbic acid) with IC50 values of 44.16 and 0.463 μg/mL determined by the free-radical scavenging DPPH and ABTS assays, respectively. Furthermore, the essential oil was evaluated for its antimicrobial activity using disc agar diffusion and microdilution methods. The results demonstrated that the zone of inhibition varied from moderate to strong (15–80 mm) and the minimum inhibition concentration values ranged from 0.32 to 20 mg/mL. In addition, essential oil evaluated in vivo against Listeria monocytogenes showed clear and strong inhibitory effect. The application of 0.25 or 1% (v/w) essential oil of T. capitata to minced beef significantly reduced the L. monocytogenes population when compared to those of control samples (P-value  <0.01).
doi:10.1155/2014/152487
PMCID: PMC3955612  PMID: 24719640
25.  Antioxidant Activity and Volatile and Phenolic Profiles of Essential Oil and Different Extracts of Wild Mint (Mentha longifolia) from the Pakistani Flora 
The antioxidant activity and free radical scavenging capacity of the essential oil and three different extracts of wildly grown Mentha longifolia (M. longifolia) were studied. The essential oil from M. longifolia aerial parts was isolated by hydrodistillation technique using Clevenger-type apparatus. The extracts were prepared with three solvents of different polarity (n-hexane, dichloromethane, and methanol) using Soxhlet extractor. Maximum extract yield was obtained with methanol (12.6 g/100 g) while the minimum with dichloromethane (3.50 g/100 g). The essential oil content was found to be 1.07 g/100 g. A total of 19 constituents were identified in the M. longifolia oil using GC/MS. The main components detected were piperitenone oxide, piperitenone, germacrene D, borneol, and β-caryophyllene. The total phenolics (TP) and total flavonoids (TF) contents of the methanol extract of M. longifolia were found to be significantly higher than dichloromethane and hexane extracts. The dichloromethane and methanol extracts exhibited excellent antioxidant activity as assessed by 2,2′-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging ability, bleaching β-carotene, and inhibition of linoleic acid peroxidation assays. The essential oil and hexane extract showed comparatively weaker antioxidant and free radical scavenging activities. The results of the study have validated the medicinal and antioxidant potential of M. longifolia essential oil and extracts.
doi:10.1155/2013/536490
PMCID: PMC3808703  PMID: 24224115

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