Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 20
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
J Chem Ecol ; 22(2): 287-94, 1996 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24227410

RESUMO

A sequence of reactions is presented for inverting the configurations of both epoxide carbons in 1,2-disubstituted epoxides. As examples, (+)-disparlure was converted to its enantiomer, (-)-disparlure, andexo-endo conversion of a cyclohexene oxide was demonstrated.

2.
J Chem Ecol ; 22(4): 729-38, 1996 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24227581

RESUMO

Oechalia schellenbergii is one of the most common predatory insects in Australia and the islands of the South Pacific. Adult males of this predaceous "true bug" collected during March near Gatton, Queensland, Australia, had a pair of enlarged exocrine glands opening underneath their wings that presumably produce an attractant pheromone. The two major components of the secretion are 3-methylenehexyl acetate and 9-hydroxygeranyl diacetate [2,6-dimethyl-2(E),6(E)-octadien-1,8-diol diacetate].

3.
J Chem Ecol ; 21(2): 199-211, 1995 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24234019

RESUMO

A method has been developed to convert disparlure (2-methyl-7,8-epoxyoctadecane) to the correspondingN-(α-methylbenzyl)aziridine with inversion of configuration at both the 7 and 8 positions. The diastereomeric aziridines can be separated on an efficient gas chromatography column, permitting determination of the enantiomeric constitution of the starting disparlure. As little as ca. 0.1% of the minor enantiomer can be detected.

4.
J Chem Ecol ; 20(10): 2705-19, 1994 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24241842

RESUMO

Partially fluorinated analogs of the European corn borer (Ostrinia nubilalis) female sex pheromone, 11-tetradecenyl acetate (97:3Z:E), having mono- and trifluorsubstitutions at the terminal carbon of the pheromone chain, mimicked the biological activity of the pheromone, while analogs with fluorine at either side of the double bond and a pentafluoro analog were essentially inactive. Comparison of the pheromonal activity of these analogs with the previously reported activity of similarly fluorinated pheromones in five other species of moths revealed an unpredictable relationship between fluorine substitution pattern and pheromone-mimicking activity. Fluorine substitution patterns that rendered pheromonal analogs biologically inactive in the European corn borer had no detrimental influence upon pheromonal activity in other species and the converse was also true. This is evidence that the relative importance of electronic qualities of sites within a pheromone molecule differ from species to species. Furthermore, it indicates that the biochemical components (pheromone receptor proteins, binding proteins, and enzymes) that make up moth olfactory chemosensory systems must also vary structurally from species to species, despite the fact that they are involved in olfactory sensing of compounds having very similar chemical structure.

5.
Int J Pept Protein Res ; 41(5): 467-75, 1993 May.
Artigo em Inglês | MEDLINE | ID: mdl-8100557

RESUMO

Synthesized beta 1- and beta 2-pentapeptide sequences corresponding to published adrenoceptor transmembrane activation site subtypes were investigated in vitro for selectivity in association for drug ligands of known selectivity. Both nuclear magnetic resonance spectroscopy and molecular mechanics demonstrated that structural differences among the corresponding pentapeptide activation-site sequences can explain agonist selectivity. Results suggest the agonists bind across the activation site loop on the second transmembrane alpha-helix by dipole/dipole interactions between a ligand and the peptide. Since electrostatic interactions within the membrane may determine the rate of intercellular ion flux, agonist association across the activation site sequence could thereby decrease electrostatic resistance to positive ion flux into the cell. Interactions between the peptides and the ligands may provide insight into the structures and mechanisms involved in association of ligands for the identical sequences on the beta-adrenoreceptors.


Assuntos
Agonistas Adrenérgicos beta/metabolismo , Oligopeptídeos/metabolismo , Fragmentos de Peptídeos/metabolismo , Receptores Adrenérgicos beta/metabolismo , Albuterol/farmacologia , Sequência de Aminoácidos , Isoproterenol/farmacologia , Modelos Moleculares , Dados de Sequência Molecular , Fragmentos de Peptídeos/farmacologia , Fenetilaminas/farmacologia , Receptores Adrenérgicos beta/efeitos dos fármacos
6.
Brain Behav Evol ; 41(3-5): 219-23, 1993.
Artigo em Inglês | MEDLINE | ID: mdl-8477343

RESUMO

The response of adult red-sided garter snakes, Thamnophis sirtalis parietalis, to airborne odor trails was studied. An airtight T-maze was used, through which a constant airflow was drawn by a vacuum pump. The arms of the 'T' provided a choice between earthworm extract and distilled water. Experiment 1 tested the snake's responses to varying concentrations of earthworm extract. Snakes accurately trailed the extract at tested concentrations (0.0, 0.01, 0.1, 1, 10, 100%). At ten percent concentration, tongue-flick rate and speed along the maze increased significantly above lower levels, suggesting the existence of a threshold concentration. A correlation between mean tongue-flick rate and mean speed was demonstrated. Experiment 2 tested the effect of differentially blocked vomeronasal ducts on a snake's ability to trail. When both ducts were blocked, no trailing was observed, suggesting that vomeronasal stimulation is required. Blocking a single duct resulted in a significant number of snakes turning to the side of the functioning duct, suggesting that the tongue-vomeronasal system may function as a chemotaxic system.


Assuntos
Células Quimiorreceptoras/fisiologia , Comportamento Predatório/fisiologia , Olfato/fisiologia , Serpentes/fisiologia , Animais , Nível de Alerta/fisiologia , Atenção/fisiologia , Mucosa Nasal/inervação , Condutos Olfatórios/fisiologia , Feromônios/fisiologia , Limiar Sensorial/fisiologia , Meio Social
7.
J Chem Ecol ; 19(12): 2935-46, 1993 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24248786

RESUMO

A general synthetic approach to various catechol derivatives was developed using a copper-catalyzed cross-coupling reaction of 1,2-dimethoxy-4-brornomethyl, 1-ethoxy-2-methoxy-4-bromomethyl- and 2-ethoxy-1-methoxy-4-bromomethylbenzenes with Grignard reagents. Dilithium tetrachlorocuprate was an acceptable catalyst in the dimethoxy series, whereas copper(I) iodide in THF-HMPA was a superior catalyst in all cases due to decreased side reactions, i.e., reduction and reductive coupling. Methyl-substituted analogs of methyl eugenol, a potent attractant of Oriental fruit fly,Dacus dorsalis Hendel, were synthesized by this method and evaluated for attractancy in field tests.

8.
J Chem Ecol ; 16(1): 199-210, 1990 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24264907

RESUMO

Scentless plant bugs (Heteroptera: Rhopalidae) are so named because adults of the Serinethinae have vestigial metathoracic scent glands. Serinethines are seed predators of Sapindales, especially Sapindaceae that produce toxic cyanolipids. In two serinethine species whose ranges extend into the southern United States,Jadera haematoloma andJ. sanguinolenta, sequestration of host cyanolipids as glucosides renders these gregarious, aposematic insects unpalatable to a variety of predators. The blood glucoside profile and cyanogenesis ofJadera varies depending on the cyanolipid chemistry of hosts, and adults and larvae fed golden rain tree seeds (Koelreuteria paniculata) excrete the volatile lactone, 4-methyl-2(5H)-furanone, to which they are attracted.Jadera fed balloon vine seeds (Cardiospermum spp.) do not excrete the attractive lactone. Loss of the usual heteropteran defensive glands in serinethines may have coevolved with host specificity on toxic plants, and the orientation ofJadera to a volatile excretory product could be an adaptive response to save time.

9.
Pharm Res ; 6(8): 706-8, 1989 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-2813263

RESUMO

Proton NMR spectroscopy was applied to the assignment of the isomeric identity of commercially available chlorprothixene. Nuclear Overhauser effect studies confirmed that the clinically useful isomer is the cis (Z) configuration. An NMR method for determining the isomeric content of chlorprothixene was developed based on integration of the ratio of areas of signal strength of the cis-N-methyl in comparison to the trans-N-methyl resonances.


Assuntos
Clorprotixeno/análise , Espectroscopia de Ressonância Magnética/métodos , Isomerismo , Conformação Molecular
10.
J Chem Ecol ; 15(12): 2607-23, 1989 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24271675

RESUMO

Structure-activity relationships of naturally occurring enedials with antifeedant activity againstSpodoptera species have been extended via the synthesis and bioassay of a series of Reimer-Tiemann adducts. The activities attributed to the different chemical structures of these and other analogs interacting with the chemoreceptor site have been observed; a three-pronged mode of substrate binding via aromatic pyrrole formation, Michael addition of free sulfhydryl moieties, and van der Waals interactions of the A ring has been postulated to account for these observations.

11.
Environ Lett ; 10(2): 97-120, 1975.
Artigo em Inglês | MEDLINE | ID: mdl-1204592

RESUMO

A comparison of the field attractiveness of five samples of American-synthesized and one sample of Japanese-synthesized (Z,E)-9,11-tetradecadien-1-01 acetate (9,11-TDDA), the sex pheromone of Spodoptera littoralis Boisd. and S. litura (F.), showed that traps baited with one of the American-produced samples and the Japanese product were equally effective in attracting and capturing S. littoralis males in cotton and alfalfa fields of Israel. Optimum captures were obtained for periods up to three months with 4800 mug of 9,11-TDDA plus 8 mg of an antioxidant; higher doses were not advantageous. Paper squares were superior to two types of rubber septa and to closed polyethylene vials as dispensers for the pheromone; the polyethylene vials were least effective. In terms of numbers of moths captured, open polyethylene vials were as effective as paper dispensers when both were baited with 9-11-TDDA plus antioxidant. Admixture of (Z,E)-9,12-tetradecadien-1-o1 acetate (9,12-TDDA) with 9,11-TDDA was antagonistic at ratios of 1:20 and 1:50, but ratios from 1:500 to 1:1600 were synergistic, increasing moth catches up to 2.5-fold. Pheromone traps placed in Caesarea sand dunes located at least 3 km from the nearest host area captured larger numbers of males than traps placed in cultivated areas. It is therefore recommended that safety belts of pheromone traps, about 500 m apart, be used around cultivated areas to prevent invasion of the pest from outside and to attract males present inside such areas, thus reducing both the male population and mating through mass trapping and disruption of sex communication.


Assuntos
Controle de Insetos , Lepidópteros , Mariposas , Feromônios , Animais , Fenômenos Químicos , Química , Ácidos Decanoicos/síntese química , Sinergismo Farmacológico , Israel , Masculino , Papel , Veículos Farmacêuticos , Feromônios/síntese química , Polietilenos , Borracha
15.
Bull World Health Organ ; 46(4): 485-91, 1972.
Artigo em Inglês | MEDLINE | ID: mdl-4538193

RESUMO

During 1971 worldwide experiments on the disinsection of passenger cabins at "blocks away" (as the aircraft starts taxiing for take-off) were conducted in several types of jet aircraft. A procedure was developed whereby the high capacity Boeing 747 could be disinsected by four stewardesses in less than 1 minute. The favourable results of these and previous trials indicate that this method is suitable as a standard procedure for aircraft disinsection for international quarantine purposes.The biological effectiveness against resistant and non-resistant mosquitos of a 2% concentration of a pyrethroid, resmethrin, in Freon 11+Freon 12 (1:1) (without kerosine) and a favourable passenger response make it suitable as a standard formulation for aircraft disinsection.


Assuntos
Aeronaves , Controle de Insetos , Inseticidas , Aedes , Aerossóis , Humanos , Controle de Mosquitos
19.
J Econ Entomol ; 63(3): 943-5, 1970 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-5431687
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...