The pig caecum model: A suitable tool to study the intestinal metabolism of flavonoids

Pig caecum was used under anaerobic conditions to metabolize flavonoids from several classes, i. e. , chrysin 1 , naringenin 2, quercetin 3 , and hesperetin 4 . Whereas chrysin 1 was not converted by the pig intestinal flora under the experimental conditions used, naringenin 2 was transformed to 3‐(4‐hydroxyphenyl)‐propionic acid and 3‐phenylpropionic acid. Quercetin 3 was metabolized to phloroglucinol, 3,4‐dihydroxyphenylacetic acid, and 3,4‐dihydroxytoluene. Hesperetin 4 was degraded via eriodictyol to 3‐(3‐hydroxyphenyl)‐propionic acid and phloroglucinol. Structural elucidation of the formed metabolites was performed by high‐performance liquid chromatography – diode array detection (HPLC–DAD) as well as HPLC‐electrospray ionization – mass spectrometry (ESI‐MS (MS)) and high resolution gas chromatography‐mass spectrometry (HRGC‐MS) analyses. The time course of microbial conversion of 2 – 4 was determined by HPLC‐DAD analysis, revealing slow degradation of 2 and rapid transformation of 3 and 4 . The results lead to the conclusion that the pig caecum model is a suitable ex vivo model for studying the intestinal degradation of flavonoids.