Bioisosteric ferrocenyl 1,3-thiazolidine-4-carboxylic acid derivatives: In vitro antiproliferative and antimicrobial evaluations

To improve the antiproliferative effect of ALC67 (diastereomeric mixture of ethyl 2-phenyl-3-propioloyl-1,3-thiazolidine-4-carboxylate), its structure was modified via (i) bioisosteric substitution of the phenyl ring by the ferrocene unit and (ii) replacing the propiolamide side-chain in ACL67 with other acyl groups having differing electrophilicities. In this way, a small library of methyl N-acyl-2-ferrocenyl-1,3-thiazolidine-4-carboxylates (13 compounds in total) was created and characterized by spectral and crystallographic means. The last N-acylation step was highly diastereoselective toward the cis-diastereomer. In solution, most of the obtained compounds existed as a mixture of two rotamers and displayed a preference for the syn-orientation around the CN bond. A twisted 5T4 envelope conformation was adopted by the derivative containing the N-phenoxyacetyl group in the crystalline state. Two derivatives with chloroacetyl and bromoacetyl groups in the N-3 side chain were cytotoxic to fibroblasts and hepatocellular cancer cells in the low micromolar range (IC50(MRC5) = 9.0 and 11.8 μM, respectively, and IC50(HepG2) = 10.6 and 18.4 μM, respectively) causing an effect similar to the lead compound (IC50(HepG2) = 10.0 μM) and cisplatin (IC50(MRC5) = 4.0 μM and IC50(HepG2) = 7.7 μM). Several derivatives also manifested modest antimicrobial effects against the studied microbial strains (MICs in the range from 0.44 to 4.0 μmol/mL). Our findings demonstrated that the introduction of a ferrocene core facilitated the preparation of optically pure analogs of ALC67 and that the cytotoxicity of compounds may be enhanced by adding proper electrophilic centers to the N-acyl side-chain.

α-Glucosidase and α-Amylase Inhibitory Potentials of Quinoline-1,3,4-oxadiazole Conjugates Bearing 1,2,3-Triazole with Antioxidant Activity, Kinetic Studies, and Computational Validation

Diabetes mellitus (DM) is a multifaceted metabolic disorder that remains a major threat to global health security. Sadly, the clinical relevance of available drugs is burdened with an upsurge in adverse effects; hence, inhibiting the carbohydrate-hydrolyzing enzymes α-glucosidase and α-amylase while preventing oxidative stress is deemed a practicable strategy for regulating postprandial glucose levels in DM patients. We report herein the α-glucosidase and α-amylase inhibition and antioxidant profile of quinoline hybrids 4a–t and 12a–t bearing 1,3,4-oxadiazole and 1,2,3-triazole cores, respectively. Overall, compound 4i with a bromopentyl sidechain exhibited the strongest α-glucosidase inhibition (IC₅₀ = 15.85 µM) relative to reference drug acarbose (IC₅₀ = 17.85 µM) and the best antioxidant profile in FRAP, DPPH, and NO scavenging assays. Compounds 4a and 12g also emerged as the most potent NO scavengers (IC₅₀ = 2.67 and 3.01 µM, respectively) compared to gallic acid (IC₅₀ = 728.68 µM), while notable α-glucosidase inhibition was observed for p-fluorobenzyl compound 4k (IC₅₀ = 23.69 µM) and phenyl-1,2,3-triazolyl compound 12k (IC₅₀ = 22.47 µM). Moreover, kinetic studies established the mode of α-glucosidase inhibition as non-competitive, thus classifying the quinoline hybrids as allosteric inhibitors. Molecular docking and molecular dynamics simulations then provided insights into the protein–ligand interaction profile and the stable complexation of promising hybrids at the allosteric site of α-glucosidase. These results showcase these compounds as worthy scaffolds for developing more potent α-glucosidase inhibitors with antioxidant activity for effective DM management.

Drug re-engineering and repurposing: A significant and rapid approach to tuberculosis drug discovery

The prevalence of tuberculosis (TB) remains the leading cause of death from a single infectious agent, ranking it above all other contagious diseases. The problem to tackle this disease seems to become even worse due to the outbreak of SARS-CoV-2. Further, the complications related to drug-resistant TB, prolonged treatment regimens, and synergy between TB and HIV are significant drawbacks. There are several drugs to treat TB, but there is still no rapid and accurate treatment available. Intensive research is, therefore, necessary to discover newer molecular analogs that can probably eliminate this disease within a short span. An increase in efficacy can be achieved through re-engineering old TB-drug families and repurposing known drugs. These two approaches have led to the production of newer classes of compounds with novel mechanisms to treat multidrug-resistant strains. With respect to this context, we discuss structural aspects of developing new anti-TB drugs as well as examine advances in TB drug discovery. It was found that the fluoroquinolone, oxazolidinone, and nitroimidazole classes of compounds have greater potential to be further explored for TB drug development. Most of the TB drug candidates in the clinical phase are modified versions of these classes of compounds. Therefore, here we anticipate that modification or repurposing of these classes of compounds has a higher probability to reach the clinical phase of drug development. The information provided will pave the way for researchers to design and identify newer molecular analogs for TB drug development and also broaden the scope of exploring future-generation potent, yet safer anti-TB drugs.

Quinoline-based thiazolidinone derivatives as potent cytotoxic and apoptosis-inducing agents through EGFR inhibition

Quinoline-based thiazolidinone heterocycles exhibited potent activity in the field of cancer therapy. Hence, ten quinoline-based thiazolidinone derivatives were evaluated for their anticancer activity through cytotoxic activity, epidermal growth factor receptor (EGFR) inhibition pathway, apoptosis investigation through flow cytometric analyses, RT-PCR gene expression, in vivo solid-Ehrlich carcinoma model, and finally in silico approach for highlighting the interaction pose. Results revealed that compound 7 exhibited cytotoxic activity against HCT-116 cells with an IC₅₀ value of 7.43 µM compared to 5-FU (IC₅₀  = 11.36 µM) with moderate cytotoxic activity against the FHC (IC₅₀  = 35.27 µM), and it exhibited remarkable inhibition activity of EGFR with IC₅₀ value of 96.43 nM compared to Erlotinib (IC₅₀  = 78.65 nM). Moreover, it significantly stimulated apoptotic colon cancer cell death with 171.58-fold arresting cell cycle at G2 and S-phases. Additionally, it ameliorated both biochemical and histochemical structures near normal with tumor inhibition ratio of 52.92% compared to 5-FU of 57.16%, with immunohistochemical examinations of EGFR inhibition in the treated group compared to control. Finally, molecular docking study highlighted its good binding affinity through good interactive binding pose inside the EGFR protein. In conclusion, the potent EGFR inhibitory activity of compound 7 was investigated using three integrated approaches in vitro, in vivo, and in silico, so it worth be validated and developed as a chemotherapeutic anticancer agent.

In vivo biological evaluation of sodium salt of ethyl (E)-2-cyano-3-(7-hydroxy-4-methyl-2-oxoquinoline-1(2H)-yl)-3-(4-hydroxyphenyl) acrylate as anticancer agent

Nowadays, quinoline scaffold is among the most vital construction compounds for the development of new drugs. The purpose of this research is to evaluate the anti-cancer activity of sodium salt of ethyl (E)-2-cyano-3-(7-hydroxy-4-methyl-2-oxoquinoline-1(2H)-yl)-3-(4-hydroxyphenyl) acrylate against Ehrlich ascites carcinoma (EAC) cells residing in female mice's peritoneal cavity. The docking study exhibited a favourable interaction between the compound and the receptors 1MOY and 3KJF of osteopontin and caspase 3, respectively. The compound's sodium salt showed potential antioxidant and anti-cancer effects against Ehrlich ascites carcinoma (EAC) cells in vivo. Herein, the results elucidated that treatment with the compound's sodium salt exerted significant chemopreventive and chemotherapeutic effects, which reduced both EAC cell volume and count. Our results revealed that treatment with the sodium salt of the compound demonstrated a remarkable in vivo apoptotic effect through elevation of the expression of caspase 3 and reduction of osteopontin levels. Histopathological examination confirmed that the compound's sodium salt improved liver and kidney tissues without any apparent adverse effects.

Recent Developments in Oxazole Derivatives as Anticancer Agents: Review on Synthetic Strategies, Mechanism of Action and SAR studies

BACKGROUND

Cancer is the world's third deadliest disease. Despite the availability of numerous treatments, researchers are focusing on the development of new drugs lacking resistance and toxicity issues. Many newly synthesized drugs fail to reach clinical trials due to poor pharmacokinetic properties. Therefore, there is an imperative requisite to expand novel anticancer agents with in vivo efficacy.

OBJECTIVE

This review emphasizes synthetic methods, contemporary strategies used for the inclusion of oxazole moiety, mechanistic targets along with comprehensive structure-activity relationship studies to provide perspective into the rational design of highly efficient oxazole-based anticancer drugs.

METHODS

Literature related to oxazole derivatives engaged in cancer research is reviewed. This article gives a detailed account of synthetic strategies, targets of oxazole in cancer, including STAT3, Microtubules, G-quadruplex, DNA topoisomerases, DNA damage, Protein kinases, miscellaneous targets, in vitro studies, and some SAR studies.

RESULTS

Oxazole derivatives possess potent anticancer activity by inhibiting novel targets such as STAT3 and G-quadruplex. Oxazoles also inhibit tubulin protein to induce apoptosis in cancer cells. Some other targets such as DNA topoisomerase enzyme, protein kinases, and miscellaneous targets including Cdc25, mitochondrial enzymes, HDAC, LSD1, HPV E2 TAD, NQO1, Aromatase, BCl-6, Estrogen receptor, GRP-78, and Keap-Nrf2 pathway are inhibited by oxazole derivatives Many derivatives showed excellent potencies on various cancer cell lines with IC50 values in nanomolar concentrations.

CONCLUSION

Oxazole is a five-membered heterocycle, with oxygen and nitrogen at 1 and 3 positions respectively. It is often combined with other pharmacophores in the expansion of novel anticancer drugs. In summary, oxazole is a promising entity to develop new anticancer drugs.

Recent Developments of Quinoline Derivatives and their Potential Biological Activities

Heterocyclic compounds containing the quinoline ring play a significant role in organic synthesis and therapeutic chemistry. Polyfunctionalized quinolines have attracted the attention of many research groups, especially those who work on drug discovery and development. These derivatives have been widely explored by the research biochemists and are reported to possess wide biological activities. This review focuses on the recent progress in the synthesis of heterocyclic compounds based-quinoline and their potential biological activities.