RESUMO
In search of bioactive metabolites in cultured microalgae, a novel acylated iminopseudotetrasaccharide was isolated from a filamentous cyanobacterium Anabaena sp., and its structure was established by NMR, chemical degradation, and X-ray crystallography. The compound consists of glucose, glucuronic acid, arabinose, and 1,4,6-trideoxy-1,4-imino-D-allitol, which is closely related to potent glucosidase inhibitors such as nojirimycin. The tetrasaccharide itself showed moderate inhibitory activity against beta-D-glucuronidase.
Assuntos
Anabaena/química , Inibidores Enzimáticos/isolamento & purificação , Glucuronidase/antagonistas & inibidores , Oligossacarídeos/química , Oligossacarídeos/isolamento & purificação , 1-Desoxinojirimicina/análogos & derivados , Austrália , Cristalografia por Raios X , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Glucosamina/análogos & derivados , Glucosamina/química , Glucosamina/farmacologia , Conformação Molecular , Estrutura Molecular , Ressonância Magnética Nuclear Biomolecular , Oligossacarídeos/farmacologiaRESUMO
In the course of our search for antitumor compounds in dinoflagellates, the culture broths of two strains of Protoceratium cf. reticulatum showed extremely potent cytotoxicity against human tumor cell lines. The four equally active principles, named protoceratins I (1), II (2), III (3), and IV (4), were purified and their structures were studied. The major principle, protoceratin I (1), proved to be identical with 2-homoyessotoxin, a well-known shellfish toxin. Protoceratins II (2), III (3), and IV (4) were determined to be di-, mono-, and triarabinoside of 1, respectively. They are the first examples of glycosides of dinoflagellate polyethers.
Assuntos
Antineoplásicos/isolamento & purificação , Dinoflagellida/química , Éteres Cíclicos/isolamento & purificação , Glicosídeos/isolamento & purificação , Toxinas Marinhas/isolamento & purificação , Oxocinas/isolamento & purificação , Animais , Antineoplásicos/química , Antineoplásicos/farmacologia , Ensaios de Seleção de Medicamentos Antitumorais , Éteres Cíclicos/química , Éteres Cíclicos/farmacologia , Glicosídeos/química , Glicosídeos/farmacologia , Humanos , Toxinas Marinhas/química , Toxinas Marinhas/farmacologia , Oceanos e Mares , Oxocinas/química , Oxocinas/farmacologia , Células Tumorais CultivadasRESUMO
The extraordinary chemical diversity seen in the cyanobacteria (blue-green algae) is especially pronounced in the ubiquitous tropical marine species, Lyngbya majuscula. The gene clusters responsible for the production of some of the secondary metabolites have recently been elucidated. The dinoflagellates, which are lower eukaryotic algae, also demonstrate chemical diversity and produce unique polycyclic ethers of polyketide origin. A new mechanism for the formation of the truncated polyketide backbones has recently been proposed. The toxicogenicity of dinoflagellates of the genus Pfiesteria has been the focus of controversy--are they 'killer organisms', as alleged? A recent investigation of Pfiesteria genes seems to rule out the presence of polyketide synthase, which is the gene responsible for the production of most dinoflagellate toxins.
