The metabolism of di-(3,5-di-tert.-butyl-4-hydroxybenzyl) ether (Ionox 201) in the rat

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Abstract
Up to one-third of a single oral dose of Ionox 201 was absorbed in rats. In rats dosed with [14c] Ionox 201 86.8-97-2% of the label is excreted in the feces in 24 days (much of this is eliminated in the first 4 days after dosage), 5-6% in the urine and not more than 0.8% in the exhaled air; 5.0% of 14C is present in the carcass and viscera after removal of the gut, and most of this is in the fatty tissues. About 65.0% of 14C in the feces is due to unchanged antioxidant, 30.0% to 3,5-di-tert-butyl-4-hydroxybenzoic acid, 3.5% to unidentified polar constituent(s), 1.4% to 3,5-di-tert. butyl-4-hydroxybenzaldehyde and 0.1% to 3,3[image],5,5[image]-tetra-tert-butyl-4-,4[image]-stilbenequinone. A variable proportion of 14C in the urine is due to 3,5-di-tert.-butyl-4-hydroxybenzoic acid (40-60%) and the remainder (60-40%) to the ester glucuronide, when the animals were treated with different doses of antioxidant. In 8 individual animals dosed with 6.78 mg of [14c]Ionox 201, one-third of 14C in the bile is due to the free acid, 45% to the ester glucuronide, 20% to an unidentified constituent and 2% to unchanged antioxidant, and, in 2 animals dosed with 13.56 mg, there is a small proportion of free acid and a larger proportion of ester glucuronide. About 80% of 14C in the body fat is due to unchanged antioxidant, 19% to the free acid and 1%to 3,5-di-tert-butyl-4-hydroxy-benzaldehyde. At least 36.2% of a single oral dose of Ionox 201 is metabolized: 3,5-di-tert.-butyl-4-hydroxybenzoic acid accounts for 30.2% of a dose, (3,5-di-ter.-butyl-4-hydroxybenzoyl [beta]-D-glucopy-ranosid) uronic acid for 1.4%, 3,5-di-tert.-butyl-4-hydroxybenzaldehyde for 1.3%, 3,3[image],5,5[image]-tetra-tert-butyl-4,4[image]-stilbenequinone for 0.1% and unidentified polar metabolite(s) for 3.2%. The metabolism of Ionox 201 in vivo is closely related to its antioxidant action in vitro.