17-SUBSTITUTED STEROIDAL TETRAZOLES – NOVEL LIGANDS FOR HUMAN STEROID-CONVERTING CYP ENZYMES

In animal and human organisms, there are many enzymes, members of the family of heme- containing proteins, cytochromes P450 (CYPs), included in the biosynthesis and metabolism of many biomolecules, as cholesterol, bile acids, sex, and corticosteroid hormones, as well as in metabolism of drugs and xenobiotics. It is also well-known that different imidazole and triazole derivatives are efficient inhibitors of CYPs activity. In this study, we present in vitro screening of binding of novel androstane derivatives with tetrazole- containing substituents in position 17 to human recombinant steroid-converting CYP enzymes: CYP7A1, CYP7B1, CYP17A1, CYP19, and CYP21. Initial screening was performed using a high throughput screening approach, while the affinity of the ligands was analyzed using spectrophotometric titration. For some among tested compounds type I spectral response (substrate-like binding) for CYP7A1 selectively, while for one compound type II spectral response (inhibitor-like binding) for CYP21 were detected, with micromolar values of Kds. Interestingly, one compound with mixed spectral response was found to bind for CYP7B1, which means that there are two optimal positions of the ligand inside the protein active site. Such results could be useful in CYP-inhibiting drug development, during a fast, high-throughput screening of pharmacological potential of novel compounds, as well as in side- effects recognizing.