Variation in the susceptibility of two Callosobruchus species to essential oils

GC/MS analysis of essential oils extracted from two Cymbopogon species revealed that limonene (23%) and p-mentha-2,8-dien-1-ol in cis (14.3%) and trans (5.6%) forms were the main compounds in Cymbopogon giganteus oil whereas citronellal (31%) and geraniol (24%) were identified in Cymbopogon nardus oil. The toxicity tests performed by fumigation on eggs and adults of Callosobruchus maculatus and Callosobruchus subinnotatus using both essential oils showed a variation in bruchid susceptibility. Essential oil of C. giganteus was more toxic to adults of both bruchid species while essential oil of C. nardus showed the better ovicidal activity. Comparative susceptibility analysis suggested that eggs and adults of C. subinnotatus were two-fold more tolerant to essential oils than C. maculatus in both stages. Oviposition of treated females was strongly reduced in the presence of essential oils. Callosobruchus subinnotatus was more affected than C. maculatus by the essential oil of C. giganteus (oviposition reduction by at least 91% v.s 81% in C. maculatus at 5 μL/L) but the two species were affected similarly by the essential oil of C. nardus.     

Activity of essential oil and its major compound, 1,8-cineole, from Eucalyptus globulus Labill., against the storage fungi Aspergillus flavus Link and Aspergillus parasiticus Speare

The essential oil from leaves of Eucalyptus globulus obtained by hydrodistillation, as well as its major compound 1,8-cineole, identified by gas chromatography coupled with a mass selective detector, were evaluated for their effectiveness against the storage fungi Aspergillus flavus and Aspergillus parasiticus. The evaluation was performed by compound dissolution in yeast extract sucrose (YES) medium and exposure to headspace volatiles. Complete fungal growth inhibition of both species was achieved with the essential oil by contact and volatile assays. Volatile exposure showed total inhibition at the lower level tested of 500 μL. The 1,8-cineole tested alone showed partial inhibition only at the highest level of 1.3492 μL. Aflatoxin B₁ production was reduced in headspace volatile assays and partial inhibition was observed at the 200 μL dose of the essential oil.     

Chemical and biological characteristics of Cuminum cyminum and Rosmarinus officinalis essential oils

Essential oils extracted by hydrodistillation from Cuminum cyminum and Rosmarinus officinalis were characterized by means of GC and GC–MS. C. cyminum and R. officinalis contained α-pinene (29.1%, 14.9%), 1,8-cineole (17.9%, 7.43%) and linalool (10.4%, 14.9%), respectively, as the major compounds. C. cyminum oil exhibited stronger antimicrobial activity than did R. officinalis oil against E. coli, S. aureus and L. monocytogenes. Complete death time on exposure to Cuminum cyminum L. and Rosmarinus officinalis L. oils were 20 and 25 min 180 and 240 min and 90 and 120 min for E. coli, S. aureus and L. monocytogenes, respectively. Radical-scavenging and antioxidant properties were tested by means of 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay and the β-carotene bleaching test. These properties were compared to those of Thymus x-porlock essential oil, used as a reference ingredient. The radical scavenging performance of the rosemary oil was better than that of C. cyminum. Results from the antioxidant test were better than those provided by the radical-scavenging activity. C. cyminum and R. officinalis essential oils may be considered as potent agents in food preservation.     

Fumigant toxicity of essential oil from Artemisia sieberi Besser against three stored-product insects

Artemisia sieberi is a widely distributed plant in Iran. Because some species of Artemisia are insecticidal, experiments were conducted to investigate fumigant toxicity of the essential oil. Dry ground leaves were subjected to hydrodistillation using a modified Clevenger-type apparatus and the resulting oil contained camphor (54.7%), camphene (11.7%), 1,8-cineol (9.9%), β-thujone (5.6%) and α- pinene (2.5%).The mortality of 7 days old adults of Callosobruchus maculatus, Sitophilus oryzae, and Tribolium castaneum increased with concentration from 37 to 926 μL/L and with exposure time from 3 to 24 h. A concentration of 37 μL/L and an exposure time of 24 h was sufficient to obtain 100% kill of the insects. Callosobruchus maculatus was significantly more susceptible than S. oryzae and T. castaneum; a second more detailed bioassay gave estimates for the LC₅₀ of C. maculatus as 1.45 μL/L, S. oryzae 3.86 μL/L and T. castaneum 16.76 μL/L. These results suggested that A. sieberi oil may have potential as a control agent against C. maculatus, S. oryzae and T. castaneum.     

Comparative chemical composition,free radical-scavenging and cytotoxic properties of essential oils of six Stachys species from different regions of the Mediterranean Area

The chemical composition of essential oils of six Stachys species, S. cretica L. ssp. vacillans Rech. fil., S. germanica L., S. hydrophila Boiss., S. nivea Labill., S. palustris L. and S. spinosa L., obtained by hydrodistillation, was studied by GC and GC–MS. All the oils have in common a great percentage of fatty acids and esters (24.2–58.5%) and a high amount of sesquiterpenes (16–35.9%), with the exception of the oil from S. palustris, which consisted mainly of carbonylic compounds (25.4%). The antioxidant activity by DPPH test and the antiproliferative activity on a series of human cancer cell lines (C32, amelanotic melanoma and ACHN, renal cell adenocarcinoma) were investigated for all the oils. S. palustris,S. cretica and S. hydrophila showed the highest antiradical effect, with IC₅₀ values of 0.482, 0.652 and 0.664 mg/ml, respectively. The most antiproliferative essential oil against C32 cell line was the oil of S. germanica with a 77% of inhibition at a concentration of 100 μg/ml. S. germanica, S. palustris and S. spinosa showed the most antiproliferative activity on ACHN cell line, at a concentration of 100 μg/ml,with 81%, 77% and 73% inhibition, respectively.     

High-efficient column chromatographic extraction of curcumin from Curcuma longa

Curcumin is an important food additive and a potential therapeutic agent for various diseases from turmeric, the rhizome of Curcuma longa L. High-efficient column chromatographic extraction (CCE) procedures were developed for the extraction of curcumin from turmeric. Turmeric powder was loaded into a column with 2-fold 80% ethanol. The column was eluted with 80% ethanol at room temperature. For quantitative analysis with a non-cyclic CCE, 8-fold eluent was collected as extraction solution. For large preparation with a cyclic CCE, only the first 2-fold of eluent was collected as extraction and other eluent was sequentially circulated to the next columns. More than 99% extraction rates were obtained through both CCE procedures, compared to a 59% extraction rate by the ultrasonic-assisted maceration extraction with 10-fold 80% ethanol. The CCE procedures are high-efficient for the extraction of curcumin from turmeric with minimum use of solvent and high concentration of extraction solution.     

Insecticidal activities of aromatic plant extracts and essential oils against Sitophilus oryzae and Callosobruchus chinensis

Methanol extracts from 30 aromatic medicinal plant species and five essential oils were tested for their insecticidal activities against adults of Sitophilus oryzae (L.) and Callosobruchus chinensis (L.), using direct contact application and fumigation methods. Responses varied with plant material, insect species, and exposure time. In a test with a filter paper diffusion method at 3.5 mg/cm², potent insecticidal activity against both species was produced by an extract from Cinnamomum cassia bark, cinnamon (C. cassia) oil, horseradish (Cocholeria aroracia) oil, and mustard (Brassica juncea) oil within 1 day after treatment. Over 90% mortality at 3 or 4 days after treatment was achieved using extracts of Acorus calamus var. angustatus rhizome, Acorus gramineus rhizome, Illicium verum fruit, and Foeniculum vulgare fruit. An extract from Cinnamomum sieboldii root bark gave 100% mortality at 2 days after treatment. At 0.7 mg/cm², extracts from C. cassia, C. sieboldii, and F. vulgare as well as cinnamon oil, horseradish oil and mustard oil were highly effective against both species. In a fumigation test with S. oryzae adults, the oils described were much more effective in closed containers than in open ones, indicating that the insecticidal activity of the oils was attributable to fumigant action. The plant extracts and essential oils described could be useful for managing field populations of S. oryzae and C. chinensis.     

In vitro antimicrobial activity of essential oil from endemic Origanum minutiflorum on ciprofloxacin-resistant Campylobacter spp.

This study evaluated the antimicrobial activities of an essential oil of Origanum minutiflorum (O. Schwarz and P.H. Davis) against ciprofloxacin-resistant Campylobacter spp., by broth microdilution and agar well-diffusion methods. Moreover, O. minutiflorum oil was analyzed by gas chromatography/mass spectrometry (GC/MS). Twenty-nine components were identified, representing 98.7 of the oil. The oil yield from the plants was 4.0–4.4% v/w. The major components of O. minutiflorum oil were carvacrol (73.9%) and p-cymene (7.20%). The oil has lower contents of carvacrol methyl ether (0.05%), heptadecanol (0.06%) and carvacryl acetate (0.06%). Twenty-one Campylobacter spp. (12 C. jejuni, 5 C. lari and 4 C. coli) strains using in this study were selected among 300 isolates according to their resistance to ciprofloxacin. The minimum inhibitory concentration (MIC) values for bacterial strains, which were sensitive to the essential oil of O. minutiflorum, were in the range of 7.8–800 μg/ml. The essential oil obtained showed strong antimicrobial activity against all of the tested ciprofloxacin-resistance Campylobacter spp. These results suggest that the essential of O. minutiflorum may be used as a natural preservative in food against food-born disease, such as Campylobacteriosis.     

Efficacy of powder and essential oil from Chenopodium ambrosioides leaves as post-harvest grain protectants against six-stored product beetles

Powder and essential oil obtained from dry ground leaves of Chenopodium ambrosioides were tested under laboratory conditions (25±1°C, 70-75% r.h.) for their ability to protect grains from damage by six insect pests, Callosobruchus chinensis, C. maculatus, Acanthoscelides obtectus, Sitophilus granarius, S. zeamais and Prostephanus truncatus. The insects were reared and tested on whole maize grain for S. zeamais and P. truncatus, whole wheat for S. granarius, green peas for C. chinensis, mung bean for C. maculatus and white bean for A. obtectus. The powder prepared from dry leaves of C. ambrosioides was mixed with grains at different dosages ranging from 0.05-0.80% (wt/wt) for C. chinensis, C. maculatus and A. obtectus and from 0.8-6.4% (wt/wt) for S. granarius, S. zeamais and P. truncatus. The dosage of 0.4% killed more than 60% of all the bruchids 2 days after treatment, while a dosage of 6.4% induced total mortality of S. granarius and S. zeamais within the same exposure time. All levels of the dry ground leaf concentrations inhibited F1 progeny production and adult emergence of the tested insects. The dosage of 0.2 μl/cm² of the essential oil killed 80-100% of the beetles within 24 h except C. maculatus and S. zeamais, where this dosage induced only 20% and 5% mortality, respectively. These results indicate a scientific rationale for the use of this plant in grain protection by local communities in the western highlands of Cameroon.     

Satureja horvatii essential oil: In vitro antimicrobial and antiradical properties and in situ control of Listeria monocytogenes in pork meat

The dominant compounds in Satureja horvatii oil were p-cymene (33.14%), thymol (26.11%) and thymol methyl ether (15.08%). The minimum inhibitory concentration (MIC) varied from 0.03 to 0.57 mg/mL for bacteria, and from 0.56 to 2.23 mg/mL for yeast strains, while minimum bactericidal/yeast-cidal concentration (MBC/MYC) varied from 0.07 to 1.15 mg/mL and 1.11 to 5.57 mg/mL for bacteria and yeasts, respectively. The antiradical potential of the essential oil was evaluated using hydroxyl radical (•OH) generated in Fenton reaction. The meat preserving potential of essential oil from Satureja horvatii was investigated against L. monocytogenes. Essential oil successfully inhibited development of L. monocytogenes in pork meat. Sensorial evaluation on flavor and color of meat was performed. The color and flavor of meat treated with essential oil improved after 4 days of storage. S. horvatii essential oil can act as a potent inhibitor of food spoiling microorganisms, in meat products and also can be a useful source of natural antioxidants.     

Response surface methodology applied to supercritical carbon dioxide extraction of Piper nigrum L. essential oil

This study was conducted to optimize the supercritical carbon dioxide (SC-CO₂) extraction of Piper nigrum L. essential oil using response surface methodology (RSM). In order to obtain the maximum yield of the essential oil, experiments were carried out using a three-factor central composite design (CCD) under following conditions: pressure of 15–30 MPa, temperature of 40–50 °C and dynamic extraction time of 40–80 min. A second-order polynomial regression model expressing the total extraction yield as a function of main SC-CO₂ variables was significantly (p < 0.05) fitted, with high coefficient of determination value (R² > 0.985). The results showed that the best extraction yield (2.16%) was obtained at 30 MPa, 50 °C and 80 min. Pressure showed the most significant (p < 0.05) effect on the yield variation. The chemical composition of the essential oil was determined using GC-flame ionization detection (FID) and gas chromatography–mass spectrometry (GC–MS) analysis. The main constituents (concentration > 3.0%, calculated as % peak area) in the P. nigrum L. essential oil obtained through SC-CO₂ extraction were determined to be β-caryophyllene (24.34%), limonene (15.84%), sabinene (15.04%), 3-carene (9.44%), β-pinene (9.27%) and copaene (4.52%).     

Major chemotypes and antioxidative activity of the leaf essential oils of Cinnamomum osmophloeum Kaneh. from a clonal orchard

Essential oils of 92 cutting clones from a clonal orchard of Cinnamomum osmophloeum Kaneh. were obtained by hydrodistillation and characterised by gas chromatography–mass spectrometry. Our results showed that the yields of essential oils ranged between 0.09% and 2.65% (vol/fresh wt). The constituents of essential oils varied among samples. The major chemotypes classified in the individual cutting clones were cinnamaldehyde (50 plants, representing 50–95% of the total volatiles), linalool (1 plant, 73.3%), β-cubebene (2 plants, 59.4% and 78.7%), and cinnamyl acetate (1 plant, 61.8%). The antioxidant activities of the four chemotypes were determined using a 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The antioxidant activities of the essential oil decreased in the order of cinnamyl acetate > cinnamaldehyde > β-cubebene > linalool. Indigenous cinnamon oil extract showed a good free radical-scavenging capacity at all concentrations studied, except at 2 μg/ml. The scavenging activity increased with increasing concentration of the extract. The capability of the four essential oil chemotypes to reduce the stable radical, DPPH, to DPPH-H was assayed by a decrease in the IC₅₀ values of 10.4 (cinnamyl acetate type) to 29.7 (linalool type) μg/ml. These results suggest that the leaf essential oil of C. osmophloeum possesses chemical compounds with antioxidant activity which can be used as natural preservatives in food and/or by the pharmaceutical industry. Trees in this plantation which can be used for further propagation for the production of chemotypes of interest were identified.     

Interference of Origanum vulgare L. essential oil on the growth and some physiological characteristics of Staphylococcus aureus strains isolated from foods

The aim of this study was to investigate the chemical composition of Origanum vulgare L. essential oil, the inhibitory effect of the oil on the cell viability of Staphylococcus aureus strains isolated from foods, and the influence of sub-inhibitory concentrations of the oil on some physiological attributes of these strains. GC-MS analysis showed that carvacrol (57.71%) was the most prevalent compound in the oil, followed by p-cymene (10.91%), γ-terpinene (7.18%), terpinen-4-ol (6.68%) and thymol (3.83%). The results showed that O. vulgare essential oil at 0.03, 0.6 and 0.12 μL mL⁻¹ inhibited the cell viability of Staph. aureus. At 0.12 μL mL⁻¹ the oil caused cidal effect with decrease ≥3 log cycles of the initial inoculum after 15 min of exposure. Sub-inhibitory concentrations (0.03 and 0.015 μL mL⁻¹) of the oil suppressed some physiological attributes of the Staph. aureus strains such as coagulase, lipase and salt tolerance. The oil interfered on the microbial metabolic activity in a dose-dependent manner. O. vulgare essential oil could be a novel antimicrobial with capability to suppress some physiological characteristics, in addition to inhibit the growth and survival of pathogen bacteria in foods, particularly Staph. aureus.     

Solvent-free microwave extraction of essential oil from Dryopteris fragrans and evaluation of antioxidant activity

Solvent-free microwave extraction (SFME) of the essential oil from Dryopteris fragrans and its antioxidant activity were investigated. A central composite design combined with response surface methodology was applied to study the influences of extraction time, irradiation power and humidity (proportion of water pretreatment). A maximal extraction yield of 0.33% was achieved under optimal conditions of extraction time 34 min, irradiation power 520 W and humidity 51%. Sixteen compounds, representing 89.65% of the oil, were identified, of which the major ones, (1R,4S,11R)-4,6,6,11-tetramethyltricyclo[5.4.0.0(4,8)]undecan-1-ol (30.49%), 1R,4S,7S,11R-2,2,4,8-tetramethyltricyclo[5.3.1.0(4,11)]undec-8-ene (22.91%) and, 1,4,4a,5,6,7,8,8a-octahydro-2,5,5,8a-tetramethyl-1-naphthalenemethanol (15.11%), accounted for 68.51% of the oil. The antioxidant activity of the essential oil was assessed by 2,2-diphenyl-1-picrylhydrazyl (DPPH), β-carotene/linoleic acid, and reducing power assay, the IC₅₀ values were 0.19, 0.09 and 0.18 mg/mL, respectively. All these results suggest that SFME represents an excellent alternative protocol for production of essential oils from plant materials.     

Antifungal,antiaflatoxin and antioxidant potential of chemically characterized Boswellia carterii Birdw essential oil and its in vivo practical applicability in preservation of Piper nigrum L. fruits

The study explores the chemical profile, antimicrobial and antioxidant activity of Boswellia carterii essential oil (EO). The EO significantly inhibited growth and aflatoxin production by the food borne toxigenic strain of Aspergillus flavus at 1.75 μl/ml and 1.25 μl/ml respectively. It exhibited broad fungitoxic spectrum against 12 food borne moulds and also showed strong antioxidant activity, IC₅₀ value and % inhibition of linoleic acid peroxidation being 0.64 μl/ml and 51.68% respectively. The antifungal action of EO was observed in terms of reduction in ergosterol content of plasma membrane of A. flavus. As fumigant in food system in storage containers, the EO provided 65.38% protection against fungal deterioration of Piper nigrum. GC–MS results revealed 31 components of EO. The chemically characterized B. carterii EO may thus be recommended as plant based preservative in view of its antifungal, antiaflatoxigenic, antioxidant activity and efficacy in food system.     

The in vitro antioxidative properties of the essential oils and methanol extracts of Satureja spicigera (K. Koch.) Boiss. and Satureja cuneifolia ten

This study was designed to examine the in vitro antioxidant activities of the essential oil and methanol extracts of Satureja spicigera and S. cuneifolia from Turkish flora. GC and GC/MS analysis of the essential oils resulted in the identification of 40 and 29 compounds, representing the 99.4% and 99.5% of the oils, respectively. Major constituents of the oils were carvacrol (42.5% and 67.1%), γ-terpinene (21.5% and 15.2%) and p-cymene (20.9% and 6.7%), respectively. Methanol extracts were also obtained from the aerial parts of the plants. The samples were subjected to a screening for their possible antioxidant activities by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and β-carotene–linoleic acid assays. In general, samples obtained from S. cuneifolia exerted greater antioxidant activities than did those obtained from S. spicigera. In the DPPH test system, free radical-scavenging activity of S. spicigera oil was determined to be 127 ± 1.63 μg/ml, whereas IC₅₀ value of S. cuneifolia was 89.1 ± 2.29 μg/ml. In the β-carotene–linoleic acid test system, antioxidant activities of the oil were 81.7 ± 1.14% and 93.7 ± 1.83%, respectively. Antioxidant activities of the synthetic antioxidant, BHT, ascorbic acid, curcumin and α-tocopherol were also determined in parallel experiments.     

Chemical composition and antioxidant and antimicrobial activity of two Satureja essential oils

Hydro-distilled volatile oils from the aerial parts of Satureja montana L., and Satureja subspicata Bartl. ex Vis., growing wild in Bosnia and Herzegovina, were analyzed by GC/MS. More than one hundred compounds were identified in both plant oils, representing 92.4–98.1% of the total oil. The major constituents of essential oils obtained from the plant material of S. montana, collected from two different localities, were thymol (31.7%), and geraniol (22.3%), respectively. The most abundant compounds in essential oils of S. subspicata, collected at two different stages of development, were thymol (28.6%), and spathulenol (37.6%), respectively. The screening of antimicrobial activity of essential oil samples was individually evaluated against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis using a paper disc diffusion method. All tested microorganisms were inhibited by essential oil samples. Antioxidant activity was tested using the DPPH radical-scavenging method. All samples showed activity comparable to thymol, which was used as a positive probe.     

Fumigant toxicity of essential oils from three Thai plants (Zingiberaceae) and their major compounds against Sitophilus zeamais, Tribolium castaneum and two parasitoids

Fumigant toxicity of essential oils from rhizomes of Alpinia conchigera, Zingiber zerumbet, Curcuma zedoaria and their major compounds; camphene, camphor, 1,8-cineole, α-humulene, isoborneol, α-pinene, β-pinene and terpinen-4-ol was investigated with adults of Sitophilus zeamais, Tribolium castaneum, Anisopteromalus calandrae and Trichogramma deion larvae. The last two insects are parasitoids commonly used to control stored-product weevils and moths. The trial was evaluated at 0, 37, 74, 148, 296, 444, 593 μL/L in air after 12, 24 and 48 h for S. zeamais, T. castaneum and A. calandrae, and 24 h for T. deion. Alpinia conchigera oils were toxic to S. zeamais, T. castaneum and T. deion, while the other two plant oils had low toxicity. Adults of S. zeamais and T. castaneum were more susceptible to A. conchigera oils than their eggs, larvae or pupae. Sitophilus zeamais adults (LC₅₀ 85 μL/L in air) were slightly more tolerant of A. conchigera oils than T. castaneum (LC₅₀ 73 μL/L in air) after 48 h exposure. Synthetic essential oils, a mixture of pure compounds in the same ratios of the extracted essential oils, were tested with S. zeamais and T. castaneum adults. Synthetic essential oils were more toxic than the extracted essential oils to both insects. Zingiber zerumbet oils (LC₅₀ 26 μL/L in air) and C. zedoaria oils (LC₅₀ 25 μL/L in air) were significantly more toxic to adults of A. calandrae than A. conchigera oils (LC₅₀ 37 μL/L in air) whereas T. deion larvae were more sensitive to A. conchigera oils (LC₅₀ 62 μL/L in air) than Z. zerumbet and C. zedoaria oils (LC₅₀ > 593 μL/L in air). Tribolium castaneum was more susceptible than S. zeamais to the eight pure compounds. Terpinen-4-ol was highly toxic to both insects.     

Chemical analysis,antioxidant, antiinflammatory and anticholinesterase activities of Origanum ehrenbergii Boiss and Origanum syriacum L. essential oils

The essential oils of Origanum ehrenbergii and O. syriacum collected in Lebanon were analysed by GC and GC–MS and evaluated for their anticholinesterase, NO production inhibitory activities, and antioxidant properties. O.ehrenbergi essential oil was characterised by the presence of 37 components, representing 94.9% of the total oil of which thymol (19%) and p-cymene (16.1%) were the main abundant compounds. Thirty-six compounds characterised the O.syriacum essential oil, representing 90.6% of the total oil. The most abundant components were thymol (24.7%) and carvacrol (17.6%). O. ehrenbergii demonstrated interesting scavenging effects on DPPH with an IC₅₀ value of 0.99 μg/ml. In addition, both O. ehrenbergii and O. syriacum oils inhibited oxidation of linoleic acid after 30 min of incubation, as well as after 60 min of incubation with IC₅₀ values of 42.1 and 33.6 μg/ml, and 46.9 and 58.9 μg/ml, respectively. Interestingly, O. ehrenbergii oil inhibited NO production in the murine monocytic macrophage cell line RAW 264.7 with an IC₅₀ value of 66.4 μg/ml. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibition was assessed by modifications of the Ellman’s method. O. ehrenbergii exhibited a strong activity against both cholinesterases with IC₅₀ values of 0.3 μg/ml. The data suggest that O. ehrenbergii and O. syriacum oils could be used as a valuable new flavour with functional properties for food or nutriceutical products with particular relevance to supplements for the elderly.