Synthesis of coumarin-piperazine derivatives as potent anti-microbial and anti-inflammatory agents, and molecular docking studies

Molecular modeling and biological investigation of novel s-triazine linked benzothiazole and coumarin hybrids as antimicrobial and antimycobacterial agents

A novel series of s-triazine linked benzothiazole and coumarin hybrids (6a-6d, 7a-7d, and 8a-8d) were synthesized and characterized by IR, NMR, and mass spectrometry. The compound's in vitro antibacterial and antimycobacterial activities were also evaluated. Remarkable antibacterial activity with MIC in the range of 12.5-62.5 μM and antifungal activity of 100-200 μM were demonstrated by in vitro antimicrobial analysis. Compounds 6b, 6d, 7b, 7d, and 8a strongly inhibited all bacterial strains, while 6b, 6c, and 7d had good to moderate efficacy against M. tuberculosis H37Rv. Synthesized hybrids are observed in the active pocket of the S. aureus dihydropteroate synthetase enzyme, according to a molecular docking investigations. Among the docked compounds, 6d had a strong interaction and a greater binding affinity, and the dynamic stability of protein-ligand complexes was examined using molecular dynamic simulation with various settings at 100 ns. The proposed compounds successfully maintained their molecular interaction and structural integrity inside the S. aureus dihydropteroate synthase, according to the MD simulation analysis. These in silico analyses supported the in vitro antibacterial results of compound 6d, which demonstrated outstanding in vitro antibacterial efficacy against all bacterial strains. In the quest for new antibacterial drug-like molecules, compounds 6d, 7b, and 8a have been identified as promising lead compounds.Communicated by Ramaswamy H. Sarma.

A Profound Insight into the Structure-activity Relationship of Ubiquitous Scaffold Piperazine: An Explicative Review

Despite extensive research in the field of drug discovery and development, still there is a need to develop novel molecular entities. Literature reveals a substantial heterocyclic nucleus named, piperazine, which shows an immense therapeutic voyage. For several decades, molecules having the piperazine nucleus have entered the market as a drug exhibiting biological potential. It was known to possess antipsychotic, antihistamine, antianginal, antidepressant, anticancer, antiviral, cardioprotective, and anti-inflammatory activity with a specific basis for structural activity relationship. Thus, it is regarded as a key structural feature in most of the already available therapeutic drugs in the market. Reports also suggest that the extensive utilization of these currently available drugs having a piperazine nucleus shows increasing tolerance significantly day by day. In addition to this, various other factors like solubility, low bioavailability, cost-effectiveness, and imbalance between pharmacokinetics and pharmacodynamics profile limit their utilization. Focusing on that issues, various structural modification studies were performed on the piperazine moiety to develop new derivatives/analogs to overcome the problems associated with available marketed drugs. Thus, this review article aims to gain insight into the number of structural modifications at the N-1 and N-4 positions of the piperazine scaffold. This SAR approach may prove to be the best way to overcome the above-discussed drawbacks and lead to the design of drug molecules with better efficacy and affinity. Hence, there is an urgent need to focus on the structural features of this scaffold which paves further work for deeper exploration and may help medicinal chemists as well as pharmaceutical industries.

An efficient one pot synthesis of (2-hydroxyphenyl)-5-phenyl-6-(pyrrolidine-1-carbonyl)-1H-pyrano[2,3-d]pyrimidine-2,4(3H,5H)-dione derivatives as a potent biological agents

In this paper, we reported the synthesis of a novel series of (2-hydroxyphenyl)-5-phenyl-6-(pyrrolidine-1-carbonyl)-1H-pyrano[2,3-d]pyrimidine-2,4(3H,5H)-dione derivatives 5(a-j) by the reaction of 4-hydroxy coumarin, substituted aldehydes, barbituric acid, and pyrolidine in ethanol at ambient temperature. The titled pyranopyrimidines 5(a-j) were characterized by spectral analysis including IR, NMR (¹H & ¹³C), and HRMS. The newly synthesized compounds were examined for in vitro anti-inflammatory activity. The results demonstrated that compound 5b displayed excellent efficacy and the remaining compounds exhibited moderate activity. Also, the potency of the new compounds toward antimicrobial and antifungal activity was investigated by a disk diffusion method. The results show that compounds 5b and 5g were more potent than the other compounds. Furthermore, the molecular docking studies were carried out using a COX-2 receptor.

The Effect of the New Imidazole Derivatives Complexation with Betacyclodextrin, on the Antifungal Activity in Oropharyngeal Infections

Ketoconazole (KZ) is a broad-spectrum drug used to treat fungal infections. Local use of ketoconazole has been associated with some side effects in healthy adults, especially local reactions, such as stinging, severe irritation, and itching. Moreover, the bioavailability of KZ after oral administration is low in tablets due to its low water solubility. In addition, oral administration of ketoconazole produces systemic exposure, associated with significant side effects, such as cholestatic and hepatocellular lesions. In an attempt to reduce hepatotoxicity, ketoconazole may be administered at the primary site of infection with cutaneous candidiasis, specifically on the skin tissue. However, the use of ketoconazole in topical dosage forms is limited by its high lipophilicity and extremely poor aqueous solubility (1 ng/mL), thus leading to the rare availability of topical dosage forms on the market. Therefore, a new approach to the effective delivery of ketoconazole to the site of infection is targeted, including obtaining new derivatives (keeping the imidazolic nucleus), with a similar spectrum of action, and finally, their inclusion in betacyclodextrin complexes in order to optimize bioavailability and physico-chemical stability.

Ultrasound-Assisted Synthesis and In Silico Modeling of Methanesulfonyl-Piperazine-Based Dithiocarbamates as Potential Anticancer, Thrombolytic, and Hemolytic Structural Motifs

Piperazine-based dithiocarbamates serve as important scaffolds for numerous pharmacologically active drugs. The current study investigates the design and synthesis of a series of dithiocarbamates with a piperazine unit as well as their biological activities. Under ultrasound conditions, the corresponding piperazine-1-carbodithioates 5a–5j were synthesized from monosubstituted piperazine 2 and N-phenylacetamides 4a–4j in the presence of sodium acetate and carbon disulfide in methanol. The structures of the newly synthesized piperazines were confirmed, and their anti-lung carcinoma effects were evaluated. A cytotoxic assay was performed to assess the hemolytic and thrombolytic potential of the synthesized piperazines 5a–5j. The types of substituents on the aryl ring were found to affect the anticancer activity of piperazines 5a–5j. Piperazines containing 2-chlorophenyl (5b; cell viability = 25.11 ± 2.49) and 2,4-dimethylphenyl (5i; cell viability = 25.31 ± 3.62) moieties demonstrated the most potent antiproliferative activity. On the other hand, piperazines containing 3,4-dichlorophenyl (5d; 0.1%) and 3,4-dimethylphenyl (5j; 0.1%) rings demonstrated the least cytotoxicity. The piperazine with the 2,5-dimethoxyphenyl moiety (5h; 60.2%) showed the best thrombolytic effect. To determine the mode of binding, in silico modeling of the most potent piperazine (i.e., 5b) was performed, and the results were in accordance with those of antiproliferation. It exhibits a similar binding affinity to PQ10 and an efficient conformational alignment with the lipophilic site of PDE10A conserved for PQ10A.

Molecular Insights into Coumarin Analogues as Antimicrobial Agents: Recent Developments in Drug Discovery

Simple Summary

Coumarins are a large family of benzopyrones, and more than 1300 coumarins have been reported to date. Natural, as well as synthetic, coumarins have demonstrated a diverse activity spectrum. On the other hand, the demands of the current health scenario witnessing morbidity and mortality due to microbial infections and multidrug-resistant bacterial strains, the well-reported phytochemical coumarin can be of interest. Some of the well-reported coumarin analogues as antimicrobial agents include β-lactum derivatives, coumarin-based 1,2,3-triazole compounds, the miconazole analogue, coumarin-substituted pyrazole hybrids, pyranocoumarin, coumarin−sulphonamide hybrids, pyranocoumarins, coumarin−sulphonamide derivatives, chromenylpyrazoles candidates, 3-amidocoumarins analogues, uracil−coumarin hybrids, indolinedione−coumarin hybrids, coumarin−imidazole hybrids, coumarin-fused pyrazolones and methyl thiazole derivatives, coumarin−theophylline hybrids, etc. In the present review, several methods for the synthesis of coumarin derivatives as antimicrobial agents are reported, along with structure−activity relationship (SAR) studies focusing on the developments reported since 2016.

Abstract

A major global health risk has been witnessed with the development of drug-resistant bacteria and multidrug-resistant pathogens linked to significant mortality. Coumarins are heterocyclic compounds belonging to the benzophenone class enriched in different plants. Coumarins and their derivatives have a wide range of biological activity, including antibacterial, anticoagulant, antioxidant, anti-inflammatory, antiviral, antitumour, and enzyme inhibitory effects. In the past few years, attempts have been reported towards the optimization, synthesis, and evaluation of novel coumarin analogues as antimicrobial agents. Several coumarin-based antibiotic hybrids have been developed, and the majority of them were reported to exhibit potential antibacterial effects. In the present work, studies reported from 2016 to 2020 about antimicrobial coumarin analogues are the focus. The diverse biological spectrum of coumarins can be attributed to their free radical scavenging abilities. In addition to various synthetic strategies developed, some of the structural features include a heterocyclic ring with electron-withdrawing/donating groups conjugated with the coumarin nucleus. The suggested structure−activity relationship (SAR) can provide insight into how coumarin hybrids can be rationally improved against multidrug-resistant bacteria. The present work demonstrates molecular insights for coumarin derivatives having antimicrobial properties from the recent past. The detailed SAR outcomes will benefit towards leading optimization during the discovery and development of novel antimicrobial therapeutics.

Exploration of piperazine-derived thioureas as antibacterial and anti-inflammatory agents. In vitro evaluation against clinical isolates of colistin-resistant Acinetobacter baumannii

A. baumannii is one of the most important multidrug-resistant microorganisms in hospital units. It is resistant to many classes of antibiotics and the development of new therapeutic strategies is necessary. The aim of this study was to evaluate the antibacterial activity of a set of piperazine-derived thioureas against 13 clinical strains of colistin-resistant A. baumannii. Six derivatives were identified to inhibit bacterial growth of 46% of the A. baumannii strains at low micromolar concentrations (Minimum Inhibitory Concentration from 1.56 to 6.25 μM). A common structural feature in most active compounds was the presence of a 3,5-bis-trifluoromethyl phenyl ring at the thiourea function. In addition, the ability of the compounds to inhibit production of nitric oxide (NO) was examined in RAW 264.7 murine macrophages, highlighting the potential of piperazine-derived thioureas as promising scaffolds for the design of new combined anti-bacterial/anti-inflammatory agents.