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United States Department of Agriculture

Agricultural Research Service

Title: Activation of Fusarium Naphthazarin Toxins and Other P-Quinones by Reduced Thioctic Acid

Authors
item Heiser, Ingrid - UNIV OF MUNICH
item Obwald, Wolfgang - LMU-MUNICH, FOREST PHYTO
item Baker, Robert
item Nemec, Stan - RETIRED FROM USDA
item Elstner, Erich - UNIV OF MUNICH

Submitted to: Journal of Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 20, 1998
Publication Date: N/A

Interpretive Summary: Fusarium solani, a fungal pathogen of many plants, produces naphthazarian toxins which cause plant wilting and bleaching of leaf chlorophyll by destroying chloroplast membranes. This paper shows that these naphthazarins are activated by reaction with dithiol compounds such as reduced thioctic acid. The activated naphthazarins then react with oxygen to produce superoxide, hydrogen peroxide and another oxidant, all of which can disrupt the membranes and biochemical processes of chloroplasts.

Technical Abstract: Dihydrofusarubin, marticin and isomarticin are naphthazarin toxins produced by Fusarium solani, a pathogen of citrus, peas and tomato. Like other p- quinones such as 1,4-naphthoquinone, menadione or juglone, these compounds can be reductively activated by dithiols such as dihydrolipoic acid (reduced thioctic acid) or dithiothreitol but not by monothiols such as cystein or glutathione. Upon autoxidation, reduced p-quinones with appropriately negative redox potentials between -100 and -250 mV activate oxygen in a dithiol-dependent reaction producing superoxide, hydrogen peroxide and a strong oxidant similar to the OH-radical-type oxidant ("crypto-OH") but apparently not identical to the free OH-radical.

Last Modified: 10/21/2014
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