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Special Issue "Heterocycles in Medicinal Chemistry"

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Medicinal Chemistry".

Deadline for manuscript submissions: 31 January 2019

Special Issue Editor

Guest Editor
Prof. Dr. Josef Jampilek

Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Comenius University, Odbojarov 10, SK-832 32 Bratislava, Slovakia
Website | E-Mail
Phone: +421250117229
Interests: medicinal chemistry of anti-infective and antineoplastic; naphthalenes, quinolines; quinazolines; quinoxalines; amides; ADME; polymorphism; pharmaceutical analysis, solid-state analytical techniques

Special Issue Information

Dear Colleagues,

Heteroatoms constitute a very common fragment of a number of active pharmaceutical ingredients, as well as excipients; from the point of view of significance, it is all the same if these are isosterically/bioisosterically replaced carbons/carbon substructures in aliphatic structures or real heterocycles. Many heterocyclic scaffolds can be considered as privilege structures. Most frequently, nitrogen heterocycles or various positional combinations of nitrogen atoms, sulphur and oxygen in five- or six-membered rings can be found. According to statistics, more than 85% of all biologically-active chemical entities contain a heterocycle. This fact reflects the central role of heterocycles in modern drug design. The application of heterocycles provides a useful tool for modification of solubility, lipophilicity, polarity and hydrogen bonding capacity of biologically active agents, which results in the optimization of the ADME/Tox properties of drugs or drug candidates. The increasing presence of various heterocycles in drugs is related to advances in synthetic methodologies, such as metal-catalysed cross-coupling and hetero-coupling reactions, that allow rapid access to a wide variety of functionalized heterocycles. On the other hand, many heterocyclic lead compounds were isolated from natural resources, and their structures were subsequently simplified and modified by medicinal chemists. Thus, heterocycles have critical importance for medicinal chemists, because using them, it is possible to expand the available drug-like chemical space and drive more effective drug discovery programs. As medicinal chemistry is “a chemistry-based discipline, also involving aspects of biological, medical and pharmaceutical sciences” and “concerned with the invention, discovery, design, identification and preparation of biologically active compounds, the study of their metabolism, the interpretation of their mode of action at the molecular level and the construction of structure-activity relationships”, this Special Issue of Molecules titled “Heterocycles in Medicinal Chemistry” is devoted to the following research topics focused on heterocycles: (i) synthesis and analysis; (ii) natural compounds; (iii) carbohydrates; (iv) drug design; (v) in silico investigations; (vi) biological screening; (vii) chemical biology and biological chemistry; (vii) biomaterials; and in general, other topics related to heterocycles.

Prof. Dr. Josef Jampilek
Guest Editor

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • drugs
  • heterocycles
  • pharmacophore
  • drug design
  • computer study
  • synthesis
  • analysis
  • natural compounds
  • carbohydrates
  • physicochemical properties
  • ADMET
  • biological screening
  • chemical biology
  • biological chemistry
  • biomaterials

Published Papers (6 papers)

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Research

Open AccessArticle Design, Synthesis, Molecular Modeling, and Biological Evaluation of Novel Thiouracil Derivatives as Potential Antithyroid Agents
Molecules 2018, 23(11), 2913; https://doi.org/10.3390/molecules23112913
Received: 10 September 2018 / Revised: 29 October 2018 / Accepted: 30 October 2018 / Published: 8 November 2018
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Abstract
Hyperthyroidism is the result of uncontrolled overproduction of the thyroid hormones. One of the mostly used antithyroid agents is 6-n-propyl-2-thiouracil (PTU). The previously solved X-ray crystal structure of the PTU bound to mammalian lactoperoxidase (LPO) reveals that the LPO-PTU binding site
[...] Read more.
Hyperthyroidism is the result of uncontrolled overproduction of the thyroid hormones. One of the mostly used antithyroid agents is 6-n-propyl-2-thiouracil (PTU). The previously solved X-ray crystal structure of the PTU bound to mammalian lactoperoxidase (LPO) reveals that the LPO-PTU binding site is basically a hydrophobic channel. There are two hydrophobic side chains directed towards the oxygen atom in the C-4 position of the thiouracil ring. In the current study, the structural activity relationship (SAR) was performed on the thiouracil nucleus of PTU to target these hydrophobic side chains and gain more favorable interactions and, in return, more antithyroid activity. Most of the designed compounds show superiority over PTU in reducing the mean serum T4 levels of hyperthyroid rats by 3% to 60%. In addition, the effect of these compounds on the levels of serum T3 was found to be comparable to the effect of PTU treatment. The designed compounds in this study showed a promising activity profile in reducing levels of thyroid hormones and follow up experiments will be needed to confirm the use of the designed compounds as new potential antithyroid agents. Full article
(This article belongs to the Special Issue Heterocycles in Medicinal Chemistry)
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Open AccessArticle Synthesis of New Furothiazolo Pyrimido Quinazolinones from Visnagenone or Khellinone and Antimicrobial Activity
Molecules 2018, 23(11), 2793; https://doi.org/10.3390/molecules23112793
Received: 5 October 2018 / Revised: 23 October 2018 / Accepted: 24 October 2018 / Published: 27 October 2018
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Abstract
Substituted-6-methyl-1-thioxo-1,2-dihydro-3H-furo[3,2-g]pyrimido[1,6-a]quinazolin-3-ones (5a,b) were synthesized from condensation of visnagenone (2a) or khellinone (2b) with 6-amino-thiouracil (3) in dimethylformamide or refluxing of (4a) or (4b) in dimethylformamide. Hence, compounds
[...] Read more.
Substituted-6-methyl-1-thioxo-1,2-dihydro-3H-furo[3,2-g]pyrimido[1,6-a]quinazolin-3-ones (5a,b) were synthesized from condensation of visnagenone (2a) or khellinone (2b) with 6-amino-thiouracil (3) in dimethylformamide or refluxing of (4a) or (4b) in dimethylformamide. Hence, compounds (5a,b) were used as the starting materials for preparing many new heterocyclic compounds such as; furo[3,2-g]pyrimido[1,6-a]quinazoline (6a,b), furo[3,2-g]thiazolo[2′,3′:2,3]pyrimido[1,6-a]quinazolinone (7a,b), substituted-benzylidene-furo[3,2-g]thiazolo[2′,3′:2,3]pyrimido[1,6-a]quinazoline-3,5-dione (8af), 3-oxo-furo[3,2-g]pyrimido[1,6-a]quinazoline-pentane-2,4-dione (9a,b), 1-(pyrazole)-furo[3,2-g]pyrimido[1,6-a]quinazolinone (10a,b), 2-(oxo or thioxo)-pyrimidine-furo[3,2-g]pyrimido[1,6-a]quinazolinone (11ad), 1-(methylthio)-furo[3,2-g]pyrimido[1,6-a]quinazolinone (12a,b), 1-(methyl-sulfonyl)-furo[3,2-g]pyrimido[1,6-a]quinazolinone (13a,b) and 6-methyl-1-((piperazine) or morpholino)-3H-furo[3,2-g]pyrimido[1,6-a]quinazolin-3-one (14ad). The structures of the prepared compounds were elucidated on the basis of spectral data (IR, 1H-NMR, 13C-NMR, MS) and elemental analysis. Antimicrobial activity was evaluated for the synthesized compounds against Gram-positive, Gram-negative bacteria and fungi. The new compounds, furothiazolo pyrimido quinazolines 8af and 11ad displayed results excellent for growth inhibition of bacteria and fungi. Full article
(This article belongs to the Special Issue Heterocycles in Medicinal Chemistry)
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Open AccessArticle New Nitrogen Compounds Coupled to Phenolic Units with Antioxidant and Antifungal Activities: Synthesis and Structure–Activity Relationship
Molecules 2018, 23(10), 2530; https://doi.org/10.3390/molecules23102530
Received: 9 September 2018 / Revised: 27 September 2018 / Accepted: 2 October 2018 / Published: 3 October 2018
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Abstract
A selection of 1-amino-2-arylidenamine-1,2-(dicyano)ethenes 3 was synthesized and cyclized to 2-aryl-4,5-dicyano-1H-imidazoles 4 upon reflux in ethyl acetate/acetonitrile, in the presence of manganese dioxide. These compounds were tested for their antioxidant capacity by cyclic voltammetry, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and deoxyribose degradation assays.
[...] Read more.
A selection of 1-amino-2-arylidenamine-1,2-(dicyano)ethenes 3 was synthesized and cyclized to 2-aryl-4,5-dicyano-1H-imidazoles 4 upon reflux in ethyl acetate/acetonitrile, in the presence of manganese dioxide. These compounds were tested for their antioxidant capacity by cyclic voltammetry, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and deoxyribose degradation assays. The minimum inhibitory concentration of all compounds was evaluated against two yeast species, Saccharomyces cerevisiae and Candida albicans. Their toxicity was tested in mammal fibroblasts. Among the synthesised compounds, two presented dual antioxidant/antifungal activity without toxic effects in fibroblasts. The new compounds synthesized in this work are potential biochemical tools and/or therapeutic drugs. Full article
(This article belongs to the Special Issue Heterocycles in Medicinal Chemistry)
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Open AccessArticle Dibasic Derivatives of Phenylcarbamic Acid against Mycobacterial Strains: Old Drugs and New Tricks?
Molecules 2018, 23(10), 2493; https://doi.org/10.3390/molecules23102493
Received: 5 September 2018 / Revised: 21 September 2018 / Accepted: 24 September 2018 / Published: 28 September 2018
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Abstract
In order to provide a more detailed view on the structure–antimycobacterial activity relationship (SAR) of phenylcarbamic acid derivatives containing two centers of protonation, 1-[2-[({[2-/3-(alkoxy)phenyl]amino}carbonyl)oxy]-3-(dipropylammonio)propyl]pyrrolidinium oxalates (1ad)/dichlorides (1eh) as well as 1-[2-[({[2-/3-(alkoxy)phenyl]amino}carbonyl)oxy]-3-(di-propylammonio)propyl]azepanium oxalates (
[...] Read more.
In order to provide a more detailed view on the structure–antimycobacterial activity relationship (SAR) of phenylcarbamic acid derivatives containing two centers of protonation, 1-[2-[({[2-/3-(alkoxy)phenyl]amino}carbonyl)oxy]-3-(dipropylammonio)propyl]pyrrolidinium oxalates (1ad)/dichlorides (1eh) as well as 1-[2-[({[2-/3-(alkoxy)phenyl]amino}carbonyl)oxy]-3-(di-propylammonio)propyl]azepanium oxalates (1il)/dichlorides (1mp; alkoxy = butoxy to heptyloxy) were physicochemically characterized by estimation of their surface tension (γ; Traube’s stalagmometric method), electronic features (log ε; UV/Vis spectrophotometry) and lipophilic properties (log kw; isocratic RP-HPLC) as well. The experimental log kw dataset was studied together with computational logarithms of partition coefficients (log P) generated by various methods based mainly on atomic or combined atomic and fragmental principles. Similarities and differences between the experimental and in silico lipophilicity descriptors were analyzed by unscaled principal component analysis (PCA). The in vitro activity of compounds 1ap was inspected against Mycobacterium tuberculosis CNCTC My 331/88 (identical with H37Rv and ATCC 2794, respectively), M. tuberculosis H37Ra ATCC 25177, M. kansasii CNCTC My 235/80 (identical with ATCC 12478), the M. kansasii 6509/96 clinical isolate, M. kansasii DSM 44162, M. avium CNCTC My 330/80 (identical with ATCC 25291), M. smegmatis ATCC 700084 and M. marinum CAMP 5644, respectively. In vitro susceptibility of the mycobacteria to reference drugs isoniazid, ethambutol, ofloxacin or ciprofloxacin was tested as well. A very unique aspect of the research was that many compounds from the set 1ap were highly efficient almost against all tested mycobacteria. The most promising derivatives showed MIC values varied from 1.9 μM to 8 μM, which were lower compared to those of used standards, especially if concerning ability to fight M. tuberculosis H37Ra ATCC 25177, M. kansasii DSM 44162 or M. avium CNCTC My 330/80. Current in vitro biological assays and systematic SAR studies based on PCA approach as well as fitting procedures, which were supported by relevant statistical descriptors, proved that the compounds 1ap represented a very promising molecular framework for development of ‘non-traditional’ but effective antimycobacterial agents. Full article
(This article belongs to the Special Issue Heterocycles in Medicinal Chemistry)
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Open AccessArticle Synthesis, Bacteriostatic and Anticancer Activity of Novel Phenanthridines Structurally Similar to Benzo[c]phenanthridine Alkaloids
Molecules 2018, 23(9), 2155; https://doi.org/10.3390/molecules23092155
Received: 31 July 2018 / Revised: 23 August 2018 / Accepted: 24 August 2018 / Published: 27 August 2018
PDF Full-text (1478 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In this study, we report the synthesis, antibacterial and anticancer evaluation of 38 novel phenanthridines that were designed as analogs of the benzo[c]phenanthridine alkaloids. The prepared phenanthridines differ from the benzo[c]phenanthridines in the absence of a benzene A-ring. All
[...] Read more.
In this study, we report the synthesis, antibacterial and anticancer evaluation of 38 novel phenanthridines that were designed as analogs of the benzo[c]phenanthridine alkaloids. The prepared phenanthridines differ from the benzo[c]phenanthridines in the absence of a benzene A-ring. All novel compounds were prepared from 6-bromo-2-hydroxy-3-methoxybenzaldehyde in several synthetic steps through reduction of Schiff bases and accomplished by radical cyclization. Twelve derivatives showed high antibacterial activity against Bacillus subtilis, Micrococcus luteus and/or Mycobacterium vaccae at single digit micromolar concentrations. Some compounds also displayed cytotoxicity against the K-562 and MCF-7 cancer cell lines at as low as single digit micromolar concentrations and were more potent than chelerythrine and sanguinarine. The active compounds caused cell-cycle arrest in cancer cells, increased levels of p53 protein and caused apoptosis-specific fragmentation of PARP-1. Biological activity was connected especially with the presence of the N-methyl quaternary nitrogen and 7-benzyloxy substitution (compounds 7i, 7j, 7k, and 7l) of phenanthridine. Full article
(This article belongs to the Special Issue Heterocycles in Medicinal Chemistry)
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Open AccessArticle Synthesis of 2,6-Diamino-Substituted Purine Derivatives and Evaluation of Cell Cycle Arrest in Breast and Colorectal Cancer Cells
Molecules 2018, 23(8), 1996; https://doi.org/10.3390/molecules23081996
Received: 16 July 2018 / Revised: 6 August 2018 / Accepted: 8 August 2018 / Published: 10 August 2018
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Abstract
Reversine is a potent antitumor 2,6-diamino-substituted purine acting as an Aurora kinases inhibitor and interfering with cancer cell cycle progression. In this study we describe three reversine-related molecules, designed by docking calculation, that present structural modifications in the diamino units at positions 2
[...] Read more.
Reversine is a potent antitumor 2,6-diamino-substituted purine acting as an Aurora kinases inhibitor and interfering with cancer cell cycle progression. In this study we describe three reversine-related molecules, designed by docking calculation, that present structural modifications in the diamino units at positions 2 and 6. We investigated the conformations of the most stable prototropic tautomers of one of these molecules, the N6-cyclohexyl-N6-methyl-N2-phenyl-7H-purine-2,6-diamine (3), by Density Functional Theory (DFT) calculation in the gas phase, water and chloroform, the last solvent considered to give insights into the detection of broad signals in NMR analysis. In all cases the HN(9) tautomer resulted more stable than the HN(7) form, but the most stable conformations changed in different solvents. Molecules 13 were evaluated on MCF-7 breast and HCT116 colorectal cancer cell lines showing that, while being less cytotoxic than reversine, they still caused cell cycle arrest in G2/M phase and polyploidy. Unlike reversine, which produced a pronounced cell cycle arrest in G2/M phase in all the cell lines used, similar concentrations of 13 were effective only in cells where p53 was deleted or down-regulated. Therefore, our findings support a potential selective role of these structurally simplified, reversine-related molecules in p53-defective cancer cells. Full article
(This article belongs to the Special Issue Heterocycles in Medicinal Chemistry)
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