Metabolism of chlorogenic acid by human plasma, liver, intestine and gut microflora

Extracts of human small intestine epithelium, liver, plasma and colonic microflora (as a faecal sample) were prepared and esterase activity determined by incubation with chlorogenic acid and subsequent analysis by high-performance liquid chromatography. There was no evidence of enzymic hydrolysis by the intestine, liver or plasma extracts. However, esterase activity was observed in the faecal sample, and this activity was abolished if the extract was boiled prior to incubation. These results show that chlorogenic acid ingested by humans is most likely cleaved into caffeic acid and quinic acid by an esterase enzyme(s) provided by the colonic microflora.