New polyene macrolide family produced by submerged culture of Streptomyces durmitorensis

A new polyene macrolide family, closely related to the pentaene macrolide antibiotic roflamycoin, was isolated from the both fermentation broth and biomass of Streptomyces durmitorensis wild-type strain MS405. The main compound was identified by NMR and Fourier transform ion cyclotron resonance mass spectrometry as 32,33-didehydroroflamycoin (1; DDHR). Additional four structurally related compounds were determined solely by MS analysis. DDHR induces cell death by apoptosis in various cancer cell lines as demonstrated by DNA fragmentation. Striking feature of DDHR is its internal fluorescence allowing visualization of labeled plasma membranes and internal membrane structures. The Journal of Antibiotics (2011) 64, 717-722; doi:10.1038/ja.2011.81; published online 14 September 201

CEC enantioseparations of carboxylic acids on silica-based monoliths modified with ergot alkaloid derivative

The enantioseparation of carboxylic acids, including amino acid dansyl-derivatives, 2-arylpropionic acids and 2-aryloxypropionic acids, was tested by CEC on a porous silica sol-gel monolithic column that was prepared by polycondensation of tetramethoxysilane in acidic conditions and post-gelation heat treatment (120 degrees C for 3 h) in the presence of urea, and successively, by anchoring to the silica (+)-1-allyl-(5R,8S,10R)-terguride as the chiral selector. The bimodal structure of the sorbent showed through pores with a median value of 1.39 mu m and a mesopore size distribution ranging between 6 and 12 nm (average pore size of 9.9 nm). To attain optimum separation conditions, the influence of the pH and the concentration of the buffer solution in the mobile phase on resolution were investigated. The monolithic column showed: (i) for the compounds studied resolution values two or three times higher in comparison with previously developed separation systems where the same chiral selector was used. For example, on the monolithic column Dns-serine enantiomers were much better separated (8 min with a selectivity factor of 1.34) than by HPLC (20 min, alpha = 1.17); (ii) high chemical and mechanical stability as demonstrated by the use of such column for hundreds of analysis along about 1 year without significant variations of the resolution and the retention parameters