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Use of the pig caecum model to mimic the human intestinal metabolism of hispidulin and related compounds
Author(s) -
Labib Samira,
Hummel Sylvia,
Richling Elke,
Humpf HansUlrich,
Schreier Peter
Publication year - 2006
Publication title -
molecular nutrition and food research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.495
H-Index - 131
eISSN - 1613-4133
pISSN - 1613-4125
DOI - 10.1002/mnfr.200500144
Subject(s) - apigenin , chemistry , luteolin , kaempferol , galangin , biochemistry , chrysin , flavonoid , hydroxylation , glucuronidation , pinocembrin , quercetin , chromatography , acacetin , antioxidant , microsome , enzyme
Up to now, the metabolism of hispidulin (5,7,4′‐trihydroxy‐6‐methoxyflavone), a potent ligand of the central human benzodiazepine receptor, has not been investigated. To elucidate the metabolism of hispidulin in the large intestine, its biotransformation by the pig caecal microflora was studied. In addition, the efficiency of the pig caecal microflora to degrade galangin (3,5,7‐trihydroxyflavone), kaempferol (3,5,7,4′‐tetrahydroxyflavone), apigenin (5,7,4′‐trihydroxyflavone), and luteolin (5,7,3′,4′‐tetrahydroxyflavone) was investigated. Identification of the formed metabolites was performed by high‐performance liquid chromatography (HPLC)‐diode array detection, HPLC‐electrospray ionization‐tandem mass spectrometry, and high‐resolution gas chromatography‐mass spectrometry. The caecal microflora transformed hispidulin to scutellarein (5,6,7,4′‐tetrahydroxyflavone), an effective α‐glucosidase inhibitor, and 3‐(4‐hydroxyphenyl)‐propionic acid; galangin to phenylacetic acid and phloroglucinol; kaempferol to 4‐hydroxyphenylacetic acid, phloroglucinol, and 4‐methylphenol; apigenin to 3‐(4‐hydroxyphenyl)‐propionic acid and 3‐phenylpropionic acid, and luteolin to 3‐(3‐hydroxyphenyl)‐propionic acid, respectively. To elucidate to what extent different hydroxylation patterns on the B‐ring influence the degradation degree of flavonoids, the conversions of galangin and kaempferol as well as that of apigenin and luteolin were compared with those of quercetin (3,5,7,3′,4′‐pentahydroxyflavone) and chrysin (5,7‐dihydroxyflavone), respectively. Regardless of the flavonoid subclass, the presence of a hydroxy group at the 4′‐position seems to be a prerequisite for fast breakdown. An additional hydroxy group at the B‐ring did not affect the degradation degree.