Quinazoline-Based Hydroxamic Acids: Design, Synthesis, and Evaluation of Histone Deacetylase Inhibitory Effects and Cytotoxicity

The Impact of Fluorination on the Design of Histone Deacetylase Inhibitors

In recent years, histone deacetylases (HDACs) have emerged as promising targets in the treatment of cancer. The approach is to inhibit HDACs with drugs known as HDAC inhibitors (HDACis). Such HDACis are broadly classified according to their chemical structure, e.g., hydroxamic acids, benzamides, thiols, short-chain fatty acids, and cyclic peptides. Fluorination plays an important role in the medicinal-chemical design of new active representatives. As a result of the introduction of fluorine into the chemical structure, parameters such as potency or selectivity towards isoforms of HDACs can be increased. However, the impact of fluorination cannot always be clearly deduced. Nevertheless, a change in lipophilicity and, hence, solubility, as well as permeability, can influence the potency. The selectivity towards certain HDACs isoforms can be explained by special interactions of fluorinated compounds with the structure of the slightly different enzymes. Another aspect is that for a more detailed investigation of newly synthesized fluorine-containing active compounds, fluorination is often used for the purpose of labeling. Aside from the isotope ¹⁹F, which can be detected by nuclear magnetic resonance spectroscopy, the positron emission tomography of ¹⁸F plays a major role. However, to our best knowledge, a survey of the general effects of fluorination on HDACis development is lacking in the literature to date. Therefore, the aim of this review is to highlight the introduction of fluorine in the course of chemical synthesis and the impact on biological activity, using selected examples of recently developed fluorinated HDACis.

Chemical Profile and Biological Activities of Fungal Strains Isolated from Piper nigrum Roots: Experimental and Computational Approaches

The current report describes the chemical investigation and biological activity of extracts produced by three fungal strains Fusarium oxysporum, Penicillium simplicissimum, and Fusarium proliferatum isolated from the roots of Piper nigrum L. growing in Vietnam. These fungi were namely determined by morphological and DNA analyses. GC/MS identification revealed that the EtOAc extracts of these fungi were associated with the presence of saturated and unsaturated fatty acids. These EtOAc extracts showed cytotoxicity towards cancer cell lines HepG2, inhibited various microbacterial organisms, especially fungus Aspergillus niger and yeast Candida albicans (the MIC values of 50-100 μg/mL). In α-glucosidase inhibitory assay, they induced the IC₅₀ values of 1.00-2.53 μg/mL were better than positive control acarbose (169.80 μg/mL). The EtOAc extract of F. oxysporum also showed strong anti-inflammatory activity against NO production and PGE-2 level. Four major compounds linoleic acid (37.346 %), oleic acid (27.520 %), palmitic acid (25.547 %), and stearic acid (7.030 %) from the EtOAc extract of F. oxysporum were selective in molecular docking study, by which linoleic and oleic acids showed higher binding affinity towards α-glucosidase than palmitic and stearic acids. In subsequent docking assay with inducible nitric oxide synthase (iNOS), palmitic acid, oleic acid and linoleic acid could be moderate inhibitors.

QSAR analysis and experimental evaluation of new quinazoline-containing hydroxamic acids as histone deacetylase 6 inhibitors

Histone deacetylase inhibitors represent the most important class of drugs for the treatment of human cancer and other diseases due to their influence on cell growth, differentiation, and apoptosis. Among the well-known eighteen histone deacetylases, histone deacetylase 6 (HDAC6), which is involved in oncogenesis, cell survival, and cancer cell metastasis, is of great importance. Using the CDK and alvaDesc molecular descriptors and the Random Forest and EXtreme Gradient Boosting methods, we propose a number of adequate QSAR classification models, which are integrated into a consensus model and are freely available on the OCHEM web platform (https://ochem.eu). The consensus QSAR model is used for virtual screening of a series of seven new compounds, the derivatives of N-((hydroxyamino)-oxoalkyl)-2-(quinazoline-4-ilamino)-benzamides, the synthesis schemes of which are also presented in this work. In vitro evaluation of the inhibitory activity (IC₅₀) of this series of compounds against HDAC6 allowed us to confirm the results of virtual screening and to reveal promising compounds V-2 and V-4, IC₅₀ of which is 3.25 nM and 0.04 nM, respectively. The subsequent in silico evaluation of the main ADMET properties of active compounds V-2 and V-4 allowed us to find that they have acceptable pharmacokinetic parameters and level of acute toxicity.

Design, Synthesis and Evaluation of Novel (E)-N'-((1-(4-chlorobenzyl)-1H-indol-3-yl)methylene)-2-(4-oxoquinazolin-3(4H)-yl)acetohydrazides as Antitumor Agents

BACKGROUND

Herein, we have designed and synthesized a series of the novel (E)-N'-((1-(4-chlorobenzyl)-1H-indol-3-yl)methylene)-2-(4-oxoquinazolin-3(4H)-yl)acetohydrazides (5) as potent small molecules activating procaspase-3. The compounds were designed by the amalgamation of structural features of PAC-1 (the first procaspase-3 activator) and oncrasin-1, one potential anticancer agent.

METHODS

The target acetohydrazides (5a-m) were prepared via the Niementowski condensation of anthranilic acid (1a) or 5-substituted-2-aminobenzoic acid (1b-m) and formamide. The compound libraries were evaluated for their cytotoxicity, caspase-3 activation, cell cycle analysis, and apoptosis. In addition, computational chemistry is also performed.

RESULTS

A biological evaluation revealed that all thirteen compounds designed and synthesized showed strong cytotoxicity against three human cancer cell lines (SW620, colon cancer; PC-3, prostate cancer; NCI-H23, lung cancer) with eight compounds (5a, 5c-i, 5k), which were clearly more potent than both PAC-1 and oncrasin-1. In this series, four compounds including 5c, 5e, 5f, and 5h, were the most potent members with approximately 4- to 5-fold stronger than the reference compounds PAC-1 and oncrasin-1 in terms of IC50. In comparison to 5-FU, these compounds were even 18- to 29-fold more potent in terms of cytotoxicity in three human cell lines tested. In the caspase activation assay, the caspase activity was activated to 285% by compound 5e in comparison to PAC-1, the first procaspase activating compound, which was used as a control. Our docking simulation revealed that compound 5e was a potent allosteric inhibitor of procaspase-3 through chelation of inhibitory zinc ion. Physicochemical and ADMET calculations for 5e provided useful information of its suitable absorption profile and some toxicological effects that need further optimization to be developed as a promising anticancer agent.

CONCLUSION

Compound 5e has emerged as a potential hit for further design and development of caspases activators and anticancer agents.

Novel 4-Oxoquinazoline-Based N-Hydroxypropenamides as Histone Deacetylase Inhibitors: Design, Synthesis, and Biological Evaluation

Two series of novel 4-oxoquinazoline-based N-hydroxypropenamides (9a-m and 10a-m) were designed, synthesized, and evaluated for their inhibitory and cytotoxicity activities against histone deacetylase (HDAC). The compounds showed good to potent HDAC inhibitory activity and cytotoxicity against three human cancer cell lines (SW620, colon; PC-3, prostate; NCI-H23, lung cancer). In this series, compounds with the N-hydroxypropenamide functionality impeded at position 7 on the 4-oxoquinazoline skeleton (10a-m) were generally more potent than compounds with the N-hydroxypropenamide moiety at position 6 (9a-m). Also, the N ³-benzyl-substituted derivatives (9h-m, 10h-m) exhibited stronger bioactivity than the N ³-alkyl-substituted ones (9a-e, 10a-e). Two compounds 10l and 10m were the most potent ones. Their HDAC inhibitory activity (IC₅₀ values, 0.041-0.044 μM) and cytotoxicity (IC₅₀ values, 0.671-1.211 μM) were approximately 2- to 3-fold more potent than suberoylanilide hydroxamic acid (SAHA). Some compounds showed up to 10-fold more potent HDAC6 inhibition compared to their inhibitory activity in total HDAC extract assay. Analysis of selected compounds 10l and 10m revealed that these compounds strongly induced both early and late apoptosis and arrested SW620 cells at the G2/M phase. Docking studies were carried out on the HDAC6 isoform for series 10a-m and revealed some important features contributing to the inhibitory activity of synthesized compounds.

Design, Synthesis and Bioevaluation of Two Series of 3-[(1-Benzyl-1H-1,2,3-triazol-4-yl)methyl]quinazolin-4(3H)-ones and N-(1-Benzylpiperidin-4-yl)quinazolin-4-amines

Two series of 3-[(1-benzyl-1H-1,2,3-triazol-4-yl)methyl]quinazolin-4(3H)-ones and N-(1-benzylpiperidin-4-yl)quinazolin-4-amines were designed initially as potential acetylcholine esterase inhibitors. Biological evaluation demonstrated that N-(1-benzylpiperidin-4-yl)quinazolin-4-amines significantly inhibited AChE activity. Especially, two compounds of them were found to be the most potent with relative AChE inhibition percentages of 87 % in comparison to donepezil. The docking studies with AChE showed similar interactions between donepezil and four derivatives. N-(1-Benzylpiperidin-4-yl)quinazolin-4-amines also exhibited significant DPPH scavenging effects. The two series of compound also exerted moderate to good cytotoxicity against three human cancer cell lines, including SW620 (human colon cancer), PC-3 (prostate cancer), and NCI-H23 (lung cancer), with 3-[(1-benzyl-1H-1,2,3-triazol-4-yl)methyl]quinazolin-4(3H)-one being the most cytotoxic agent. 3-[(1-Benzyl-1H-1,2,3-triazol-4-yl)methyl]quinazolin-4(3H)-one significantly induced early apoptosis and arrested the SW620 cells at G2/M phase. From this study, two compounds of N-(1-benzylpiperidin-4-yl)quinazolin-4-amines could serve as new leads for further design and AChE inhibitors, while 3-[(1-benzyl-1H-1,2,3-triazol-4-yl)methyl]quinazolin-4(3H)-one could serve as a new lead for the design and development of more potent anticancer agents.

Design, Synthesis and Biological Evaluation of Novel N-hydroxyheptanamides Incorporating 6-hydroxy-2-methylquinazolin-4(3H)-ones as Histone Deacetylase Inhibitors and Cytotoxic Agents

BACKGROUND

Target-based approach to drug discovery currently attracts a great deal of interest from medicinal chemists in anticancer drug discovery and development worldwide, and Histone Deacetylase (HDAC) inhibitors represent an extensive class of targeted anti-cancer agents. Among the most explored structure moieties, hydroxybenzamides and hydroxypropenamides have been demonstrated to have potential HDAC inhibitory effects. Several compounds of these structural classes have been approved for clinical uses to treat different types of cancer, such as vorinostat and belinostat.

AIMS

This study aims at developing novel HDAC inhibitors bearing quinazolinone scaffolds with potential cytotoxicity against different cancer cell lines.

METHODS

A series of novel N-hydroxyheptanamides incorporating 6-hydroxy-2 methylquinazolin-4(3H)-ones (14a-m) was designed, synthesized and evaluated for HDAC inhibitory potency as well as cytotoxicity against three human cancer cell lines, including HepG-2 (liver cancer), MCF-7 (breast cancer) and SKLu-1 (lung cancer). Molecular simulations were finally carried out to gain more insight into the structure-activity relationships. ADME-T predictions for selected compounds were also performed to predict some important features contributing to the absorption profile of the present hydroxamic derivatives.

RESULTS

It was found that the N-hydroxyheptanamide 14i and 14j were the most potent, both in terms of HDAC inhibition and cytotoxicity. These compounds displayed up to 21-71-fold more potent than SAHA (suberoylanilide hydroxamic acid, vorinostat) in terms of cytotoxicity, and strong inhibition against the whole cell HDAC enzymes with IC₅₀ values of 7.07-9.24μM. Docking experiments on HDAC2 isozyme using Autodock Vina showed all compounds bound to HDAC2 with relatively higher affinities (from -7.02 to -11.23 kcal/mol) compared to SAHA (-7.4 kcal/mol). It was also found in this research that most of the target compounds seemed to be more cytotoxic toward breast cancer cells (MCF-7) than liver (HepG2), and lung (SKLu-1) cancer cells.

Design, Synthesis, and Cytotoxic Activity of 3-Aryl-N-hydroxy-2-(sulfonamido)propanamides in HepG2, HT-1080, KB, and MCF-7 Cells

A new series of (sulfonamido)propanamides (6a1-6a13, 6b1-6b15, 7c1-7c5, 6d1-6d5, 6e1-6e6) was designed and synthesized. All the synthesized compounds were characterized by NMR and mass spectrometry. The target compounds were evaluated for their in vitro cytotoxic activity against hepatocellular carcinoma (HepG2), fibrosarcoma (HT-1080), mouth epidermal carcinoma (KB), and breast adenocarcinoma (MCF-7) cell lines with the sulforhodamine B (SRB) assay, with gemcitabine and mitomycin C as positive controls. Most of these compounds exhibit a more potent cytotoxic effect than the positive control group on various cancer cell lines and the most potent compound, 6a7, shows the IC₅₀ values of 29.78±0.516 μm, 30.70±0.61 μm, and 64.89±3.09 μm in HepG2, HT-1080, KB, and MCF-7 cell lines, respectively. Thus, these compounds with potent cytotoxic activity have potential for development as new chemotherapy agents.

Quinazolin-4(3H)-one-Based Hydroxamic Acids: Design, Synthesis and Evaluation of Histone Deacetylase Inhibitory Effects and Cytotoxicity

The present article describes the synthesis and biological activity of various series of novel hydroxamic acids incorporating quinazolin-4(3H)-ones as novel small molecules targeting histone deacetylases. Biological evaluation showed that these hydroxamic acids were potently cytotoxic against three human cancer cell lines (SW620, colon; PC-3, prostate; NCI-H23, lung). Most compounds displayed superior cytotoxicity than SAHA (suberoylanilide hydroxamic acid, Vorinostat) in term of cytotoxicity. Especially, N-hydroxy-7-(7-methyl-4-oxoquinazolin-3(4H)-yl)heptanamide (5b) and N-hydroxy-7-(6-methyl-4-oxoquinazolin-3(4H)-yl)heptanamide (5c) (IC₅₀ values, 0.10-0.16 μm) were found to be approximately 30-fold more cytotoxic than SAHA (IC₅₀ values of 3.29-3.67 μm). N-Hydroxy-7-(4-oxoquinazolin-3(4H)-yl)heptanamide (5a; IC₅₀ values of 0.21-0.38 μm) was approximately 10- to 15-fold more potent than SAHA in cytotoxicity assay. These compounds also showed comparable HDAC inhibition potency with IC₅₀ values in sub-micromolar ranges. Molecular docking experiments indicated that most compounds, as represented by 5b and 5c, strictly bound to HDAC2 at the active binding site with binding affinities much higher than that of SAHA.

Design, Synthesis and Evaluation of Novel 3/4-((Substituted benzamidophenoxy) methyl)-N-hydroxybenzamides/propenamides as Histone Deacetylase Inhibitors and Antitumor Agents

BACKGROUND

Histone Deacetylase (HDAC) inhibitors represent an extensive class of targeted anticancer agents. Among the most explored structure moieties, hydroxybenzamides and hydroxypropenamides have been demonstrated to have potential HDAC inhibitory effects. Several compounds of these structural classes have been approved for clinical uses to treat different types of cancer, such as givinostat (ITF2357) and belinostat (PXD-101).

AIMS

This study aims at developing novel HDAC inhibitors bearing N-hydroxybenzamides and Nhydroxypropenamides scaffolds with potential cytotoxicity against different cancer cell lines.

METHODS

Two new series of N-hydroxybenzamides and N-hydroxypropenamides analogues (4a-j, 6a-j) designed based on the structural features of nexturastat A, AR-42, and PXD-101, were synthesized and evaluated for HDAC inhibitory potency as well as cytotoxicity against three human cancer cell lines (SW620 (colorectal adenocarcinoma), PC3 (prostate adenocarcinoma), and NCI-H23 (adenocarcinoma, non-small cell lung cancer). Molecular simulations were finally carried out to gain more insight into the structure-activity relationships.

RESULTS

It was found that the N-hydroxypropenamides (6a-e) displayed very good HDAC inhibitory potency and cytotoxicity. Various compounds, e.g. 6a-e, especially compound 6e, were up to 5-fold more potent than suberanilohydroxamic acid (SAHA) in terms of cytotoxicity. These compounds also comparably inhibited HDACs with IC50 values in the sub-micromolar range. Docking experiments showed that these compounds bound to HDAC2 at the enzyme active binding site with the same binding mode of SAHA, but with higher binding affinities.

CONCLUSIONS

The two series of N-hydroxybenzamides and N-hydroxypropenamides designed and synthesized were potential HDAC inhibitors and antitumor agents. Further development of these compounds should be warranted.