Annual Report of Activities CNC 2011 - Center for Neuroscience and ...

Bioorganic and Medicinal Chemistry GroupHead: Maria Luísa Sá e Melo48Drug discovery and development is the core research of the Bioorganic and Medicinal Chemistry Group. At present, the main focus is on drug discovery in oncology. Oxysterols are oxygenated derivatives of cholesterol endogenously found and formed through enzymatic and non-­enzymatic processes. Oxysterols exert profound biological effects in cholesterol and fatty-­‐acid metabolism, immune regulation, neurodegenerative mechanisms and cell differentiation and proliferation. Our group has been interested in the study of the structural requirements of oxysterols to display cytotoxicity (J. Med. Chem. 2009, 52, 4007-­‐4127; J. Med. Chem., 2010, 53, 7632-­‐7638). Aiming to push forward potency and selectivity, a large number of chemically diverse sterols, heavily oxygenated in rings A and B, has been recently prepared and evaluated for cytotoxicity against human cancer and non-­‐cancer cells. The SAR analysis of the oxysterols synthesized to define the sterol structural determinants for a selective activity will complement our aim. Pentacyclic triterpenoids are a class of pharmacologically active and structurally rich natural products with privileged motifs for further modifications and structure-­‐activity relationship (SAR) analyses.The naturally occurring lupane-­‐type triterpenoids betulin and betulinic acid have been thoroughly investigated during the past years for their promising chemopreventive and antitumor activities.We focused our attention on the synthesis of lupane-­type imidazole carbamates and N-­acylimidazole bearing derivatives (Bioorg. & Med. Chem., 2009, 17, 6241-­‐6250). The promising results prompted us to extend our study to 2´-­‐methylimidazole and triazole derivatives, in order to establish meaningful SAR (Bioorg. & Med. Chem., 2010, 18, 4385-­‐4396). The compounds with better cytotoxicy, were tested for their ability to induce apoptosis and cell cycle arrest in HepG2, Hela and Jurkat cells. The rapid growth in the number of high quality X-­‐ray crystal structures bound to multiple ligands, and the recent large online publicly available chemical databases with annotated activity for thousands of known modulators creates an opportunity to develop accurate computational models for fast in silico prediction of ligand binding affinity. We are currently interested in deriving high quality benchmarking test sets for docking and scoring, as well as developing and validating new software algorithms that account for the flexible nature of protein-­‐ligand interactions. The research activities of the group are supported by the following expertise: -­‐ Computational approaches in drug discovery: 4D (pocket ensemble) molecular docking; pharmacophore-­‐ and structure-­‐based drug design; virtual screening; focused library design based on hit and target. -­‐ Synthesis in drug discovery: asymmetric synthesis for chiral drugs; biocatalysis; chemo-­‐enzymatic methods; clean processes. -­‐ Analysis of structure-­‐activity relationships (SAR) to predict potency and improve “hits” to “lead candidates” by optimizing their selectivity against the target and pharmacokinetics. The most cytotoxic endogenous oxysterols, the 4beta-­‐OHChol, 7beta-­‐OHChol and 3beta, 5alpha, 6beta-­triOHChol, were used as scaffolds and different oxygen functionalities, as hydroxy, oxo, oxime, acetamide, acetate and alkoxy groups were introduced on rings A and B of the steroid. The 33 oxygenated compounds synthesized were evaluated in vitro for cytotoxicity in a panel of human cancer and noncancer cells, using the Alamar Blue assay. This panel encompassed HT-­‐29 (from colorectal adenocarcinoma), HepG2 (from hepatocellular carcinoma), A549 (from lung adenocarcinoma epithelium), PC3 (from prostate metastasis), MCF-­‐7 (from breast adenocarcinoma) and SH-­‐SY5Y (from neuroblastoma bone marrow). ARPE-­‐