Pseudochelin A, a siderophore of Pseudoalteromonas piscicida S2040

A new siderophore containing a 4,5-dihydroimidazole moiety was isolated from Pseudoalteromonas piscicida S2040 together with myxochelins A and B, alteramide A and its cycloaddition product, and bromo- and dibromoalterochromides. The structure of pseudochelin A was established by spectroscopic techniques including 2D NMR and MS/MS fragmentation data. In bioassays selected fractions of the crude extract of S2040 inhibited the opportunistic pathogen Pseudomonas aeruginosa. Pseudochelin A displayed siderophore activity in the chrome azurol S assay at concentrations higher than 50 μM, and showed weak activity against the fungus Aspergillus fumigatus, but did not display antibacterial, anti-inflammatory or anticonvulsant activity

Stelliferin Riboside, a Triterpene Monosaccharide Isolated from the Fijian Sponge Geodia globostellifera

A triterpene monosaccharide, stelliferin riboside (1), was isolated from the Fijian marine sponge Geodia globostellifera. In addition, stellettins A and B (2, 3) were also isolated. This is the first report of a stelliferin from this species and the first example of a saccharide derivative of a stelliferin

NMR characterisation of natural products derived from under-explored microorganisms

Microbial natural products has drawn a great attention from both academia and industry. Obtaining the planar, relative, and possibly the absolute configuration of such novel metabolites requires considerable efforts. In this chapter, the general NMR experiments that were traditionally used, and the recently introduced pulse sequences that provide more precise output in significantly shorter times, and applicable to high throughput screening are discussed. Additionally, various dereplication approaches that allow tracking of new metabolites were highlighted. Lastly, the power of CASE in the structural identification and confirmation of manually-elucidated molecules using selected examples from our research projects was demonstrated

The effect of varying ozone concentration on surface UV-B radiation: a Fiji perspective

Projects studying the effect of column ozone levels on UV-B radiation reaching the surface of the Earth as part of a wider global observation of vertical profiling were initiated by NASA/NOAA in the 1990s. A comparison of the changes in UV-B radiation as a function of ozone concentration revealed a negative correlation. We have shown for the first time in Fiji that a similar trend exists but with more scatter. Previous studies at this site (USP) have shown that the atmospheric concentration of aerosols varies seasonally and this may have a bearing on the scatter of the results

Identification of novel inhibitors of UDP-Glc 4'-epimerase, a validated drug target for african sleeping sickness

Novel inhibitors of Trypanosoma brucei and mammalian UDP-Glc 4'-epimerase were identified by screening a small library of natural products and commercially available drug-like molecules. The inhibitors possess low micromolar potency against the T. brucei and human enzymes in vitro, display a degree of selectivity between the two enzymes, and are cytotoxic to cultured T. brucei and mammalian cells