Opaliferin, a polyketide with a unique partial structure in which a cyclopentanone and tetrahydrofuran were connected with an external double bond, was isolated from the insect pathogenic fungus Cordyceps sp. NBRC 106954. The structure and relative configuration of opaliferin were determined by spectroscopic analysis and X-ray crystallography. The absolute configuration was established by anomalous dispersion effects in X-ray diffraction measurements on the crystal of di(p-bromobenzoyl) ester of opaliferin. A plausible biosynthetic pathway for opaliferin is proposed.
Genetic, biochemical and morphological analysis of flagella formation in gram-negative bacteria, Escherichia coli and Salmonella typhimurium, established an outline of the mechanism of stepwise biogenesis of flagella.1>2) The basal body is joined with the cell surface through several rings.3) In gram-positive bacteria, two ringlike structures also exist.3) The inner ring appears to be in contact with the plasma membrane and the outer ring may be associated with the teichoic acid polymers on the outer surface of the cell.2) Non-flagellate mutants of grampositive bacteria have not been so intensively studied in contrast to gram-negative bacteria. However, Kunst et al.,A) Sekiguchi et al.5) and Ayusawa et al.6) described pleiotropic mutants of Bacillus subtilis, almost all of which were non-motile. All of these mutants seem to be defective in the same unknown component of the cell surface,7) which results in pleiotropic changes such as overproduction of a-amylase and exocellular proteases, and inability of flagella formation. The pap mutant, moreover, was not transformable.8) During the course of studies on isolation and characterization of carbohydrate metabolism mutants of Bacillus, it was found that the transketolase mutation (tkt) in B. subtilis IFO 12114 generated pleiotropic changes; the
During the search for new antitrypanosomal drug leads, three new antitrypanosomal compounds, cardinalisamides A-C (1-3), were isolated from cultures of the insect pathogenic fungus Cordyceps cardinalis NBRC 103832. Their structures were elucidated using MS analyses and extensive 2D-heteronuclear NMR. The absolute configurations of 1-3 were addressed by chemical degradation and Marfey's analysis. 1-3 showed in vitro antitrypanosomal activity against Trypanosoma brucei brucei with IC50 values of 8.56, 8.65 and 8.63 μg ml(-1), respectively.
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