The stereochemistry of non-enzyme catalyzed nucleophilic addition of GSH to 4'-hydroxychalcone 1 and its bis-Mannich derivative 2 was investigated at different pH values (pH 3.2, 6.1, 7.4, and 8.0). The stereochemical outcome of the reactions was evaluated by HPLC-UV-Vis method. Under strongly acidic conditions (pH 3.2), an unexpected diastereoselective addition of GSH onto the bis-Mannich derivative 2 was observed. Such a selectivity could not be observed in the similar reaction of 2 with N-acetylcysteine. The observed stereoselectivity can be rationalized by ion-pair formation between the protonated Mannich nitrogens and the deprotonated GSH(glutamate)-carboxylate. To the best of our knowledge, this is the first example of reagent-induced asymmetric induction in Michael-type additions of thiols.

Biotransformation of the antiproliferative (E)-2-[(4’-methoxyphenyl)methylene]-benzosuberon-1-one (2c) was studied using rat liver microsomes. As a result of the CYP-catalyzed transformations, one monooxygenated (2c+O) and the demethylated (2c-CH2) metabolites were identified by HPLC-MS. (E)-2-[(4’-methoxyphenyl)methylene]-benzosuberon-1-ol, the expected product of rat liver microsomal carbonyl reductase, was not found in the incubates. Microsomal GST-catalyzed reaction of the compound resulted in formation of diastereomeric GST-conjugates. Under the present HPLC conditions, the diastereomeric adducts were separated into two chromatographic peaks (2c-GSH-1 and 2c-GSH-2).

No abstract

No abstract

No abstract