Directed search for diuretics among 6-substituted pteridine-2,4,7(1H,3H,8H)-triones

Directed search for biologically active compounds among heterocycles still remains a relevant area of medical chemistry. Among the significant number of heterocyclic compounds, pteridines deserve special attention. Among the above-mentioned ones the drugs with antitumor, antimicrobial, antiviral, diuretic and other types of biological action are known. Nevertheless, 6-substituted pteridine-2,4,7(1H,3H,8H)-triones, which are structurally similar to triamterene (6-phenylpteridine-2,4,7-triamine) – a diuretic with potassium-sparing action are interesting objects for search for diuretics. All the more, they are characterized by prototropic tautomerism, able to form hydrogen and donor-acceptor bonds with various ligands, and it is likely that these structural features will provide their diuretic effect. The aim of the study is the directed search for diuretics among 6-substituted pteridine2,4,7(1H,3H,8H)-triones using in silico and in vivo methodology and elucidation of the probable mechanism of action. 1-methyl-3-R-6- (2-oxo-2-aryl- (hetaryl-) ethyl) pteridine-2,4,7(1H,3H,8H)-triones were selected to study the effect on renal excretory function. and 1-methyl-3-R-6- (2-hydroxy-2-aryl- (hetaryl-) ethyl) pteridine-2,4,7(1H,3H,8H)-triones. Directed search for compounds that affect the excretory function of the kidneys of rats was conducted by the conventional method of E.B. Berkhin with water load. The content of creatinine, sodium, potassium and chlorides in blood and urine plasma was determined by biochemical methods using standard test kits of NPV "Philisit-Diagnostics" (Ukraine) and calculations were performed according to generally accepted methods. Research of the probable mechanism was conducted by flexible molecular docking, as an approach of finding molecules with affinity to a specific biological target. Macromolecular data were downloaded from the Protein Data Bank (PDB) namely, the crystal structures of Human carbonic anhydrase II (PDB ID – 3HS4) and epithelial sodium channel (ENaC) (PDB ID – 4NTX). Studies of the effect of the synthesized compounds on the excretory function of the kidneys of rats showed that 1-methyl-3-R-6- (2-oxo-2-aryl- (hetaryl-) ethyl) pteridine-2,4,7(1H,3H,8H)-triones containing 4-fluorophenyl, 2,4-difluorophenyl, 4-chlorophenyl fragments in the molecule increase diuresis by the second hour by 27.3-70.1% compared with the control group. According to the results of the impact on daily diuresis, it was found that the most active was 1-methyl-6- (2-oxo-2-phenyl) ethyl) pteridine-2,4,7(1H,3H,8H)-triones, which increased daily diuresis by 168.1%, exceeding the effect of Hydrochlorothiazide (41.8%) and Triamterene (49.1%). However, substituted 1-methyl-3-R-6- (2-hydroxy-2-aryl- (hetaryl-) ethyl) pteridine-2,4,7(1H,3H,8H)-triones are inactive compounds. In-depth studies using biological tests and molecular docking have suggested that 1-methyl-6- (2-oxo-2-aryl) ethyl) pteridine-2,4,7(1H,3H,8H)-triones 2.1, 2.5 and 2.6) probable mechanisms of diuretic action are disruption of sodium transport in the distal convoluted tubules, causing sodium excretion and water loss and possibly inhibition of epithelial sodium channels that promote sodium uptake and potassium secretion in the distal convolutions and tubules, which implements potassium-sparing action. A well-founded and developed strategy for the search for diuretics among 6-substituted pteridine-2,4,7(1H,3H,8H)-triones has identified a number of effective compounds that by diuretic effect are superior to the reference drugs "Hydrochlorothiazide" and "Triamterene". Importantly, the results of molecular docking suggested a mechanism of action of the compounds under study, similar to thiazide diuretics. This action may be related to the tautomerism of these compounds and, as a consequence, their ability to form coordination bonds with the zinc cation and the additional interaction of halogens in the active site of CA II. It was possible to detect the presence of potassium-sparing action, probably due to the ability to inhibit epithelial sodium channels (ENaC). The obtained results substantiate the further purposeful search for potential diuretics among this class of compound

In silico and in vivo screening of triamterene synthetic analogues as promising diuretics

The modification of lead-compound aimed to the increasing of activity, decrement of toxicity or improvement of selectivity is one of the most important methods used for elaboration of novel medications. Natural compounds, approved or investigational drugs or just compounds with proved biological activity could be the lead-compound. Often the chemical modification of lead compounds is directed at the enhancement of ligand-biological target interactions. Abovementioned approach, namely structural modification of known drug triamterene was used for purposeful search for novel diuretics. The preliminary prognostication of ligand-target interactions and affinity levels allow to reduce quantity of experimental animals, synthesis, and pharmacological studies costs. Conducted studies revealed the series of promising 6,7-disubstituted pteridine-2,4(1H,3H)-diones with diuretic activity that comparable with pharmacological effect of triamterene. Aim – purposeful search for promising diuretics among structural analogues of triamterene that includes preliminary in silico studies, synthesis and in vivo screening of novel compounds for diuretic activity. Methods used: organic synthesis, physicochemical methods of analysis of organic compounds (NMR 1 H-spectroscopy, chromato-mass spectrometry, elemental analysis). Prediction of affinity for a biological target, prediction of toxicity and lipophilicity of the combinatorial library, which was created on the basis of the drug triamterene, was carried out using computer services. Studies of compounds that affect the excretory function of the kidneys of rats were performed according to the generally accepted method of E.B. Berkhin with water load. Research of the probable mechanism was conducted by flexible molecular docking, as an approach of finding molecules with affinity to a specific biological target. Macromolecular data were downloaded from the Protein Data Bank (PDB) namely, the crystal structures of epithelial sodium channel (ENaC) ((PDB ID – 6WTH). The substantiation of potential diuretics design was conducted by in silico methods (prediction of affinity, ligandenzyme interactions and pharmacokinetic characteristics). The structural modification of triamterene molecule was carried out by replacing of amino-group in positions 2, 4 and 7 by others “pharmacophore” fragments. Abovementioned transformation is aimed at the changing of ligand-enzyme interactions in active site, lipophility and toxicity. Synthesis of 6,7- disubstituted pteridine-2,4(1H,3H)-diones was conducted by condensation 5,6-diamino-2-oxo-(thioxo-)-2,3-dihydropyrimidin4(1H)-ones with carbonyl-containing compounds or oxocarboxylic acids. The further modification of obtained compounds was performed by alkylation, hydrazinolysis and nucleophilic addition/elimination. The structure of obtained compounds was proven by elemental analysis, chromato-mass and 1 H NMR-spectral analysis. The studies of synthesized compounds effect on excretion function of kidneys allowed to detect series of promising structural analogues of triamterene that exceed it in pharmacological activity by 27.3-99.0%. The “structure-biological activity” relationship was discussed and perspective of the further search of diuretics among abovementioned compounds were shown. The design of new biologically active compounds with diuretic activity was performed using in silico methodologies and realized by structural modification of the well-known diuretic triamterene. Traditional organic synthesis was used for preparation of target compounds, in vivo experiments wereused to detect compounds with significant biological activity. Several effective compounds were identified among pteridines, which exceed the reference drug triamterene in terms of daily diuresis. The obtained results substantiate further purposeful search, in-depth research on experimental pathologies and study of the mechanism of action of potential diuretics among this class of compound

Design and search for prospective diuretics (CA II Inhibitors) among aroylhydrazones of esters quinone oxime using in silico and in vivo methodology

The design and search for new selective inhibitors of CA II with a better pharmacological profile, which would cause minimal electrolyte disturbances in the body, remains an urgent problem of medical chemistry and pharmacology today. It is important that the discovered new classes of inhibitors do not always contain the main “pharmacophoric” function (sulfamide), which is characteristic of “classic” drugs (Acetazolamide, Methazolamide, Ethoxzolamide, Dorzolamide and others), but are derivatives of phenols, polyamines, coumarins/thiocoumarins, ureas, thioureas, hydroxamates, etc. These molecules also bind in the active site of the enzyme, but do not interact directly with the catalytic zinc ion or interact through zinc-coordinated water molecules/hydroxide ion. However, this leads to an increase in their selectivity and, as a result, pharmacological action. Continuing the search for compounds that affect urination, we were interested in aroylhydrazones of esters of quinone oxime. Firstly, they are characterized by certain structural features (dynamic and geometric isomerism); secondly, they exhibit redox properties; thirdly, the presence of aromatic fragments makes it possible to create a voluminous combinatorial library for analysis. These compounds are ligands in complexation reactions, and an additional increase in the number of hydrogen acceptors in the molecule due to structural modification will improve ligand-enzymatic interactions with carbonic anhydrase (CAII) and, as a result, reveal new promising diuretics. The aim – design and search for potential diuretics (CA II inhibitors) among aroylhydrazones of esters of quinone oxime using in silico, traditional synthesis and in vivo methodologies. Methods of organic synthesis, physico-chemical methods of analysis of organic compounds (NMR 1H-spectroscopy, elemental analysis). Prediction of affinity to the biological target, prediction of toxicity and lipophilicity of the combinatorial library of benzohydrazides O-aroyl esters of quinone oxime using computer services. The study of compounds affecting the excretory function of rat kidneys was carried out according to the generally accepted method of E.B.Berkhin with water load. The investigation of the probable mechanism was carried out using flexible molecular docking, as an approach to search for molecules that have affinity for human carbonic anhydrase type II (CA II). Macromolecular data of the crystal structure of CA II (PDB ID – 3HS4) were downloaded from the Protein Data Bank (PDB). The design was developed and the search for diuretic agents among benzohydrazides of O-aroyl esters of quinone oximes was developed using in silico methods (prediction of affinity, lipophilicity, toxicity and enzyme-ligand interactions), traditional organic synthesis, and in vivo methods (effect on excretory function of rat kidneys). The synthesis of benzohydrazides of O-aroyl esters of quinone oxime was carried out by the interaction of aroylhydrazines with 4-[(aroylimino)]cyclohexa-2,5-dien-1-ones. The structure of the synthesized compounds was confirmed by elemental analysis and 1H NMR spectra. Studies of the effect of synthesized compounds on the excretory function of rat kidneys allowed us to identify a number of promising compounds among aroylhydrazones of quinonexime esters, which increase daily diuresis by 54.2-352.8% compared to the control group. At the same time, it was established that the most active was N'-(4-[(2-chlorobenzoyloxy)imino]cyclohexa-2,5-dien-1-ylidene)-3-nitrobenzohydrazide, which increased daily diuresis by 352.8% in comparison with the control group, while exceeding the effect of “Hydrochlorothiazide” (170.8%). The developed and implemented strategy for the search for diuretics among benzohydrazides of O-aroylesters of quinone oxime allowed the identification of an effective compound, which in terms of diuretic effect exceeds the comparison drug “Hydrochlorothiazide”. Visualization of the molecular docking of the active compounds showed that their geometry makes it difficult to place them in the pocket of the active site of CA II, but the pronounced diuretic effect can also be associated with their ability to form coordination bonds with the zinc cation. The obtained results justify the further targeted search for potential diuretics among this class of compounds for a more detailed understanding and study of the mechanism of action