RESUMO
From aerial parts of the fern Pteris multifida Poir. (Polypodiaceae) two diterpenes, entkaurane-2 beta, 16 alpha-diol and ent-kaur-16-ene-2 beta, 15 alpha-diol, were isolated by repeated column chromatography using silica gel and silica gel impregnated with silver nitrate. The structures were confirmed by spectroscopic methods. Both compounds showed a moderate cytotoxicity to Ehrlich ascites tumour cells.
Assuntos
Antineoplásicos/isolamento & purificação , Diterpenos/isolamento & purificação , Diterpenos/toxicidade , Plantas Medicinais , Animais , Antineoplásicos/química , Antineoplásicos/toxicidade , Carcinoma de Ehrlich , Divisão Celular , Sobrevivência Celular/efeitos dos fármacos , Diterpenos/química , Medicina Tradicional Chinesa , Camundongos , Estrutura Molecular , Células Tumorais CultivadasRESUMO
The mannitol-specific phosphotransferase system transport protein, Enzyme IIMtl, contains two catalytically important phosphorylated amino acid residues, both present on the cytoplasmic part of the enzyme. Recently, this portion has been subcloned, purified, and shown to be an enzymatically active domain. The N-terminal half has also been subcloned and shown to be the mannitol-binding domain. When combined the two domains catalyze mannitol phosphorylation at the expense of phospho-HPr (van Weeghel, R. P., Meyer, G. H., Pas, H. H., Keck, W. H., and Robillard, G. T., Biochemistry in press). The phospho-NMR spectrum of the purified phosphorylated cytoplasmic domain, taken at pH 8.0, shows two signals, one at -6.9 ppm compared with inorganic phosphate resulting from phosphohistidine and one at +11.9 ppm originating from phosphocysteine. Addition of mannitol plus membranes containing the N-terminal mannitol-binding domain results in the formation of mannitol 1-phosphate and the disappearance of the two signals at -6.9 and +11.9 ppm.