Synthesis of some new thiazolo[3,2-a]pyrimidine derivatives and screening of their in vitro antibacterial and antitubercular activities

Synthesis and biological studies of pyrimidine derivatives targeting metabolic enzymes

Novel synthesized pyrimidine derivatives were investigated against carbonic anhydrase isoenzymes I and II (hCA I and II), acetylcholinesterase (AChE), butyrylcholinesterase (BChE), α-glycosidase, and aldose reductase (AR) enzymes associated with some common diseases such as epilepsy, glaucoma, Alzheimer's disease, diabetes, and neuropathy. When the results were examined, novel synthesized pyrimidine derivatives were found to have effective inhibition abilities toward the metabolic enzymes. IC50 values and Ki values were calculated for each pyrimidine derivative and compared to positive controls. The synthesized novel pyrimidine derivatives exhibited Ki values in the range of 39.16 ± 7.70-144.62 ± 26.98 nM against hCA I, 18.21 ± 3.66-136.35 ± 21.48 nM toward hCA II, which is associated with different pathological and physiological processes, 33.15 ± 4.85-52.98 ± 19.86 nM on AChE, and 31.96 ± 8.24-69.57 ± 21.27 nM on BChE. Also, Ki values were determined in the range of 17.37 ± 1.11-253.88 ± 39.91 nM against α-glycosidase and 648.82 ± 53.74-1902.58 ± 98.90 nM toward AR enzymes. Within the scope of the study, the inhibition types of the novel synthesized pyrimidine derivatives were evaluated.

Synthesis, antifungal evaluation, and molecular docking studies of steroidal thiazolopyrimidines

A series of steroidal thiazolopyrimidine derivatives were developed and evaluated for their antifungal properties against Candida species using steroid as the basic skeletonand a thiazolopyrimidine heterocycle as a pharmacophore in the D-ring. Dehydroepiandrosterone, aromatic aldehydes, and 2-aminothiazole were used in a one-pot multicomponent reaction with silica sulphuric acid to generate the target molecules. Additionally, molecular docking studies were conducted to determine how synthesized steroidal derivatives interacted with the amino acid residues of CYP51 ofCandida albicans.

Small molecule inhibitors of intestinal epithelial anion exchanger SLC26A3 (DRA) with a luminal, extracellular site of action

The anion exchanger protein SLC26A3 (down-regulated in adenoma, DRA) is expressed in the luminal membrane of intestinal epithelial cells in colon, where it facilitates the absorption of Cl^- and oxalate. We previously identified a 4,8-dimethylcoumarin class of SLC26A3 inhibitors that act from the SLC26A3 cytoplasmic surface, and demonstrated their efficacy in mouse models of constipation and hyperoxaluria. Here, screening of 50,000 new compounds and 1740 chemical analogs of active compounds from the primary screen produced five novel classes of SLC26A3-selective inhibitors (1,3-dioxoisoindoline-amides; N-(5-sulfamoyl-1,3,4-thiadiazol-2-yl)acetamides; thiazolo-pyrimidin-5-ones; 3-carboxy-2-phenylbenzofurans and benzoxazin-4-ones) with IC₅₀ down to 100 nM. Kinetic washout and onset of action studies revealed an extracellular site of action for the thiazolo-pyrimidin-5-one and 3-carboxy-2-phenylbenzofuran inhibitors. Molecular docking computations revealed putative binding sites for these inhibitors. In a loperamide model of constipation in mice, orally administered 7-(2-chloro-phenoxymethyl)-3-phenyl-thiazolo [3,2-a]pyrimidin-5-one (3a) significantly increased stool weight, pellet number and water content. SLC26A3 inhibitors with an extracellular site of action offer the possibility of creating non-absorbable, luminally acting inhibitors with minimal systemic exposure following oral administration. Our findings also suggest that inhibitors of related SLC26 anion transporters with an extracellular site of action might be identified for pharmacological modulation of selected epithelial ion transport processes.

(2-Hydroxy-3-Methoxybenzylidene)thiazolo[3,2-a]pyrimidines: Synthesis, Self-Assembly in the Crystalline Phase and Cytotoxic Activity

A series of new 2-hydroxy-3-methoxybenzylidenethiazolo[3,2-a]pyrimidines with different aryl substituents at the 5 position are synthesized and characterized by ¹H/ ¹³C NMR and IR-spectroscopy and mass-spectrometry, as well as single crystal X-ray diffraction (SCXRD). It was demonstrated that the type of hydrogen bonding can play a key role in the chiral discrimination of these compounds in the crystalline phase. The hydrogen bond of the O-H...N type leads to 1D supramolecular heterochiral chains or conglomerate crystallization in the case of the formation of homochiral chains. The hydrogen bond of O-H...O type gave racemic dimers, which are packed into 2D supramolecular layers with a parallel or angular dimers arrangement. Halogen bonding of the N...Br or O...Br type brings a new motif into supramolecular self-assembly in the crystalline phase: the formation of 1D supramolecular homochiral chains instead 2D supramolecular layers. The study of cytotoxicity against various tumor cells in vitro was carried out. It was found that 2-hydroxy-3-methoxybenzylidenethiazolo[3,2-a]pyrimidines with 3-nitrophenyl substituent at C5 carbon atom demonstrated a high efficiency against M-HeLa (cervical adenocarcinoma) and low cytotoxicity against normal liver cells.

Diarylation of thiazolopyrimidines by laccase and their in vitro evaluation as antitumor agents

A mild and efficient method was developed for the synthesis of new derivatives of thiazolo[3,2-a] pyrimidin-3(2H)-ones from available starting materials based on the oxidation of catechols to ortho-quinone by Myceliophthora thermophila laccase (Novozym 51,003) and 1,4-addition of active methylene carbon to these in situ generated intermediates in moderate to good yields (35-93%). The structure of the products was confirmed through ¹H NMR, ¹³C NMR, HMBC, HSQC, DEPT-135, and mass spectroscopy techniques. These novel compounds were evaluated as active antitumor agents against human colorectal adenocarcinoma and liver adenocarcinoma cell lines. All compounds displayed potent inhibition activities against the HT-29 cell line with IC₅₀ values of 9.8-35.9 µM, superior to the positive control doxorubicin, and most showed potent anticancer activities against the HepG2 cell line.

Synthesis and biological screening of new thiadiazolopyrimidine-based polycyclic compounds

Novel tri-and tetra-cyclic compounds based on the thiadiazolopyrimidine ring system were synthesized, and their antimicrobial activity was estimated. The obtained results evidenced the substantial efficiencies of pyrano-thiadiazolopyrimidine compounds 8a-b and 9a-b toward the two strains of gram-positive bacteria (S. aureus and B. cereus). Besides, tetracyclic pyrazolopyrimido-thiadiazolopyrimidine derivatives 16a-b and 17a-b displayed prominent efficiencies toward the two strains of gram-negative bacteria (E. coli and P. aeruginosa). In addition, compounds 8a-b and 9a-b displayed good efficacy toward C. albicans. The activity of antiquorum sensing (anti-QS) inhibition of the newly synthesized thiadiazolopyrimidine-based compounds toward C. violaceum was tested, suggesting satisfactory activity for derivatives 16a-b, 17a-b, 8b, and 9a. The cytotoxic activity of these derivatives was screened toward various cancer cell lines (MCF-7, PC3, Hep-2, and HepG2) and standard normal fibroblast cells (WI38) by utilizing the MTT assay. The pyrazolopyrimido-thiadiazolopyrimidine derivatives 16a, 16b17a, and 17b showed potent cytotoxic efficacy against the MCF-7 cells with the IC50 values ranging from 5.69 to 9.36 µM. Also, the endorsed structural activity relationship (SAR) of the inspected thiadiazolopyrimidine derivatives provided a correlation between the chemical structure and anticancer efficiency. The in silico docking studies were implemented for silencing the hormonal signaling in the breast (PDB Code-5NQR). The results were found to be consistent with the cytotoxic activity.

Synthetic and Medicinal Perspective of Fused-Thiazoles as Anticancer Agents

BACKGROUND

Cancer is second leading disease after cardiovascular disease. Presently, Chemotherapy, Radiotherapy and use of chemicals are some treatments available these days. Thiazole and its hybrid compounds extensively used scaffolds in drug designing and development of novel anticancer agents due to their wide pharmacological profiles. Fused thiazole scaffold containing drugs are available in market as a promising group of anticancer agents.

METHODS

The detailed study has been done using different database that focused on potent thiazole hybrid compounds with anticancer activity. The literature included in this review is focused on novel fused thiazole derivatives exhibiting anticancer potency in last decade.

RESULTS

Literature suggested that thiazoles and its fused and linked congener serve excellent pharmacological profile as an anticancer agent. Various synthetic strategies for fused thiazole are also summarized in this article. Novel thiazole and its fused congener showed anticancer activity against various cancer cell lines.

INTERPRETATION

Thiazole is a promising scaffold reported in literature with broad range of biological activities. This article covers the thiazole compounds fused with other carbocyclic/heterocycle including benzene, imidazole, pyridine, pyrimidine, quinoline, phenothiazine, thiopyrano, steroids, pyrrole etc. with anticancer activity from last decades. Several inhibitors for breast cancer, colon cancer, melanoma cancer, ovarian cancer, tubulin cancer etc. were reported in this review. Thus, this review will definitely aid to develop a lead for the new selective anticancer agents in future.

Triazolopyrimidine Nuclei: Privileged Scaffolds for Developing Antiviral Agents with a Proper Pharmacokinetic Profile

Viruses are a continuing threat to global health. The lack or limited therapeutic armamentarium against some viral infections and increasing drug resistance issues make the search for new antiviral agents urgent. In recent years, a growing literature highlighted the use of triazolopyrimidine (TZP) heterocycles in the development of antiviral agents, with numerous compounds that showed potent antiviral activities against different RNA and DNA viruses. TZP core represents a privileged scaffold for achieving biologically active molecules, thanks to: i) the synthetic feasibility that allows to variously functionalize TZPs in the different positions of the nucleus, ii) the ability of TZP core to establish multiple interactions with the molecular target, and iii) its favorable pharmacokinetic properties. In the present review, after mentioning selected examples of TZP-based compounds with varied biological activities, we will focus on those antivirals that appeared in the literature in the last 10 years. Approaches used for their identification, the hit-to-lead studies, and the emerged structure-activity relationship will be described. A mention of the synthetic methodologies to prepare TZP nuclei will also be given. In addition, their mechanism of action, the binding mode within the biological target, and pharmacokinetic properties will be analyzed, highlighting the strengths and weaknesses of compounds based on the TZP scaffold, which is increasingly used in medicinal chemistry.

Promising Antidiabetic and Antimicrobial Agents Based on Fused Pyrimidine Derivatives: Molecular Modeling and Biological Evaluation with Histopathological Effect

Diabetes is the most common metabolic disorder in both developing and non-developing countries, and a well-recognized global health problem. The WHO anticipates an increase in cases from 171 million in 2000 to 366 million by 2030. In the present study, we focus on the preparation of pyrimidine derivatives as potential antidiabetic and antimicrobial agents. Thein vivoeffect on total serum glucose concentration, cholesterol and antioxidant activity was assessed in adult male albino Wister rats and compared to the reference drug glimperide. Promising results were observed for compound 5. The histopathological study confirms that compound 5 results in significant activity with liver maintenance. The antimicrobial activities were evaluated against several bacterial strains such as Salmonella typhimurium ATCC 25566, Bacillus cereus, Escherichia coli NRRN 3008, Pseudomonas aeruginosa ATCC 10145, Staphylococcus aureus ATCC 6538and fungi such as Rhizopus oligosporus, Mucor miehei and Asperillus niger. Compounds 4 and 5 showed a good inhibition of the bacterial zone compared to the reference drug cephradine. Finally, we suggest protein targets for these drugs based on computational analysis, and infer their activities from their predicted modes of binding using molecular modeling. The molecular modeling for compounds 4 and 5 resulted in improved docking scores and hydrogen bonding. The docking studies are in good agreement with the in vitro and in vivo studies.

Green synthesis and characterisation of novel [1,3,4]thiadiazolo/benzo[4,5]thiazolo[3,2-a]pyrimidines via multicomponent reaction using vanadium oxide loaded on fluorapatite as a robust and sustainable catalyst

We synthesised materials with different loadings of vanadia on fluorapatite (V₂O₅/FAp), fully characterised their structural properties using various spectral techniques including TEM, BET, XRD, FT-IR, SEM and EDX and assessed their prowess as catalysts. The 2.5% V₂O₅/FAp exhibited excellent activity for the synthesis of novel [1,3,4]thiadiazolo[3,2-a]pyrimidines and benzo[4,5]thiazolo[3,2-a]pyrimidines. The one-pot three-component fusion reaction between chosen substrates of 1,3,4-thiadiazole-amines or 2-amino-benzothiazole, aldehydes and active methylene compounds in ethanol solvent at room temperature gave an excellent yield of products (90–97%) in a swift reaction (25–30 min). The advantages of this protocol are rapid synthesis, mild reaction conditions, green solvent, easy work-up, eco-friendliness, reusability of catalyst and no need for column chromatography.

We synthesized material with different loading of vanadia on fluorapatite (V₂O₅/FAp), and excellent activity was showed for the synthesis of pyrimidine derivatives (90–97%) in ethanol medium for short reaction time.

Synthesis and antitumor activity of isolongifoleno[7,8-d]thiazolo[3,2-a]pyrimidine derivatives via enhancing ROS level

A series of novel isolongifoleno[7,8-d]thiazolo[3,2-a]pyrimidine derivatives (4a-4x) were synthesized from isolongifolanone according fragment-based design strategy, and their anticancer activity against human aortic smooth muscle cells (HASMC), human breast cancer (MCF-7) cells, human cervical cancer (HeLa) cells, and human liver cancer (HepG2) cells were investigated. Results of the anticancer activity illustrated that most of the compounds showed potent antitumor activity and compound 4i proved to be the most active derivative with IC₅₀ values of 0.33 ± 0.24 (for MCF-7 cells), 0.52 ± 0.13 (for HeLa cells), and 3.09 ± 0.11 μM (for HepG2 cells), respectively. Moreover, we assessed the effects of 4i on cell apoptosis, cell cycle distribution, mitochondrial membrane potential, and reactive oxygen species (ROS) generation. The results indicated that compound 4i altered mitochondrial membrane potential and produced ROS leading to cell apoptosis of MCF-7 cells in a dose-dependent manner, however, without affecting cell cycle progression. These findings suggested that 4i was an effective compound and provided a promising candidate for anticancer drugs.

Synthesis and biological screening of new thiazolo[4,5-d]pyrimidine and dithiazolo[3,2-a:5',4'-e]pyrimidinone derivatives as antimicrobial, antiquorum-sensing and antitumor agents

New thiazolopyrimidine and dithiazolopyrimidinone derivatives 2-11 were synthesized and estimated for antimicrobial activity against S. aureus, B. cereus, E. coli, C. albicans, A. fumigatus and A. terreus. The attained results proved that 4, 8a and 11g have significant effectiveness against S. aureus and B. cereus. On the other hand, 7, 10b, 10c and 11h exhibited prominent activity against B. cereus, whereas 8a, 10b and 11g were proved to be active against E. coli. From another point of view, 4 and 8a exhibited promising efficacy against A. fumigatus and A. terreus; moreover, 8a showed outstanding efficacy against C. albicans. Quorum-sensing inhibitory activity of the new compounds was esteemed against C. violaceum, where 7, 8a, 9b, 10a-c, 11d and 11g have acceptable efficacy. In vitro antitumor efficacy of the same compounds against HepG2, HCT-116 and MCF-7 cancer cell lines was also tested. Compounds 4 and 11h showed enhanced effectiveness against the three cell lines, whereas 10b displayed eminent activity against HCT-116 and MCF-7 cells. Moreover, 11a was found to have outstanding activity against MCF-7 cells, while 11i showed promising efficacy against HepG2 cells. The in vitro active antitumor compounds were evaluated for in vivo antitumor effectiveness against EAC in mice, as well as in vitro cytotoxicity against WI38 and WISH normal cells. Results manifested that 4 has the strongest in vivo activity, and that all investigated analogs are less cytotoxic than 5-FU against both normal cell lines. DNA-binding affinity of the active compounds was examined, where 4, 8a, 10c, 11d and 11g,h displayed strong affinity. In silico studies proved that majority of the analyzed compounds are in conformity with the optimum needs for good oral absorption.

Microwave assisted synthesis of some new thiazolopyrimidine and pyrimidothiazolopyrimidopyrimidine derivatives with potential antimicrobial activity

Background and objective

A series of thiazolopyrimidine derivatives have been synthesized via multicomponent reaction and tested for biological activities. This research aims to develop a new synthetic method of poly fused pyrimidines under microwave irradiation. 6-Amino-4-aryl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carbonitriles reacted with bromomalono-nitrile to give 3,7-diamino-5-aryl-5H-thiazolo[3,2-a]pyrimidine-2,6-dicarbonitrile more willingly than the isomeric 7H-thiazolo[3,2-a]pyrimidines. Thiazolopyrimidine derivatives reacted with carbon disulphide to produce 11-aryl-11H-1,2,3,4,7,8,9,10-octahydropyrimido[4″,5″:4′,5′]thiazolo[3′,2′-a]pyrimido[4,5-d]pyrimidine-2,4,8,10-tetrathione. The above mentioned reactions were established by using both conventional methods and microwave-assisted irradiation.

Conclusion

This work provides a new method for preparing poly fused pyrimidines. The microwave-assisted technique is preferable due to the yield enhancements attained, time saving, and environmental safety reactions. The newly prepared compounds were verified for their antimicrobial activities. Also, the absorption and emission of some of the prepared compounds were studied.

Pharmacological activities of some triazinopyrazolothieno pyrimidine derivatives

Triazinopyrazolothieno pyrimidine derivatives 1-5 were evaluated for their anti-inflammatory, analgesic and anticancer activities and acute toxicity. Anti-inflammatory activity of the compounds was studied using the carrageenan test. All tested compounds showed analgesic activity, 3-methoxycarbonyl-4,6-dimethyl-8-[(N-methylindolyl)methyl] pyrimido [5',4':4,5]thieno [3',2'-3,4]pyrazolo [5,1-c]triazine (4) showed activity comparable to that of diclofenac. Compounds 1-5 were also screened for anticancer activity on a human lung cancer cell line (A549) and a human prostate cancer cell line (DU145) using the MTT micro-cultured tetrazolium assay method. Compound 4 showed also significant anticancer activity against both cancer cell lines, comparable to that of doxorubicin. The most active compounds were tested for their acute toxicity and median lethal doses were evaluated.