The biosynthesis of fungal metabolites: sclerin, a plant growth hormone from Sclerotinia sclerotiorum

Abstract

Sclerin, a plant-growth hormone from Sclerotinia sclerotiorum, incorporates five intact acetate units from [1,2-¹³C₂]-acetate. The hydrogen atom at C-4 was shown not to be acetate-derived by a ²H n.m.r. study with [²H₃]acetate. The specific incorporations of 6,8-dihydroxy-3,4,5,7-tetramethylisocoumarin (10) and 3,6,8-trihydroxy-3,4,5,7-tetramethyl-3,4-dihydroisocoumarin (2) support the proposal that sclerotinin A (2) is an intermediate in sclerin biosynthesis. A ²H n.m.r. investigation showed that 4,6-dihydroxy-3-[²H₁]methyl-5-methyl-2-(1-methyl-2-oxopropyl)benzaldehyde (11) is not involved in the formation of sclerin.