Medicinal Chemistry - Volume 19, Issue 5, 2023

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV2), responsible for generating COVID-19, has spread worldwide and was declared a pandemic by the World Health Organization (WHO) on 11 March 2020, being responsible for various damages to public health, social life, and the economy of countries. Its high infectivity and mutation rates have stimulated researchers and pharmaceutical companies to search for new therapies against this disease. These efforts resulted in several vaccines and the identification of Molnupiravir as an oral treatment for this disease. However, identifying new alternatives and critical information is necessary to fight against this devastating agent. The findings in recent years regarding the structure and biochemistry of SARS-CoV2 are remarkable. In anti-CoV drug discovery, various targets, such as structural, non-structural, and hostrelated proteins are explored. In fact, 3CL^pro is the most used among non-structural proteins since this protease cleaves peptide sequences after the glutamine residue, and no human protease has this function. This makes this macromolecule an excellent drug target for discovering new compounds. Another promising target is the transmembrane protease serine 2 (TMPRSS2). Recent studies point to TMPRSS2 as one of the main targets responsible for viral entry related to the cleavage of the S protein. Similar to cathepsins, TMPRSS2 is also responsible for cleaving the spike protein SARS-CoV2, which binds to the ACE2 receptor. Thus, TMPRSS2 is one of the targets that may represent new alternatives in treating SARS-CoV2. In this context, would discovering a multitarget inhibitor be the new strategy in searching for drugs against SARS-CoV2? For many years, new drug discovery was based on the "one drug, one target" premise, where the biological action is related to interactions with only one biological target. However, this paradigm has been overcome as new evidence of multiple mechanisms of action for a single drug. Finally, this review will present a perspective on drug design based on a multitarget strategy against 3CL^pro and TMPRSS2. We hope to provide new horizons for researchers worldwide searching for more effective drugs against this devastating agent.

Pathogenic bacteria, with their innate resistance to drugs, pose a constant threat to human health and well-being and put a persistent strain on the health care system. Development of more effective and safer novel antibacterial drugs is warranted to counter the menace unleashed by pathogenic bacteria. Integration of privileged pharmacophores from various bioactive molecules into a single template is a promising strategy to obtain new leads with unique mechanisms of action to overcome drug resistance. In the past few years, numerous isatin-based hybrid molecules were screened and their pharmacological properties were explored in efforts to develop novel therapeutics. The results of screening show that isatin conjugates exhibit promising activity against a broad range of highly pathogenic gram-positive and gram-negative bacteria and can serve as important leads in the discovery of highly potent broad spectrum antibacterial drugs. Herein, we review the antibacterial bioactive profile of a variety of hybrid isatin derivatives, including isatin–azole, isatin-quinoline/ quinolone, isatin-furan/coumarin, isatin-hydrazone/(thio)semicarbazone, isatin dimers, and isatin– indole hybrids.

Background: The prospective uses of tryptanthrin and its analogues in cancer chemotherapy are well known, and they are also predicated on their capacity to reverse drug resistance in cancer therapy. Objective: The current project entails developing a novel hybrid analogue that includes modifying the tryptanthrin molecule at the C-6 carbonyl position and is expected to exhibit substantial anticancer action. Methods: In the ATPase domain of human topoisomerase II, a series of 162 substituted Schiff base analogues of tryptanthrin were developed, and molecular docking experiments were done using Gold 5.1 software interfaced with Hermes 1.6.2. (PDB ID: 1ZXM). Results: Most of the compounds were found to have Goldscore above 100 and formed interactions with the residues like ASN91, ALA92, ASN95, ARG98, ASN120, ILE125, ILE141, PHE142, SER149, THR215, and ILE217. Compound RK-149 had highest Goldscore of 132.59, forming an interaction with ASN91 but had a lesser Goldscore as compared to the standard drug etoposide and had a better score than tryptanthrin. Conclusion: The nitrogen in the imine bond of the proposed compounds is responsible for significant interactions, demonstrating their anticancer potential.

Background: 1,3,4-oxadizole and pyrazole derivatives are very important scaffolds for medicinal chemistry. A literature survey revealed that they possess a wide spectrum of biological activities including anti-inflammatory and antitumor effects. Objectives: To describe the synthesis and evaluation of two classes of new niflumic acid (NF) derivatives, the 1,3,4-oxadizole derivatives (compounds 3 and (4A-E) and pyrazole derivatives (compounds 5 and 6), as EGFR tyrosine kinase inhibitors in silico and in vitro. Methods: The designed compounds were synthesized using conventional organic synthesis methods. The antitumor activities of the new NF derivatives against HepG2 hepatocellular carcinoma and A549 non-small cell lung cancer cell lines were assessed in vitro via MTT assay, flow cytometry, RT-PCR, as well as via molecular docking studies. Results: The cytotoxicity results indicated that the newly synthesized NF derivatives were cytotoxic against the two cancer cell lines, with compound 6 being the most cytotoxic, achieving the lowest IC50 concentration. Furthermore, compound 6 targeted EGFR tyrosine kinase leading to cell cycle arrest at the G2/M cell cycle phase and induction of apoptosis. The in vitro biological investigation results matched those of the molecular docking analysis. In conclusion, the new NF derivatives, specifically compound 6, exhibited favorable pharmacokinetic features and are promising EGFR tyrosine kinase inhibitors. Conclusion: A series of niflumic acid derivatives (3, 4A-E, 5, and 6) were successfully created, and FT-IR,^{1H, 13CNMR, and HRMS were used to confirm their chemical structures. According to molecular docking studies, compounds 3, 5, and 6 have the highest docking scores (ΔG), and most tested compounds have a good pharmacokinetic profile. Results of compound 6 in vitro antitumor activities showed that it is a promising EGFR tyrosine kinase inhibitor.}

Background: The synthesis of conjugates with nonsteroidal anti-inflammatory drugs could improve their activity with less toxicity and these compounds could be used for the treatment of cancer. Objective: The aim of the present investigation was the synthesis of 3,5-bis(dodecyloxy)benzoate - PAMAM conjugates with indomethacin and mefenamic acid to examine their anticancer activity. Methods: The anticancer activity was studied of the conjugates against six human cancer cells U- 251, PC-3, K-562, HCT-15, MCF-7, SKLU-1, and the COS-7 (as a control) cell lines. The conjugates with indomethacin and mefenamic acid were characterized by ¹H, ¹³C NMR one- and twodimension spectroscopy. Results: All the conjugates synthetized with indomethacin or mefenamic acid showed anticancer activity against all the human cancer cell lines. The first generation of indomethacin conjugates showed better activity against the PC-3 (human prostatic adenocarcinoma) cell line than the second generation. But the second generation with indomethacin showed better activity against PC-3 than the first generation. The second-generation conjugate with mefenamic acid had strong selectivity to PC-3 cells with an IC50 value of 10.23 ± 1.2 μM in vitro. Conclusion: In the paper, we report the synthesis and spectroscopic analyses of new indomethacin or mefenamic acid conjugates. The overall results showed that the conjugate of the second generation with mefenamic acid could be a potential nanocarrier for human prostatic adenocarcinoma cancer treatment, our research will be continued.

Background: In 1980, smallpox became the first viral disease eradicated through vaccination. After the termination of the Smallpox Eradication Program, the global immunization of the population also ceased. Now, most people do not have any immunity against infections caused by orthopoxviruses. Emerging cases of zoonotic orthopox infections transferring to humans inspire the search for new small organic molecules possessing antiviral activity against orthopoxviruses. Objective: Here, we present the synthesis and evaluation of antiviral activity against one of the orthopoxviruses, i.e., Vaccinia virus, of hybrid structures containing 1-hydroxyimidazole and benzopyranone moieties. Methods: Novel 2-(3-coumarinyl)-1-hydroxyimidazoles were synthesized. Their prototropic tautomerism was considered using ¹H NMR spectroscopy. Antiviral activity of both new 2-(3-coumarinyl)- 1-hydroxyimidazoles and previously described 2-(3-chromenyl)-1-hydroxyimidazoles against Vaccinia virus was evaluated in Vero cell culture. Results: Newly synthesized 2-(3-coumarinyl)-1-hydroxyimidazoles existed in CDCl3 as a mixture of prototropic tautomers (N-hydroxyimidazole and imidazole N-oxide), transition to DMSO-d6 resulting in the prevalence of N-oxide tautomer. Evaluation of cytotoxicity and antiviral activity against Vaccinia virus was performed in Vero cell culture. Compounds possessing high antiviral activity were present in both series. It was demonstrated that the structure of heterocyclic substituent in position 2 of imidazole impacted the cytotoxicity of substances under consideration. Thus, molecules containing coumarin moiety exhibited lower toxicity than similarly substituted 2-(3-chromenyl)-1- hydroxyimidazoles. Conclusion: Perspective virus inhibiting compounds possessing antiviral activity against Vaccinia virus were revealed in the series of 2-(3-coumarinyl)-1-hydroxyimidazoles.

Objective: A series of novel, substituted tetracyclic benzothiazepines were designed and prepared in an effort to optimize the potency of this chemical class against drug-resistant strains of the malaria parasite. Methods: Tetracyclic benzothiazepines bearing structural modification at seven distinct positions within the structure were synthesized in Knoevenagel condensation reactions followed by sequential intermolecular thio-Michael and then intramolecular imine formation reactions. Following purification and chemical characterization, the novel compounds were tested for in vitro efficacy against blood-stage P. falciparum and liver-stage P. berghei and also for in vivo efficacy against P. berghei. Results: Benzothiazepines bearing structural modification at the sulfur atom and at the three carbocycles within the molecule were successfully synthesized. The majority of analogs inhibited bloodstage P. falciparum with submicromolar IC50 values. The potency of an 8-methoxy-substituted analog 12 exceeded that of chloroquine in all three P. falciparum strains tested. The parent benzothiazepine 1 possessed liver-stage activity, inhibiting P. berghei sporozoites infecting HepG2 cells with an IC50 of 106.4 nM and an IC90 of 408.9 nM, but failed to enhance the longevity of P. berghei infected mice compared to the controls. Compounds displayed modest toxicity toward HepG2 cells and were tolerated by mice at the highest dose tested, 640 mg/kg/dose once daily for three days. Conclusion: The tetracyclic benzothiazepine described, which inhibits P. berghei infected hepatic cells with an IC50 of 106.4 nM, would appear to warrant further investigation. Optimization of ADME properties may be required since the most active analogs are probably excessively lipophilic.

Background: The carbonic anhydrases (CAs) which are found in most living organisms is a member of the zinc-containing metalloenzyme family. The abnormal levels and activities are frequently associated with various diseases therefore CAs have become an attractive target for the design of inhibitors or activators that can be used in the treatment of those diseases. Methods: Herein, we have designed and synthesized new benzimidazole-hydrazone derivatives to investigate the effects of these synthesized compounds on CA isoenzymes. Chemical structures of synthesized compounds were confirmed by ¹H NMR,¹³C NMR, and HRMS. The synthetic derivatives were screened for their inhibitory potential against carbonic anhydrase I and II by in vitro assay. Results: These compounds have IC50 values of 5.156-1.684 μM (hCA I) and 4.334-2.188 μM (hCA II). Inhibition types and Ki values of the compounds were determined. The Ki values of the compounds were 5.44 ± 0.14 μM-0.299 ± 0.01 μM (hCA I) and 3.699 ± 0.041 μM-1.507 ± 0.01 μM (hCA II). The synthetic compounds displayed inhibitory action comparable to that of the clinically utilized reference substance, acetazolamide. According to this, compound 3p was the most effective molecule with an IC50 value of 1.684 μM. Accordingly, the type of inhibition was noncompetitive and the Ki value was 0.299 ± 0.01 μM. Conclusion: According to the in vitro test results, detailed protein-ligand interactions of the compound 3p, which is more active against hCA I than standard azithromycin (AZM), were analyzed. In addition, the cytotoxic effects of the compounds on the L929 healthy cell line were evaluated.

Background: Cobalt is an essential trace element, but it can also rarely cause cobalt toxicity due to its release from cobalt-containing medical devices. Currently, there are no approved selective cobalt chelators, which would represent an optimal treatment modality. Objective: This study aimed to develop a simple and complex methodological approach for screening potential cobalt chelators and evaluating their potential toxicity. Methods: Firstly, a simple spectrophotometric assay employing 1-nitroso-2-naphthol-3,6- disulfonic acid disodium salt (NNDSA) for screening cobalt chelation was standardized at a pathophysiologically relevant range of pH 4.5-7.5. Then, the suitability of the method was verified using four known metal chelators (EDTA, 8-hydroxyquinoline, chloroxine and nitroxoline). As cobalt can catalyse the Fenton reaction, the potential toxicity of cobalt-chelator complexes was also determined by employing a novel HPLC method with coulometric detection. The effect on erythrocyte haemolysis was tested as well. Results: The NNDSA method had high sensitivity enabling the detection of 25-200 nM of cobalt ions depending on pH conditions. Measurements could be carried out in a wide range of wavelengths from 470 to 540 nm. All tested complexes of the selected chelators decreased the rate of the Fenton reaction. Interestingly, chloroxine mixed with cobalt ions caused marked lysis of erythrocytes in contrast to the other compounds. Conclusion: The described complex methodological approach could serve as a simple yet precise tool for evaluating novel, effective and safe cobalt chelators.