A new series of bicalutamide, enzalutamide and enobosarm derivatives carrying pentafluorosulfanyl (SF5) and pentafluoroethyl (C2F5) substituents: Improved antiproliferative agents against prostate cancer.

SAR studies on bicalutamide, enobosarm and enzalutamide analogues, functionalised with polyfluorinated groups, is presented. Among the novel bicalutamide and enobosarm derivatives synthesised, several displayed significantly improved in vitro anticancer activity, with IC50 values in the low micromolar range against four different prostate cancer cell lines (LNCaP, VCaP, DU-145 and 22Rv1), showing up to 48-fold increase in comparison with the parent structures. In particular, SF5 enobosarm analogues were found to be most potent compounds, full AR antagonists and with favourable ADME properties. The most promising compound (48a) was evaluated for its in vivo efficacy in PC xenograft mouse model (22Rv1) with results comparable to the standard-of-care docetaxel.

Hybrid Enzalutamide Derivatives with Histone Deacetylase Inhibitor Activity Decrease Heat Shock Protein 90 and Androgen Receptor Levels and Inhibit Viability in Enzalutamide-Resistant C4-2 Prostate Cancer Cells.

Histone deacetylase inhibitors (HDACIs) can disrupt the viability of prostate cancer (PCa) cells through modulation of the cytosolic androgen receptor (AR) chaperone protein heat shock protein 90 (HSP90). However, toxicities associated with their pleiotropic effects could contribute to the ineffectiveness of HDACIs in PCa treatment. We designed hybrid molecules containing partial chemical scaffolds of enzalutamide and suberoylanilide hydroxamic acid (SAHA), with weakened intrinsic pan-HDACI activities, to target HSP90 and AR in enzalutamide-resistant PCa cells. The potency of the new molecules, compounds 2-75 [4-(3-(4-cyano-3-(trifluoromethyl)phenyl)-5,5-dimethyl-4-oxo-2-thioxoimidazolidin-1-yl)-2-fluoro-N-(7-(hydroxyamino)-7-oxoheptyl)benzamide] and 1005 [(E)-3-(4-(3-(4-cyano-3-(trifluoromethyl)phenyl)-5,5-dimethyl-4-oxo-2-thioxoimidazolidin-1-yl)-2-fluorophenyl)-N-hydroxyacrylamide], as inhibitors of nuclear and cytosolic histone deacetylases was substantially lower than that of SAHA in cell-free and in situ assays. Compounds 2-75 and 1005 antagonized gene activation by androgen without inducing chromatin association of AR. Enzalutamide had no effect on the levels of AR or HSP90, whereas the hybrid compounds induced degradation of both AR and HSP90, similar to (compound 1005) or more potently than (compound 2-75) SAHA. Similar to SAHA, compounds 2-75 and 1005 decreased the level of HSP90 and induced acetylation in a predicted approximately 55 kDa HSP90 fragment. Compared with SAHA, compound 2-75 induced greater hyperacetylation of the HDAC6 substrate α-tubulin. In contrast with SAHA, neither hybrid molecule caused substantial hyperacetylation of histones H3 and H4. Compounds 2-75 and 1005 induced p21 and caused loss of viability in the enzalutamide-resistant C4-2 cells, with efficacies that were comparable to or better than SAHA. The results suggest the potential of the new compounds as prototype antitumor drugs that would downregulate HSP90 and AR in enzalutamide-resistant PCa cells with weakened effects on nuclear HDACI targets.

Design and synthesis of novel bicalutamide and enzalutamide derivatives as antiproliferative agents for the treatment of prostate cancer.

Prostate cancer (PC) is one of the major causes of male death worldwide and the development of new and more potent anti-PC compounds is a constant requirement. Among the current treatments, (R)-bicalutamide and enzalutamide are non-steroidal androgen receptor antagonist drugs approved also in the case of castration-resistant forms. Both these drugs present a moderate antiproliferative activity and their use is limited due to the development of resistant mutants of their biological target. Insertion of fluorinated and perfluorinated groups in biologically active compounds is a current trend in medicinal chemistry, applied to improve their efficacy and stability profiles. As a means to obtain such effects, different modifications with perfluoro groups were rationally designed on the bicalutamide and enzalutamide structures, leading to the synthesis of a series of new antiproliferative compounds. Several new analogues displayed improved in vitro activity towards four different prostate cancer cell lines, while maintaining full AR antagonism and therefore representing promising leads for further development. Furthermore, a series of molecular modelling studies were performed on the AR antagonist conformation, providing useful insights on potential protein-ligand interactions.

S-glucosylated hydantoins as new antiviral agents.

S-Glycosylation took place on reaction of 5-alkylidene- and 5-arylidene-3-aryl-2-thiohydantoins with glycosyl halides under alkaline conditions. Bisglucosylation also took place when N-3 unsubstituted hydantoins were reacted. The bisglucosylated hydantoins produced N-3 glucosylated hydantoins on treatment with ammonia in methanol. In antiviral studies the most active compounds against both HSV-1 and HSV-2 were 5-(2-thienylmethylene)-3-phenyl-2-(2,3,4,6- tetra-O-acetyl-beta-D-glucopyranosyl)-2-thiohydantoin and 5-(2-thienylmethylene)-3-(4-chlorophenyl)-2-(2,3,4,6-tetra-O-acety l-beta-D- glucopyranosyl)-2-thiohydantoin.

Protein modification by diazotized arsanilic acid: synthesis and characterization of the phenylthiohydantoin derivatives of azobenzene arsonate-coupled tyrosine, histidine, and lysine residues and their sequential allotment in labeled peptides.

Analytical procedures are elaborated for the sequential allotment of azobenzene arsonate binding sites in proteins and peptides. The reaction of diazotized arsanilic acid with proteins leads to covalent modification of tyrosine, histidine and, in part, lysine residues. Synthetic peptides containing these amino acids were modified with diazotized arsanilic acid and subjected to N-terminal sequence analysis. The amino acid derivatives phenylthiohydantoin(Pth)-azobenzene-arsonate-tyrosine, Pth-azobenzene-arsonate-histidine, and alpha-Pth-epsilon-hydroxycaproic acid are recovered upon Edman degradation of selected peptides. Phenylthiohydantoins of modified and nonmodified amino acids are fully separated by reverse-phase HPLC on a Zorbax-PTH column. For identification purposes, phenylthiohydantoins of azobenzene arsonate-labeled amino acids have been synthetized. They are characterized with respect to spectral absorption characteristics and retention times on reverse-phase supports.

Preparation and characterization of 5-(4-hydroxy-3-nitrobenzyl)-3-phenyl-2-thiohydantoin, the phenylthiohydantoin derivative of 3-nitrotyrosine.

The phenylthiocarbamoyl derivative of 3-nitrotyrosine was synthesized according to the known Edman method and then converted to its phenylthiohydantoin derivative [5-(4-hydroxy-3-nitrobenzyl)-3-phenyl-2-thiohydantion] by incubation in 0.5M HCl for 24 h at room temperature. After drying over P2O5 the chromatographically pure substance could be obtained by double recrystallization from hot acetic acid. It could be established that a shorter incubation time leads to an incomplete conversion and higher temperatures cause polymerization of the product. The compounds could be characterized by thin-layer and high-performance liquid chromatography, melting point, elemental analysis as well as NMR- and absorption spectroscopy.

Synthesis of side chain-protected amino acid phenylthiohydantoins and their use in quantitative solid-phase Edman degradation.

Solid-phase Edman degradation of synthetic peptidyl-resins has been used advantageously to detect errors of deletion which might occur during Merrifield peptide synthesis. To facilitate complete quantitation of the resulting phenylthiohydantoin(PTH)-amino acids, the PTH derivatives of the following side chain-protected amino acid residues have been synthesized: Arg(Tos), Asp(OBzl), Cys(3,4-(CH3)2-Bzl), Glu(OBzl), Lys(2-ClZ), Ser(Bzl), Thr(Bzl), Tyr(2-BrZ), and Tyr(2,6-Cl2Bzl). For each derivative, a melting point, elemental analysis, and extinction coefficient were obtained. With these new compounds as HPLC standards, an unequivocal assignment and quantification of each side chain protected amino acid was possible. A quantitative analysis was performed for six model peptides with the general formula Ala-X-Leu-Y-Ala-Gly-NHCH2-resin (where X and Y represented different side chain-protected amino acyl residues). We have found solid-phase Edman degradation to be a useful aid for the characterization of peptides when they are used unpurified as synthetic antigens.