Mono-n-Butyl Phthalate Distributes to the Mouse Ovary and Liver and Alters the Expression of Phthalate-Metabolizing Enzymes in Both Tissues

Abstract Humans are exposed to phthalates daily via items such as personal care products and medications. Reproductive toxicity has been documented in mice exposed to di-n-butyl phthalate (DBP); however, quantitative evidence of its metabolite, mono-n-butyl phthalate (MBP), reaching the mouse ovary and its effects on hepatic and ovarian biotransformation enzymes in treated mice is still lacking. Liquid chromatography/tandem mass spectrometry (LC-MS/MS) was employed to quantify MBP levels in liver, serum, and ovary from mice treated with a single or repeated exposure to the parent compound, DBP. Adult CD-1 females were pipet fed once or for 10 days with vehicle (tocopherol-stripped corn oil) or DBP at 1, 10, and 1000 mg/kg/day. Tissues and serum were collected at 2, 6, 12, and 24 h after the single or final dose and subjected to LC-MS/MS. Ovaries and livers were processed for qPCR analysis of selected phthalate-associated biotransformation enzymes. Regardless of duration of exposure (single vs repeated), MBP was detected in the tissues of DBP-treated mice. In single dose mice, MBP levels peaked at ≤6 h and fell close to background levels by 24 h post-exposure. Following the last repeated dose, MBP levels peaked at ≤2 h and fell to background levels by 12 h. Hepatic and ovarian expression of Lpl, Aldh1a1, Adh1, Ugt1a6a, and Cyp1b1 were altered in DBP-treated mice in a time- and dose-specific manner. These findings confirm that MBP reaches the mouse liver and ovary after oral exposure to DBP and influences the expression of hepatic and ovarian phthalate-associated biotransformation enzymes.