Schistosomiasis is a neglected parasitic disease that affects more than 265 million people worldwide and for which the control strategy relies on mass treatment with only one drug: praziquantel. Based on the 3-chlorobenzothiophene-2-hydroxamic acid J1075, a series of hydroxamic acids with different scaffolds were prepared as potential inhibitors of Schistosoma mansoni histone deacetylase 8 (SmHDAC8). The crystal structures of SmHDAC8 with four inhibitors provided insight into the binding mode and orientation of molecules in the binding pocket as well as the orientation of its flexible amino acid residues. The compounds were evaluated in screens for inhibitory activity against schistosome and human HDACs. The most promising compounds were further investigated for their activity toward the major human HDAC isotypes. The most potent inhibitors were additionally screened for lethality against the schistosome larval stage using a fluorescence-based assay. Two of the compounds showed significant, dose-dependent killing of the schistosome larvae and markedly impaired egg laying of adult worm pairs maintained in culture.

Abstract:The versatile oxidase enzyme laccase was immobilized on porous supports such as polymer membranes and cryogels with a view of using such biocatalysts in bioreactors aiming at the degradation of environmental pollutants in wastewater. Besides a large surface area for supporting the biocatalyst, the aforementioned porous systems also offer the possibility for simultaneous filtration applications in wastewater treatment. Herein a "green" water-based, initiator-free, and straightforward route to highly reactive membrane and cryogel-based bioreactors is presented, where laccase was immobilized onto the porous polymer supports using a water-based electron beam-initiated grafting reaction. In a second approach, the laccase redox mediators 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and syringaldehyde were cross-linked instead of the enzyme via electron irradiation in a frozen aqueous poly(acrylate) mixture in a one pot set-up, yielding a mechanical stable macroporous cryogel with interconnected pores ranging from 10 to 50 µm in size. The membranes as well as the cryogels were characterized regarding their morphology, chemical composition, and catalytic activity. The reactivity towards wastewater pollutants was demonstrated by the degradation of the model compound bisphenol A (BPA). Both membrane-and cryogel-immobilized laccase remained highly active after electron beam irradiation. Apparent specific BPA removal rates were higher for cryogelthan for membrane-immobilized and free laccase, whereas membrane-immobilized laccase OPEN ACCESSMolecules 2014, 19 11861 was more stable with respect to maintenance of enzymatic activity and prevention of enzyme leakage from the carrier than cryogel-immobilized laccase. Cryogel-immobilized redox mediators remained functional in accelerating the laccase-catalyzed BPA degradation, and especially ABTS was found to act more efficiently in immobilized than in freely dissolved state.

Writing and erasing of posttranslational modifications are crucial to phenotypic plasticity and antigenic variation of eukaryotic pathogens. Targeting pathogens' modification machineries, thus, represents a valid approach to fighting parasitic diseases. However, identification of parasitic targets and the development of selective anti-parasitic drugs still represent major bottlenecks. Here, we show that the zinc-dependent histone deacetylases (HDACs) of the protozoan parasite Trypanosoma cruzi are key regulators that have significantly diverged from their human counterparts. Depletion of T. cruzi class I HDACs tcDAC1 and tcDAC2 compromises cell-cycle progression and division, leading to cell death. Notably, tcDAC2 displays a deacetylase activity essential to the parasite and shows major structural differences with human HDACs. Specifically, tcDAC2 harbors a modular active site with a unique subpocket targeted by inhibitors showing substantial anti-parasitic effects in cellulo and in vivo. Thus, the targeting of the many atypical HDACs in pathogens can enable anti-parasitic selective chemical impairment.

Introduction: Posttranslational modification of proteins by reversible acetylation regulates key biological processes. Histone deacetylases (HDACs) catalyze protein deacetylation and are frequently dysregulated in tumors. This has spurred the development of HDAC inhibitors (HDACi). Such epigenetic drugs modulate protein acetylation, eliminate tumor cells, and are approved for the treatment of blood cancers. Objectives: We aimed to identify novel, nanomolar HDACi with increased potency over existing agents and selectivity for the cancer-relevant class I HDACs (HDAC1/-2/-3/-8). Moreover, we wanted to define how such drugs control the apoptosis-autophagy interplay. As test systems, we used human leukemic cells and embryonic kidney-derived cells. Methods: We synthesized novel pyrimidine-hydroxamic acid HDACi (KH9/KH16/KH29) and performed in vitro activity assays and molecular modeling of their direct binding to HDACs. We analyzed how these HDACi affect leukemic cell fate, acetylation, and protein expression with flow cytometry and immunoblot. The publicly available DepMap database of CRISPR-Cas9 screenings was used to determine sensitivity factors across human leukemic cells. Results: Novel HDACi show nanomolar activity against class I HDACs. These agents are superior to the clinically used hydroxamic acid HDACi vorinostat. Within the KH-series of compounds, KH16 (yanostat) is the most effective inhibitor of HDAC3 (IC50 = 6 nM) and the most potent inducer of apoptosis (IC50 = 110 nM; p<0.0001) in leukemic cells. KH16 though spares embryonic kidney-derived cells. Global data analyses of knockout screenings verify that HDAC3 is a dependency factor in human blood cancer cells of different lineages, independent of mutations in the tumor suppressor p53. KH16 alters pro- and anti-apoptotic protein expression, stalls cell cycle progression, and induces a caspase-dependent processing of the autophagy proteins ULK1 and p62. Conclusion: These data reveal that HDACs are required to stabilize autophagy proteins through a suppression of apoptosis in leukemic cells. HDAC3 appears as a valid anti-cancer target for pharmacological intervention.

Cannabinoid type 2 receptors (CB receptors) are involved in various pathological processes, and the visualization of their availability with positron emission tomography (PET) is of high interest. The study focuses on the introduction of fluorine into the structure of the highly affine and selective CB receptor ligand -(adamantan-1-yl)-5-ethyl-2-methyl-1-phenyl-1-imidazole-4-carboxamide (). A novel series of compounds was developed by modifying (i) the adamantane-3-position, (ii) the imidazole--phenyl ring, and (iii) the imidazole-2-position, and the impact on the CB binding affinity and selectivity toward cannabinoid type 1 receptors (CB) was evaluated. This study identified compound as one of the most potent ((CB) = 0.29 nM) and selective (CB/CB > 10000) CB receptor ligands discovered so far, eligible for the development of an F-labeled PET radiotracer.