1.Identification of amino acid and glutathione N-conjugates of toosendanin: bioactivation of the furan ring mediated by CYP3A4.
Yu J1, Deng P, Zhong D, Chen X. Chem Res Toxicol. 2014 Sep 15;27(9):1598-609. doi: 10.1021/tx5002145. Epub 2014 Aug 19.
Toosendanin (TSN) is a hepatotoxic triterpenoid extracted from Melia toosendan Sieb et Zucc. Considering that TSN contains the structural alert of the furan ring, it is believed that bioactivation of TSN may be responsible for its toxicity. Herein, the bioactivation potential and metabolism profiles of TSN were investigated. After an oral administration of 10 mg/kg TSN to rats, esterolysis and conjugation with amino acids were identified as the main metabolic pathways. The same types of conjugates were detected in liver microsomes in an NADPH-dependent manner. According to the remaining amount of the parent drug, the reactivity of trapping reagents with TSN reactive metabolites was sorted in a decreasing order of N(α)-(tert-butoxycarbonyl)-l-lysine (Boc-Lys) > alanine, lysine, taurine, phenylalanine, serine, glutamic acid, glycine, and glutathione (GSH) > cysteine. No conjugates were observed in NADPH and N-acetyl cysteine (NAC)-supplemented human liver microsomal incubations.
