New Bacterial Aryl Sulfotransferases: Effective Tools\nfor Sulfation of Polyphenols

The preparation of\npure metabolites of bioactive compounds, particularly\n(poly)phenols, is essential for the accurate determination of their\npharmacological profiles <i>in vivo</i>. Since the extraction\nof these metabolites from biological material is tedious and impractical,\nthey can be synthesized enzymatically <i>in vitro</i> by\nbacterial PAPS-independent aryl sulfotransferases (ASTs). However,\nonly a few ASTs have been studied and used for (poly)phenol sulfation.\nThis study introduces new fully characterized recombinant ASTs selected\naccording to their similarity to the previously characterized ASTs.\nThese enzymes, produced in Escherichia coli, were purified, biochemically characterized, and screened for the\nsulfation of nine flavonoids and two phenolic acids using <i>p-</i>nitrophenyl sulfate. All tested compounds were proved\nto be substrates for the new ASTs, with kaempferol and luteolin being\nthe best converted acceptors. ASTs from <i>Desulfofalx alkaliphile</i> (<i>Dal</i>AST) and <i>Campylobacter fetus</i> (<i>Cf</i>AST) showed the highest efficiency in the sulfation\nof tested polyphenols. To demonstrate the efficiency of the present\nsulfation approach, a series of new authentic metabolite standards,\nregioisomers of kaempferol sulfate, were enzymatically produced, isolated,\nand structurally characterized.