NMR studies of tautomerism in the fungal melanin biosynthesis intermediate 1,3,8-trihydroxynaphthalene

Abstract

The naphthol reductase catalysed conversion of 1,3,8-trihydroxynaphthalene (T3HN) to vermelone has been studied using a partially purified cell-free enzyme preparation from Verticillium dahliae. NMR studies show that in aqueous buffer T3HN exists as an equilibrium mixture of the parent phenol and a keto-tautomer. 1,3,6,8-Tetrahydroxynaphthalene (T4HN) is a more efficient substrate than T3HN for the naphthol reductase. 1,3-Dihydroxynaphthalene also acts as a substrate and is converted to 8-deoxyvermelone. © The Royal Society of Chemistry 2000.