Addressing cytotoxicity of 1,4-biphenyl amide derivatives: Discovery of new potent and selective 17ß-hydroxysteroid dehydrogenase type 2 inhibitors.

Four different classes of new 17ß-hydroxysteroid dehydrogenase type 2 (17ß-HSD2) inhibitors were synthesized, in order to lower the cytotoxicity exhibited by the lead compound A, via disrupting the linearity and the aromaticity of the biphenyl moiety. Compounds 3, 4, 7a and 8 displayed comparable or better inhibitory activity and selectivity, as well as a lower cytotoxic effect, compared to the reference compound A. The best compound 4 (IC50=160nM, selectivity factor=168, LD50≈25µM) turned out as new lead compound for inhibition of 17ß-HSD2.

17ß-Hydroxysteroid Dehydrogenase Type 2 Inhibition: Discovery of Selective and Metabolically Stable Compounds Inhibiting Both the Human Enzyme and Its Murine Ortholog.

Design and synthesis of a new class of inhibitors for the treatment of osteoporosis and its comparative h17ß-HSD2 and m17ß-HSD2 SAR study are described. 17a is the first compound to show strong inhibition of both h17ß-HSD2 and m17ß-HSD2, intracellular activity, metabolic stability, selectivity toward h17ß-HSD1, m17ß-HSD1 and estrogen receptors α and ß as well as appropriate physicochemical properties for oral bioavailability. These properties make it eligible for pre-clinical animal studies, prior to human studies.

Vascular endothelial growth factor receptor-2 (VEGFR-2) inhibitors: development and validation of predictive 3-D QSAR models through extensive ligand- and structure-based approaches.

Vascular endothelial growth factor receptor-2, (VEGFR-2), is a key element in angiogenesis, the process by which new blood vessels are formed, and is thus an important pharmaceutical target. Here, 3-D quantitative structure-activity relationship (3-D QSAR) were used to build a quantitative screening and pharmacophore model of the VEGFR-2 receptors for design of inhibitors with improved activities. Most of available experimental data information has been used as training set to derive optimized and fully cross-validated eight mono-probe and a multi-probe quantitative models. Notable is the use of 262 molecules, aligned following both structure-based and ligand-based protocols, as external test set confirming the 3-D QSAR models' predictive capability and their usefulness in design new VEGFR-2 inhibitors. From a survey on literature, this is the first generation of a wide-ranging computational medicinal chemistry application on VEGFR2 inhibitors.

Metabolic stability optimization and metabolite identification of 2,5-thiophene amide 17ß-hydroxysteroid dehydrogenase type 2 inhibitors.

17ß-HSD2 is a promising new target for the treatment of osteoporosis. In this paper, a rational strategy to overcome the metabolic liability in the 2,5-thiophene amide class of 17ß-HSD2 inhibitors is described, and the biological activity of the new inhibitors. Applying different strategies, as lowering the cLogP or modifying the structures of the molecules, compounds 27, 31 and 35 with strongly improved metabolic stability were obtained. For understanding biotransformation in the 2,5-thiophene amide class the main metabolic pathways of three properly selected compounds were elucidated.

Novel, potent and selective 17ß-hydroxysteroid dehydrogenase type 2 inhibitors as potential therapeutics for osteoporosis with dual human and mouse activities.

17ß-Hydroxysteroid dehydrogenase type 2 (17ß-HSD2) is responsible for the oxidation of the highly active estradiol (E2) and testosterone (T) into the less potent estrone (E1) and Δ(4)-androstene-3,17-dione (Δ(4)-AD), respectively. As 17ß-HSD2 is present in bones and as estradiol and testosterone are able to induce bone formation and repress bone resorption, inhibition of this enzyme could be a new promising approach for the treatment of osteoporosis. Herein, we describe the design, the synthesis and the biological evaluation of 24 new 17ß-HSD2 inhibitors in the 5-substituted thiophene-2-carboxamide class. Structure-activity and structure-selectivity relationships have been explored by variation of the sulfur atom position in the central core, exchange of the thiophene by a thiazole, substitution of the amide group with a larger moiety, exchange of the N-methylamide group with bioisosteres like N-methylsulfonamide, N-methylthioamide and ketone, and substitutions at positions 2 and 3 of the thiophene core with alkyl and phenyl groups leading to 2,3,5-trisubstituted thiophene derivatives. The compounds were evaluated on human and mouse enzymes. From this study, a novel highly potent and selective compound in both human and mouse 17ß-HSD2 enzymes was identified, compound 21 (IC50(h17ß-HSD2) = 235 nM, selectivity factor toward h17ß-HSD1 = 95, IC50 (m17ß-HSD2) = 54 nM). This new compound 21 could be used for an in vivo proof of principle to demonstrate the true therapeutic efficacy of 17ß-HSD2 inhibitors in osteoporosis. New structural insights into the active sites of the human and mouse enzymes were gained.

Novel N-methylsulfonamide and retro-N-methylsulfonamide derivatives as 17ß-hydroxysteroid dehydrogenase type 2 (17ß-HSD2) inhibitors with good ADME-related physicochemical parameters.

Under physiological conditions healthy bones are maintained by a well tightened balance between osteoclast (OCs) and osteoblast (OBs) activity. Disruption of this balance leads to osteoporosis characterized by decline in bone function and skeletal rigidity. Inhibition of 17ß-hydroxysteroid dehydrogenase type 2 (17ß-HSD2) could help maintaining the appropriate bone mass density by increasing the level of estradiol and testosterone in bone. Herein, we described the synthesis, the physicochemical properties and the biological evaluation of novel N-methylsulfonamide and retro-N-methylsulfonamide derivatives as 17ß-HSD2 inhibitors showing high potency (compound 10f, IC50 = 23 nM), with a good selectivity toward 17ß-HSD1 (the isoenzyme responsible of the reverse reaction), and a likely good in vitro ADME profile. It was also shown that the acidity of the phenolic hydroxy correlates with the inhibitory potency, suggesting pKa as a predictive parameter for the activity of this class of inhibitors.

Synthesis and biological evaluation of thieno[3,2-d]- pyrimidinones, thieno[3,2-d]pyrimidines and quinazolinones: conformationally restricted 17b-hydroxysteroid dehydrogenase type 2 (17b-HSD2) inhibitors.

In this study, a series of conformationally restricted thieno[3,2-d]pyrimidinones, thieno[3,2-d]pyrimidines and quinazolinones was designed and synthesized with the goal of improving the biological activity as 17b-hydroxysteroid dehydrogenase type 2 inhibitors of the corresponding amidothiophene derivatives. Two moderately active compounds were discovered and this allowed the identification of the biologically active open conformer as well as the extension of the enzyme binding site characterisation.

Design, synthesis and biological evaluation of new classes of thieno[3,2-d]pyrimidinone and thieno[1,2,3]triazine as inhibitor of vascular endothelial growth factor receptor-2 (VEGFR-2).

Driven by a multidisciplinary approach combination (Structure-Based (SB) Three-Dimensional Quantitative Structure-Activity Relationships (3-D QSAR), molecular modeling, organic chemistry and various biological evaluations) here is reported the disclosure of new thienopyrimidines 1-3 as inhibitors of KDR activity and human umbilical vein endothelial cell (HUVEC) proliferation. More specifically, compound 2f represents a new lead compound that inhibits VEGFR-2 and HUVEC at µM concentration. Moreover by the mean of an endothelial cell tube formation in vitro model 2f tartaric acid salt proved to block angiogenesis of HUVEC at µM level.

Structural optimization of 2,5-thiophene amides as highly potent and selective 17ß-hydroxysteroid dehydrogenase type 2 inhibitors for the treatment of osteoporosis.

Inhibition of 17ß-HSD2 is an attractive mechanism for the treatment of osteoporosis. We report here the optimization of human 17ß-HSD2 inhibitors in the 2,5-thiophene amide class by varying the size of the linker (n equals 0 and 2) between the amide moiety and the phenyl group. While none of the phenethylamides (n = 2) were active, most of the anilides (n = 0) turned out to moderately or strongly inhibit 17ß-HSD2. The four most active compounds showed an IC50 of around 60 nM and a very good selectivity toward 17ß-HSD1, 17ß-HSD4, 17ß-HSD5, 11ß-HSD1, 11ß-HSD2 and the estrogen receptors α and ß. The investigated compounds inhibited monkey 17ß-HSD2 moderately, and one of them showed good inhibitory activity on mouse 17ß-HSD2. SAR studies allowed a first characterization of the human 17ß-HSD2 active site, which is predicted to be considerably larger than that of 17ß-HSD1.

Introduction of an electron withdrawing group on the hydroxyphenylnaphthol scaffold improves the potency of 17ß-hydroxysteroid dehydrogenase type 2 (17ß-HSD2) inhibitors.

Estrogen deficiency in postmenopausal women or elderly men is often associated with the skeletal disease osteoporosis. The supplementation of estradiol (E2) in osteoporotic patients is known to prevent bone fracture but cannot be administered because of adverse effect. As 17ß-hydroxysteroid dehydrogenase type 2 (17ß-HSD2) oxidizes E2 to its inactive form estrone (E1) and has been found in osteoblastic cells, it is an attractive target for the treatment of osteoporosis. Twenty-one novel, naphthalene-derived compounds have been synthesized and evaluated for their 17ß-HSD2 inhibition and their selectivity toward 17ß-HSD1 and the estrogen receptors (ERs) α and ß. Compound 19 turned out to be the most potent and selective inhibitor of 17ß-HSD2 in cell-free assays and had a very good cellular activity in MDA-MB-231 cells, expressing naturally 17ß-HSD2. It also showed marked inhibition of the E1-formation by the rat and mouse orthologous enzymes and strong inhibition of monkey 17ß-HSD2. It is thus an appropriate candidate to be further evaluated in a disease-oriented model.

Direct metallation of thienopyrimidines using a mixed lithium-cadmium base and antitumor activity of functionalized derivatives.

A series of thieno[2,3-d]- and thieno[3,2-d]pyrimidines have been easily synthesized using as key step a deproto-cadmiation-trapping sequence. Some of the compounds thus synthesized were screened for anticancer (cytotoxic) activities, and (S)-2-(6-iodo-2-phenylthieno[2,3-d]pyrimidin-4-ylamino)-3-phenylpropanoic acid proved to have a significant activity towards liver, human breast and cervix carcinoma cell lines.