Enzymatic Sulfation of Phenolic Hydroxy Groups of Various Plant Metabolites by an Arylsulfotransferase

The bacterial arylsulfate sulfotransferase (AST) from Desulfitobacterium hafniense was used as a catalytic tool to derivatize poorly soluble aromatic compounds (polyphenols). As examples, we sulfated the natural occurring compounds p ‐coumaric acid, 6‐hydroxyflavone, resveratrol, phloretin, and quercetin, using p ‐nitrophenylsulfate as the sulfate donor. The water‐soluble sulfate esters were purified and characterized. Depending on the nature of the compound, one or more sulfate groups could be introduced in a stepwise order. The sulfation of resveratrol resulted in two different monosulfates (4′‐ and 3‐sulfates), the 3,4′‐disulfate, and the 3,5,4′‐trisulfate. Sulfation of phloretin resulted in a monosulfate (4′‐sulfate) and a disulfate (4,4′‐disulfate). Although quercetin has five hydroxy groups that could be sulfated, surprisingly this enzyme system primarily catalyses the sulfation only at the 4′ position. This simple enzymatic one‐step sulfation method is easy to use, and it allows a convenient and simple production of sulfated compounds with improved solubility.