Synthesis and DAF-12 receptor activity of a 27-nor-dafachronic acid

SAMAJA GA; ALVAREZ, LD; VELEIRO, AS; A. PECCI; BURTON, G.

Amsterdam

Congreso; Challenges in Bioorganic & Organic Medicinal Chemistry. 13th Tetrahedron Symposium; 2012

Tetrahedron

Synthesis and DAF-12 receptor activity of a 27-nor-dafachronic acid G.A. Samaja, L.D. Alvarez, A.S. Veleiro, A. Pecci, G. Burton* Universidad de Buenos Aires, Argentina The nematode worm Caenorhabditis elegans (ce) is an important model organism for biomedical research.1 The study of the nuclear receptor ceDAF-12, has acquired special attention because it is involved in multiple physiological functions, such as developmental timing, metabolism, fertility and longevity.2 Its ligands named dafachronic acids, are C-27 cholesterol metabolites, compounds 1 and 3 being the most active and abundant in the animal. The configuration of the C-25 methyl group is an important determinant on the activity of the ligand-receptor complex; transactivation assays and in vivo experiments have shown that the 25S dafachronic acids (1, 3) are more active than the 25R diastereoisomers (2, 4).Recently, we developed a model for the ligand binding domain (LBD) of the ceDAF-12 receptor, that allowed us to simulate its complexes with ligands 3 and 4 using molecular dynamics and explain their relative activities at the molecular level.3 The model showed that removal of the C-25 methyl would not impede the strong interaction of the carboxylate with the NR, predicting that the 27- nor-dafachronic acids are putative ceDAF-12 ligands. Based on these findings, we report the molecular dynamics study for the binding of the 27-nordafachronic acid 5, its synthesis and biological activity in vitro. Compound 5 was prepared by two sequential 2-carbon homologations of aldehyde 6 (Scheme). The key steps for this transformation were two Wittig reactions each followed by regioselective reduction of the side chain double bond. Compound 5 induced DAF-12 activity in transient transfections of GAL4- DAF12 and GAL4-LUC reporter in HEK-293T cell cultures. Molecular dynamics simulation of the ceDAF-12-LBD/5 complex showed that the side-chain of 5 adopts mostly a torsioned conformation and the carboxylate binds strongly to the 3 arginines in the LBD. 1. T. Kaletta, M. O. Hengartner. Nat. Rev. Drug Discov., 2006, 5, 387. 2. D. L. Motola, C. L. Cummins, V. Rottiers, K. K. Sharma, T. Li, Y. Li, K. Suino Powell, H. E. Xu, R. J. Auchus, A. Antebi, D. J. Mangelsdorf. Cell, 2006, 124,1209. 3. L. D. Alvarez, P. Arroyo Mañez, D. A. Estrín, G. Burton, Proteins Struct. Func. Bioinf., submitted Keywords: Caenorhabditis elegans, dafachronic acid, DAF-12