Flavonoid metabolism: the synthesis of phenolic glucuronides and sulfates as candidate metabolites for bioactivity studies of dietary flavonoids

Epidemiological studies indicate that flavonoid intake is inversely associated with the risk of coronary heart disease, yet the mechanisms responsible for their bioactivity are still a matter of debate. Based on the rapid and extensive metabolism of most flavonoids, their health effects most likely result from the biological activity of their metabolites. However, a lack of commercially available compounds/standards has prevented the study of metabolite bioactivity and resulted in a focus on non-physiologically relevant precursor/parent structures. This paper details the synthesis of a series of phenolic glucuronide 1a–e and sulfate 2a–e derivates as candidate metabolites for use as reference compounds in metabolic profiling studies and for the exploration of flavonoid bioactivity.