Metabolism and excretion of butein, 2',3,4-trihydroxychalcone, 3-O-methylbutein, 4-O-methylbutein and 2',4',4-trihydroxychalcone in the rat.

Butein (2',3,4,4'-tetrahydroxychalcone) and 2',3,4-trihydroxychalcone, following administration to bile-duct-cannulated rats, gave rise to the corresponding 3-O-methyl ethers which were excreted in conjugated forms in bile and urine. After parenteral and oral administration of [14C]butein, 53% and 20% of the dose, respectively, was excreted in bile in 24h. After oral administration of [14C]butein, 4-O-methylbutein, or 2',4',4-trihydroxychalcone to non-cannulated rats, 51%, 58% and 40% dose, respectively, was excreted in faeces, and 39%, 37% and 56%, respectively, in urine. Intraperitoneal administration of butein to non-cannulated rats led to excretion of 41% dose in urine and 56% in faeces. 3-O-Methylbutein and 4-O-methylbutein were demethylated in vivo and on incubation with rat-intestinal microflora in vitro, whilst 2',4-dihydroxy-3-methoxychalcone and 2',3-dihydroxy-4-methoxychalcone were not demethylated in vivo or in vitro. Following parenteral and oral administration of 4-O-methylbutein to bile-duct-cannulated rats, 91% and 21% dose, respectively, was excreted in the bile in 24h. After parenteral or oral administration of 2',4',4-trihydroxychalcone to cannulated rats, approx. 100% and 45% dose, respectively, was excreted in the bile in 24h. Trace amounts of 2',4',4-trihydroxychalcone were hydroxylated to give butein.