RESUMO
Quorum sensing (QS) is a cell-to-cell signaling communication system that controls the virulence behavior of a broad spectrum of bacterial pathogens, participating also in the development of biofilms, responsible of the antibiotic ineffectiveness in many infections. Therefore, QS system is an attractive target for antimicrobial therapy. In this study, we compare the effect of seven structurally related coumarins against bacterial growth, biofilm formation and elastase activity of Pseudomonas aeruginosa. In addition, the anti-pathogenic capacity of the seven coumarins was evaluated on the wild type and the biosensor strain of Chromobacterium violaceum. The comparative study of coumarins showed that molecules with hydroxyl groups on the aromatic ring displayed higher activity on the inhibition of biofilm formation of P. aeruginosa over coumarins with substituents in positions 3 and 4 or without the double 3,4-bond. These 3 or 4-hydroxylated positions caused a decrease in the anti-biofilm activity obtained for coumarin. However, the hydroxyl group in position 3 of the pyrone ring was important for the inhibition of C. violaceum QS and elastolytic activity of P. aeruginosa. The effects observed were active independently of any effect on growth. According to our results, coumarin and its hydroxylated derivatives represent an interesting group of compounds to use as anti-virulence agents against the human pathogen P. aeruginosa.
Assuntos
Antibacterianos/farmacologia , Chromobacterium/efeitos dos fármacos , Cumarínicos/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , Percepção de Quorum/efeitos dos fármacos , Antibacterianos/síntese química , Antibacterianos/química , Chromobacterium/química , Cumarínicos/síntese química , Cumarínicos/química , Relação Dose-Resposta a Droga , Indóis/antagonistas & inibidores , Indóis/metabolismo , Testes de Sensibilidade Microbiana , Estrutura Molecular , Relação Estrutura-AtividadeRESUMO
Porella, the largest genus of the family Porellaceae (Hepaticae) is widespread in the tropical and subtropical regions of South America. Most Porella species are rich sources of sesqui- and diterpenoids, many of which show interesting biological activities. Secondary metabolites produced by plants can interact with insects and act as antifeedants and growth regulators affecting hormone and nervous systems as well as stomach and muscle tissues. A previous chemical investigation of a Patagonian collection of Porella chilensis yielded sesqui- and diterpenoids that were now evaluated for their effects against Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), a serious pest affecting corn crops mainly in the Americas. Four pinguisanes (1-4), three fusicoccanes (5-7), and one aromadendrane (8) from P. chilensis displayed larvicidal activity against S. frugiperda when incorporated to the larval diet at 100 and 200 µg/g of diet with a significant decrease in the larval growing rate. The observed effects were in part produced by severe alterations of the epithelial cells of the midgut as indicated by our histological studies.
Assuntos
Agentes de Controle Biológico , Diterpenos/toxicidade , Hepatófitas , Sesquiterpenos/toxicidade , Spodoptera/efeitos dos fármacos , Spodoptera/fisiologia , Zea mays/parasitologia , Animais , Larva/efeitos dos fármacosRESUMO
A series of experiments were conducted to evaluate the toxicity of lemon peel extracts incorporated into mediterranean fruit fly Ceratitis capitata diet. Extracts were obtained with different solvents: diethyl ether, ethyl acetate, and methanol. All three extracts were toxic to some extent; the diethyl ether extract was selected for further studies. Ether extracts of lemon peel were prepared weekly over a 2-month period, from fruits collected on the 1st d of the bioassay. Weekly GC-MS and UV analyses of the extracts demonstrated that the concentration of citral and coumarins decreased in the peel after harvest. We conducted a series of bioassays to evaluate the toxicity of the ether extract, and mixtures of this extract with citral, 5,7-dimethoxycoumarin. and linalool incorporated to C. capitata larvae's natural diet (lemon slices endocarp) at a concentration of 250 microg/g of diet. Significant larvicidal activity can be obtained from a fresh lemon peel extract; however, when the extract was obtained from stored lemons, toxicity decreased. Addition of small amounts of citral or 5,7-dimethoxycoumarin, and linalool to the stored lemon peel extract would bring back the toxicity to the rates of fresh lemons extracts. Finally, female adults of C. capitata fed on diets containing additional amounts of ether extract, 5,7-dimethoxycoumarin, and linalool, were exposed to different photoperiods to test for phototoxicity. The treatment was toxic and affected the oviposition capacity of females depending on photoperiod.
Assuntos
Ceratitis capitata , Citrus/química , Oviposição , Administração Oral , Ração Animal , Animais , Feminino , Larva , Fotoperíodo , Extratos Vegetais/toxicidade , Solventes , Testes de ToxicidadeRESUMO
Aerial parts of Pterocaulon polystachyum from Chaco province, Argentina, afforded the known coumarins ayapin, isoscopoletin, prenyletin, prenyletin methyl ether, virgatenol, obtusinin, 5-methoxy-6,7-methylenedioxycoumarin, 5-(3,3-dimethylallyloxy)-6,7-methylenedioxycoumarin, 5-(2',3'-dihydroxy-3-methylbutanoxy)-6,7-methylenedioxycoumarin, haplopinol methyl ether, 6-(1,1-dimethyl-2-propenyl)-7-hydroxycoumarin and demethylnieshoutin; the last two are new as natural products while the five new coumarins from the collection were isovirgatenol, 3'-deoxyobtusinin, 6-methoxy-7-(2'-hydroxyethoxy)-coumarin, 5-(2'-hydroxyethoxy)-6,7-methylenedioxycoumarin and a substance tentatively identified as 5-hydroxy-6,7-methylenedioxy-8-(3,3-dimethylallyl)-coumarin.
Assuntos
Asteraceae , Cumarínicos/isolamento & purificação , Extratos Vegetais/química , Argentina , Cumarínicos/química , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Plantas MedicinaisRESUMO
Flowers and leaves of Disynaphia multicrenulata from Argentina afforded a large number of known germacradienolides and heliangolides, a new germacradienolide, a known melampolide, a new parthenolide derivative, one known and seven new cronquistiolides, a new 4Z-melampolide, three known and five new eudesmanolides, a new elemadienolide, a known grazielolide, an isoguaiagrazielolide, two diepoxygermacran-8,12-olides, three common kauranoic acids, pinoresinol, jaceosidin and the sesquiterpene oplopanone. Structures were elucidated by high-field 1H NMR spectrometry. The relationship to the known chemistry of other members of the Disynaphiinae is discussed.
RESUMO
The investigation of an Argentine collection of Enydra anagallis afforded sesquiterpene lactones of the melampolide type two of which were previously known. Their structures were elucidated by spectroscopic methods.
Assuntos
Asteraceae/química , Lactonas/isolamento & purificação , Sesquiterpenos/isolamento & purificação , Lactonas/química , Sesquiterpenos/química , Análise EspectralRESUMO
The sesquiterpenoid fractions from the chloroform extracts of roots and aerial parts of the weed Cyrtocymura cincta (Griseb.) H. Robinson (Compositae) were tested to observe the effects on seed germination and growth of three dicot and four monocot species. Promotion and inhibition effects were observed according to the examined compound, specific seed or cultivar, and concentration.
Assuntos
Asteraceae/química , Germinação/efeitos dos fármacos , Lactonas/isolamento & purificação , Desenvolvimento Vegetal , Plantas Medicinais/química , Plantas/efeitos dos fármacos , Sesquiterpenos/isolamento & purificação , Argentina , Avena/efeitos dos fármacos , Avena/crescimento & desenvolvimento , Cromatografia em Agarose , Cromatografia Líquida de Alta Pressão , Daucus carota/efeitos dos fármacos , Daucus carota/crescimento & desenvolvimento , Relação Dose-Resposta a Droga , Lactonas/química , Lactonas/farmacologia , Lactuca/efeitos dos fármacos , Lactuca/crescimento & desenvolvimento , Solanum lycopersicum/efeitos dos fármacos , Solanum lycopersicum/crescimento & desenvolvimento , Estrutura Molecular , Cebolas/efeitos dos fármacos , Cebolas/crescimento & desenvolvimento , Panicum/efeitos dos fármacos , Panicum/crescimento & desenvolvimento , Folhas de Planta/química , Fenômenos Fisiológicos Vegetais , Raízes de Plantas/química , Sementes/efeitos dos fármacos , Sementes/crescimento & desenvolvimento , Sesquiterpenos/química , Sesquiterpenos/farmacologia , Espectrofotometria Infravermelho , EstereoisomerismoRESUMO
The aerial parts of an Argentinian collection of Acanthospermum hispidum afforded 26 sesquiterpene lactones, including the two guaianolides (1 and 2) having a novel oxygen bridge between C-4 and C-14, three new cis,cis-germacranolides (4, 7, and 8), and two new melampolides (25 and 26). Guaianolides 1 and 2 seem to derive biosynthetically from the germacranolide 27 having the (1)D(14, 15)D(5) conformation. The structures were elucidated using extensive spectroscopic analysis.