Tiron as a spin-trap for superoxide radicals produced by the respiratory chain of submitochondrial particles

Tiron can be used as a spin-trap for O2 radicals generated by the respiratory chain of submitochondrial particles (SMP). Using this sensitive method, it was shown that the O2 (radical) production by the succinate-oxidizing SMP can be reduced by antimycin or 4-nonyl-2-hydroxyquinoline-N-oxide, the effects of both antibiotics being abolished and prevented by cyanide. It is suggested tht the O2 radicals are produced due to autooxidation of ubisemiquinone which is formed as an intermediate upon one-electron oxidation of CoQH2 by cytochrome c1. The effects of antimycin, 2-nonyl-4-hydroxyquinoline-N-oxide and cyanide on the O2 (radical) generation correlate with the effects of these inhibitors on a steady-state concentration of ubisemiquinone predicted by the Mitchell's Q-cycle hypothesis.     

Anwendung der automatisierten Festphasenextraktion bei der Bestimmung von Ochratoxin A

For some foodstuffs, determination of the mycotoxin ochratoxin A (OTA) requires time consuming clean up by means of solid phase extraction (SPE). Therefore a system for automated SPE was tested for cleaning up roasted coffee as a possible way of shortening preparation time. Validation of the method in accordance to the so called “Concept '98” led to a LOD of 0.2 μg/kg and a recovery rate of 92%. By using the described procedure with samples of roasted coffee the OTA contents varied between the LOD and 3.4 μg/kg. This method was also used to determine ochratoxin A in liquorice roots, ginger and valerian.

Presented at the 26^th Mykotoxin Workshop in Herrsching, Germany, May 17–19, 2004