RESUMO
The mating hormones α1 and α2 induce sexual reproduction of the phytopathogenic genus Phytophthora. To demonstrate the structural elements responsible to hormonal activity, 17 derivatives of α1 and α2 were synthesized and their hormonal activity (oospore-inducing activity) was evaluated. The terminal ester derivatives of α1 (diacetate and dibenzoate) retained the hormonal activity, whereas a dicarbamate derivative completely suppressed the activity. Even monocarbamates showed weak activities; among them the 1-O-carbamate was less active than 16-O-carbamate, suggesting that the 1-OH group is a little more important than 16-OH. Dihydro, dehydro, and demethyl derivatives exhibited the minimum level of activity. Surviving activity of 15-epi-α1 suggested a less importance of this stereochemistry. Contrary to α1, not only the terminal diacetate derivative but also monoacetates of α2 exhibited no or little activity. Among the monoacetates, 1-O-acetyl-α2 exhibited little yet relatively better activity than the others. No activity was observed for mono- and dicarbamoyl derivatives of α2. Dihydro α2 with the saturated double bond lost most of the activity. These findings suggest that both the mating hormones α1 and α2 require most of the functional (hydroxyl, keto, and olefinic) groups they possess in their natural form for inducing the sexual reproduction of Phytophthora.
Assuntos
Diterpenos/química , Phytophthora/metabolismo , Carbamatos/química , Diterpenos/síntese química , Diterpenos/farmacologia , Phytophthora/efeitos dos fármacos , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
An important biological event in phytopathogens of the genus Phytophthora is sexual reproduction, which is conducted by two mating types, A1 and A2. A factor known as hormone alpha1 is secreted by the A1 mating type and induces the formation of sexual spores (oospores) in the A2 mating type. Here we describe the asymmetric synthesis and assignment of the absolute configuration of hormone alpha1 by oospore-inducing assays of the synthesized isomers.
Assuntos
Diterpenos/química , Diterpenos/síntese química , Proteínas Fúngicas/química , Proteínas Fúngicas/síntese química , Phytophthora/química , Espectroscopia de Ressonância Magnética/métodos , Conformação Molecular , Tamanho da Partícula , EstereoisomerismoRESUMO
Four stereoisomers of roseoside (vomifoliol glucosides) were synthesized using glucose as a chiral resolving reagent. The four synthetic stereoisomers exhibited inhibitory activity on leukotriene release from mouse bone marrow-derived cultured mast cells (BMCMC). The (6S)-isomers of roseoside were about twice as active as (6R)-isomers.
Assuntos
Glucosídeos/síntese química , Leucotrienos/metabolismo , Norisoprenoides/síntese química , Animais , Medula Óssea , Glucose , Glucosídeos/farmacologia , Mastócitos , Camundongos , Norisoprenoides/farmacologia , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
The four stereoisomers of small bacteriocin, an autoinducer of the symbiotic nitrogen-fixing bacterium Rhizobium leguminosarum, were synthesized via a versatile methodology for 3'-hydroxyacyl homoserine lactones based on the Nagao asymmetric aldol reaction. The synthetic isomers were much less effective at inhibiting the growth of R. leguminosarum RBL5523 than the natural isomer, showing the importance of stereochemistry for activity.
Assuntos
4-Butirolactona/análogos & derivados , Bacteriocinas/química , Bacteriocinas/síntese química , Nitrogênio/química , Rhizobium leguminosarum/química , 4-Butirolactona/síntese química , 4-Butirolactona/química , 4-Butirolactona/farmacologia , Bacteriocinas/farmacologia , Testes de Sensibilidade Microbiana , Estrutura Molecular , Rhizobium leguminosarum/efeitos dos fármacos , EstereoisomerismoRESUMO
An asymmetric total synthesis of ent-sandaracopimaradiene, a biosynthetic intermediate of oryzalexins, via B-alkyl Suzuki-Miyaura coupling and Lewis acid-mediated B-ring formation as key steps was achieved.
Assuntos
Diterpenos/síntese química , Terpenos/síntese química , Sesquiterpenos , Estereoisomerismo , FitoalexinasRESUMO
An efficient and stereoselective synthesis of three stereoisomers of the sex pheromone of the cowpea weevil, Callosobruchus maculatus, is reported.
Assuntos
Ácidos Carboxílicos/síntese química , Atrativos Sexuais/síntese química , Gorgulhos/metabolismo , Monoterpenos Acíclicos , Animais , Ácidos Carboxílicos/química , Ácidos Dicarboxílicos/síntese química , Ácidos Dicarboxílicos/química , Atrativos Sexuais/química , EstereoisomerismoRESUMO
The stereoisomeric composition of the copulation release pheromone of the azuki bean weevil, Callosobruchus chinensis L., was determined to be R:S=3.3-3.4:1 by the 2D-Ohrui-Akasaka method.
Assuntos
Copulação , Atrativos Sexuais/química , Comportamento Sexual Animal , Gorgulhos/fisiologia , Animais , Cromatografia Líquida de Alta Pressão , Espectrometria de Fluorescência , EstereoisomerismoRESUMO
A diastereomeric mixture and the four stereoisomers of 2,6-dimethyloctane-1,8-dioic acid (2), a copulation release pheromone of the cowpea weevil, Callosobruchus maculatus, were synthesized. The stereoisomeric purities of the four synthetic isomers of 2 were determined by the HPLC analyses of their bis-2-(2,3-anthracenedicarboximide)-1-cyclohexyl esters.
Assuntos
Ácidos Dicarboxílicos/síntese química , Atrativos Sexuais/síntese química , Gorgulhos/química , Monoterpenos Acíclicos , Cromatografia Líquida de Alta Pressão , Ácidos Dicarboxílicos/química , Indicadores e Reagentes , Espectroscopia de Ressonância Magnética , Conformação Molecular , Oxirredução , Atrativos Sexuais/química , Espectrofotometria Infravermelho , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
We have isolated and characterized a cDNA encoding a novel diterpene cyclase, OsDTC1, from suspension-cultured rice cells treated with a chitin elicitor. OsDTC1 functions as ent-cassa-12,15-diene synthase, which is considered to play a key role in the biosynthesis of (-)-phytocassanes recently isolated as rice diterpenoid phytoalexins. The expression of OsDTC1 mRNA was also confirmed in ultraviolet (UV)-irradiated rice leaves. In addition, we identified ent-cassa-12,15-diene, a putative diterpene hydrocarbon precursor of (-)-phytocassanes, as an endogenous compound in the chitin-elicited suspension-cultured rice cells and the UV-irradiated rice leaves. The OsDTC1 cDNA isolated here will be a useful tool to investigate the regulatory mechanisms of the biosynthesis of (-)-phytocassanes in rice.