Figure 1.

Simplified schemes of proposed pathways for microbial degradation of different flavonoids in humans: flavanols (a) and flavonol quercetin (b). PC: procyanidin. 3-hydroxyphenylacetic acid (3-HPAA) is depicted in red; the structures in black are metabolites that were detected, whereas structures in grey represent hypothetical intermediates. Data were obtained from the following references: [16,17,20,21,22,23].