The role of methylsulfonium compounds in the biosynthesis of N-methylated metabolites in Chondria coerulescens

The possible metabolic relationships between methylsulfonium and N-methylated compounds were investigated in the red alga Chondria coerulescens by means of radiotracer techniques. The alga, whose H2O-soluble fraction contains S-methylmethyionine [1], dimethyl-beta-propiotethin [2], 4-hydroxy-N-methylproline [3] and gamma-aminobutyric acid betaine [4], was fed with methionine, S-methylmethyionine, dimethyl-beta-propiotethin and gamma-aminobutyric acid betaine, all [14CH3]-labeled. Following administration of [14CH3]-dimethyl-beta-propiotethin, methyl labeled 4-hydroxy-N-methylproline was isolated, thus supporting the hypothesis that sulfonium salts may function as methyl donors in the biosynthesis of N-methylated compounds.