RESUMO
Focused on our interest to develop novel antiparasistic agents, the present study was aimed to evaluate the biological activity of an extract of Laurencia johnstonii collected in Baja California Sur, Mexico, against an Acantamoeba castellanii Neff strain. Bioassay-guided fractionation allowed us to identify the amoebicidal diastereoisomers α-bromocuparane (4) and α-isobromocuparane (5). Furthermore, bromination of the inactive laurinterol (1) and isolaurinterol (2) yielded four halogenated derivatives, (6)â»(9), which improved the activity of the natural sesquiterpenes. Among them, the most active compound was 3α-bromojohnstane (7), a sesquiterpene derivative which possesses a novel carbon skeleton johnstane.
Assuntos
Acanthamoeba castellanii/efeitos dos fármacos , Antiparasitários/farmacologia , Organismos Aquáticos/química , Laurencia/química , Sesquiterpenos/farmacologia , Antiparasitários/química , Antiparasitários/isolamento & purificação , Bioensaio/métodos , Halogenação , Concentração Inibidora 50 , México , Estrutura Molecular , Sesquiterpenos/química , Sesquiterpenos/isolamento & purificação , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
Ptilonines A-F, pyranosylmagellanicus D-E and magellenediol are previously undescribed acetogenins isolated from the red alga Ptilonia magellanica. Their structures were determined from spectroscopic evidence. The absolute configuration of the known pyranosylmagellanicus A, was established by derivatization with (R)- and (S)-α-methoxy -α-phenylacetic acids (MPA). Ptilonines exhibit an unusual halogenation pattern, that may confer evolutionary advantages to Ptilonia magellanica, for which a biogenetic origin is proposed. The antimicrobial effect of some of these compounds was evaluated.
Assuntos
Acetogeninas/farmacologia , Antibacterianos/farmacologia , Antifúngicos/farmacologia , Rodófitas/química , Acetogeninas/química , Acetogeninas/isolamento & purificação , Antibacterianos/química , Antibacterianos/isolamento & purificação , Antifúngicos/química , Antifúngicos/isolamento & purificação , Bacillus cereus/efeitos dos fármacos , Candida albicans/efeitos dos fármacos , Relação Dose-Resposta a Droga , Enterococcus faecalis/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Klebsiella pneumoniae/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Proteus mirabilis/efeitos dos fármacos , Salmonella/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Relação Estrutura-AtividadeRESUMO
It is known that some strains of Vibrio parahaemolyticus are responsible for gastroenteric diseases caused by the ingestion of marine organisms contaminated with these bacterial strains. Organic products that show inhibitory activity on the growth of the pathogenic V. parahaemolyticus were extracted from a Vibrio native in the north of Chile. The inhibitory organic products were isolated by reverse phase chromatography and permeation by Sephadex LH20, and were characterized by spectroscopic and spectrometric techniques. The results showed that the prevailing active product is oleic acid, which was compared with standards by gas chromatography and high-performance liquid chromatography (HPLC). These active products might be useful for controlling the proliferation of pathogenic clones of V. parahaemolyticus.
Assuntos
Anti-Infecciosos/farmacologia , Ácido Oleico/farmacologia , Vibrio parahaemolyticus/efeitos dos fármacos , Vibrio/fisiologia , Anti-Infecciosos/isolamento & purificação , Cromatografia Gasosa , Cromatografia Líquida de Alta Pressão , Cromatografia de Fase Reversa , Testes de Sensibilidade Microbiana , Ácido Oleico/isolamento & purificação , Ácido Oleico/fisiologia , Vibrio/químicaRESUMO
Six guaiane sesquiterpenes recurvatiane A-F, including the previously known recurvatiane E and xanthomicrol, were isolated from the Andean Perezia recurvata and their structures determined by spectroscopic evidence. The absolute stereochemistry of recurvatiane A was established by derivatization with (R)- and (S)-α-methoxy-α-phenylacetic acids (MPA). The suite of guaiane-based metabolites here reported, which we have named recurvatianes A-F, provide an example of a pathway by which molecular diversity is generated by the occurrence of specific oxidation reactions in the late biosynthetic steps of the frame structure.
Assuntos
Asteraceae/química , Fenilacetatos/química , Sesquiterpenos de Guaiano/isolamento & purificação , Chile , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Oxirredução , Sesquiterpenos de Guaiano/química , EstereoisomerismoRESUMO
Pronuciferine N-oxide (1), a proaporphine N-methyl-N-oxide alkaloid, along with the parent alkaloid pronuciferine (2) were isolated from Berberis coletioides. The structure of the new compound was determined by spectroscopic evidence. Compound 1 is the first naturally occurring proaporphinoid alkaloid with an N-oxide functionality.
Assuntos
Berberis/química , Compostos de Espiro/isolamento & purificação , Alcaloides/química , Chile , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Compostos de Espiro/químicaRESUMO
In this work the antifeedant effects of the halogenated monoterpenes 1-13 were tested against several divergent insect species. These compounds have been isolated from Plocamium cartilagineum (6 was isolated as an acetyl derivative), except for 4, which was isolated from Pantoneura plocamioides. We have also included the semisynthetic derivatives 1a, 2a, and 7. Compounds 1, 1a, 2, 4, 5, 7, 8-10, and 13 were antifeedants against Leptinotarsa decemlineata with varying potencies. The aphids Myzus persicae and Ropalosiphum padi were strongly deterred in the presence of compounds 2, 12, and 13. This effect was correlated with the electronic recording of their probing behavior. Compounds 2 and 12 were toxic to L. decemlineata and had selective cytotoxicity to insect-derived Sf9 cells. None of the tested compounds showed phytotoxic effects. The antifeedant and cytotoxic effects of these compounds were compared with those of the polyhalogenated insecticide gamma-hexachlorocyclohexane (lindane).
Assuntos
Ingestão de Alimentos/efeitos dos fármacos , Insetos/fisiologia , Monoterpenos/farmacologia , Rodófitas/química , Animais , Afídeos/fisiologia , Besouros/fisiologia , Inseticidas/isolamento & purificação , Inseticidas/farmacologia , Monoterpenos/isolamento & purificação , Spodoptera/fisiologiaRESUMO
Two new sesquiterpenes belonging to a novel oxacyclic structural type of chamigrene skeleton, oxachamigrene (1) and 5-acetoxyoxachamigrene (2), have been isolated from the red alga Laurencia obtusa. The structures of the compounds were determined on the basis of spectroscopic evidence. A biogenetic route for these metabolites has been proposed.
Assuntos
Rodófitas/química , Sesquiterpenos/isolamento & purificação , Cromatografia Líquida , Cuba , Conformação Molecular , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Sesquiterpenos/química , Espectrofotometria InfravermelhoRESUMO
Three new minor linear polyhalohydroxylated marine monoterpenes, plocamenols A-C (1-3), have been isolated from the red alga Plocamium cartilagineum. The structure and relative stereochemistry of these compounds were determined on the basis of spectroscopic evidence.