Evaluation of Insecticides for the Control of Linepithema micans (Hymenoptera: Formicidae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Formulations of Melia azedarach to control diabrotica speciosa (germar) (coleoptera: chrysomelidae) larvae in corn and plant enhancement

We evaluated oil and powder formulations of Melia azedarach for controlling larvae of Diabrotica speciosa (Germar) in corn and plant enhancement. Five concentrations of each formulation were evaluated and compared to fipronil (negative control) and distilled water (positive control). After treatment, the number of surviving insects (larvae, pupae, and adults), the adult body weight, the sex ratio, and the longevity were recorded, while the height, dry weight of aerial part and roots, and number of leaves of plants were measured. The oil formulation at 4.0 mL reduced the larvae population of D. speciosa similarly to the insecticide fipronil, which resulted in greater height, dry weight of the root system, and number of leaves. Powder formulation at concentrations of 40, 80, and 160 mg caused larval mortality above 80%; however, these concentrations did not prevent reduction of plant height and dry weight of aerial part. Further studies assessing the residual period of M. azedarach control against D. speciosa larvae and its phytotoxicity, which are common traits associated with azadirachtin application, are necessary to subsidize the next steps of this alternative control strategy.

Investigação dos efeitos tóxicos, citotóxicos, genotóxicos e mutagênicos do inseticida Curbix® 200SC (ethiprole) em organismos não alvos

Pós-graduação em Ciências Biológicas (Biologia Celular e Molecular) - IBRC

Seletividade de inseticidas a alguns dos inimigos naturais na cultura do algodão

The aim of this work was study the selectivity of insecticides in favor of natural enemies in cotton (Gossypium hirsutum latifolium Hurtch Lr), DeltaOpal cultivar, in the city of Malhada (BA), and to know the associated beneficial fauna. The study was conducted at the agricultural year of 2010/2011. The design was conducted in randomized blocks with six treatments and four replications. The treatments were: (1) Fipronil 200 SC (0.38 L.ha-1); (2) Alphacypermethrin 100 SC (0.30 L.ha-1), (3) Lufenuron 50 EC (0.30 L.ha-1), (4) Imidacloprid 200 SC (0.30 L.ha-1), (5) Methyl parathion 600 EC (1.00 L.ha-1), and (6) control (water). The product was applied 80 days after emergence, and the evaluations were performed one day before application and 1, 7 and 14 days after application (DAA). The samples were taken using the sampling method beating cloth and Moericke traps. Natural enemies were brought to the laboratory for sorting, counting and identification by family. The toxicity of the products ranged according to the group of natural enemies. Imidacloprid is selective to the spiders and insecticides are moderately toxic (Methyl Parathion and Alphacypermethrin: 1 and 14th DAA; Lufenuron: 14th DAA) or toxic (Fipronil and Alphacypermethrin: 7th DAA). Fipronil (1 DAA), Alphacypermethrin (7th DAA) and Methyl  Parathion (14th DAA) are moderately toxic to adult ladybirds. The analyzed insecticides are toxic to the larvae of ladybirds, with more impact until seven days after the application, with the exception of Methyl Parathion classified, as innocuous until this period. The occurrence of 13 families of spiders and 18 families of parasitic Hymenoptera is registered in cotton agroecosystems in the region of Malhada, in the state of Bahia.

Development of methodology for determination of pesticides residue in water by SPE/HPLC/DAD

To boost crop yield, sugarcane growers are using increasing amounts of pesticides to combat insects and weeds. But residues of these compounds can pollute water resources, such as lakes, rivers and aquifers. The present paper reports the results of a study of water samples from the Feijao River, which is the source of drinking water for the city of Sao Carlos, Sao Paulo, Brazil. The samples were evaluated for the presence of four leading pesticides - ametryn, atrazine, diuron and fipronil - used on sugarcane, the dominant culture in the region. The samples were obtained from three points along the river: the headwaters, along the middle course of the river and just before the municipal water intake station. The pesticides were extracted from the water samples by solid-phase extraction (SPE) and then analyzed by liquid chromatography with diode array detection (LC-DAD). The analytical method was validated by traditional methods, obtaining recovery values between 90 and 95%, with precision deviations inferior to 2.56%, correlation coefficients above 0.99 and detection and quantification limits varying from 0.02 to 0.05 mg L-1 and 0.07 to 0.17 mg L-1, respectively. No presence of residues of the pesticides was detected in the samples, considering the detection limits of the method employed.

Assessment of the stereoselective fungal biotransformation of albendazole and its analysis by HPLC in polar organic mode

A high-performance liquid chromatographic method using polar organic mode was developed to analyze albendazole (ABZ), albendazole sulfone (ABZSO(2)) and the chiral and active metabolite albendazole sulfoxide (ABZSOX, ricobendazole) that was further applied in stereoselective fungal biotransformation studies. The chromatographic separation was performed on a Chiralpak AS column using acetonitrile:ethanol (97:3, v/v) plus 0.2% triethylamine and 0.2% acetic acid as the mobile phase at a flow rate of 0.5 mL min(-1). The present study employed hollow fiber liquid-phase microextraction as sample preparation. The method showed to be linear over the concentration range of 25-5000 ng mL(-1) for each ABZSOX enantiomer, 200-10,000 ng mL(-1) for ABZ and 50-1000 ng mL(-1) for ABZSO(2) metabolite with correlation coefficient (r)> 0.9934. The mean recoveries for ABZ, rac-ABZSOX and ABZSO(2) were, respectively, 9%, 33% and 20% with relative standard deviation below 10%. Within-day and between-day precision and accuracy assays for these analytes were studied at three concentration levels and were lower than 15%. This study opens the door regarding the possibility of using fungi in obtaining of the active metabolite ricobendazole. Nigrospora sphaerica (Sacc.) E. W. Mason (5567), Pestalotiopsis foedans (VR8), Papulaspora immersa Hotson (SS13) and Mucor rouxii were able to stereoselectively metabolize ABZ into its chiral metabolite. Among them, the fungus Mucor rouxii was the most efficient in the production of (+)-ABZSOX. (C) 2011 Elsevier B.V. All rights reserved.

The Carmaphycins: New Proteasome Inhibitors Exhibiting an alpha,beta-Epoxyketone Warhead from a Marine Cyanobacterium

Two new peptidic proteasome inhibitors were isolated as trace components from a Curacao collection of the marine cyanobacterium Symploca sp. Carmaphycin A (1) and carmaphycin B (2) feature a leucine-derived a,beta-epoxyketone warhead directly connected to either methionine sulfoxide or methionine sulfone. Their structures were elucidated on the basis of extensive NMR and MS analyses and confirmed by total synthesis, which in turn provided more material for further biological evaluations. Pure carmaphycins A and B were found to inhibit the beta 5 subunit (chymotrypsin-like activity) of the S. cerevisiae 20S proteasome in the low nanomolar range. Additionally, they exhibited strong cytotoxicity to lung and colon cancer cell lines, as well as exquisite antiproliferative effects in the NCI60 cell-line panel. These assay results as well as initial structural biology studies suggest a distinctive binding mode for these new inhibitors.

Applicability of in vitro bioassays for the diagnosis of ivermectin resistance in Rhipicephalus microplus (Acari: Ixodidae)

The applicability of laboratory bioassays to diagnose ivermectin (IVM) resistance in Rhipicephalus microplus was evaluated. Adult immersion tests (AITs), larval immersion tests (LITs) and larval packet tests (LPTs) were performed to characterise the effects of ivermectin toxicity on adults and larvae of a susceptible reference strain. The AIT was determined to be a reasonable assay but requires a large number of individuals to attain interpretable results. The LIT and LPT were validated with an IVM resistant strain, revealing resistance ratios (RRs) of 6.73 and 1.49, respectively. In a field survey, nine different populations of cattle tick from the states of Sao Paulo and Mato Grosso do Sul, Brazil, were analysed with the LIT. Populations without previous exposure to ivermectin exhibited RRs between 0.87 and 1.01. Populations previously exposed to IVM showed RRs between 1.83 and 4.62. The LIT was more effective at discriminating between resistant and susceptible populations than the LPT. The use of the LIT is recommended for the diagnosis of ivermectin resistance in R microplus. (C) 2011 Elsevier B.V. All rights reserved.

Binary and ternary inclusion complexes of dapsone in cyclodextrins and polymers: preparation, characterization and evaluation

Dapsone (DAP) is a synthetic sulfone drug with bacteriostatic activity, mainly against Mycobacterium leprae. In this study we have investigated the interactions of DAP with cyclodextrins, 2-hydroxypropyl-beta-cyclodextrin (HP beta CD) and beta-cyclodextrin (beta CD), in the presence and absence of water-soluble polymers, in order to improve its solubility and bioavailability. Solid systems DAP/HP beta CD and DAP/beta CD, in the presence or absence of polyvinylpyrrolidone (PVP K30) or hydroxypropyl methylcellulose (HPMC), were prepared. The binary and ternary systems were evaluated and characterized by SEM, DSC, XRD and NMR analysis as well as phase solubility assays, in order to investigate the interactions between DAP and the excipients in aqueous solution. This study revealed that inclusion complexes of DAP and cyclodextrins (HP beta CD and beta CD) can be produced in order to improve DAP solubility and bioavailability in the presence or absence of polymers (PVP K30 and HPMC). The more stable inclusion complex was obtained with HP beta CD, and consequently HP beta CD was more efficient in improving DAP solubility than beta CD, and the addition of polymers had no influence on DAP solubility or on the stability of the DAP/CDs complexes.

Microwave-Mediated Hetero Diels-Alder reaction: Synthesis of biologically active compounds

Heterocyclic compounds represent almost two-thirds of all the known organic compounds: they are widely distributed in nature and play a key role in a huge number of biologically important molecules including some of the most significant for human beings. A powerful tool for the synthesis of such compounds is the hetero Diels-Alder reaction (HDA), that involve a [4+2] cycloaddition reaction between heterodienes and suitable dienophiles. Among heterodienes to be used in such six-membered heterocyclic construction strategy, 3-trialkylsilyloxy-2-aza-1,3-dienes (Fig 1) has been demonstrated particularly attractive. In this thesis work, HDA reactions between 2-azadienes and carbonylic and/or olefinic dienophiles, are described. Moreover, substitution of conventional heating by the corresponding dielectric heating as been explored in the frame of Microwave-Assisted-Organic-Synthesis (MAOS) which constitutes an up-to-grade research field of great interest both from an academic and industrial point of view. Reaction of the azadiene 1 (Fig 1) will be described using as dienophiles carbonyl compounds as aldehyde and ketones. The six-membered adducts thus obtained (Scheme 1) have been elaborated to biologically active compounds like 1,3-aminols which constitutes the scaffold for a wide range of drugs (Prozac®, Duloxetine, Venlafaxine) with large applications in the treatment of severe diseases of nervous central system (NCS). Scheme 1 The reaction provides the formation of three new stereogenic centres (C-2; C-5; C-6). The diastereoselective outcome of these reactions has been deeply investigated by the use of various combination of achiral and chiral azadienes and aliphatic, aromatic or heteroaromatic aldehydes. The same approach, basically, has been used in the synthesis of piperidin-2-one scaffold substituting the carbonyl dienophile with an electron poor olefin. Scheme 2 As a matter of fact, this scaffold is present in a very large number of natural substances and, more interesting, is a required scaffold for an huge variety of biologically active compounds. Activated olefins bearing one or two sulfone groups, were choose as dienophiles both for the intrinsic characteristic flexibility of the “sulfone group” which may be easily removed or elaborated to more complex decorations of the heterocyclic ring, and for the electron poor property of this dienophiles which makes the resulting HDA reaction of the type “normal electron demand”. Synthesis of natural compounds like racemic (±)-Anabasine (alkaloid of Tobacco’s leaves) and (R)- and (S)-Conhydrine (alkaloid of Conium Maculatum’s seeds and leaves) and its congeners, are described (Fig 2).

Effects of pesticides on honey bees (Apis mellifera L.): study of a specific route of exposure and evaluation of biochemical-physiological changes in the assessment of the pesticides toxicity

In this study, some important aspects of the relationship between honey bees (Apis mellifera L.) and pesticides have been investigated. In the first part of the research, the effects of the exposure of honey bees to neonicotinoids and fipronil contaminated dusts were analyzed. In fact, considerable amounts of these pesticides, employed for maize seed dressing treatments, may be dispersed during the sowing operations, thus representing a way of intoxication for honey bees. In particular, a specific way of exposure to this pesticides formulation, the indirect contact, was taken into account. To this aim, we conducted different experimentations, in laboratory, in semi-field and in open field conditions in order to assess the effects on mortality, foraging behaviour, colony development and capacity of orientation. The real dispersal of contaminated dusts was previously assessed in specific filed trials. In the second part, the impact of various pesticides (chemical and biological) on honey bee biochemical-physiological changes, was evaluated. Different ways and durations of exposure to the tested products were also employed. Three experimentations were performed, combining Bt spores and deltamethrin, Bt spores and fipronil, difenoconazole and deltamethrin. Several important enzymes (GST, ALP, SOD, CAT, G6PDH, GAPDH) were selected in order to test the pesticides induced variations in their activity. In particular, these enzymes are involved in different pathways of detoxification, oxidative stress defence and energetic metabolism. The results showed a significant effect on mortality of neonicotinoids and fipronil contaminated dusts, both in laboratory and in semi-field trials. However, no effects were evidenced in honey bees orientation capacity. The analysis of different biochemical indicators highlighted some interesting physiological variations that can be linked to the pesticide exposure. We therefore stress the attention on the possibility of using such a methodology as a novel toxicity endpoint in environmental risk assessment.

Novel organic semiconductors and their applications in electronics

The main goals of this thesis were the design, synthesis, and characterization of novel organic semiconductors, together with their applications in electronics, such as OFETs, OPVs, and OLEDs. The results can be summarized as follows:rn1. In chapter II, two novel angular n-type molecules were presented. Their different alkyl chains play a pivotal role in the molecular orientation relative to surface. One molecule with longer branched chains is tilted with respect to the substrate, thereby resulting in poor device performance, while the other adopt an edge-on orientation with an OFET electron mobility of 0.01 cm2 V-1 s-1.rn2. In chapter III, fused bis-benzothiadiazoles with different molecular geometries, namely linear benzoquinone-fused bis(benzothiadiazole) and V-shaped sulfone-fused bis(benzothiadiazole), were shown. This work not only contributes to the diversity of electron acceptors based on bis-benzothiadiazole moieties, but also highlights the important role of molecular shape for the solid-state packing of organic conjugated materials. In chapter IV, we demonstrated the synthesis of layered acceptors via dimerization of thiadiazole end-capped acenes. Interestingly, they feature huge differences in their photophysical properties. One compound showed a new strong emission in the near-infrared region introduced by the aggregation effect. The planosymmetric compound featured intramolecular excimer (IEE) fluorescence in solution. rn3. In chapter V and VI, we have demonstrated the synthesis of novel spiro-bifluorene based asymmetric and symmetric cruciform electron acceptors with dicyanovinylene substitutions. The solar cells based on PTB7:asymmetric acceptor yields the highest PCE of 0.80%. Such results demonstrate for the first time that dicyanovinylene substituted acceptor could be an alternative to fullerene-based acceptors. rn4. In chapter VII, two novel blue-emitting compounds were shown, which consist of dihydroindenofluorenyl units and ladder-type poly-p-phenylene groups, respectively. The two novel cruciform rigid compounds present not only excellent thermal and electrochemical stability but also high PLQYs. Through analysis of their triplet energy levels, both molecules can be served as hosts for other normal fluorescent or phosphorescent materials.rn

Monepantel allosterically activates DEG-3/DES-2 channels of the gastrointestinal nematode Haemonchus contortus

Monepantel is the first drug of a new family of anthelmintics, the amino acetonitrile derivatives (AAD), presently used to treat ruminants infected with gastrointestinal nematodes such as Haemonchus contortus. Monepantel shows an excellent tolerability in mammals and is active against multidrug-resistant parasites, indicating that its molecular target is absent or inaccessible in the host and is different from those of the classic anthelmintics. Genetic approaches with mutant nematodes have suggested acetylcholine receptors of the DEG-3 subfamily as the targets of AADs, an enigmatic clade of ligand-gated ion channels that is specific to nematodes and does not occur in mammals. Here we demonstrate direct interaction of monepantel, its major active metabolite monepantel sulfone, and other AADs with potential targets of the DEG-3 subfamily of acetylcholine receptors. H. contortus DEG-3/DES-2 receptors were functionally expressed in Xenopus laevis oocytes and were found to be preferentially activated by choline, to permeate monovalent cations, and to a smaller extent, calcium ions. Although monepantel and monepantel sulfone did not activate the channels by themselves, they substantially enhanced the late currents after activation of the channels with choline, indicating that these AADs are type II positive allosteric modulators of H. contortus DEG-3/DES-2 channels. It is noteworthy that the R-enantiomer of monepantel, which is inactive as an anthelmintic, inhibited the late currents after stimulation of H. contortus DEG-3/DES-2 receptors with choline. In summary, we present the first direct evidence for interaction of AADs with DEG-3-type acetylcholine receptors and discuss these findings in the context of anthelmintic action of AADs.

Macrocyclic chelator-coupled gastrin-based radiopharmaceuticals for targeting of gastrin receptor-expressing tumours

PURPOSE: Diethylenetriamine-pentaacetic acid (DTPA)-coupled minigastrins are unsuitable for therapeutic application with the available beta-emitting radiometals due to low complex stability. Low tumour-to-kidney ratio of the known radiopharmaceuticals is further limiting their potency. We used macrocyclic chelators for coupling to increase complex stability, modified the peptide sequence to enhance radiolytic stability and studied tumour-to-kidney ratio and metabolic stability using (111)In-labelled derivatives. METHODS: Gastrin derivatives with decreasing numbers of glutamic acids were synthesised using (111)In as surrogate for therapeutic radiometals for in vitro and in vivo studies. Gastrin receptor affinities of the (nat)In-metallated compounds were determined by receptor autoradiography using (125)I-CCK as radioligand. Internalisation was evaluated in AR4-2J cells. Enzymatic stability was determined by incubating the (111)In-labelled peptides in human serum. Biodistribution was performed in AR4-2J-bearing Lewis rats. RESULTS: IC(50) values of the (nat)In-metallated gastrin derivatives vary between 1.2 and 4.8 nmol/L for all methionine-containing derivatives. Replacement of methionine by norleucine, isoleucine, methionine-sulfoxide and methionine-sulfone resulted in significant decrease of receptor affinity (IC(50) between 9.9 and 1,195 nmol/L). All cholecystokinin receptor affinities were >100 nmol/L. All (111)In-labelled radiopeptides showed receptor-specific internalisation. Serum mean-life times varied between 2.0 and 72.6 h, positively correlating with the number of Glu residues. All (111)In-labelled macrocyclic chelator conjugates showed higher tumour-to-kidney ratios after 24 h (0.37-0.99) compared to (111)In-DTPA-minigastrin 0 (0.05). Tumour wash out between 4 and 24 h was low. Imaging studies confirmed receptor-specific blocking of the tumour uptake. CONCLUSIONS: Reducing the number of glutamates increased tumour-to-kidney ratio but resulted in lower metabolic stability. The properties of the macrocyclic chelator-bearing derivatives make them potentially suitable for clinical purposes.

The laulimalide family: total synthesis and biological evaluation of neolaulimalide, isolaulimalide, laulimalide and a nonnatural analogue

We herein describe in full detail the first total synthesis of the antitumor agents neolaulimalide and isolaulimalide as well as a highly efficient route to laulimalide. A Kulinkovich reaction followed by a cyclopropyl-allyl rearrangement is used to install the exo-methylene group. The C(2)-C(16) aldehyde fragment is coupled with the C(17)-C(28) sulfone fragments by a highly (E)-selective Julia-Lythgoe-Kocienski olefination to deliver the key intermediates of all three syntheses. Various conditions for the Yamaguchi macrolactonization are applied to close the individual macrocycles. Finally a carefully elaborated endgame was developed to solve the problem of acyl migration in the case of neolaulimalide. All compounds were tested against several cell lines. The cytotoxicity of neolaulimalide could be confirmed for the first time since its original isolation and it could be shown that it induces tubulin polymerization as efficiently as laulimalide.