Diastereomeric quinolinone alkaloids from the marine-derived fungus Penicillium janczewskii.

From Penicillium janczewskii, obtained from a marine sample, two new diastereomeric quinolinones, 3S,4R-dihydroxy-4-(4'-methoxyphenyl)-3,4-dihydro-2(1H)-quinolinone (1) and 3R,4R-dihydroxy-4-(4'-methoxyphenyl)-3,4-dihydro-2(1H)-quinolinone (2), were identified, along with two known alkaloids, peniprequinolone (3) and 3-methoxy-4-hydroxy-4-(4'-methoxyphenyl)-3,4-dihydro-2(1H)-quinolinone (4). Cytotoxicity testing on eight tumor cell lines revealed a moderate specificity of 2 on SKOV-3 cells.

Cervimycin A-D: a polyketide glycoside complex from a cave bacterium can defeat vancomycin resistance.

Cervimycins A-D are novel polyketide glycosides with significant activity against multi-drug-resistant staphylococci and vancomycin-resistant enterococci. They are produced by a strain of Streptomyces tendae, isolated from an ancient cave. The structures of the cervimycins were determined by performing extensive NMR and chemical degradation studies. All cervimycins have a common tetracyclic polyketide core that is substituted with unusual di- and tetrasaccharide chains, composed exclusively of trideoxysugars; however, they differ in the acetyl and carbamoyl ring substituent and in the highly unusual terminal methylmalonyl and dimethylmalonyl residues.

Biosynthesis of cervimycin C, an aromatic polyketide antibiotic bearing an unusual dimethylmalonyl moiety.

Cervimycin C is the major component of an antibiotic complex produced by Streptomyces tendae HKI-179 consisting of a tetracycline-type aglycon, six tridesoxysugars and a rare dimethylmalonyl moiety. The biosynthetic origin of cervimycin was studied by molecular studies and feeding experiments, which reveal that the dimethylmalonate unit is not derived from malonate, but from valine.

New quinones and hydroquinones from Malbranchea cinnamomea HKI 286 and HKI 296 and interaction with Tax/CREB expression system in yeast.

In addition to malbranicin (1) and dihydromalbranicin (5), new substituted quinones 2, 3, 6 and hydroquinone 4 were isolated from the culture brothes of two strains of Malbranchea cinnamomea. The chemical constitutions of new metabolites 2, 3, 4 and 6 were elucidated by optical spectroscopy, mass spectrometry and 1D/2D NMR spectroscopy. 2 (7-methoxymalbranicin) at a concentration of 42 microM inhibited by 67% Tax/CREB-mediated expression of beta-galactosidase in a recombinant strain of Saccharomyces cerevisiae.

New and bioactive compounds from Streptomyces strains residing in the wood of Celastraceae.

Wood from three different plants of the Celastraceae growing in their natural habitats in Brazil (Maytenus aquifolia Mart.) and South Africa [Putterlickia retrospinosa van Wyk and Mostert, P. verrucosa (E. Meyer ex Sonder) Szyszyl.] was established as a source of endophytic bacteria using a medium selective for actinomycetes. Two isolates were identified as Streptomyces setonii and S. sampsonii whereas two others were not assignable to any of the known Streptomyces species. They were preliminarily named Streptomyces Q21 and Streptomyces MaB-QuH-8. The latter strain produces a new chloropyrrol and chlorinated anthracyclinone. The chloropyrrol showed high activity against a series of multiresistent bacteria and mycobacteria.

Solution structure of dAATAA and dAAUAA DNA bulges.

The NMR structure analysis is described for two DNA molecules of identical stem sequences with a five base loop containing a pyrimidine, thymin or uracil, in between purines. These five unpaired nucleotides are bulged out and are known to induce a kink in the duplex structure. The dAATAA bulge DNA is kinked between the third and the fourth nucleotide. This contrasts with the previously studied dAAAAA bulge DNA where we found a kink between the fourth and fifth nucleotide. The total kinking angle is approximately 104 degrees for the dAATAA bulge. The findings were supported by electrophoretic data and fluorescence resonance energy transfer measurements of a similar DNA molecule end-labeled by suitable fluorescent dyes. For the dAAUAA bulge the NMR data result in a similar structure as reported for the dAATAA bulge with a kinking angle of approximately 87 degrees. The results are discussed in comparison with a rAAUAA RNA bulge found in a group I intron. Generally, the sequence-dependent structure of bulges is important to understand the role of DNA bulges in protein recognition.