Maltol, a metabolite of Scytalidium uredinicola which inhibits spore germination of Endocronartium harknessii, the western gall rust

Abstract

Twenty-four isolates of Scytalidium uredinicola were screened for their ability to inhibit germination of Endocronartium harknessii spores. The most active isolate, 4149, was grown in 2% malt extract broth for 10 days. From the spent culture medium an inhibitory compound was isolated and identified as 3-hydroxy-2-methyl-4H-pyranone, or maltol. This compound has rarely been described as a microbial metabolite. Maltol caused a 50% decrease in spore germination at 50 μg/mL and showed varying activity against several wood-rot fungi at 550 μg/mL.