Chemical analysis of essential oils of Eupatorium adenophorum and their antimicrobial,antioxidant and phytotoxic properties

Essential oils from inflorescences and roots of Eupatorium adenophorum Spreng (Asteraceae) have been investigated for their antimicrobial, phytotoxic and antioxidant activities. Based on GC–MS, the oil from inflorescences is dominated by sesquiterpenes (55.9 %) with γ-cadinene (18.4 %), γ-muurolene (11.7 %), 3-acetoxyamorpha-4,7(11)-diene-8-one (7.4 %) and bornyl acetate (6.3 %) as the major constituents. The oil obtained from the roots contained both sesquiterpenes (34.3 %) and monoterpenes (32.5 %) in almost equal proportions with E,E-cosmene (19.9 %), γ-muurolene (10.1 %), isothymol (7.5 %), β-cadinene (7.0 %) and α-phellandren-8-ol (5.9 %) as the major constituents. Both oils exhibited significant antifungal activity against five phytopathogenic fungi. The inflorescence oil showed higher antibacterial activity against Klebsiella pneumoniae, while the root oil was more effective against Staphylococcus aureus. The oils strongly inhibited or delayed germination and seedling growth of the weed Phalaris minor in a dose-dependent manner. As evidenced by a DPPH assay, the essential oils also exhibited significant free radical scavenging activity.     

Chemical composition,insecticidal and repellence activities of essential oils of three Achillea species against the Khapra beetle (Coleoptera: Dermestidae)

Essential oils of Achillea biebersteinii, Achillea santolina and Achillea mellifolium were obtained by hydrodistillation and analyzed using gas chromatography/mass spectrometry. The plant oils were tested for their toxic and repellent activities against the Khapra beetle, Trogoderma granarium (Everts) (Coleoptera: Dermestidae). T. granarium was sensitive to the oils via topical application, contact and fumigation bioassays, where A. biebersteinii oil was the most toxic regardless of the technique used. Using topical application, a dosage of 15 μg/mg insect of A. biebersteinii oil was sufficient to kill 100 and 83.2.0 % after 7 days exposure of adults and 2nd instar larvae, respectively. Meanwhile, twice this concentration of A. santolina and A. mellifolium oils caused 90.4 (72.5 %) and 73.8 (60.1 %) adult and larval mortality after 7 days, respectively. Using fumigation and 7 days exposure, a concentration of 50.0 μl/l air of A. biebersteinii oil displayed the strongest activity (percentage adult and larval mortalities of 100.0 and 88.0 %), respectively, while A. santolina and A. mellifolium oils at the same concentration caused 92.5 (76.8 %) and 76.1 (61.3 %) adult and larval mortality, respectively. The three oils were strongly repellent to the larvae and adults of T. granarium. The repellent activity was time and concentration-dependent, where A. biebersteinii oil was the most effective, even though at low concentrations (percentage repellency of 100 and 81.0 % were recorded against adults and larvae after 6 h exposure to a concentration of 0.22 μl/cm², respectively). Results suggested the potential use of Achillea oils as natural grain protectants against T. granarium.     

Chemical composition and anti-inflammatory activity of <Emphasis Type="Italic">Boswellia ovalifoliolata</Emphasis> essential oils from leaf and bark

We isolated the essential oils from Boswellia ovalifoliolata N.P.Balakr and A.N.Henry using hydrodistillation, identified the obtained compounds using gas chromatography–mass spectrometry (GC–MS) and Fourier transform-infrared spectroscopy (FT-IR), and studied the photophysical and electrochemical properties using UV–visible and fluorescence spectroscopy and cyclic voltammetry. On the basis of GC–MS spectra, 38 compounds were identified in the essential oil from leaves and 26 in the oil from bark. The bark oil contained 13.44% β-Farnesene (sesquiterpene), 10.45% caryophyllene oxide (sesquiterpene) and 6.6% spathulenol, (2Z,6E)-(sesquiterpene alcohol); the leaf oil contained 11.1% spathulenol (sesquiterpene alcohol), 9.0% caryophyllene oxide (sesquiterpenoids) and 6.3% decyl acetate (ester). FT-IR spectra confirmed the presence of aliphatic aldehydes and ketones, carboxylic acid, alcohols, esters and ethers in both oil types. UV–visible absorption spectra showed maximum absorbance at 245, 290 and 402 nm for bark oil, and 250, 285 and 325 nm for leaf. Bark oil showed strong emission with maximum emission wavelength at 456 nm was higher than that of leaf oil at 414 nm. The essential oil had significant anti-inflammatory activity, and the reduction potential of the leaf oil was ?0.44 and ?0.56 eV for bark.     

Antioxidant, anti-hyaluronidase and antifungal activities of Melaleuca leucadendron Linn. leaf oils

The present study examined the chemical composition, in vitro antioxidant, anti-hyaluronidase and antifungal activities of essential oils of Melaleuca leucadendron Linn. from Gundih-Central Java, Indonesia in different plant ages of 5, 10 and 15 years old. The Chemical composition of essential oils were analyzed by GC/MS. Twenty-six components were identified, of which 1,8-cineole (49.22–55.04 %), α-terpineol (8.79–10.70 %), d-limonene (5.58–6.39 %), and β-caryophyllene (5.03–7.64 %) were the main compounds in these oils. The antioxidant assay and anti-hyaluronidase assay showed that M. leucadendron leaf oils possess mild antioxidant activity with IC₅₀ between 7.21 and 9.23 mg/ml and anti-hyaluronidase activity with IC₅₀ between 1.94 and 3.03 mg/ml. The antifungal assay showed the effectiveness of these essential oils against Fomitopsis palustris (IC₅₀ 0.12–3.16 mg/ml), Trametes versicolor (IC₅₀ 0.01–0.06 mg/ml), Cladosporium cladosporioides (IC₅₀ 0.03–0.49 mg/ml), and Chaetomium globosum (IC₅₀ 0.06–0.15 mg/ml).     

Toxicity and antitermite activity of the essential oils from Cinnamomum camphora, Cymbopogon nardus, Melaleuca cajuputi and Dipterocarpus sp. against Coptotermes curvignathus

Efficacy of four different essential oils against the subterranean termite, Coptotermes curvignathus Holmgren, was assessed in various bioassays. Laboratory results indicate that the highest termite mortality was found in Dipterocarpus sp. essential oil after 24 h (LC₅₀ = 1.62 %) and the lowest in Melaleuca cajuputi (LC₅₀ = 4.60 %). The wood consumption in the filter paper treated with Dipterocarpus sp. oil is also smaller than for the other three essential oils tested. However, the other three essential oils also inhibited termite susceptibility of the specimens. Dipterocarpus sp. (keruing oil) was the most effective insect antifeedant and repellent against C. curvignathus. The results suggest that essential oils might have some beneficial activity of economic value and are considered good candidates for the development of new chemicals (repellents or antifeedants) for termite control.     

MA-chitosan nanogel loaded with Cuminum cyminum essential oil for efficient management of two stored product beetle pests

Natural essential oils have received increased attention as alternatives to synthetic pesticides for pest management of foodstuffs. Recently, microencapsulation and other controlled release techniques are used to increase insecticidal efficiency and persistence of essential oils with slow and controlled release. In this study, the possibility of improving the insecticidal activity of plant essential oils was investigated for effective management of two stored product beetle pests. Self-assembly technique was used to prepare nanogels of myristic acid-chitosan loaded by essential oil extracted from cumin, Cuminum cyminum L. Fumigant toxicity of C. cyminum oil and oil-loaded nanogels (OLNs) were investigated at 4, 7, 10, 13, and 16 µL/L air against the granary weevil Sitophilus granarius L. and 8, 11, 14, 17, and 20 µL/L air for confused flour beetle Tribolium confusum Jacquelin du Val. Experiments were conducted at 27 ± 1 °C and 55 ± 5 % relative humidity in continuous darkness. Insecticidal bioassay revealed that OLNs were more toxic than C. cyminum oil against tested beetle pests. The persistence of the oil and OLNs was also evaluated against two tested species. Results indicated that C. cyminum oil completely lost its insecticidal activity after 12 days, whereas at the same period, the OLNs lost about 60 % of its activity when applied against S. granarius and 15% for T. confusum. Therefore, it could be concluded that encapsulation improved the persistence of the oil.     

Chemical composition and bioactivities of three Chrysanthemum essential oils against Tribolium confusum (du Val) (Coleoptera: Tenebrionidae)

Essential oils from three species of Chrysanthemum growing in Tunisia (C. coronarium, C. fuscatum, and C. grandiflorum) were first analyzed by gas chromatography (GC) and GC/mass spectrometry (MS) and then evaluated for toxicity and antifeeding action against Tribolium confusum. The essential oils obtained from leaves and flowers shared a similar qualitative composition, but the relative proportions of the constituents were quite different. The essential oil of C. grandiflorum was rich in sesquiterpenoids, while those of C. fuscatum and C. coronarium were rich in monoterpenoids. The main common constituents of all the essential oils were ??-pinene, myrcene, ??-humulene, ??-caryophylene, spathulenol, and caryophyllene oxide. The most effective essential oil was obtained from the leaves of C. grandiflorum, that inhibited the relative growth rate (?0.03?mg/mg/d), efficiency of conversion of ingested food (?50.69%), relative consumption rate, caused an antifeeding effect (66.43%) and a high mortality (80%) of T. confusum larvae. Topical application C. grandiflorum essential oil caused a significant insect mortality that attends 27% after 7?days of treatment. While essential oil from C. coronarium flowers has contact and fumigant toxicity with a mortality of 9 and 13%, respectively. Results analysis highlights a relationship between essential oils composition and insecticidal activity against T. confusum. The study showed that each essential oil has specific chemical composition and act differently according to the nature of attributed test. The use of essential oils from different Chrysanthemum species with different methods helps poor farmers who store small amounts of grains to preserve it against pest infestation.     

Chemical composition,phytotoxic and antifungal activities of <Emphasis Type="Italic">Pinus pinea</Emphasis> essential oil

The chemical composition of essential oils isolated by hydrodistillation from the aerial parts of Tunisian Pinus pinea Linn. was analyzed by GC and GC/MS. Sixty-six compounds were identified, representing 98.5% of total oil, which was found to be rich in monoterpene hydrocarbons (73.1%) particularly limonene (54.1%), α-pinene (7.7%), and β-pinene (3.4%). The yield and the physico-chemical properties were determined. Results of the antifungal activity study by in vitro contact assay showed that P. pinea oil significantly inhibited the growth of ten plant pathogenic fungi. Moreover, herbicidal properties of the oil, tested on Sinapis arvensis L., Lolium rigidum Gaud., and Raphanus raphanistrum L., indicated that the oil completely inhibited the seed germination at a high concentration, while at low doses the oil acted by decreasing and delaying the germination and inhibiting the seedling growth of all tested weeds unlike the commercial herbicide. Our results showed that P. pinea essential oil could be valorized as bioproduct for biocontrol of weeds and fungal plant diseases.     

Chemical composition,antioxidant and antibacterial activities of extracts from <Emphasis Type="Italic">Schinus molle</Emphasis> wood branch growing in Egypt

In the present work, for the first time, the chemical components of essential oils (EOs) and extracts from wood branch (WB) resulted from the tree pruning wastes of Schinus molle L. grown in Egypt were evaluated for their antioxidant and antibacterial activities. EOs, methanol (ME), dichloromethane (DCME) and water (WE) extracts as antioxidant and antibacterial activities were measured. Total phenolic and flavonoid contents as well as analysis of extracts by gas chromatography–mass spectrometry (GC–MS) were reported. The major components in EOs were α-elemol, β-pinene, and α-phellandrene, in ME were 6-(4-chlorophenyl)-3-cyano-4-(N-benzylpiperazino)-2H-pyran-2-one, and 2-naphthalene methanol, decahydro-α,α,4a-trimethyl-8-methylene, in DCME were 12-methyl-E,E-3,13-octadecadien-1-ol, and 1,2-benzenedicarboxylic acid, dioctyl ester, and in WE were β-eudesmol, and (Z,Z,Z)-9,12,15-octadecatrienoic acid, 2,3-dihydroxypropyl ester. The highest total antioxidant activity was found with EOs (90 ± 1.23 %) and WE (86.30 ± 1.40 %). The lowest IC₅₀ values of 13.11 ± 3.00, and 12.66 ± 2.15 μg/mL were found with WE and EOs, respectively. EOs and WE were observed to have good antibacterial activity against Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, Escherichia coli, Sarcina lutea, Pseudomonas aeruginosa, and Micrococcus luteus. In conclusion, the Schinus molle L. WB EOs and extracts might, indeed, be used as a potential source for pharmaceutical or food industries.     

Evaluation of the concentrations of hydrogen and methane emitted by termite using a semiconductor gas sensor

A gas detection apparatus equipped with a semiconductor gas sensor was employed for qualitative and quantitative measurement of hydrogen and methane emitted by termites. A gas sample of 2.5 ml was injected into the semiconductor gas sensor through the gas detection apparatus, and the maximum voltage of the sensor was converted into gas concentration. The gas samples were collected from three distinct experiments: (1) five combinations of workers and soldiers of Coptotermes formosanus with and without a wood specimen; (2) C. formosanus under six temperature conditions; and (3) four different termite species, C. formosanus, Reticulitermes speratus, Incisitermes minor, and Zootermopsis nevadensis. The hydrogen and methane concentrations increased with an increase in the number of termites. Concentrations were higher in samples with a wood specimen than without it. Both hydrogen and methane concentrations were the highest for the samples at 35 °C and were lowest at 15 and 5 °C. The concentrations were very low at 45 °C because all the termites had died in a few hours. The concentrations of hydrogen and methane were highest for Z. nevadensis, the dampwood termite, among the four species, and no methane was detected for I. minor, the drywood termite, at 28 °C and 75 % RH.     

Evaluation of anti-acne activity of selected Sudanese medicinal plants

Acne vulgaris is the most common skin disease in the world, and the number of antibiotics resistant to acne-inducing bacterial strains has been increasing in the past years. Natural substances from plants are promising candidates to treat this disease. The methanol and 50 % (v/v) ethanol extracts of 29 plant species traditionally used in Sudan for treatment of a variety of diseases were tested in vitro for their potential anti-acne activity. The activities of these extracts were determined using an antibacterial assay against Propionibacterium acnes, a lipase inhibitory assay, and l,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity assay. The results showed that methanol and 50 % ethanol extracts of Terminalia laxiflora Engl & Diels wood exhibited good antibacterial activity (minimum inhibitory concentration 0.13 mg/ml). The 50 % ethanol extracts of Abrus precatorius L. seed, T. laxiflora Engl & Diels and methanol extract of Acacia nilotica (L.) pods showed lipase inhibitory activity more than 70 % at 500 μg/ml. The methanol extracts of A. nilotica (L.) pods showed the best DPPH radical scavenging activity (IC₅₀ 1.32 μg/ml). Total phenolic, flavonoid and total tannin contents of selected plant extracts shown anti-acne activities were investigated. Almost all selected extracts contained phenolic compound. The highest level of flavonoids (38.87 μg/mg) was detected in T. brownii bark, whereas the highest amount of tannin was detected in A. nilotica (L.) bark (88.01 %).     

Toxicity and repellence of Taiwanese indigenous djulis, Chenopodium formosaneum, against Aedes albopictus (Diptera: Culicidae) and Forcipomyia taiwana (Diptera: Ceratopogonidae)

The biological activity of djulis (Chenopodium formosaneum) extracts was evaluated against mosquitoes and biting midges. Djulis extracts were relatively nontoxic to Aedes albopictus larvae. However, they showed interesting repellence against adult mosquitoes as estimated by the median effective dosages (ED₅₀). ED₅₀ values for djulis extracts against mosquito adults in descending order were: seed extracted with methanol (0.83 %), seed extracted with dichloromethane (0.66 %), leaf extracted with methanol (0.50 %), and leaf extracted with dichloromethane (0.40 %). Field tests also suggested that djulis methanol extracts were effective at about a 1 % level against biting midges (Forcipomyia taiwana). A total of 15 and 20 compounds accounting for 88.8 and 79.9 % in the seed and leaf extract, respectively were identified by gas chromatography coupled to mass spectrometry (GC–MS). Among these, 9, 12-octadecadienoyl chloride, (Z, Z) was found in both as well as being the major constituent in the leaf extract (35.7 %). Further studies on the repellent property of the extracts against mosquitoes and biting midges are warranted.     

Composition and antimicrobial activity of <Emphasis Type="Italic">Cistus munbyi</Emphasis> essential oil: an endemic plant from Algeria

The chemical composition and antimicrobial potential of Cistus munbyi essential oil were studied for the first time. GC and GC–MS analysis revealed 48 compounds representing 96.98% of the oil. Terpinen-4-ol (23.75%), meta-Cymene (17.30%), and Sabinene (12.38%) were the major constituents. Antimicrobial activity was evaluated against nine pathogens using the disc diffusion and broth micro-dilution methods. Results show that C. munbyi essential oil possesses strong antimicrobial activity against all strains, regardless if Gram-positive or Gram-negative bacteria, or yeast, with MICs values not exceeding 10 (mg/ml). In addition to its efficacy, C. munbyi essential oil has an unusual antimicrobial potency which is attributed to its specific chemical composition. Thus, findings presented here suggest that endemic C. munbyi contains a very interesting essential oil that may be valuable in several areas.     

Influence of duration of storage at room temperature,pre-sowing seed treatment and fruit colour harvest index on germination and seedling growth of <Emphasis Type="Italic">Jatropha curcas</Emphasis> L.

Jatropha curcas L. is being promoted by governments for greening marginal areas for rural development and biodiesel production in sub-Saharan Africa, however large gaps in knowledge on its agronomy and yield potential exist. The effect of duration of storage at room temperature, pre-sowing seed treatment of Jatropha seed and fruit colour harvest index on germination and seedling growth parameters was investigated. There was a significant negative correlation between the duration of storage of Jatropha seed and seed oil content (P < 0.001, r = ?0.99), viability (P < 0.01, r = ?0.93), percent germination (P < 0.05, r = ?0.90) and germination index (P < 0.05, r = ?0.89). The relationship between duration of seed storage and seed oil content and seed germination parameters was best described by quadratic and exponential functions which showed rapid declines in seed oil content and germination parameters in the first 3 years of storage and a slower decline between 3 and 8 years of storage. There was a significant negative correlation between duration of storage and seedling height (P < 0.01, r = ?0.97), stem diameter (P < 0.01, r = ?0.93) and dry weight (P < 0.05, r = 0.91) that was best described by quadratic functions. Seed oil content was significantly and positively correlated to seed viability (P < 0.01, r = 0.96), germination per cent (P < 0.01, r = 0.94) and germination index (P < 0.01, r = 0.93). The relationship between seed oil content and seed germination parameters was best described by exponential functions which showed an exponential increase in seed germination parameters as oil content increased above 30% and smaller increases below 30% oil content. Progressive peroxidation of lipids as seed aged explains the loss of oil from the seed. Peroxidation of lipids produced highly reactive radicals that damaged membranes and proteins reducing seed germination and seedling growth parameters as seed aged. Pre-sowing seed treatments (seed soaking and scarification) produced marginal gains in germination and seedling growth parameters in Jatropha seed stored for 3 months to 8 years. Seeds harvested at the yellow fruit maturity index, 60 days after anthesis (DAA), showed the highest seed germination percent while seed harvested at the black fruit maturity index, 75 DAA, had the highest oil content. Harvesting of Jatropha seed for oil expression is therefore recommended at the black maturity index while harvesting for seed is recommended at the yellow maturity stage. The results of this study indicate that Jatropha seed should be stored for as short a period of time as possible to maximize seed germination, seedling growth and oil yield.     

In vitro regeneration and multiplication for mass propagation of Acacia ehrenbergiana Hayne: a potential reclaiment of denude arid lands

Acacia ehrenbergiana Hayne, an indigenous legume of the Middle East is an abiotic stress resistant nitrogen fixing legume which possesses valuable medicinal and economic properties. It has great potential to be used as reclaiment of denuded barren lands if only it could be propagated at a large scale. However, low seed germination and high seedling mortality apprehend its uses. Use of tissue culture technology could overcome these limitations but unfortunately there is no report describing micropropagation protocol for this species. The present study thus describes the first successful report on micropropagation of A. ehrenbergiana and also discusses the possible physiological and molecular reasons responsible to make particular culture condition, type and concentration of PGR most effective. It uses cotyledonary node explants cultured on PGR augmented Murashige and Skoog (MS) medium. A maximum of 90.3 ± 2.4 % of culture showed regeneration on benzyl adenine (BA) (10 μM) supplemented medium, maximum number of shoots (7.3 ± 0.15) were obtained on BA and NAA (0.1 μM) supplemented medium. Culture conditions were optimized by manipulation of pH of the medium, 5.8 being the best. Sub-culturing up to three passages for multiplication and thereafter induction of in vitro rooting was found to be most economical both in terms of time and money. Rizogenesis was observed best in MS medium supplemented with IBA (5.0 μM). 80 % of the rooted plants were successfully transferred to the natural condition under the sun.     

Plant-derived essential oils affecting settlement and oviposition of Bemisia tabaci (Genn.) biotype B on tomato

The silverleaf whitefly Bemisia tabaci (Genn.) biotype B (Hemiptera: Aleyrodidae) is an economically important pest of tomatoes Solanum lycopersicum (L.), causing irregular ripening on fruits and transmitting several plant pathogenic geminiviruses. The management of this pest is commonly based on repetitive spraying with synthetic pesticides, causing serious environmental damages and increase of resistance by insect population. In the present study, essential oils from the leaves of Artemisia camphorata Vill., Ageratum conyzoides L., Foeniculum vulgare Mill., Lippia alba (Mill.) N. E. Br., Plectranthus neochilus Schltr., and Tagetes erecta L. were investigated for their possible repellent and oviposition-deterrent effects against B. tabaci biotype B on tomato. In a multi-choice assay, P. neochilus essential oil was the most active repellent and oviposition deterrent. Essential oils of A. conyzoides and T. erecta significantly deterred the female B. tabaci biotype B from laying eggs on treated tomato leaflets compared with the control. (E)-Caryophyllene (30.67 %) and the monoterpenes α-pinene (15.02 %) and α-thujene (11.70 %) were identified as the major constituents of the essential oil of P. neochilus. Our findings demonstrated the potential of essential oil of P. neochilus and other oils in the reduction of settlement and oviposition of B. tabaci biotype B on tomato.     

Hyptis suaveolens and Hyptis spicigera (Lamiaceae) essential oils: qualitative analysis, contact toxicity and repellent activity against Sitophilus granarius (L.) (Coleoptera: Dryophthoridae)

Essential oils from Hyptis suaveolens (L.) Poiteau (Lamiaceae) and Hyptis spicigera Lamarck (Lamiaceae) were first analysed by gas chromatography and by gas chromatography/electron impact mass spectroscopy and then evaluated for toxicity and repellent activity against Sitophilus granarius (L.) (Coleoptera: Dryophthoridae), one of the most serious worldwide stored grain pests. Fifty-six compounds have been identified in the essential oil of H. suaveolens: monoterpene hydrocarbons were the most represented volatiles (64.1%), followed by sesquiterpene hydrocarbons (24.0%), oxygenated monoterpenes (8.1%) and oxygenated sesquiterpenes (2.4%). Diterpenes and non-terpene derivatives were scarcely represented. Sixty compounds have been identified in the essential oil of H. spicigera: monoterpene hydrocarbons were the most represented class of volatiles (70.4%), followed by sesquiterpene hydrocarbons (22.6%). Results from topical applications on insects showed that both essential oils had an effective insecticidal activity. The complete kill of S. granarius was observed 24 h after treatment at a minimum effective dose of 0.4 and 0.6 μl per insect with H. suaveolens and H. spicigera oil, respectively. Results from repellency tests showed that the two essential oils had a repellent activity on S. granarius adults: at the lowest dose (2 × 10⁻⁴ μl oil per cm²), H. spicigera essential oil exhibited a higher repellent effect in comparison to H. suaveolens. No significant differences were observed for the repellent effect between the two essential oils at the highest dose (2 × 10⁻² μl oil per cm²).     

Effects of a nitric oxide donor and nitric oxide scavengers on <Emphasis Type="Italic">Sorbus pohuashanensis</Emphasis> embryo germination

The effects of an exogenous nitric oxide donor (sodium nitroprusside, SNP), a NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxode (PTIO) and carboxy-PTIO potassium salt (cPTIO) on the embryo germination of Sorbus pohuashanensis were studied in a petri dish test. SNP at 0.5–5 mmol L^?1 increased germination percentage, mean time to germination, germination index and germination energy compared with the control to different degrees. Treatment with 2 mmol L^?1 SNP improved germination most significantly; embryo germination percentage for mother tree 1 (91.11%) and mother tree 2 (64.44%) were much higher than the control. In addition, excessive SNP levels did not enhance embryo germination. Combined treatment with SNP and an NO scavenger delayed embryo germination. Treatment with cPTIO inhibited embryo germination; germination percentage was 42.22% and was lower than that of the control. These results show that low concentrations of exogenous NO can enhance the embryo germination of S. pohuashanensis, providing a simple, effective way for promoting germination of S. pohuashanensis.     

The antibiofilm activity of lingonberry flavonoids against oral pathogens is a case connected to residual complexity

The antimicrobial activity of lingonberry (Vaccinium vitis-idaea L.) was evaluated against two oral pathogens, Streptococcus mutans and Fusobacterium nucleatum. Long-bed gel permeation chromatography (GPC; Sephadex LH-20) yielded purified flavonoids, with the most efficient minimum inhibitory concentrations (MICs) against planktonic cells in the anthocyanin and procyanidin primary fractions against F. nucleatum (63–125 μg/ml) and in the procyanidin rich fraction against S. mutans (16–31 μg/ml). The purified flavonol glycosides and procyanidins inhibited biofilm formation of S. mutans (MICs 16–31 μg/ml), while the corresponding reference compounds showed no activity. Secondary GPC purification yielded flavonol glycosides devoid of antibiofilm activity in the 50% MeOH fraction, while elution with 70% acetone recovered a brownish material with activity against S. mutans biofilm (MIC 8 μg/ml). Even after HPLC-PDA, NMR, and MALDI-TOF analyses, the structural identity of this material remained unknown, while its color and analytical characteristics appear to be consistent with flavonoid oxidation products.     

Insecticidal properties of <Emphasis Type="Italic">Thymus persicus</Emphasis> essential oil against <Emphasis Type="Italic">Tribolium castaneum</Emphasis> and <Emphasis Type="Italic">Sitophilus oryzae</Emphasis>

Red flour beetle Tribolium castaneum (Herbst) and rice weevil Sitophilus oryzae (L.) are considered to be the major insect pests in storage. Essential oils from aromatic plants are recognized as proper alternatives to fumigants. Thymus persicus (Ronniger ex Rech. f.) is one of these plants that have medicinal properties and is indigenous to Iran. The essential oil was obtained from aerial parts of the plant and analyzed by GC and GC–MS. Carvacrol (44.69%) and thymol (11.05%) were the major constituents of the oil extracted. In this experiment, fumigant toxicity of the essential oil was studied against T. castaneum, S. oryzae at 27 ± 1°C and 60 ± 5% RH in dark condition. The adult insects were exposed to the concentrations of 51.9, 111.1, 207.4 and 370.4 μl/l air to estimate median lethal time (LT₅₀) values. The fumigant toxicity was increased in response to increased essential oil concentrations. The LT₅₀ values at the lowest and the highest concentrations tested were ranged from 28.09 to 13.47 h for T. castaneum, and 3.86 to 2.30 h for S. oryzae. It was found that S. oryzae adults were much more susceptible to the oil than T. castaneum. After 24 h of exposure, the LC₅₀ values (95% fiducial limit) for T. castaneum and S. oryzae were estimated to be 236.9 (186.27–292.81) and 3.34 (2.62–4.28) μl/l air, respectively. These results suggest that T. persicus essential oil merits further study as potential fumigant for the management of these stored-product insects.