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Antibiotic resistance is one of the most serious global health threats. Therefore, there is a need to develop antimicrobial agents with new mechanisms of action. Targeting of bacterial cystathionine γ-lyase (bCSE), an enzyme essential for bacterial survival, is a promising approach to overcome antibiotic resistance. Here, we described a series of (heteroarylmethyl)benzoic acid derivatives and evaluated their ability to inhibit bCSE or its human ortholog hCSE using known bCSE inhibitor NL2 as a lead compound. Derivatives bearing the 6-bromoindole group proved to be the most active, with IC 50 values in the midmicromolar range, and highly selective for bCSE over hCSE. Furthermore, none of these compounds showed significant toxicity to HEK293T cells. The obtained data were rationalized by ligand-based and structure-based molecular modeling analyses. The most active compounds were also found to be an effective adjunct to several widely used antibacterial agents against clinically relevant antibiotic-resistant strains of such bacteria as Staphylococcus aureus , Klebsiella pneumoniae , and Pseudomonas aeruginosa . The most potent compounds, 3h and 3i, also showed a promising in vitro absorption, distribution, metabolism, and excretion (ADME) profile. Finally, compound 3i manifested potentiating activity in pneumonia, sepsis, and infected-wound in vivo models.

LSD1 is a histone lysine demethylase proposed as therapeutic target in cancer. Chemical modifications applied at C2, C4 and/or C7 positions of the quinazoline core of the previously reported dual LSD1/G9a inhibitor 1 led to a series of non-covalent, highly active, and selective LSD1 inhibitors (2-4 and 6-30) and to the dual LSD1/G9a inhibitor 5 that was more potent than 1 against LSD1. In THP-1 and MV4-11 leukemic cells, the most potent compounds (7, 8, and 29) showed antiproliferative effects at sub-micromolar level without significant toxicity at 1 μM in non-cancer AHH-1 cells. In MV4-11 cells, the new derivatives increased the levels of the LSD1 histone mark H3K4me2 and induced the re-expression of the CD86 gene silenced by LSD1, thereby confirming the inhibition of LSD1 at cellular level. In breast MDA-MB-231 as well as in rhabdomyosarcoma RD and RH30 cells, taken as examples of solid tumors, the same compounds displayed cell growth arrest in the same IC 50 range, highlighting a crucial anticancer role for LSD1 inhibition and suggesting no added value for the simultaneous G9a inhibition in these tumor cell lines., (Copyright © 2022 Elsevier Masson SAS. All rights reserved.)

MINA53 is a JmjC domain 2-oxoglutarate-dependent oxygenase that catalyzes ribosomal hydroxylation and is a target of the oncogenic transcription factor c -MYC. Despite its anticancer target potential, no small-molecule MINA53 inhibitors are reported. Using ribosomal substrate fragments, we developed mass spectrometry assays for MINA53 and the related oxygenase NO66. These assays enabled the identification of 2-(aryl)alkylthio-3,4-dihydro-4-oxoypyrimidine-5-carboxylic acids as potent MINA53 inhibitors, with selectivity over NO66 and other JmjC oxygenases. Crystallographic studies with the JmjC demethylase KDM5B revealed active site binding but without direct metal chelation; however, molecular modeling investigations indicated that the inhibitors bind to MINA53 by directly interacting with the iron cofactor. The MINA53 inhibitors manifest evidence for target engagement and selectivity for MINA53 over KDM4-6. The MINA53 inhibitors show antiproliferative activity with solid cancer lines and sensitize cancer cells to conventional chemotherapy, suggesting that further work investigating their potential in combination therapies is warranted.

Treatment and control of schistosomiasis still rely on only one effective drug, praziquantel (PZQ) and, due to mass treatment, the increasing risk of selecting for schistosome strains that are resistant to PZQ has alerted investigators to the urgent need to develop novel therapeutic strategies. The histone-modifying enzymes (HMEs) represent promising targets for the development of epigenetic drugs against Schistosoma mansoni. In the present study, we targeted the S. mansoni lysine-specific demethylase 1 (SmLSD1), a transcriptional corepressor, using a novel and selective synthetic inhibitor, MC3935, which was used to treat schistosomula and adult worms in vitro. By using cell viability assays and optical and electron microscopy, we showed that treatment with MC3935 affected parasite motility, egg-laying, tegument, and cellular organelle structures, culminating in the death of schistosomula and adult worms. In silico molecular modeling and docking analysis suggested that MC3935 binds to the catalytic pocket of SmLSD1. Western blot analysis revealed that MC3935 inhibited SmLSD1 demethylation activity of H3K4me1/2. Knockdown of SmLSD1 by RNAi recapitulated MC3935 phenotypes in adult worms. RNA-Seq analysis of MC3935-treated parasites revealed significant differences in gene expression related to critical biological processes. Collectively, our findings show that SmLSD1 is a promising drug target for the treatment of schistosomiasis and strongly support the further development and in vivo testing of selective schistosome LSD1 inhibitors., Competing Interests: The authors have declared that no competing interests exist.

LSD1 is a lysine demethylase highly involved in initiation and development of cancer. To design highly effective covalent inhibitors, a strategy is to fill its large catalytic cleft by designing tranylcypromine (TCP) analogs decorated with long, hindered substituents. We prepared three series of TCP analogs, carrying aroyl- and arylacetylamino (1 a-h), Z-amino acylamino (2 a-o), or double-substituted benzamide (3 a-n) residues at the C4 or C3 position of the phenyl ring. Further fragments obtained by chemical manipulation applied on the TCP scaffold (compounds 4 a-i) were also prepared. When tested against LSD1, most of 1 and 3 exhibited IC 50 values in the low nanomolar range, with 1 e and 3 a,d,f,g being also the most selective respect to monoamine oxidases. In MV4-11 AML and NB4 APL cells compounds 3 were the most potent, displaying up to sub-micromolar cell growth inhibition against both cell lines (3 a) or against NB4 cells (3 c). The most potent compounds in cellular assays were also able to induce the expression of LSD1 target genes, such as GFI-1b, ITGAM, and KCTD12, as functional read-out for LSD1 inhibition. Mouse and human intrinsic clearance data highlighted the high metabolic stability of compounds 3 a, 3 d and 3 g. Further studies will be performed on the new compounds 3 a and 3 c to assess their anticancer potential in different cancer contexts., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The antitumor agent 6-((7-nitrobenzo[ c ][1,2,5]oxadiazol-4-yl)thio)hexan-1-ol ( 1 ) is a potent inhibitor of GSTP1-1, a glutathione S -transferase capable of inhibiting apoptosis by binding to JNK1 and TRAF2. We recently demonstrated that, unlike its parent compound, the benzoyl ester of 1 (compound 3 ) exhibits negligible reactivity towards GSH, and has a different mode of interaction with GSTP1-1. Unfortunately, 3 is susceptible to rapid metabolic hydrolysis. In an effort to improve the metabolic stability of 3 , its ester group has been replaced by an amide, leading to N -(6-((7-nitrobenzo[ c ][1,2,5]oxadiazol-4-yl)thio)hexyl)benzamide ( 4 ). Unlike 3 , compound 4 was stable to human liver microsomal carboxylesterases, but retained the ability to disrupt the interaction between GSTP1-1 and TRAF2 regardless of GSH levels. Moreover, 4 exhibited both a higher stability in the presence of GSH and a greater cytotoxicity towards cultured A375 melanoma cells, in comparison with 1 and its analog 2 . These findings suggest that 4 deserves further preclinical testing.

Lysine acetylation is a post-translational modification of both histone and nonhistone proteins that is catalyzed by lysine acetyltransferases and plays a key role in numerous biological contexts. The dysregulation of this enzyme activity is implicated in many human pathologies such as cancer, neurological and inflammatory disorders. Many lysine acetyltransferase inhibitors (KATi) have been developed so far, but there is still the need for new, more potent, metabolically stable and selective KATi as chemical tools for studying KAT biology and/or as potential therapeutic agents. This review will examine the features of KAT enzymes and related diseases, with particular emphasis on KATi (bisubstrate analogs, natural compounds and synthetic derivatives), analyzing their mechanism of action, structure-activity relationships, pharmacokinetic/pharmacodynamic properties and potential future applications.

Chemical inhibition of chromatin-mediated signaling involved proteins is an established strategy to drive expression networks and alter disease progression. Protein methyltransferases are among the most studied proteins in epigenetics and, in particular, disruptor of telomeric silencing 1-like (DOT1L) lysine methyltransferase plays a key role in MLL-rearranged acute leukemia Selective inhibition of DOT1L is an established attractive strategy to breakdown aberrant H3K79 methylation and thus overexpression of leukemia genes, and leukemogenesis. Although numerous DOT1L inhibitors have been several structural data published no pronounced computational efforts have been yet reported. In these studies a first tentative of multi-stage and LB/SB combined approach is reported in order to maximize the use of available data. Using co-crystallized ligand/DOT1L complexes, predictive 3-D QSAR and COMBINE models were built through a python implementation of previously reported methodologies. The models, validated by either modeled or experimental external test sets, proved to have good predictive abilities. The application of these models to an internal library led to the selection of two unreported compounds that were found able to inhibit DOT1L at micromolar level. To the best of our knowledge this is the first report of quantitative LB and SB DOT1L inhibitors models and their application to disclose new potential epigenetic modulators.

Context: The nitrobezoxadiazole derivative NBDHEX is a potent inhibitor of glutathione transferase P1-1 (GSTP1-1) endowed with outstanding anticancer activity in different tumor models., Objective: To characterize by in vitro biochemical and in silico studies the NBDHEX analogues named MC2752 and MC2753., Materials and Methods: Synthesis of MC2752 and MC2753, biochemical assays and in silico docking and normal-mode analyses., Results: The presence of a hydrophobic moiety in the side chain of MC2753 confers unique features to this molecule. Unlike its parent drug NBDHEX, MC2753 does not require GSH to trigger the dissociation of the complex between GSTP1-1 and TRAF2, and displays high stability towards the nucleophilic attack of the tripeptide under physiological conditions., Discussion and Conclusion: MC2753 may represent a lead compound for the development of novel GSTP1-1 inhibitors not affected in their anticancer action by fluctuations of cellular GSH levels, and characterized by an increased half-life in vivo.

Histone acetyltransferases (HATs) are important mediators of epigenetic post-translational modifications of histones that play important roles in health and disease. A disturbance of these modifications can result in disease states, such as cancer or inflammatory diseases. Inhibitors of HATs (HATi) such as lysine (K) acetyltransferase 8 (KAT8), could be used to study the epigenetic processes in diseases related to these enzymes or to investigate HATs as therapeutic targets. However, the development of HATi is challenged by the difficulties in kinetic characterization of HAT enzymes and their inhibitors to enable calculation of a reproducible inhibitory potency. In this study, a fragment screening approach was used, enabling identification of 4-amino-1-naphthol, which potently inhibited KAT8. The inhibitor was investigated for enzyme inhibition using kinetic and calorimetric binding studies. This allowed for calculation of the K i values for both the free enzyme as well as the acetylated intermediate. Importantly, it revealed a striking difference in binding affinity between the acetylated enzyme and the free enzyme, which could not be revealed by the IC 50 value. This shows that kinetic characterization of inhibitors and calculation of K i values is crucial for determining the binding constants of HAT inhibitors. We anticipate that more comprehensive characterization of enzyme inhibition, as described here, is needed to advance the field of HAT inhibitors., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

The implications of lysine-specific demethylase-1 (LSD1) in tumorigenesis have urged scientists to develop diagnostic tools in order to explore the function of this enzyme. In this work, we present our efforts on the development of tranylcypromine (TCP)-based functionalized probes for activity-based protein profiling (ABPP) of LSD1 activity. Biotinylated forms of selected compounds enabled dose-dependent enzyme labeling of recombinant LSD1. However, treatment with LSD1 inhibitors did not clearly reduce the LSD1 labeling efficiency thus indicating that labeling using these probes is not activity dependent. This calls for alternative strategies to develop probes for ABPP of the enzyme LSD1., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Sirtuins are NAD(+)-dependent histone deacetylases regulating important metabolic pathways in prokaryotes and eukaryotes and are involved in many biological processes such as cell survival, senescence, proliferation, apoptosis, DNA repair, cell metabolism, and caloric restriction. The seven members of this family of enzymes are considered potential targets for the treatment of human pathologies including neurodegenerative diseases, cardiovascular diseases, and cancer. Furthermore, recent interest focusing on sirtuin modulators as epigenetic players in the regulation of fundamental biological pathways has prompted increased efforts to discover new small molecules able to modify sirtuin activity. Here, we review the role, mechanism of action, and biological function of the seven sirtuins, as well as their inhibitors and activators.

Lysine acetyltransferase 8 (KAT8) is a histone acetyltransferase (HAT) responsible for acetylating lysine 16 on histone H4 (H4K16) and plays a role in cell cycle progression as well as acetylation of the tumor suppressor protein p53. Further studies on its biological function and drug discovery initiatives will benefit from the development of small molecule inhibitors for this enzyme. As a first step towards this aim we investigated the enzyme kinetics of this bi-substrate enzyme. The kinetic experiments indicate a ping-pong mechanism in which the enzyme binds Ac-CoA first, followed by binding of the histone substrate. This mechanism is supported by affinity measurements of both substrates using isothermal titration calorimetry (ITC). Using this information, the KAT8 inhibition of a focused compound collection around the non-selective HAT inhibitor anacardic acid has been investigated. Kinetic studies with anacardic acid were performed, based on which a model for the catalytic activity of KAT8 and the inhibitory action of anacardic acid (AA) was proposed. This enabled the calculation of the inhibition constant Ki of anacardic acid derivatives using an adaptation of the Cheng-Prusoff equation. The results described in this study give insight into the catalytic mechanism of KAT8 and present the first well-characterized small-molecule inhibitors for this HAT., (Copyright © 2015 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

We designed and synthesized two novel nitrobenzoxadiazole (NBD) analogues of the anticancer agent 6-((7-nitrobenzo[c][1,2,5]oxadiazol-4-yl)thio)hexan-1-ol (NBDHEX). The new compounds, namely MC3165 and MC3181, bear one and two oxygen atoms within the hydroxy-containing alkyl chain at the C4 position of the NBD scaffold, respectively. This insertion did not alter the chemical reactivity with reduced glutathione, while it conferred a remarkable increase in water solubility. MC3181 was more selective than NBDHEX towards the target protein, glutathione transferase P1-1, and highly effective in vitro against a panel of human melanoma cell lines, with IC50 in the submicromolar-low micromolar range. Interestingly, the cellular response to MC3181 was cell-type-specific; the compound triggered a JNK-dependent apoptosis in the BRAF-V600E-mutated A375 cells, while it induced morphological changes together with an increase in melanogenesis in BRAF wild-type SK23-MEL cells. MC3181 exhibited a remarkable therapeutic activity against BRAF-V600E-mutant xenografts, both after intravenous and oral administration. Outstandingly, no treatment-related signs of toxicity were observed both in healthy and tumor-bearing mice after single and repeated administrations. Taken together, these results indicate that MC3181 may represent a potential novel therapeutic opportunity for BRAF-mutated human melanoma, while being safe and water-soluble and thus overcoming all the critical aspects of NBDHEX in vivo.

The 6-((7-nitrobenzo[c][1,2,5]oxadiazol-4-yl)thio)hexan-1-ol (NBDHEX, 1), a "suicide inhibitor" of the glutathione-S-transferase GSTP1-1, showed pro-apoptotic properties in tumor cells, but in vivo studies were limited by poor bioavailability and high affinity towards GSTM2-2, expressed in many non-cancerous tissues. Here we describe the synthesis and biological characterization of new 1 analogs (2-40), in which the hydroxyhexyl portion at the C4-sulfur atom has been replaced with phenyl-containing moieties as well as substituted alkyl chains. Some of the new compounds displayed 10-100 times increased water-solubility (8, 11, 17, 26-28, 34, 35), and most of them showed higher GSTP1-1 selectivity (2-20, 23-26, 31-33, 35) than 1. The presence of a phenyl ring with polar substituents is in general associated, with some exceptions (23, 24) to low cytotoxicity in osteosarcoma U-2OS cells. Differently, some alkyl derivatives possess cytotoxicity comparable (26, 34, 35) or higher (30, 32) than 1. Among the novel compounds, selected ones (26, 27, 34, and 35) deserve further investigation for their anticancer potential., (Copyright © 2014 Elsevier Masson SAS. All rights reserved.)

Chemical manipulations performed on the histone H3 lysine 9 methyltransferases (G9a/GLP) inhibitor BIX-01294 afforded novel desmethoxyquinazolines able to inhibit the DNA methyltransferase DNMT3A at low micromolar levels without any significant inhibition of DNMT1 and G9a. In KG-1 cells such compounds, when tested at sub-toxic doses, induced the luciferase re-expression in a stable construct controlled by a cytomegalovirus (CMV) promoter silenced by methylation (CMV-luc assay). Finally, in human lymphoma U-937 and RAJI cells, the N-(1-benzylpiperidin-4-yl)-2-(4-phenylpiperazin-1-yl)quinazolin-4-amine induced the highest proliferation arrest and cell death induction starting from 10 µM, in agreement with its DNMT3A inhibitory potency.

Chemical manipulations performed on 2-methyl-3-carbethoxyquinoline (1), a histone acetyltransferase inhibitor previously identified by our research group and active at the sub-millimolar/millimolar level, led to compounds bearing higher alkyl groups at the C2-quinoline or additional side chains at the C6-quinoline positions. Such compounds displayed at least threefold improved inhibitory potency toward p300 protein lysine acetyltransferase activity; some of them decreased histone H3 and H4 acetylation levels in U937 cells and induced high degrees of apoptosis (three compounds >10-fold higher than compound 1) after treatment of U937 cells., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In prostate cancer, two different types of histone lysine demethylases (KDM), LSD1/KDM1 and JMJD2/KDM4, are coexpressed and colocalize with the androgen receptor. We designed and synthesized hybrid LSD1/JmjC or "pan-KDM" inhibitors 1-6 by coupling the skeleton of tranylcypromine 7, a known LSD1 inhibitor, with 4-carboxy-4'-carbomethoxy-2,2'-bipyridine 8 or 5-carboxy-8-hydroxyquinoline 9, two 2-oxoglutarate competitive templates developed for JmjC inhibition. Hybrid compounds 1-6 are able to simultaneously target both KDM families and have been validated as potential antitumor agents in cells. Among them, 2 and 3 increase H3K4 and H3K9 methylation levels in cells and cause growth arrest and substantial apoptosis in LNCaP prostate and HCT116 colon cancer cells. When tested in noncancer mesenchymal progenitor (MePR) cells, 2 and 3 induced little and no apoptosis, respectively, thus showing cancer-selective inhibiting action.

BIX-01294 and its analogs were originally identified and subsequently designed as potent inhibitors against histone H3 lysine 9 (H3K9) methyltransferases G9a and G9a-like protein. Here, we show that BIX-01294 and its analog E67 can also inhibit H3K9 Jumonji demethylase KIAA1718 with half-maximal inhibitory concentrations in low micromolar range. Crystallographic analysis of KIAA1718 Jumonji domain in complex with E67 indicated that the benzylated six-membered piperidine ring was disordered and exposed to solvent. Removing the moiety (generating compound E67-2) has no effect on the potency against KIAA1718 but, unexpectedly, lost inhibition against G9a-like protein by a factor of 1500. Furthermore, E67 and E67-2 have no effect on the activity against histone H3 lysine 4 (H3K4) demethylase JARID1C. Thus, our study provides a new avenue for designing and improving the potency and selectivity of inhibitors against H3K9 Jumonji demethylases over H3K9 methyltransferases and H3K4 demethylases., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

2-oxoglutarate (2-OG)-dependent oxygenases have diverse roles in human biology. The inhibition of several 2-OG oxygenases is being targeted for therapeutic intervention, including for cancer, anemia, and ischemic diseases. We report a small-molecule probe for 2-OG oxygenases that employs a hydroxyquinoline template coupled to a photoactivable crosslinking group and an affinity-purification tag. Following studies with recombinant proteins, the probe was shown to crosslink to 2-OG oxygenases in human crude cell extracts, including to proteins at endogenous levels. This approach is useful for inhibitor profiling, as demonstrated by crosslinking to the histone demethylase FBXL11 (KDM2A) in HEK293T nuclear extracts. The results also suggest that small-molecule probes may be suitable for substrate identification studies., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Histone deacetylase (HDAC) inhibitors are promising new epi-drugs, but the presence of both class I and class II enzymes in HDAC complexes precludes a detailed elucidation of the individual HDAC functions. By using the class II-specific HDAC inhibitor MC1568, we separated class I- and class II-dependent effects and defined the roles of class II enzymes in muscle differentiation in cultured cells and in vivo. MC1568 arrests myogenesis by (i) decreasing myocyte enhancer factor 2D (MEF2D) expression, (ii) by stabilizing the HDAC4-HDAC3-MEF2D complex, and (iii) paradoxically, by inhibiting differentiation-induced MEF2D acetylation. In vivo MC1568 shows an apparent tissue-selective HDAC inhibition. In skeletal muscle and heart, MC1568 inhibits the activity of HDAC4 and HDAC5 without affecting HDAC3 activity, thereby leaving MEF2-HDAC complexes in a repressed state. Our results suggest that HDAC class II-selective inhibitors might have a therapeutic potential for the treatment of muscle and heart diseases.

Latently infected, resting memory CD4+ T cells and macrophages represent a major obstacle to the eradication of HIV-1. For this purpose, "shock and kill" strategies have been proposed (activation of HIV-1 followed by stimuli leading to cell death). Histone deacetylase inhibitors (HDACIs) induce HIV-1 activation from quiescence, yet class/isoform-selective HDACIs are needed to specifically target HIV-1 latency. We tested 32 small molecule HDACIs for their ability to induce HIV-1 activation in the ACH-2 and U1 cell line models. In general, potent activators of HIV-1 replication were found among non-class selective and class I-selective HDACIs. However, class I selectivity did not reduce the toxicity of most of the molecules for uninfected cells, which is a major concern for possible HDACI-based therapies. To overcome this problem, complementary strategies using lower HDACI concentrations have been explored. We added to class I HDACIs the glutathione-synthesis inhibitor buthionine sulfoximine (BSO), in an attempt to create an intracellular environment that would facilitate HIV-1 activation. The basis for this strategy was that HIV-1 replication decreases the intracellular levels of reduced glutathione, creating a pro-oxidant environment which in turn stimulates HIV-1 transcription. We found that BSO increased the ability of class I HDACIs to activate HIV-1. This interaction allowed the use of both types of drugs at concentrations that were non-toxic for uninfected cells, whereas the infected cell cultures succumbed more readily to the drug combination. These effects were associated with BSO-induced recruitment of HDACI-insensitive cells into the responding cell population, as shown in Jurkat cell models for HIV-1 quiescence. The results of the present study may contribute to the future design of class I HDACIs for treating HIV-1. Moreover, the combined effects of class I-selective HDACIs and the glutathione synthesis inhibitor BSO suggest the existence of an Achilles' heel that could be manipulated in order to facilitate the "kill" phase of experimental HIV-1 eradication strategies.

After the approval of suberoylanilide hydroxamic acid (SAHA, vorinostat, Zolinza) for the treatment of cutaneous T cell lymphoma (CTCL), a number of HDAC inhibitors (HDACi) are currently in Phase II or III clinical trials (alone or in combination) for the treatment of a great number of tumors. In addition to these cancer uses, HDACi can be successfully used in non-cancer diseases. In this review we focused on the uses of HDACi in some infectious diseases and beta-hemoglobinopaties. In C. albicans cultures, HDACi increased the frequency of cell switching (a relevant virulence trait) in the white-to-opaque transition, reduced the azole trailing effect through reduction in azole-dependent upregulation of CDR and ERG genes, and inhibited the fluconazole-dependent resistance induction. Moreover, they inhibited germination in several strains, and caused 90% reduction in the adherence of C. albicans to human cultured pneumocytes. In HIV-1-infected cells, the treatment with HDACi reactivates the HIV-1 expression in latent cellular reservoirs. Thus, the use of HDACi as adjuvant to highly active antiretroviral therapy (HAART) can represent a new potential therapeutic strategy to eradicate the viral infection. A number of HDACi have been reported as active against P. falciparum infection. Two recent papers show some 2-aminosuberic acid-based compounds as well as a series of phenylthiazolyl suberoyl hydroxamates as very potent and selective antimalarial agents. Among the many agents capable to perform post-natal reactivation of fetal hemoglobin production, HDACi for their capacity to de-repress gamma-globin gene expression in adult red cell, are presently considered promising molecules for personalized therapy of beta-hemoglobinopathies.

Pentadecylidenemalonate 1b, a simplified analogue of anacardic acid, was identified as the first mixed activator/inhibitor of histone acetyltransferases (HATs). It potentiates PCAF HAT activity while inhibiting those of p300/CBP and recombinant CBP. The remarkable apoptotic effect together with the ability to selectively acetylate histone versus non-histone substrates appoint 1b as a lead for the development of anticancer drugs.

(Aryloxopropenyl)pyrrolyl hydroxamates were recently reported by us as first examples of class II-selective HDAC inhibitors and can be useful tools to probe the biology of such enzymes. Molecular modelling and 3-D QSAR studies have been performed on a series of 25 (aryloxopropenyl)pyrrolyl hydroxamates to gain insights about their activity and selectivity against both maize HD1-B and HD1-A, two enzymes homologous of mammalian class I and class II HDACs, respectively. The studies have been accomplished by calculating alignment-independent descriptors (GRIND descriptors) using the ALMOND software. Highly descriptive and predictive 3-D QSAR models were obtained using either class I or class II inhibitory activity displaying r(2)/q(2) values of 0.96/0.81 and 0.98/0.85 for HD1-B and HD1-A, respectively. A deeper inspection revealed that in general a bent molecular shape structure is a prerequisite for HD1-A-selective inhibitory activity, while straight shape molecular skeleton leads to selective HD1-B compounds. The same conclusions could be achieved by molecular docking studies of the most selective inhibitors.

Candida albicans is able to establish mucosal and invasive diseases by means of different virulence factors that are frequently regulated by epigenetic mechanisms, including the acetylation-deacetylation of histones and of other regulatory proteins. The focus of our work was on understanding the possible effects of several histone deacetylase inhibitors (HDACi) on the expression of phenotypes that are associated with virulence and pathogenicity in C. albicans, such as adhesion to epithelial cells and the yeast to hypha transition. Some of the HDACi used for experiments caused a 90% reduction in the adherence of C. albicans to human cultured pneumocytes and significantly inhibited serum-induced germination. Inhibition of germination was correlated with a significant reduction in transcription of EFG1. Inhibition appeared less evident when an HDA1-deficient strain was tested. These results suggest that selective and specific HDACi could prove to be a valid approach for selected at-risk patients in the combined treatment of infections caused by C. albicans.

We have identified two new histone deacetylase (HDAC) inhibitors (9 and 24) capable of inducing the expression of gamma-globin and/or beta-globin promoter-driven reporter genes in a synthetic model of Hb switch. Both compounds also increased, with different mechanisms, the gamma/(gamma+beta) ratio expressed in vitro by normal human erythroblasts. Compound 9 increased the levels of gamma-globin mRNA and the gamma/(gamma+beta) ratio (both by 2-fold). Compound 24 increased by 3-fold the level of gamma-globin and decreased by 2-fold that of beta-globin mRNA, increasing the gamma/(gamma+beta) ratio by 6-fold, and raising (by 50%) the cell HbF content. Both compounds raised the acetylation state of histone H4 in primary cells, an indication that their activity was mediated through HDAC inhibition. Compounds 9 and 24 were also tested as gamma/(gamma+beta) mRNA inducers in erythroblasts obtained from patients with beta(0) thalassemia. Progenitor cells from patients with beta(0) thalassemia generated in vitro morphologically normal proerythroblasts that, unlike normal cells, failed to mature in the presence of EPO and expressed low beta-globin levels but 10 times higher-than-normal levels of the alpha hemoglobin-stabilizing protein (AHSP) mRNA. Both compounds ameliorated the impaired in vitro maturation in beta(0) thalassemic erythroblasts, decreasing AHSP expression to normal levels. In the case of two patients (of five analyzed), the improved erythroblast maturation was associated with detectable increases in the gamma/(gamma+beta) mRNA ratio. The low toxicity exerted by compounds 9 and 24 in all of the assays investigated suggests that these new HDAC inhibitors should be considered for personalized therapy of selected patients with beta(0) thalassemia.

Among fungal pathogens such as Candida albicans, acquired drug resistance has not been associated with plasmids or other transferable elements, but it is thought to involve primarily mutations and genetic or epigenetic phenomena. This prompted us to test some histone deacetylase inhibitors (HDACi) from our library, in combination with fluconazole, against C. albicans strains in vitro. Among the tested compounds, the two chloro-containing uracil-hydroxamates 1c and 1d showed a strong reduction of the MIC values on Candida strains that show the trailing growth effect. In this assay, 1c,d were more potent than SAHA, a well-known HDAC inhibitor, in reducing the Candida growth. More interestingly, 1c,d as well as SAHA were able to inhibit the fluconazole-induced resistance induction in Candida cultures.

The reversible histone acetylation and deacetylation are epigenetic phenomena that play critical roles in the modulation of chromatin topology and the regulation of gene expression. Aberrant transcription due to altered expression or mutation of genes that encode histone acetyltransferase (HAT) or histone deacetylase (HDAC) enzymes or their binding partners, has been clearly linked to carcinogenesis. The histone deacetylase inhibitors are a new promising class of anticancer agents (some of which in clinical trials), that inhibit the proliferation of tumor cells in culture and in vivo by inducing cell-cycle arrest, terminal differentiation, and/or apoptosis. This report reviews the chemistry and the biology of HDACs and HDAC inhibitors, laying particular emphasis on agents actually in clinical trials for cancer therapy and on new potential anticancer lead compounds more selective and less toxic., (Copyright (c) 2005 Wiley Periodicals, Inc.)

Chemical manipulations performed on aroyl pyrrolyl hydroxyamides, a new class of HDAC inhibitors previously reported by us, led to (aryloxopropenyl)pyrrolyl hydroxyamides 3a-g. Such compounds, showing better inhibitory activity against maize HD1-A than HD1-B (two homologues of mammalian class IIa and I HDACs, respectively), are the first class of IIa-selective inhibitors (fold selectivity: 7-78). They could be useful as tools for probing the biology of these enzymes and eventually as new anticancer agents with low toxicity.