Biosynthesis of 8-hydroxyquinoline-2-carboxylic acid, an iron chelator from the gut of the lepidopteran Spodoptera littoralis.

Jelena Pesek, Jiří Svoboda, Martina Sattler, Stefan Bartram, Wilhelm Boland

Index: Org. Biomol. Chem. 13(1) , 178-84, (2014)

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Abstract

In the regurgitate (foregut content) of Spodoptera larvae we found high concentrations (0.5-5 mM) of 8-hydroxyquinoline-2-carboxylic acid (8-HQA). In a survey of different lepidopteran species, this compound was only detected in species belonging to the family of Noctuidae. 8-HQA was shown to derive from tryptophan metabolism. The amount of 8-HQA in the regurgitate was strongly dependent on the tryptophan content of the diet. In the insect 8-HQA is generated from tryptophan via kynurenine and 3-hydroxykynurenine. 8-HQA is produced by the larvae and not by their commensal gut bacteria. Analysis of different life stages of Spodoptera larvae revealed that 8-HQA is formed during the larval stage, probably acting as an iron chelator to control the gut microbiome.