Siderophore-based detection of Fe(iii) and microbial pathogens

Siderophores are low-molecular-weight iron chelators that are produced and exported by bacteria, fungi and plants during periods of nutrient deprivation. The structures, biosynthetic logic, and coordination chemistry of these molecules have fascinated chemists for decades. Studies of such fundamental phenomena guide the use of siderophores and siderophore conjugates in a variety of medicinal applications that include iron-chelation therapies and drug delivery. Sensing applications constitute another important facet of siderophore-based technologies. The high affinities of siderophores for both ferric ions and siderophore receptors, proteins expressed on the cell surface that are required for ferric siderophore import, indicate that these small molecules may be employed for the selective capture of metal ions, proteins, and live bacteria. This minireview summaries progress in methods that utilize native bacterial and fungal siderophore scaffolds for the detection of Fe(III) or microbial pathogens.Massachusetts Institute of Technology. Dept. of Chemistr

Photooxidation of N,N′-Diacylindigo Dyes

Irradiation of N,N′-diacylindigo dyes in the presence of oxygen resulted in an unusual oxygen insertion/acyl transfer reaction. While this process occurred over many weeks at room temperature, at 100° C it was complete in a few hours. In some cases the yield of photooxidized product was virtually quantitative. The product structures were proved by spectroscopic methods and in one example by X-ray analysis. A series of mechanistic experiments led to the conclusion that at least the oxygen insertion part of the photooxidation process proceeded via a radical mechanism. The evidence included the following observations: (1) When the photooxidation was conducted in toluene, large amounts of benzyl hydroperoxide were produced; (2) the photooxidation could be achieved in the dark with a radical initiator; (3) attempts to generate the photooxidized product using singlet oxygen chemistry failed. The postulated radical mechanism is described. © 1994, American Chemical Society. All rights reserved