Synthesis and biological evaluation of 1,2,4-oxadiazole linked 1,3,4-oxadiazole derivatives as tubulin binding agents

Design, synthesis, in silico and biological evaluation of new indole based oxadiazole derivatives targeting estrogen receptor alpha

A series of new indole-oxadiazole derivatives was designed and synthesized to develop potential anti-breast cancer agents. The compounds exhibited significant inhibitory activity with IC50 values ranging from 1.78 to 19.74 μM against ER-positive human breast cancer (BC) cell lines T-47D and MCF-7. Among them, compounds (5a, 5c, 5e-5h, 5j-5o) displayed superior activity against ER-α dominant (ratio of ER-α/ER-β is 9/1) T-47D cells compared to the standard drug bazedoxifene (IC50 = 12.78 ± 0.92 μM). Compounds 5c and 5o exhibited remarkable anti-proliferative activity with IC50 values of 3.24 ± 0.46 and 1.72 ± 1.67 μM against T-47D cells, respectively. Further, compound 5o manifested 1589-fold higher ER-α binding affinity (213.4 pM) relative to bazedoxifene (339.2 nM) in a competitive ER-α binding assay, while compound 5c showed a binding affinity of 446.6 nM. The Western blot analysis proved that both compounds influenced the ER-α protein's expression, impeding its subsequent transactivation and signalling pathway within T-47D cells. Additionally, a molecular docking study suggests that compounds 5c and 5o bind in such a fashion that induces conformational changes in the protein, culminating in their antagonistic effect. Also, pharmacokinetic profiles showed that all compounds have drug-like properties. Further, molecular dynamic (MD) simulations and density functional theory (DFT) analysis confirmed the stability, conformational behaviour, reactivity, and biological feasibility of compounds 5c and 5o. In conclusion, based on our findings, compounds 5c and 5o, which exhibit significant ER-α antagonistic activity, can act as potential lead compounds for developing anti-breast cancer agents.

Unveiling the chemistry of 1,3,4-oxadiazoles and thiadiazols: A comprehensive review

Oxadiazoles and thiadiazoles are malleable heterocycles that have recently generated major interest in the field of medicinal chemistry. Compounds based on these moieties have versatile biological applications such as anticonvulsant, anticancer, antidiabetic, and antioxidant agents. Due to the versatile nature and stability of the oxadiazole and thiadiazole nucleus, medicinal chemists have changed the structural elements of the ring in numerous ways. These compounds have shown significant anticonvulsant effects, demonstrating their potential in the management of epileptic disorders. In this review, we have covered numerous biological pathways and in silico targeted proteins of oxadiazole and thiadiazole derivatives for treating various biological disorders. The data compiled in this article will be helpful for researchers, research scientists, and research chemists who work in the field of drug discovery and drug development.

Design and synthesis of 4-aminophenol-1,3,4-oxadiazole derivative potentiates apoptosis by targeting MAP kinase in triple negative breast cancer cells

Women below 40 years greatly suffer from triple negative breast cancers (TNBCs). Compared to other breast cancer cases, the poor prognosis and lower survival rate of TNBC patients make it an alarming task to save the human era from this dreadful disease. Therefore, identifying potential novel leads is urgently required to combat the TNBC. To discover a novel anticancer agent, we synthesized a series of novel 4-aminophenolbenzamide-1,3,4 oxadiazole hybrid analogues (7a-l). The structure of the compounds was confirmed by spectral methods (1H & 13C NMR, IR and MS). All the compounds were subjected to their in-silico and in-vitro antiproliferative studies against the TNBC cell lines MDA-MB-468 and MDA-MB-231. The investigations revealed that 7i has significantly promoted apoptosis against MDA-MB-468 and MDA-MB-231 cells with IC50 values of 16.89 and 19.43 µM, respectively. Molecular docking of 7i, with MAPK has exhibited the highest binding score of -7.10 kcal/mol by interacting with crucial amino acids present at the active sites. Molecular docking is further validated with molecular dynamic studies with simulation for 100 ns, depicting various stable interactions with MAPK. Compound 7i, forms stable H-bonds and π-π stacking with amino acid residues. Molecular dynamic simulation (MDS) reveals that hydrophobic and water bridges were very prominent for 7i to bind, with the amino acid residues in close proximity to the active site of p38 MAPK. The investigations show that the In-vitro antiproliferative study of 7i agreed with the in-silico studies. Collectively, our investigations depict 7i as a potent novel lead for the inhibition of TNBCs by targeting p38 MAPK.Communicated by Ramaswamy H. Sarma.

Identification of 1,3,4-oxadiazoles as tubulin-targeted anticancer agents: a combined field-based 3D-QSAR, pharmacophore model-based virtual screening, molecular docking, molecular dynamics simulation, and density functional theory calculation approach

Cancer is one of the most prominent causes of death worldwide and tubulin is a crucial protein of cytoskeleton that maintains essential cellular functions including cell division as well as cell signalling, that makes an attractive drug target for cancer drug development. 1,3,4-oxadiazoles disrupt microtubule causing G2-M phase cell cycle arrest and provide anti-proliferative effect. In this study, field-based 3D-QSAR models were developed using 62 bioactive anti-tubulin 1,3,4-oxadiazoles. The best model characterized by PLS factor 7 was rigorously validated using various statistical parameters. Generated 3D-QSAR model having high degree of confidence showed favourable and unfavourable contours around 1,3,4-oxadiazole core that assisted in defining proper spatial positioning of desired functional groups for better bioactivity. A five featured pharmacophore model (AAHHR_1) was developed using same ligand library and validated through enrichment analysis (BEDROC160.9 value = 0.59, Average EF 1% = 27.05, and AUC = 0.74). Total 30,212 derivatives of 1,3,4-oxadiazole obtained from PubChem database was prefiltered through validated pharmacophore model and docked in XP mode on binding cavity of tubulin protein (PDB code: 1SA0) which led into the identification of 11 HITs having docking scores between -7.530 and -9.719 kcal/mol while the reference compound Colchicine exerted docking score of -7.046 kcal/mol. Following the analysis of MM-GBSA and ADME studies, HIT1 and HIT4 emerged as the two promising hits. To verify their thermodynamic stability at the target site, molecular dynamic simulations were carried out. Both HITs were further subjected to DFT analysis to determine their HOMO-LUMO energy gap for ensuring their biological feasibility. Finally, molecular docking based structural exploration for 1,3,4-oxadiazoles to set up a lead of Formula I for further advancements of tubulin polymerization inhibitors as anti-cancer agents.Communicated by Ramaswamy H. Sarma.

Cytotoxic Activity and Docking Studies of 2-arenoxybenzaldehyde N-acyl Hydrazone and 1,3,4-Oxadiazole Derivatives against Various Cancer Cell Lines

To understand whether previously synthesized novel hydrazone and oxadiazole derivatives have promising anticancer effects, docking studies and in vitro toxicity assays were performed on A-549, MDA-MB-231, and PC-3 cell lines. The antiproliferative properties of the compounds were investigated using molecular docking experiments. Each compound's best-docked poses, binding affinity, and receptor-ligand interaction were evaluated. Compounds' molecular weights, logPs, TPSAs, abilities to pass the blood-brain barrier, GI absorption qualities, and CYPP450 inhibition have been given. When the activities of these molecules were examined in vitro, for the A-549 cell line, hydrazone 1e had the minimum IC50 value of 13.39 μM. For the MDA-MB-231 cell line, oxadiazole 2l demonstrated the lowest IC50 value, with 22.73 μM. For PC-3, hydrazone 1d showed the lowest C50 value of 9.38 μM. The three most promising compounds were determined as compounds 1e, 1d, and 2a based on their minimum IC50 values, and an additional scratch assay was performed for A-549 and MDA-MB-231 cells, which have high migration capacity, for the three most potent molecules; it was determined that these molecules did not show a significant antimetastatic effect.

Design, Synthesis and Cytotoxicity Evalufation of Substituted Benzimidazole Conjugated 1,3,4-Oxadiazoles

Two series of 2-substituted benzimidazole conjugated 1,3,4-oxadiazole derivatives were designed, synthesized and evaluated for their cytotoxic activities against the three human cancer cell lines (cervical cancer (HeLa), breast cancer (MCF-7) and lung cancer (A549)). As the results 14 compounds demonstrated consistent to stronger cytotoxicities compared to the control 5-fluorouracil (5-FU) towards the tested cell lines including 4c (HeLa); 4b, 4e, 4h, 7i-j, 7m-n, 7s (MCF-7); 7b (MCF-7, A549); 7h (HeLa, MCF-7); and 4d, 4i, 7c (HeLa, MCF-7, A549), with the IC₅₀ ranging from 2.7 to 38 µM. Notably, compound 4b illustrated almost 5-fold activity against the MCF-7 while 4d, 4i were 9- and 8-fold (HeLa), 4.5- and 13-fold (MCF-7), 4.7- and 4-fold (A549) increase in activity compared to 5-FU, respectively, and were found as lead compounds. These findings suggest that compounds 4b, 4d and 4i merit further characterization and can serve as promising scaffolds in the discovery of new potent anticancer agents.

Therapeutic potential of oxadiazole or furadiazole containing compounds

As we know that, Oxadiazole or furadi azole ring containing derivatives are an important class of heterocyclic compounds. A heterocyclic five-membered ring that possesses two carbons, one oxygen atom, two nitrogen atoms, and two double bonds is known as oxadiazole. They are derived from furan by the replacement of two methylene groups (= CH) with two nitrogen (-N =) atoms. The aromaticity was reduced with the replacement of these groups in the furan ring to such an extent that it shows conjugated diene character. Four different known isomers of oxadiazole were existed such as 1,2,4-oxadiazole, 1,2,3-oxadiazole, 1,2,5-oxadiazole & 1,3,4-oxadiazole. Among them, 1,3,4-oxadiazoles & 1,2,4-oxadiazoles are better known and more widely studied by the researchers due to their broad range of chemical and biological properties. 1,3,4-oxadiazoles have become important synthons in the development of new drugs. The derivatives of the oxadiazole nucleus (1,3,4-oxadiazoles) show various biological activities such as antibacterial, anti-mycobacterial, antitumor, anti-viral and antioxidant activity, etc. as reported in the literature. There are different examples of commercially available drugs which consist of 1,3,4-oxadiazole ring such as nitrofuran derivative (Furamizole) which has strong antibacterial activity, Raltegravir as an antiviral drug and Nesapidil drug is used in anti-arrhythmic therapy. This present review summarized some pharmacological activities and various kinds of synthetic routes for 2, 5-disubstituted 1,3,4-oxadiazole, and their derived products.

Groundbreaking Anticancer Activity of Highly Diversified Oxadiazole Scaffolds

Nowadays, an increasing number of heterocyclic-based drugs found application in medicinal chemistry and, in particular, as anticancer agents. In this context, oxadiazoles—five-membered aromatic rings—emerged for their interesting biological properties. Modification of oxadiazole scaffolds represents a valid strategy to increase their anticancer activity, especially on 1,2,4 and 1,3,4 regioisomers. In the last years, an increasing number of oxadiazole derivatives, with remarkable cytotoxicity for several tumor lines, were identified. Structural modifications, that ensure higher cytotoxicity towards malignant cells, represent a solid starting point in the development of novel oxadiazole-based drugs. To increase the specificity of this strategy, outstanding oxadiazole scaffolds have been designed to selectively interact with biological targets, including enzymes, globular proteins, and nucleic acids, showing more promising antitumor effects. In the present work, we aim to provide a comprehensive overview of the anticancer activity of these heterocycles, describing their effect on different targets and highlighting how their structural versatility has been exploited to modulate their biological properties.

Novel 1,2,4-Oxadiazole Derivatives in Drug Discovery

Five-membered 1,2,4-oxadiazole heterocyclic ring has received considerable attentionbecause of its unique bioisosteric properties and an unusually wide spectrum of biological activities.Thus, it is a perfect framework for the novel drug development. After a century since the1,2,4-oxadiazole have been discovered, the uncommon potential attracted medicinal chemists'attention, leading to the discovery of a few presently accessible drugs containing 1,2,4-oxadiazoleunit. It is worth noting that the interest in a 1,2,4-oxadiazoles' biological application has been doubledin the last fifteen years. Herein, after a concise historical introduction, we present a comprehensiveoverview of the recent achievements in the synthesis of 1,2,4-oxadiazole-based compounds and themajor advances in their biological applications in the period of the last five years as well as briefremarks on prospects for further development.