ABSTRACT
Two new isomeric modified tripeptides, aspergillamides C and D (compounds 1 and 2), together with fifteen known compounds (compounds 3-17), were obtained from the marine sponge-derived fungus Aspergillus terreus SCSIO 41008. The structures of the new compounds, including absolute configurations, were determined by extensive analyses of spectroscopic data (NMR, MS, UV, and IR) and comparisons between the calculated and experimental electronic circular dichroism (ECD) spectra. Butyrolactone I (compound 11) exhibited strong inhibitory effects against Mycobacterium tuberculosis protein tyrosine phosphatase B (MptpB) with the IC being 5.11 ± 0.53 μmol·L, and acted as a noncompetitive inhibitor based on kinetic analysis.
Subject(s)
Animals , 4-Butyrolactone , Chemistry , Pharmacology , Aspergillus , Chemistry , Chemistry Techniques, Analytical , Dipeptides , Chemistry , Pharmacology , Enzyme Inhibitors , Chemistry , Pharmacology , Indoles , Chemistry , Pharmacology , Molecular Structure , Mycobacterium tuberculosis , Peptides , Chemistry , Pharmacology , Polyketides , Chemistry , Pharmacology , Porifera , Microbiology , Protein Tyrosine Phosphatases , ChemistryABSTRACT
Protozoans,the natural host of the facultative intracellular pathogen Legionella species,play an important role in survival,proliferation,virulence and stress resistance of Legionella species. By repeating transformation and selection,a spontaneous mutant of plasmid over expressing green fluorescent protein was obtained. This mutant replicates and is maintained stably in Legionella cells. The colonies of L. pneumophila harbouring the mutated plasmid were intense green in colour even under the daylight. After feeding BF1 strain of Tetrahymena thermophila with transformed L. pneumophila,the intracellular dynamic of changing of bacterial shape,bacterial proliferation and lysis of the host cell due to the bacterial proliferation were observed clearly under fluorescent microscopy. Thus,the present paper provides a simple and intuitionistic strategy for investigating the ecological and cellular relationship between L. pneumophila and its host.