Efficient synthesis and molecular docking of novel antibacterial pyrimidines and their related fused heterocyclic derivatives

Hybrids Diazine: Recent Advancements in Modern Antimicrobial Therapy

Nowadays, antimicrobial therapies have become a very challenging issue because of a large diversity of reasons such as antimicrobial resistance, over consumption and misuse of antimicrobial agents, etc. A modern, actual and very useful approach in antimicrobial therapy is represented by the use of hybrid drugs, especially combined five and six-membered ring azaheterocycles. In this review, we present an overview of the recent advanced data from the last five years in the field of hybrid diazine compounds with antimicrobial activity. In this respect, we highlight here essential data concerning the synthesis and antimicrobial activity of the main classes of diazine hybrids: pyridazine, pyrimidine, pyrazine, and their fused derivatives.

[3+2] Cycloaddition Synthesis of New Piperazine-Linked Bis(chromene) Hybrids Possessing Pyrazole Units as Potential Acetylcholinesterase Inhibitors

Two series of piperazine-linked bis(chromene) hybrids that are attached to pyrazole units were synthesized in the current study. Both series are attached to an acyl unit at pyrazole-C3, with one series attached to an acetyl unit and the other to an ethoxycarbonyl unit. A [3+2] cycloaddition protocol was conducted to produce the target hybrids with good yields by reacting the appropriate hydrazonoyl chlorides with chromene-based bis(enaminone) in dioxane containing triethylamine at reflux for 4 h. New hybrids were tested for acetylcholinesterase inhibitory activity at concentrations of 15 and 25 μM, as well as their ability to quench 2,2-diphenylpicrylhydrazyl (DPPH) free radicals at a concentration of 25 μg/mL. In general, the inhibitory activity is related to the electronic properties of the para-substituent that is attached to the arene unit at pyrazole-N1. Furthermore, the acyl unit attached to pyrazole-C3 has a significant effect on the new hybrids' inhibitory activity. At the previous concentrations, the (3-acetylpyrazole)-linked hybrid attached to p-NO₂ units demonstrated the best acetylcholinesterase inhibitory activity, with inhibition percentages of 79.7 and 90.2. Furthermore, the previous hybrid demonstrated the most effective DPPH inhibitory activity, with an inhibition percentage of 87.5.

Antibacterial potential of chalcones and its derivatives against Staphylococcus aureus

Chalcones are natural substances found in the metabolism of several botanical families. Their structure consists of 1,3-diphenyl-2-propen-1-one and they are characterized by having in their chains an α, β-unsaturated carbonyl system, two phenol rings and a three-carbon chain that unites them. In plants, Chalcones are mainly involved in the biosynthesis of flavonoids and isoflavonoids through the phenylalanine derivation. This group of substances has been shown to be a viable alternative for the investigation of its antibacterial potential, considering the numerous biological activities reported and the increase of the microbial resistance that concern global health agencies. Staphylococcus aureus is a bacterium that has stood out for its ability to adapt and develop resistance to a wide variety of drugs. This literature review aimed to highlight recent advances in the use of Chalcones and derivatives as antibacterial agents against S. aureus, focusing on research articles available on the Science Direct, Pub Med and Scopus data platforms in the period 2015-2021. It was constructed informative tables that provided an overview of which types of Chalcones are being studied more (Natural or Synthetic); its chemical name and main Synthesis Methodology. From the analysis of the data, it was observed that the compounds based on Chalcones have great potential in medicinal chemistry as antibacterial agents and that the molecular skeletons of these compounds as well as their derivatives can be easily obtained through substitutions in the A and B rings of Chalcones, in order to obtain the desired bioactivity. It was verified that Chalcones and derivatives are promising agents for combating the multidrug resistance of S. aureus to drugs.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03398-7.

Hybrid Azine Derivatives: A Useful Approach for Antimicrobial Therapy

Nowadays, infectious diseases caused by microorganisms are a major threat to human health, mostly because of drug resistance, multi-drug resistance and extensive-drug-resistance phenomena to microbial pathogens. During the last few years, obtaining hybrid azaheterocyclic drugs represents a powerful and attractive approach in modern antimicrobial therapy with very promising results including overcoming microbial drug resistance. The emphasis of this review is to notify the scientific community about the latest recent advances from the last five years in the field of hybrid azine derivatives with antimicrobial activity. The review is divided according to the main series of six-member ring azaheterocycles with one nitrogen atom and their fused analogs. In each case, the main essential data concerning synthesis and antimicrobial activity are presented.

Chloramine Trihydrate-mediated Tandem Synthesis of New Pyrrole and/or Arene-linked Mono- and Bis(1,3,4-oxadiazole) Hybrids as Potential Bacterial Biofilm and MRSA Inhibitors

A two-step tandem protocol was used to prepare new pyrrole and/or arene-linked bis(1,3,4-oxadiazoles) as well as their mono-analogues. The appropriate aldehydes and benzohydrazides were first condensed in ethanol at 80 °C to yield the corresponding N-benzoylhydrazones. Without isolation, the previous intermediates were subjected to a chloramine trihydrate-mediated oxidative cyclization in DMSO at 180 °C to yield the target molecules. The antibacterial potency of the (pyrrole-arene)-linked hybrids exceeded the arene-linked hybrids, and the bis(1,3,4-oxadiazoles) exceeded their mono-analogues against six different ATCC strains. Furthermore, the antibacterial efficacy of bis(1,3,4-oxadiazoles) 11c, and 11f, which are linked to pyrrole, and (p-tolylthio)methyl units, was highest against S. aureus, E. coli, and P. aeruginosa strains. Their MIC ranged between 3.8 and 3.9 µM, while their MBC values ranged between 7.7 and 15.8 µM. Additionally, they showed promising bacterial biofilm inhibitory activity against the same strains tested, with IC50 values ranging from 4.7 to 5.3 μM. They were also effective against MRSA ATCC:33591, and ATCC:43300 strains, with MIC, and MBC values ranging from 3.8-7.9 and 7.7-15.8 μM, respectively. When tested against the MCF-10A cell line, hybrids 11c, and 11f are cytotoxic at concentrations that are more than 6 and 13-fold higher than their MIC values against the S. aureus, E. coli, and P. aeruginosa strains, respectively. This lends support to both hybrids' potential as safe antibacterial agents.

Synthesis, screening as potential antitumor of new poly heterocyclic compounds based on pyrimidine-2-thiones

Background

Continuing our interest in preparing of new heterocyclic compounds and examining their various biological activities, this work was designed to prepare new condensed and non-condensed heterocyclic compounds 9a-c, 10a-c, 11a-c, 13a-c and 14a-c were synthesized starting with pyrimidine-2-thiones 4a-c.

Results

Thiazolo[3,2-a]pyrimidines 9a-c were synthesized by S-alkylation of pyrimidine-2-thiones,4a-c, internal cyclization in alkaline medium with ammonia, condensation with benzaldehyde and finally reaction with hydroxylamine hydrochloride.[1,2,4]thiadiazolo[4,5-a]pyrimidines 11a-c were formed by heating of the 4a-c with benzoylcholride to afford 10a-c followed by reaction with sodium hypochlorite, ammonia and sodium hydroxide. Cyclocondensation of 4a-c with ethyl acetoacetate or formic acid yielded pyrazol-3-ones 13a-c or [1,2,4] triazolo[4,3-a]pyrimidines 14a-c, respectively Elements analysis, IR, 1H-NMR, 13C-NMR and mass spectra were used to validate the structures of newly synthesized heterocycles. Screening of the selected compounds 4a, 6a, 7a, 9a, 10a, 13a and 14a against colon carcinoma cell lines (HCT-116) and hepatocellular carcinoma cell lines (HepG-2).

Conclusions

Elements analysis, IR, 1H-NMR, 13C-NMR and mass spectra were used to validate the structures of newly synthesized heterocycles. Screening of the selected compounds 4a, 6a, 7a, 9a, 10a, 13a and 14a against colon carcinoma cell lines (HCT-116) and hepatocellular carcinoma cell lines (HepG-2) showed that compound 10a exhibited the most cytotoxic, while compounds 4a, 6a and 14a exhibited considerable cytotoxic activity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13065-022-00810-4.

3-Aminopyrazolo[3,4-b]pyridine: Effective Precursor for Barium Hydroxide-Mediated Three Components Synthesis of New Mono- and Bis(pyrimidines) with Potential Cytotoxic Activity

In this study, an efficient one-pot procedure for preparing a new series of pyrazolo[3,4-b]pyridine-fused pyrimidines was described. The target hybrids were developed through a three-component reaction of 3-amino-1H-pyrazolo[3,4-b]pyridine, benzaldehydes, and acetophenones (molar ratio 1 : 1 : 1). The best conditions for the previous reaction were 2.5 equivalents of barium hydroxide in DMF at 150 °C for 6 h. New bis(pyrimidines) were synthesized in high yields using a similar one-pot reaction protocol with some modifications. Thus, two equivalents of each of the appropriate acetophenones and 3-aminopyrazolopyridine were reacted with one equivalent of the appropriate bis(aldehydes). The reaction was carried out at 150 °C for 8 h using 4.5 equivalents of barium hydroxide in DMF. Repeating the previous reaction with the appropriate bis(acetyl) derivatives and benzaldehydes resulted in good yields of the target bis(pyrimidines). The in vitro cytotoxic activity of new pyrimidines against the MCF-7, HEPG2, and Caco2 cell lines was evaluated using the reference doxorubicin (IC₅₀ values of 4.34-6.97 μM). Hybrid 6h had the best activity against Caco2 and MCF-7 cell lines, IC₅₀ values of 12.62 and 14.50 μM, respectively. The IC₅₀ values for hybrids 6c, 6e, and 6f against MCF-7 and Caco2 cell lines were 23.99-41.69 and 33.14-43.33 μM, respectively. Furthermore, hybrid 6e displayed IC₅₀ value of 20.06 μM HEPG2 cell lines, while the hybrids 6c, 6f and 6h exhibited IC₅₀ values ranging between 26.29-50.51 μM. Furthermore, hybrid 6e had an IC₅₀ value of 20.06 μM for the HEPG2 cell lines, whereas hybrids 6c, 6f, and 6h had IC₅₀ values ranging from 26.29 to 50.51 μM.

New pyrido[3′,2′:4,5]thieno[3,2-d]pyrimidin-4(3H)-one hybrids linked to arene units: synthesis of potential MRSA, VRE, and COX-2 inhibitors

In the current study, we reported the tandem synthesis of two series of arene-linked pyrimidinone hybrids with related fused thieno[2,3-b]pyridine moiety. The target hybrids were prepared, in moderate to excellent yields, by the reaction of a ternary mixture of the appropriate of 3-aminothieno[2,3-b]pyridine-2-carboxylate, DMF-DMA, and a series of aryl amines in dioxane at 110 °C for 8 h. The antibacterial activity of the new hybrids was estimated against six susceptible ATCC strains. Hybrids 5g and 7g, linked to a sulfonamide unit, showed the best efficacy against S. aureus and E. faecalis strains with minimum inhibitory concentration (MIC) values of 1.7–1.8 μM, which exceed ciprofloxacin. Furthermore, some of new hybrids were examined as potential inhibitors of four different MRSA and VRE strains. Hybrids 5g and 7g demonstrated more potent efficacy than linezolid against MRSA strains with MIC values of 3.6/3.4 and 1.8/1.7 μM against ATCC:33591 and ATCC:43300 strains, respectively. The prior hybrids displayed a comparable efficacy with linezolid against VRE strains with MIC values of 7.3/6.9 and 3.6/3.4 μM against ATCC:51299 and ATCC:51575 strains, respectively. Additionally, some of the new hybrids were examined as potential COX-2 inhibitors using the reference celecoxib (IC50 of 0.117 µM). Hybrid 7g revealed more potent inhibitory efficacy than celecoxib with IC50 of 0.112 µM, whereas hybrid 5g showed almost inhibitory activity equivalent to celecoxib with IC50 of 0.121 µM. Molecular docking was performed to predict the possible binding interactions between hybrids 5g and 7g with the target COX-2 enzyme.

Isobornylchalcones as Scaffold for the Synthesis of Diarylpyrazolines with Antioxidant Activity

The pyrazoline ring is defined as a "privileged structure" in medicinal chemistry. A variety of pharmacological properties of pyrazolines is associated with the nature and position of various substituents, which is especially evident in diarylpyrazolines. Compounds with a chalcone fragment show a wide range of biological properties as well as high reactivity which is primarily due to the presence of an α, β-unsaturated carbonyl system. At the same time, bicyclic monoterpenoids deserve special attention as a source of a key structural block or as one of the pharmacophore components of biologically active molecules. A series of new diarylpyrazoline derivatives based on isobornylchalcones with different substitutes (MeO, Hal, NO2, N(Me)2) was synthesized. Antioxidant properties of the obtained compounds were comparatively evaluated using in vitro model Fe2+/ascorbate-initiated lipid peroxidation in the substrate containing brain lipids of laboratory mice. It was demonstrated that the combination of the electron-donating group in the para-position of ring B and OH-group in the ring A in the structure of chalcone fragment provides significant antioxidant activity of synthesized diarylpyrazoline derivatives.