I50 Values Research Articles

In VitroInhibition of Polyphenol Oxidase Activity by Insecticides and Allelochemicals inClostera anastomosis(Lepidoptera: Notodontidae) Larvae and Poplar Trees

Abstract Clostera anastomosis (L.) (Lepidoptera: Notodontidae) is an important leaf-feeding insect of poplars, Populus spp. (Salicaceae) in China. As part of a continuing search for environmentally friendly insecticides for this pest, we compared the in vitro inhibition of polyphenol oxidase (PPO) activity by 21 insecticides and allelochemicals in C. anastomosis and poplar trees (populous × euramericana ‘NanLin895′). The results showed that three inhibitors (quercetin, phenyl thiourea, and phoxim) can strongly inhibit PPO activity in both C. anastomosis and poplars, but the inhibitory degree with each was significantly different. Our results further showed that three inhibitors had a certain dose relationship with the PPO activity in C. anastomosis and poplars. The I50 values (50% inhibitory concentration) of three chemicals (quercetin, phenyl thiourea, and phoxim) were estimated as 14.17, 0.18, and 127.67 μM for C. anastomosis and as 0.34, 0.15, and 0.21 mM for poplars, respectively. These results will ...

Physiological basis for isoxadifen-ethyl induction of nicosulfuron detoxification in maize hybrids.

Isoxadifen-ethyl can effectively alleviate nicosulfuron injury in the maize. However, the effects of safener isoxadifen-ethyl on detoxifying enzymes in maize is unknown. The individual and combined effects of the sulfonylurea herbicide nicosulfuron and the safener isoxadifen-ethyl on the growth and selected physiological processes of maize were evaluated. Bioassays showed that the EC50 values of nicosulfuron and nicosulfuron plus isoxadifen-ethyl for maize cultivar Zhengdan958 were 18.87 and 249.28 mg kg-1, respectively, and were 24.8 and 275.51 mg kg-1, respectively, for Zhenghuangnuo No. 2 cultivar. Evaluations of the target enzyme of acetolactate synthase showed that the I50 values of nicosulfuron and nicosulfuron plus isoxadifen-ethyl for the ALS of Zhengdan958 were 15.46 and 28.56 μmol L-1, respectively, and were 0.57 and 2.17 μmol L-1, respectively, for the acetolactate synthase of Zhenghuangnuo No. 2. The safener isoxadifen-ethyl significantly enhanced tolerance of maize to nicosulfuron. The enhanced tolerance of maize to nicosulfuron in the presence of the safener, coupled with the enhanced injury observed in the presence of piperonyl butoxide, 1-aminobenzotriazole, and malathion, suggested cytochrome P450 monooxygenases may be involved in metabolism of nicosulfuron. We proposed that isoxadifen-ethyl increases plant metabolism of nicosulfuron through non-P450-catalyzed routes or through P450 monooxygenases not inhibited by piperonyl butoxide, 1-aminobenzotriazole, and malathion. Isoxadifen-ethyl, at a rate of 33 mg kg-1, completely reversed the effects of all doses (37.5–300 mg kg-1) of nicosulfuron on both of the maize cultivars. When the two compounds were given simultaneously, isoxadifen-ethyl enhanced activity of glutathione S-transferases (GSTs) and acetolactate synthase activity in maize. The free acid 4,5-dihydro-5,5-diphenyl-1,2-oxazole-3-carboxylic was equally effective at inducing GSTs as the parent ester and appeared to be the active safener. GST induction in the maize Zhenghuangnuo No. 2 was faster than in Zhengdan 958.

Toxicity and kinetic studies of H+, K+-ATPase sensitivity to cyfluthrin and fenpropathrin in Egyptian field populations of Spodoptera littoralis

Toxicity of two pyrethroids (cyfluthrin and fenpropathrin) against cotton leafworm, Spodoptera littoralis, larvae werecollected from heavily sprayed fields in different areas in Dakahlia and El-Beheira Governorate. H+, K+-ATPase (protonpump)activity was measured in laboratory (lab.) strain and compared with enzyme activities for other collected strains. Thesensitivity of H+, K+-ATPase activity was measured by I50 values. The I50 values of cyfluthrin were 0.24; 0.46; 0.54; 0.65, and0.68 μM for lab; Abo-Hommos; Shobrakheet; Aga, and El-Senbellaween strains respectively, while I50 values offenpropathrin were 0.44; 0.58; 0.66; 0.84, and 0.87 μM for lab and four field strains respectively. Also, proton-pump enzymekinetic parameters, Km (Michaelis-Menten kinetics, constant) and Vmax (maximum velocity) values and the inhibitionconstant (Ki) were determined. The obtained data proved that cyfluthrin and fenpropathrin compounds were competitiveinhibitors of proton-pump activity. Results indicated that, the pyrethroid have shown potentiality against larvae of S.littoralis, so, these pyrethroids may be effect of a novel mechanism of action for inhibition of proton-pump activity, theserecommended for S. littoralis larvae control. It could be concluded that the use of pyrethroid, may avoid increasing ofresistance by effect of new mode of action where they disrupt the development of target pest, Therefor proton-pump may playan important role the mode of action of these pesticides in future.

Trp574 substitution in the acetolactate synthase of Sinapis arvensis confers cross-resistance to tribenuron and imazamox

Rate-response experiments with nine putative resistant wild mustard (Sinapis arvensis) populations from Greece showed cross-resistance to tribenuron and imazamox. The calculated GR50 values [herbicide rate (gaiha−1) required for 50% reduction of fresh weight] of the nine resistant (R) populations ranged from 51.8 to 555.6gaitribenuronha−1 and from 66.3 to 900.4gaiimazamoxha−1. Regarding the susceptible population, GR50 value was not estimated for tribenuron as its lower treatment reduced fresh weight by >95%, whereas the respective value for imazamox was 0.5gaiha−1. Gene sequencing of als revealed that a point mutation at Trp574 position, leading to amino acid substitution by Leu in the ALS enzyme was present and the likely cause of resistance. The in vitro activity of the ALS enzyme indicated I50 values (herbicide concentration required for 50% reduction of the ALS activity) ranging from 19.11 to 217.45μM for tribenuron, whereas the respective value for the S population was 1.17μM. All populations were susceptible to MCPA at the recommended rate. These results strongly support that cross-resistance of 9 S. arvensis populations was due a point mutation of the als gene, which resulted in a less sensitive ALS enzyme.

Purification and Characterization of Lactate Dehydrogenase in the Foot Muscle and Hepatopancreas of Otala lactea.

Lactate dehydrogenase (LDH) has a crucial role in maintaining ATP production as the terminal enzyme in anaerobic glycolysis. This study will determine the effect of posttranslational modifications (PTMs) on the activity of LDH in the foot muscle and hepatopancreas of an estivating snail, Otala lactea. LDH in foot muscle of O. lactea was purified to homogeneity and partially purified in hepatopancreas in a two-step and three-step process, respectively. The kinetic properties and stability of these isoforms were determined where there was a significant difference in Km and I50 values with pyruvate and urea separately in foot muscle; however, hepatopancreas exhibited significant differences in Km and I50 in salt between control and stress. Interestingly, hepatopancreas has a higher affinity for pyruvate in the control state whereas foot muscle has a higher affinity for its substrate in the estivated state. PTMs of each isoform were identified using immunoblotting and dot blots, which prove to be significantly higher in the control state. Overall, foot muscle LDH enters a low phosphorylation state during estivation allowing more efficiency in consuming pyruvate with higher thermal stability but less structural stability. Hepatopancreas LDH becomes dephosphorylated in the estivating snail that decreases the efficiency of the enzyme in the forward direction; however, the snail has an increased tolerance to the presence of salt when water becomes scarce. Such tissue-specific regulations indicate the organism's ability to reduce energy consumption when undergoing metabolic depression.

Leaf chlorophyll fluorescence discriminates herbicide resistance in Echinochloa species

SummaryTimely detection of herbicide resistance at an early stage of crop cultivation is essential to help farmers find alternative solutions to manage herbicide resistance in their fields. In this study, maximum quantum yield of PS II [Fv/Fm = (Fm – Fo)/Fm] was measured at the 4–5 leaf stage to discriminate between herbicide‐resistant and susceptible biotypes of Echinochloa species. The differences in Fv/Fm between herbicide‐resistant and susceptible Echinochloa spp. were consistent with the whole‐plant assay based on I50 (herbicide doses causing a 50% inhibition of Fv/Fm) and GR50 (herbicide doses causing a 50% reduction in plant fresh weight) values and R/S ratios (herbicide resistance index), regardless of the mode of action of the tested herbicides. A PS II inhibitor caused the fastest inhibition of Fv/Fm, compared with ACCase and ALS inhibitors, after herbicide treatment. The required time for discrimination between herbicide‐resistant and susceptible Echinochloa spp. was 64 h after PS II inhibitor treatment, much shorter than those of ACCase and ALS inhibitor‐treated plants, which required 168 and 192 h respectively. The leaf chlorophyll fluorescence assay provided reliable diagnostics of herbicide resistance in Echinochloa spp. with significant time savings and convenient measurement in field conditions compared with the conventional whole‐plant assay.

Biopharmaceutical Potential of Two Ramalina Lichens and their Metabolites.

This paper studies the phytochemical analysis of the acetone extracts of the Ramalina fraxinea and Ramalina fastigiata lichens and the antioxidant, antimicrobial and antitumour activities of these species and their constituents. The phytochemical analysis of two Ramalina species was evaluated using HPLC-UV test. The depsides (evernic acid, obtusatic acid, sekikaic acid and atranorin), depsidones (protocetraric acid) and dibenzofurane (usnic acid) were identified from these lichens. Antioxidant activity was evaluated by DPPH assay, reducing power assay and by measuring the amounts of total phenolics in extracts. Antimicrobial activity was tested towards five bacterial and 10 fungal species, using broth microdilution method to determine the minimum inhibitory concentration. Cytotoxic activity was tested using MTT method on the human epithelial carcinoma (Hela), human lung carcinoma (A549) and human colon carcinoma (LS174) cells. As a result of the study, tested samples showed strong free radical scavenging activity with I50 values within the range of 285.45-423.51 μg/mL. Absorbance for reducing power was found to be from 0.0043 to 0.1747. The total amount of phenol concentrations in extracts of Ramalina fraxinea and Ramalina fastigiata was 32.63 and 33.49 μg PE/mg, respectively. Methyl evernate showed the strongest antimicrobial properties with the least measured MIC value being 0.125 mg/mL. In addition, all samples exhibited strong anticancer activities against tested cells (I50 values were between 24.63 and 161.37 μg/mL). These results indicate that lichen appears to be a possible natural biopharmaceutical.

Eflatun çiçekli ballıbaba (lamium purpureum) polifenol oksidaz enziminin karakterizasyonu ve inhibisyonu

In this work, it is investigated the kinetic properties of polyphenol oxidase (PPO) obtained from Lamium purpureum (red deadnettle). 4-methylcatechol was used as substrate in the characterization studies. Michaelis-Menten constant (KM) and maximum reaction velocity (Vmax) were calculated. Enzyme’s optimum pH value was found 7,5; optimum temperature value was found 10 ℃ . KM and Vmax values were calculated 2,9977 mM and 0,0087 EU/min respectively. PPO activity substantially was inhibited from sodium azide, thiourea, L-cysteine, ascorbic acid, benzoic acid, citric acid, 2-mercaptoethanol and I50 values were calculated each inhibitor.

English

Couroupita guianensis Aubl. has been traditionally used for medicinal as well as ornamental purposes, but the allelopathic potential of this species has not yet been reported. Hence, the aim of this study is to explore the allelopathic activity of C. guianensis leaves. We examined the effect of aqueous methanol extracts of the leaves of this species at five different concentrations (1, 3, 10, 30, and 100 mg dry weight (DW) equivalent extract mL) on the germination of lettuce (Lactuca sativa L.) and barnyard grass (Echinochloa crus-galli (L.) Beauv.), and on the growth of cress (Lepidium sativum L.), lettuce, alfalfa (Medicago sativa L.), barnyard grass, timothy (Phleum pretense L.), and Italian ryegrass (Lolium multiflorum Lam.) seedlings. The germination of lettuce and barnyard grass, as well as the growth of all test plants, was inhibited by leaf extracts of C. guianensis at concentrations ≥ 1 mg DW equivalent extract mL. The extract obtained from 100 mg C. guianensis leaves completely inhibited germination of lettuce or significantly delayed germination of barnyard grass. The hypocotyl/coleoptile and root growth of all test plants were inhibited by the leaf extracts to less than 10% of control hypocotyl/coleoptile and root growth at the concentration of 100 mg DW equivalent extract mL, except for the hypocotyl/coleoptile growth of alfalfa and barnyard grass. The ranges of I50 values of hypocotyl/coleoptile and root growth of all test plants were 1.22–10.24 and 0.76–3.97 mg DW equivalent extract mL, respectively. The inhibitory activities increased with increasing extract concentrations. The present results suggest that C. guianensis may have allelopathic potential and thus possesses allelopathic substances. Therefore, the leaves of this species could potentially be used as mulch and/or soil additive to control weeds in sustainable crop production.

The Effect of Dicamba on Peanut When Applied during Vegetative Growth Stages

ABSTRACT The development of dicamba-resistant cotton and soybean cultivars has created great concern about the potential off-target movement of dicamba onto sensitive species, including broadleaf crops. Peanut is often grown in close proximity to cotton and soybean. Therefore, field studies were conducted during 2012 and 2013 at Plains, Ty Ty, and Attapulgus, GA to evaluate peanut response to rates of dicamba (35, 70, 140, 280, and 560 g ae ha−1) applied at preemergence (PRE), 10, 20, or 30 d after planting (DAP) corresponding to PRE, V2, V3, and V5 peanut growth stages, respectively. Nontreated controls were included for comparison. As dicamba rate increased, both peanut injury and peanut yield loss increased. Peanut response to dicamba was fit to log-logistic regression models for injury and linear regression models for yield loss. Peanut injury increased with rate of dicamba, but was variable among the locations. A general trend was that peanut plants became more sensitive to dicamba injury as plants approached reproductive stage, as evidenced through a declining linear relationship between I50 values (i.e. rate of dicamba that elicits a 50% crop response) and timing of application. PRE applications of dicamba had I50 values that ranged from 125 to 323 g ha−1 of dicamba, while I50 values were 44 to 48 g ha−1 of dicamba at the V5 peanut growth stage. There was a linear relationship between peanut yield and dicamba rate, with 560 g ha−1 causing maximum yield losses ranging from 0 to 86% when applied PRE, 24 to 82% when applied at V2 growth stage, 30 to 95% when applied at V3 growth stage, and 45 to 88% when applied at V5 growth stage. Across all treatments and locations, there was also a negative linear relationship between peanut yield and peanut crop injury, with a decline of 8.5% yield for every 10% increase in crop injury. Growers and their consultants/extension agents can use this peanut injury data to predict potential peanut yield loss from sprayer contamination or off-target movement of dicamba.

Target-site basis for resistance to imazethapyr in redroot amaranth (Amaranthus retroflexus L.)

Experiments were conducted to confirm imazethapyr resistance in redroot amaranth (Amaranthus retroflexus L.) and study the target-site based mechanism for the resistance. Whole-plant response experiments revealed that the resistant (R) population exhibited 19.16 fold resistance to imazethapyr compared with the susceptible (S) population. In vitro ALS activity assay demonstrated that the imazethapyr I50 value of the R population was 21.33 times greater than that of the S population. However, qRT-PCR analysis revealed that there is no difference in ALS gene expression between the R and S populations. Sequence analysis revealed an Asp-376-Glu substitution in ALS in the R population. In order to verify that the imazethapyr resistance was conferred by Asp-376-Glu mutation, the ALS-R and ALS-S genes were fused to the CaMV 35S promoter and introduced into Arabidopsis respectively. The expression of ALS-R in transgenic Arabidopsis plants exhibited 13.79 fold resistance to imazethapyr compared to ALS-S transgenic Arabidopsis.

Molecular basis of Cyperus difformis cross-resistance to ALS-inhibiting herbicides

Applications of 64 times higher rates of azimsulfuron and halosulfuron-methyl failed to reduce by 50% growth of 10 putative resistant (R) Cyperus difformis (smallflower umbrella-sedge) populations collected from rice fields located in Northern Greece. However, the growth rate of the susceptible (S) population was reduced by 50% by 1/4 of the recommended rate of both herbicides. The als gene sequencing identified point mutations at Pro-197 position, leading to amino acid substitution by Ala or Ser of the ALS enzyme. The in vitro activity of the ALS enzyme indicated that the I50 values (herbicide concentration required for 50% reduction of the ALS activity) ranged from 10.7 to 55.5μM azimsulfuron and from 6.7 to 50.6μM halosulfuron-methyl, whereas the respective values for the S population were 0.09 and 0.11μM. These results strongly support that cross-resistance of 10 C. difformis populations was due to point mutations of the als gene, which resulted in a less-sensitive ALS enzyme. This study reports the presence of a 1240bp intron in the C. difformis als gene with the Pro-197 point mutations near the splice junction.

Variable response of kochia [Kochia scoparia (L.) Schrad.] to auxinic herbicides dicamba and fluroxypyr in Montana

Jha, P., Kumar, V. and Lim, C. A. 2015. Variable response of kochia [Kochia scoparia (L.) Schrad.] to auxinic herbicides dicamba and fluroxypyr in Montana. Can. J. Plant Sci. 95: 965–972. Herbicide-resistant kochia is an increasing concern for growers in the Northern Great Plains of United States and Canada. The objective of the research was to characterize the response of the three putative auxinic herbicide-resistant kochia inbreds (derived from accessions collected from wheat/chemical fallow fields in northern Montana) to dicamba and fluroxypyr relative to a susceptible (SUS) inbred. A dicamba dose-response study indicated that the three putative resistant inbreds (Chot-01, Chot-02, and Chot-03) had R/S ratios of 1.3 to 6.1 based on the visible control response (I50 values), and R/S ratios of 1.5 to 6.8 based on the shoot dry weight response (GR50 values). Dose-response experiments with fluroxypyr determined I50 R/S ratios of 1.4 to 5.7 and GR50 R/S ratios of 1.6 to 4.0 for the three putative resistant inbreds. The selected inbreds showed variable symptomology (phenotype) in response to dicamba and fluroxypyr. Among the three inbreds, Chot-01 exhibited the least epinasty, stem curling/swelling, and chlorosis/necrosis symptoms, and was resistant to dicamba and fluroxypyr. Growers should diversify their weed management tools to manage further spread of auxinic or multiple herbicide-resistant kochia in the region.

Common Cocklebur (<i>Xanthium strumarium</i>) Response to Nicosulfuron

The response of two populations (CC1, 43.59°N & 20.40°E; CC2, 44.46°N & 20.17°E) of common cocklebur (Xanthium strumarium L.) to nicosulfuron was investigated both in field experiments and in the laboratory. Population CC1 had no history of treatment with any herbicide, while population CC2 was treated with ALS inhibitor herbicides for six consecutive years. In the field, plants were treated post-emergence with nicosulfuron (0, 10, 20, 40, 60 and 80 g ai ha-1) at four true leaves. Visual injury estimation and vegetative parameters (plant height, fresh weight, leaf area) were recorded about month after herbicide application. The acetolactate synthase (ALS) enzyme activity in response to herbicide concentrations of 0, 0.01, 0.1, 1, 10, 100 μM was determined in vitro. GR50 values for vegetative parameters and I50 values for ALS activity were slightly greater for the CC2 than for the CC1population, but the results confirmed that neither population was susceptible to nicosulfuron. Namely, based on results for fresh weight, the population CC1 was about 3.9 and 2.6-fold more susceptible to nicosulfuron than population CC2 in two consecutive years, but differences were not so prominent for other parameters (plant height, leaf area and ALS activity), ranging from 1.18 to 1.8-fold. The differences between population CC1 and CC2 could be attributed to inter-population variability in susceptibility to nicosulfuron or could be the consequence of repeated application of ALS herbicides to the CC2 population during the six previous years. Future investigations are necessary in order to clarify this dilemma.

Postemergence Herbicide Tolerance Variation in Peanut Germplasm

Although herbicide tolerance is not usually evaluated until the final stages of breeding programs, this trait is very important for grower adoption of new peanut cultivars. Understanding herbicide tolerance of breeding lines could help breeders develop selection strategies that maximize herbicide tolerance in new commercial cultivars. However, little is known about herbicide tolerance variability in peanut germplasm. Thirty-five randomly selected breeding lines from the peanut mini-core collection and cultivars ‘Florida-07’ and ‘Georgia-06G’ were evaluated for tolerance to 11 herbicides under greenhouse conditions. Variation among peanut lines in herbicide tolerance, measured as dry weight reductions (DWR), was similar across herbicides and was normally distributed. Florida-07 and Georgia-06G were in the lower two quartiles of injury and DWR among the evaluated peanut lines. Dose–response experiments showed that the most tolerant breeding lines had I50(the rate required to cause 50% injury) and GR50(the rate required to reduce dry weight 50%) values 0.4 to 2.5 times higher than the most susceptible lines, depending on the herbicide. A breeding line had a dicamba GR5013 times higher than the most susceptible line and 2.8 and 4.7 times higher than Florida-07 and Georgia-06G, respectively. The most tolerant lines were consistently tolerant to herbicides with different mechanisms of action, suggesting that nontarget site mechanisms are more likely to be responsible for the tolerance than target-site mutations. These results confirmed peanut-breeding programs would greatly benefit from screening breeding lines for tolerance to key herbicides and developing an herbicide-tolerance catalog. This information can be used when designing new crosses to reduce the risk of developing cultivars with low herbicide tolerance especially considering that one-half of the breeding lines exhibited lower tolerance than the commercial cultivars.

Detection of 3-phenoxybenzoic acid in river water with a colloidal gold-based lateral flow immunoassay

3-Phenoxybenzoic acid (3-PBA) is a general metabolite of synthetic pyrethroids. It could be used as a generic biomarker for multiple pyrethroids exposure for human or pyrethroid residues in the environment. In this study, monoclonal antibodies (mAbs) against 3-PBA were developed by using PBA–bovine serum albumin (BSA) as an immunogen. In the competitive enzyme-linked immunosorbent assay (ELISA) format, the I50 and I10 values of purified mAbs were 0.63 and 0.13μg/ml, respectively, with a dynamic range between 0.19 and 2.04μg/ml. Then, the colloidal gold (CG)-based lateral flow immunoassay was established based on the mAbs. The working concentration of coating antigen and CG-labeled antibodies and the blocking effects were investigated to get optimal assay performance. The cutoff value for the assay was 1μg/ml 3-PBA, and the detection time was within 10min. A total of 40 river water samples were spiked with 3-PBA at different levels and determined by the lateral flow immunoassay without any sample pretreatments. The negative false rate was 2.5%, and no positive false results were observed at these levels. This lateral flow immunoassay has the potential to be an on-site screening method for monitoring 3-PBA or pyrethroid residues in environmental samples.

Influence of Two Insect Growth Regulators on Chitinase Activity

Toxicity of two insect growth regulators (IGRs) (lufenuron and hexaflumuron) against two larval instars of cotton leafworm Spodoptera littoralis, laboratory and field strains were determined. Chitinase activity in the two strains also was investigated. Results revealed that, 2nd instar larvae were more sensitive than 4th instar larvae to both insecticides. The sensitivity of chitinase activity was measured by I50 values. The I50 values of lufenuron were 0.31, and 0.64 µM for lab and field strains of S. littoralis 2nd larvae respectively, while I50 values were 0.44, and 0.75 µM for lab and field strains of S. littoralis 4th larvae respectively. The hexaflumuron were 0.57, and 0.76 µM for lab and field strains of S. littoralis 2nd larvae respectively, the I50 values were 0.65, and 0.81µM for lab and field strains of S. littoralis 4th larvae respectively. Also, chitinase enzyme kinetic parameters, as Michaelies-Menten Kinetics (Km and Vmax) values and the inhibition constant (Ki) were determined. The obtained data proved that lufenuron and hexaflumuron compounds are competitive inhibitors of chitinase activity. Results indicated that, the IGRs have shown high potentiality against larvae of S. littoralis, so, these IGRs may be recommended for S. littoralis larvae control, it could be concluded that the use of IGRs instead of conventional hazardous insecticides; may avoid increasing selection pressure of S. littoralis populations to conventional insecticides, hazard effects on human health, environmental components and natural enemies, IGRs may play an important role in future insect pest management programs.

Chemical composition, insecticidal and biochemical effects of essential oils of different plant species from Northern Egypt on the rice weevil, Sitophilus oryzae L.

The extensive use of synthetic insecticides and fumigants for control stored-product insects has led to the development of resistance. Essential oils from aromatic plants may provide proper alternatives to currently used insect control agents. Essential oils from 20 Egyptian plants were obtained by hydrodistillation. The chemical composition of the oils was identified by gas chromatograph/mass spectrometer. Fumigant and contact toxicities of the essential oils were evaluated against Sitophilus oryzae. The inhibitory effects of the essential oils on acetylcholinesterase and adenosine triphosphatases activities were examined. The oils were composed of monoterpene hydrocarbons (i.e., limonene, sabinene, β-pinene and γ-terpinene) and oxygenated monoterpenes (i.e., terpinen-4-ol, β–thujone, 4-terpineol, α-citral and 1,8-cineole) with the exception of the oil of Schinus terebinthifolius which was contained sesquiterpenes, and the oil of Vitex agnus-castus which contained similar amounts of monoterpenes and sesquiterpenes. In the fumigation assay, the oils of Origanum vulgare (LC50 = 1.64 mg/L air), Citrus lemon (LC50 = 9.89 mg/L air), Callistemon viminals (LC50 = 16.17 mg/L air), Cupressus sempervirens (LC50 = 17.16 mg/L air), and Citrus sinensis (LC50 = 19.65 mg/L air) showed high toxicity to S. oryzae. In the contact assay, the oils of Artemisia judaica, C. viminals, and O. vulgare caused the highest toxicity to S. oryzae with LC50 values of 0.08, 0.09, and 0.11 mg/cm2, respectively. The oil of A. judaica (I50 = 16.1 mg/L) invoked the highest inhibitory effect on AChE activity, while the oils of C. viminals and O. vulgare were the most potent inhibitors to ATPases activity with I50 values of 4.69 and 6.07 mg/L, respectively. The results indicate that the essential oils of A. Judaica, O. vulgare, C. limon, C. viminals, and C. sempervirens could be applicable to the management of populations of S. oryzae.

Anti-vancomycin-resistant Enterococcus faecium and E. faecalis activities of (-)-gossypol and derivatives from Thespesia garckeana

The root extract of Thespesia garckeana yielded three known oxidatively coupled sesquiterpenoids, namely (-)-gossypol (1) and two of its derivatives (-)-6-methoxygossypol (2) and (+)-6,6'-dimethoxygossypol (3), and the stem bark afforded (E)-docosyl-3-(3,4-dihydroxyphenyl) acrylate (4), stigmasterol (5) and betulinic acid (6). The structures of the isolated compounds were determined on the basis of full spectral data (1D and 2D NMR and HRMS) and comparison with literature values. Compound 1 showed potent antibacterial activity against vancomycin-resistant Enterococcus faecium (VRE) with IC50/MIC/MBC values of 1.71/4.82/19.31 µM, respectively, whereas the reference standard vancomycin was found to be inactive. The mono- and di-methoxylated derivatives of this compound, (-)-6-methoxygossypol (2) and (+)-6,6'-dimethoxygossypol (3), were less active with respective IC50/MIC/MBC values of 2.73/4.70/9.40 µM and 6.14/18.32/18.32 µM against this microbe. Compound 2 was more potent than 1 against the low level VRE strain with I50/MIC/MBC values of 4.34/9.40/9.40 µM (vs 5.23/19.31/19.3 µM for 1). This compound also showed interesting activities against Candida glabrata with an I50 value of 2.97 µM, but was less active against methicillin-resistant S. aureus (MRSA) exhibiting an IC50 value of 17.33 µM. Compound 1 demonstrated modest activity against the

Screening grape seeds recovered from winemaking by-products as sources of reducing agents and mammalian α-glucosidase and α-amylase inhibitors

Grape seeds collected from vinification of various grape varieties were extracted by supercritical CO2 for oil recovery. The defatted residues thus obtained were considered as a re-utilisable co-product and assessed for phenolic content, reducing capacity and inhibitory activities against mammalian α-amylase and α-glucosidase enzymes. Supercritical CO2 treatment led to higher recovery of anthocyanins. Reducing capacity of phenolic extracts reached up to ~2200 mmolFe(II) kg−1, much higher than that of various natural phenolic sources. The anthocyanin-rich extracts showed the highest inhibitory effectiveness towards α-glucosidase (I50 value equal to ~40 μg gallic acid equivalents (GAE)/mL ~ half than acarbose). Inhibitory effectiveness towards α-amylase activity was similar among grape varieties, with I50 values comparable to that of acarbose and correlated with proanthocyanidin contents. These results could pave the way for an efficient processing of grapes, including cascade processes, namely: winemaking, oil extraction from recovered grape seeds and phenolic extraction from defatted grape seeds as potential cost-effective nutraceuticals.