Synthesis and in vitro antiproliferative activity of new 1,3,4-oxadiazole derivatives possessing sulfonamide moiety

Nitroimidazole derivatives potentiated against tumor hypoxia: Design, synthesis, antitumor activity, molecular docking study, and QSAR study

A hypoxic environment occurs predominantly in tumors. During the growth phase of a tumor, it grows until it exceeds its blood supply, leaving regions of the tumor in which the oxygen pressure is dramatically low. They are virtually absent in normal tissues, thus creating perfect conditions for selective bioreductive therapy of tumors. To this aim, a novel series of cytotoxic radiosensitizer agents were synthesized by linking the nitroimidazole scaffold with oxadiazole or triazole rings. The majority of the compounds exhibited moderate to excellent antiproliferative activities toward HCT116 cell line under normoxic and hypoxic conditions. The structure-activity relationship study revealed that compounds containing the free thiol group either in the oxadiazoles 11a,b or the triazoles 21a,b-23a,b demonstrated the strongest antiproliferative activity, which proves that the free thiol group plays a crucial role in the antiproliferative activity of our compounds under both normoxic (half-maximal inhibitory concentration [IC50 ] = 12.50-24.39 µM) and hypoxic conditions (IC50  = 4.69-11.56 µM). Radiosensitizing assay of the four most active cytotoxic compounds 11b and 21-23b assured the capability of the compounds to enhance the sensitivity of the tumor cells to the DNA damaging activity of γ-radiation (IC50  = 2.23-5.18 µM). To further investigate if the cytotoxicity of our most active compounds was due to a specific signaling pathway, the online software SwissTargetPrediction was exploited and a molecular docking study was done that proposed cyclin-dependent kinase 2 (CDK2) enzyme to be the most promising target. The CDK2 inhibitory assay assured this assumption as five out of six compounds demonstrated a comparable inhibitory activity with roscovitine, among which compound 21b showed threefold more potent inhibitory activity in comparison with the reference compound. A further biological evaluation proved compound 21b to have an apoptotic activity and cell cycle arrest activity at the G1 and S phases. During the AutoQSAR analysis, the model demonstrated excellent regression between the predicted and experimental activity with r2  = 0.86. Subsequently, we used the model to predict the activity of the test set compounds that came with r2  = 0.95.

Novel flurbiprofen clubbed oxadiazole derivatives as potential urease inhibitors and their molecular docking study

In this study, twenty eight novel oxadiazole derivatives (5-32) of the marketed available non-steroidal anti-inflammatory drug (NSAID), (S)-flurbiprofen (1), were synthesized via I2 mediated cyclo-addition reaction in better yields. The synthesized hydrazone-Schiff bases were cyclized with iodine by using potassium hydroxide as a base in DMSO solvent to obtain oxadiazole derivatives (5-32). Structures of the synthesized products were confirmed with HR-ESI-MS, 1H-NMR spectroscopy and CHN analysis. After structure confirmations all analogs were evaluated for urease (in vitro) inhibitory activity. Amongst the series, fourteen compounds 20, 26, 30, 24, 21, 16, 28, 31, 32, 7, 19, 13, 10, and 6 were found to be excellent inhibitors of urease enzyme, having IC50 values of 12 ± 0.9 to 20 ± 0.5 μM, better than the standard thiourea (IC50 = 22 ± 2.2 μM), whereas the remaining fourteen derivatives displayed good to moderate activity. The in silico study was executed to analyse the interaction between the active site of the enzyme (urease) and the produced compounds. The docking study revealed that compounds 20, 26, 30, 24, 21, 16, 28, 31, 32, 7, 19, 13, 10, and 6 had lower docking scores than the standard compound thiourea and revealed better interactions with the urease enzyme.

Synthesis, Computational Studies, Antioxidant and Anti-Inflammatory Bio-Evaluation of 2,5-Disubstituted-1,3,4-Oxadiazole Derivatives

The 1,3,4-oxadiazole derivatives Ox-6a-f have been synthesized by incorporating flurbiprofen moiety with the aim to explore the potential of target molecules to decrease the oxidative stress. The title compounds Ox-6a-f were prepared by simple reactions in which a flurbiprofen -COOH group was esterified with methanol in an acid-catalyzed medium, which was then reacted with hydrazine to afford the corresponding hydrazide. The acid hydrazide was then cyclized into 1,3,4-oxadiazole-2-thiol by reacting with CS₂ in the presence of KOH. The title compounds Ox-6a-f were synthesized by the reaction of an -SH group with various alkyl/aryl chlorides, which involves an S-alkylation reaction. The structures of the synthesized Ox-6a-f derivatives were ascertained by spectroscopic data. The in silico molecular docking was performed against target proteins cyclooxygenase-2 COX-2 (PDBID 5KIR) and cyclooxygenase-1 COX-1 (PDBID 6Y3C) to determine the binding affinity of the synthesized compounds with these structures. It has been inferred that most of the synthesized compounds bind well with an active binding site of 5KIR compared to 6Y3C, and especially compound Ox-6f showed excellent binding affinity (7.70 kcal/mol) among all synthesized compounds Ox-6a-f. The molecular dynamic (MD) simulation has also been performed to check the stability of docking complexes of ligands with COX-2 by determining their root mean square deviation and root mean square fluctuation. Little fluctuation was observed in case of Ox-6f, which forms the most stable complex with COX-2. The comprehensive antioxidant potential of the synthesized compounds has been evaluated by determining their free radical scavenging activity, including DPPH, OH, nitric oxide (NO), and iron chelation assay. The derivative Ox-6f showed promising results with 80.23% radical scavenging potential at a dose of 100 µg/mL while ascorbic acid exhibited 87.72% inhibition at the same dose. The anti-inflammatory activity of the final products has also been performed, and inflammatory markers were assayed, such as a thiobarbituric acid-reducing substance, nitric oxide, interleukin-6 (IL-6), and COX-2. The derivatives Ox-6d and Ox-6f displayed higher anti-inflammatory activity, exhibiting 70.56% and 74.16% activity, respectively. The results were compared with standard ibuprofen, which showed 84.31% activity at the same dose, 200 µg/mL. The anti-inflammatory potential has been performed by following the carrageen-induced hind paw edema model, and results showed that derivative Ox-6f exhibited 79.83% reduction in edema volume compared to standard ibuprofen, which reduced 84.31% edema volume. As dry lab and wet lab results confirm each other, it has been deduced that derivative Ox-6f may serve as the lead structure to design potent compounds to address oxidative stress.

An Understanding of Mechanism-Based Approaches for 1,3,4-Oxadiazole Scaffolds as Cytotoxic Agents and Enzyme Inhibitors

The world's health system is plagued by cancer and a worldwide effort is underway to find new drugs to treat cancer. There has been a significant improvement in understanding the pathogenesis of cancer, but it remains one of the leading causes of death. The imperative 1,3,4-oxadiazole scaffold possesses a wide variety of biological activities, particularly for cancer treatment. In the development of novel 1,3,4-oxadiazole-based drugs, structural modifications are important to ensure high cytotoxicity towards malignant cells. These structural modification strategies have shown promising results when combined with outstanding oxadiazole scaffolds, which selectively interact with nucleic acids, enzymes, and globular proteins. A variety of mechanisms, such as the inhibition of growth factors, enzymes, and kinases, contribute to their antiproliferative effects. The activity of different 1,3,4-oxadiazole conjugates were tested on the different cell lines of different types of cancer. It is demonstrated that 1,3,4-oxadiazole hybridization with other anticancer pharmacophores have different mechanisms of action by targeting various enzymes (thymidylate synthase, HDAC, topoisomerase II, telomerase, thymidine phosphorylase) and many of the proteins that contribute to cancer cell proliferation. The focus of this review is to highlight the anticancer potential, molecular docking, and SAR studies of 1,3,4-oxadiazole derivatives by inhibiting specific cancer biological targets, such as inhibiting telomerase activity, HDAC, thymidylate synthase, and the thymidine phosphorylase enzyme. The purpose of this review is to summarize recent developments and discoveries in the field of anticancer drugs using 1,3,4-oxadiazoles.

Crystal structure and Hirshfeld surface analysis of ethyl (3E)-5-(4-fluoro-phen-yl)3-{[(4-meth-oxy-phen-yl)formamido]-imino}-7-methyl-2H,3H,5H-[1,3]thia-zolo[3,2-a]pyrimidine-6-carboxyl-ate 0.25-hydrate

In the title compound, C24H23FN4O4S·0.25H2O, the di-hydro-pyrimidine ring is distinctly non-planar, with the flap C atom deviating by 0.297 (2) Å from the least-squares plane. In the crystal, zigzag chains are formed by N-H⋯N hydrogen bonds parallel to [010] and are connected into layers parallel to (100) by O-H⋯O, O-H⋯F, C-H⋯O, C-H⋯F and C-H⋯N hydrogen bonds. Additional C-H⋯O hydrogen bonds connect the layers into a three-dimensional network. A Hirshfeld surface analysis indicates that the most significant contributions to the crystal packing are from H⋯H (42.6%), O⋯H/H⋯O (16.8%) and C⋯H/H⋯C (15.5%) contacts.

Crystal structure of 5-(adamantan-1-yl)-3-[(4-trifluoromethylanilino)methyl]-2,3-dihydro-1,3,4-oxadiazole-2-thione, C20H22F3N3OS

C20H22F3N3OS, triclinic, P1 (no. 1), a = 6.9678(8) Å, b = 10.7614(14) Å, c = 13.0503(14) Å, α = 76.870(3)°, β = 88.004(4)°, γ = 87.275(4)°, V = 951.60(19) Å3, Z = 2, R gt (F) = 0.0629, wR ref (F 2) = 0.1626, T = 100 K.

Crystal structure and Hirshfeld surface analysis of ethyl (3E)-5-(4-chloro-phen-yl)-3-{[(4-chloro-phen-yl)formamido]-imino}-7-methyl-2H,3H,5H-[1,3]thia-zolo[3,2-a]pyrimidine-6-carboxyl-ate

In the title mol-ecule, C23H20Cl2N4O3S, the thia-zole ring is planar while the pyrimidine unit fused to it adopts a screw-boat conformation. In the crystal, thick sheets parallel to the bc plane are formed by N-H⋯N, C-H⋯N and C-H⋯O hydrogen bonds together with π-π inter-actions between the formamido carbonyl groups and the thia-zole rings. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (30.9%), Cl⋯H/H⋯Cl (20.7%), C⋯H/H⋯C (16.8%) and O⋯H/H⋯O (11.4%) inter-actions.

Recent Advancements in the Development of Anti-Breast Cancer Synthetic Small Molecules

Among all cancer types, breast cancer (BC) still stands as one of the most serious diseases responsible for a large number of cancer-associated deaths among women worldwide, and diagnosed cases are increasing year by year worldwide. For a very long time, hormonal therapy, surgery, chemotherapy, and radiotherapy were used for breast cancer treatment. However, these treatment approaches are becoming progressively futile because of multidrug resistance and serious side effects. Consequently, there is a pressing demand to develop more efficient and safer agents that can fight breast cancer belligerence and inhibit cancer cell proliferation, invasion and metastasis. Currently, there is an avalanche of newly designed and synthesized molecular entities targeting multiple types of breast cancer. This review highlights several important synthesized compounds with promising anti-BC activity that are categorized according to their chemical structures.

Design, Synthesis and Pharmacological Evalution of 1,3,4-Oxadiazole Derivatives as Collapsin Response Mediator Protein 1 (CRMP 1) Inhibitors

OBJECTIVE

The series of 2-(4-Phenylamino)-N-(5-((4-nitrophenoxy)methyl) -1,3,4-oxadiazol- 2-yl)aceta-mide (5a-5e) and substituted N-(5-(Phenoxymethyl)-1,3,4-oxadiazol-2-yl)-2- (phenylamino)acetamide (5f-5i) was designed, synthesized and investigated for Collapsin Response Mediator Protein 1 (CRMP 1) inhibitors as small lung cancer.

DESIGN

Design of compounds was determined by literature review and molecular docking studies in iGEMDOCK 2.0.

MATERIALS AND METHODS

Novel 1, 3, 4 Oxadiazole derivatives were synthesized and characterized by melting point, TLC, IR Spectroscopy, Mass spectroscopy and 1H NMR. In vitro biological evaluation was performed on NCI-H2066 cell line for different concentrations 10-1000μM by telomeric repeat amplification protocol assay. The assay of telomerase in cellular extracts was modified from the PCR-based Telomeric-Repeat Amplification Protocol (TRAP), using the oligonucleotides TS and CX.

RESULTS

Novel substituted 2-(4-Phenylamino)-N-(5-((4-nitrophenoxy)methyl)-1,3,4-oxadiazol-2- yl) acetamide (5a-5e) and substituted N-(5-(Phenoxymethyl)-1,3,4-oxadiazol-2-yl)-2-(phenylamino) acetamide (5f-5i) were synthesized, and characterized using spectral and analytical data. All compounds have shown considerable % inhibition of Cell Growth with respect to Bevacizumab, but compound 5a and 5f were equipotent with respect to activity as compared to standard Bevacizumab.

CONCLUSION

Amongst the hybrids, p-nitro substituted derivative (5a) and p-chloro substituted (5f) showed the highest activity against human lung cancer cell line NCI-H2066 by TRAP assay.

Synthesis and Anticancer Evaluation of New 1,3,4-Oxadiazole Derivatives

In order to develop novel chemotherapeutic agents with potent anticancer activities, a series of new 2,5-diaryl/heteroaryl-1,3,4-oxadiazoles were designed and synthesized. The structures of the new compounds were established using elemental analyses, IR and NMR spectral data. The compounds were evaluated for their anticancer potential on two standardized human cell lines, HT-29 (colon adenocarcinoma) and MDA-MB-231 (breast adenocarcinoma). Cytotoxicity was measured by MTS assay, while cell cycle arrest and apoptosis assays were conducted using a flow cytometer, the results showing that the cell line MDA-MB-231 is more sensitive to the compounds' action. The results of the predictive studies using the PASS application and the structural similarity analysis indicated STAT3 and miR-21 as the most probable pharmacological targets for the new compounds. The promising effect of compound 3e, 2-[2-(phenylsulfanylmethyl)phenyl]-5-(4-pyridyl)-1,3,4-oxadiazole, especially on the MDA-MB-231 cell line motivates future studies to improve the anticancer profile and to reduce the toxicological risks. It is worth noting that 3e produced a low toxic effect in the D. magna 24 h assay and the predictive studies on rat acute toxicity suggest a low degree of toxic risks.

Novel Selective Histone Deacetylase 6 (HDAC6) Inhibitors: A Patent Review (2016-2019)

BACKGROUND

Many human diseases are associated with dysregulation of HDACs. HDAC6 exhibits deacetylase activity not only to histone protein but also to non-histone proteins such as α- tubulin, HSP90, cortactin, and peroxiredoxin. These unique functions of HDAC6 have gained significant attention in the medicinal chemistry community in recent years. Thus a great deal of effort has devoted to developing selective HDAC6 inhibitors for therapy with the hope to minimize the side effects caused by pan-HDAC inhibition.

OBJECTIVE

The review intends to analyze the structural feature of the scaffolds, to provide useful information for those who are interested in this field, as well as to spark the future design of the new inhibitors.

METHODS

The primary tool used for patent searching is SciFinder. All patents are retrieved from the following websites: the World Intellectual Property Organization (WIPO®), the United States Patent Trademark Office (USPTO®), Espacenet®, and Google Patents. The years of patents covered in this review are between 2016 and 2019.

RESULTS

Thirty-six patents from seventeen companies/academic institutes were classified into three categories based on the structure of ZBG: hydroxamic acid, 1,3,4-oxadiazole, and 1,2,4-oxadiazole. ZBG connects to the cap group through a linker. The cap group can tolerate different functional groups, including amide, urea, sulfonamide, sulfamide, etc. The cap group appears to modulate the selectivity of HDAC6 over other HDAC subtypes.

CONCLUSION

Selectively targeting HDAC6 over other subtypes represents two fold advantages: it maximizes the pharmacological effects and minimizes the side effects seen in pan-HDAC inhibitors. Many small molecule selective HDAC6 inhibitors have advanced to clinical studies in recent years. We anticipate the approval of selective HDAC6 inhibitors as therapeutic agents in the near future.

Synthesis and Screening of New [1,3,4]Oxadiazole, [1,2,4]Triazole, and [1,2,4]Triazolo[4,3-b][1,2,4]triazole Derivatives as Potential Antitumor Agents on the Colon Carcinoma Cell Line (HCT-116)

New derivatives of [1,3,4]oxadiazole-2-thione and triazole-3-thione were synthesized through the cyclocondensation of dicarbonyl ester 2 with phenyl hydrazine followed by hydrazinolysis to give the corresponding hydrazide, which reacted with carbon disulfide or ammonium thiocyanate to afford [1,3,4]oxadiazole 5 or triazole-3-thione 7, respectively. Hydrazinolysis of compound 5 gave [1,2,4]triazole-3-thiol 9 which was treated with different aromatic aldehydes to obtain 10a-c. Mannich bases 11a-c were obtained from the reaction of Schiff bases 10a-c with morpholine and formaldehyde. Moreover, treatment of triazole-3-thione 7 with hydrazine was followed by cyclocondensation with diethyl oxalate, chloroacetic acid, or formic acid to give the corresponding [1,2,4]triazine-3,4-dione 14, [1,2,4]triazin-4-one 15, or [1,2,4]triazolo[4,3-b][1,2,4] triazole 16, respectively. Screening of some chosen synthesized compounds against the human colon carcinoma cancer cell lines showed that the compound [1,2,4]triazole-3-thiol 9 exhibiting cytotoxic activity was roughly equivalent to standard Vinblastine, while compounds 4, 7, 10, 11a, 14, and 16 exhibited moderate cytotoxic activity.

Design and synthesis of pyrimidine-5-carbonitrile hybrids as COX-2 inhibitors: Anti-inflammatory activity, ulcerogenic liability, histopathological and docking studies

Two new series of 1,3,4-oxadiazole and coumarin derivatives based on pyrimidine-5-carbonitrile scaffold have been synthesized and evaluated for their COX-1/COX-2 inhibitory activity. Compounds 10c, 10e, 10h-j, 14e-f, 14i and 16 were found to be the most potent and selective inhibitors of COX-2 (IC₅₀ 0.041-0.081 μM, SI 139.74-321.95). Eight compounds were further investigated for their in vivo anti-inflammatory activity. The most active derivatives 10c, 10j and 14e displayed superior in vivo anti-inflammatory activity (% edema inhibition 39.3-48.3, 1 h; 58.4-60.5, 2 h; 70.8-83.2, 3 h; 78.9-89.5, 4 h) to the reference drug celecoxib (% edema inhibition 38.0, 1 h; 48.8, 2 h; 58.4, 3 h; 65.4, 4 h). These derivatives were also tested for their ulcerogenic liability, compound 10j showed better safety profile with reference to celecoxib while 10c and 14e exhibited mild lesions. Molecular docking studies of 10c, 10j, and 14e in the COX-2 active site revealed similar orientation and binding interactions as selective COX-2 inhibitors with a higher liability to access the selectivity side pocket.

Development of a novel thymidylate synthase (TS) inhibitor capable of up-regulating P53 expression and inhibiting angiogenesis in NSCLC

Introduction

The development of a new type of Thymidylate synthase (TS) inhibitor that could inhibit cancer cells' proliferation and anti-angiogenesis is of great significance for cancer's clinical treatment.

Objectives

Our research hopes to develop a TS inhibitor that is more effective than the current first-line clinical treatment of pemetrexed (PTX) and provide a new reference for the clinical treatment of non-small cell lung cancer (NSCLC).

Methods

We obtained a series of novel TS inhibitors by chemical synthesis. Moreover, TS assay and molecular docking to verify the target compound's inhibitory mode. Use MTT assay, colony-forming assay, flow cytometry, and western blot to verify the compound's inhibitory effect on cancer cell proliferation and its mechanism; and explore the compound’s effect on angiogenesis in vitro and in vivo. Further, explore the hit compound's anti-cancer ability through the xenograft tumor model and the orthotopic cancer murine model.

Results

A series of N-(3-(5-phenyl-1,3,4-oxadiazole-2-yl) phenyl)-2,4-dihydroxypyrimidine-5-sulfamide derivatives were synthesized as TS inhibitors for the first time. All target compounds significantly inhibited hTS enzyme activity and demonstrated significant antitumor activity against five cancer cell lines. Notably, 7f had a high selectivity index (SI) and unique inhibitory effects on eight NSCLC cells. In-depth research indicated that 7f could induce apoptosis by the mitochondrial pathway in A549 and PC-9 cells through the upregulation of wild-type P53 protein expression. Additionally, 7f was shown to inhibit angiogenesis in vitro and in vivo. In vivo studies, compared to PTX, 7f significantly inhibited tumor growth in A549 cell xenografts and had a higher therapeutic index (TGI). Moreover, 7f could prolong the survival of the orthotopic lung cancer murine model more effectively than PTX.

Conclusion

The anti-angiogenic effect of 7f provides a new reference for the development of TS inhibitors and the clinical treatment of NSCLC.

Zn(ii) detection and biological activity of a macrocycle containing a bis(oxadiazole)pyridine derivative as fluorophore

The synthesis, photochemical properties, biological effects and the X-ray crystal structure of a fluorescent polyamine macrocycle L are reported. L is a polyamine cyclophane macrocycle in which 2,6-bis(5-(2-methylphenyl)-1,3,4-oxadiazol-2-yl)pyridine (POXAPy) acts as a fluorescent sensor and the polyamine as a metal ion binding unit. L performs as a PET-mediated chemosensor, with a maximum emission wavelength close to 360 nm. This gives rise to a signal that is visible to the naked eye in the blue visible range. L is able to detect the Zn(ii) and Cd(ii) metal ions in an aqueous solution at pH = 7, with the coordination of the ions switching the emission ON through a CHEF effect. In contrast, paramagnetic metal ions like Cu(ii) and Ni(ii) completely quench the already low emission of L at this pH value. L affects the cell survival of a leukemic cellular model (U937) at micromolar concentrations with cell death starting after only 24 h of exposure; starting from a final concentration of 5 μM, L almost completely abrogates the survival of the leukemic cells over 72 h, with a mechanism that is compatible with a genomic DNA interaction.

Synthesis and Cytotoxic Activity of New Thiazolopyrimidine Sugar Hydrazones and Their Derived Acyclic Nucleoside Analogues

New thienyl- or chlorophenyl-substituted thiazolopyrimidine derivatives and their derived sugar hydrazones incorporating acyclic d-galactosyl or d-xylosyl sugar moieties in addition to their per-O-acetylated derivatives were synthesized. Heterocyclization of the formed sugar hydrazones afforded the derived acyclic nucleoside analogues possessing the 1,3,4-oxadiazoline as modified nucleobase via acetylation followed by the cyclization process. The cytotoxic activity of the synthesized compounds was studied against human breast cancer MCF7 and MDA-MB-231 cell lines as well as human colorectal cancer HCT 116 and Caco-2 cell lines. High activities were revealed by compounds 1, 8, 10, 11, and 13 against Caco-2 and MCF7 cells in addition to moderate activities exhibited by other compounds against HCT116 or MDA-MB-231 cells.

1,2,3-Triazole-Chalcone hybrids: Synthesis, in vitro cytotoxic activity and mechanistic investigation of apoptosis induction in multiple myeloma RPMI-8226

A new series of 1,2,3-triazole-chalcone hybrids has been synthesized and screened in vitro against a panel of 60 human cancer cell lines according to NCI (USA) protocol. Compound 4d having 3, 4-dimethoxyphenyl chalcone moiety, the most potent derivative, inhibited the growth of RPMI-8226 and SR leukemia cell lines by 99.73% and 94.95% at 10 μM, respectively. Also, it inhibited the growth of M14 melanoma, K-562 leukemia, and MCF7 breast cancer cell lines by more than 80% at the same test concentration. 4d showed IC₅₀ values less than 1 μM on six types of tumor cells and high selectivity index reached to 104 fold on MCF7. Compound 4d showed superior activity than methotrexate and gefitinib against the most sensitive leukemia cell lines in addition to higher or comparable activity against the rest sensitive cell lines. Flow cytometry analysis in RPMI-8226 cells revealed that compound 4d caused cell cycle arrest at G2/M phase and induced apoptosis in a dose dependant manner. Mechanistic evaluation referred this apoptosis induction to triggering mitochondrial apoptotic pathway through inducing ROS accumulation, increasing Bax/Bcl-2 ratio and activation of caspases 3, 7 and 9.

Synthesis and anti-H5N1 virus activity of triazole- and oxadiazole-pyrimidine hybrids and their nucleoside analogs

New 1,2,3-triazole glycosides and 1,2,4-thioglycosides incorporating a substituted pyrimidinedione ring system were synthesized via click dipolar cycloaddition and heterocyclization of hydrazine-1-carbodithioate derivatives, respectively. The sugar hydrazine derivatives linked aminodimethyluracil were also prepared. In addition, the oxadiazoline substituted with acyclic sugar moieties linked to the pyrimidinedione as acyclic nucleoside analogs were synthesized. The antiviral activity of the synthesized compounds against avian influenza H5N1 virus was investigated and compounds 18, 13 and 19 showed good activities against the virus strains.

Benzo[d]imidazol-5-yl)-5-(substituted)-1,3,4-Oxadiazoles: Synthesis, Anticancer, Antimicrobial and In Silico Studies

Background:

Cancer is a fatal disease for mankind; continuous research is still going on for the invention of potent anticancer drugs. In this view, 1, 3, 4-Oxadiazoles are privileged molecules which attracted medicinal chemists towards their anticancer properties.

Methods:

A new series of benzo[d]imidazol-5-yl)-5-(substituted)-1,3,4-oxadiazole derivatives was synthesized in an efficient ‘one-pot’ nitro reductive cyclization using sodium dithionite as a cyclizing agent by a conventional method with good yield. All the structures of the synthesized molecules were characterized by IR, 1H NMR, HRMS and Mass spectral analysis. Anticancer activity screening against A375 melanoma cancer cell line and MDA-MB-231 breast cancer cell line along with antimicrobial activity were carried out using agar well diffusion method.

Results:

Compounds 8a and 8j of the series emerged as potent anticancer agents against A375 melanoma cancer cell line with IC50 47.06 µM and 36.76 µM, respectively. In silico studies also revealed that compounds 8a and 8j showed highest interaction with 2OH4 protein of VEGFR-2 tyrosine kinase. Substantial antibacterial and antifungal activities against the tested microorganism were observed for compounds 8j and 8g.

Conclusion:

Potent anticancer property has been observed with 1,3,4-Oxadiazole linked tetrafluro substituted benzene ring 8j indicating that future research on these type of molecules can be continued to improve the anticancer activity.

Synthesis and Anticancer Activity of New ((Furan-2-yl)-1,3,4-thiadiazolyl)-1,3,4-oxadiazole Acyclic Sugar Derivatives

New sugar hydrazones incorporating furan and/or 1,3,4-thiadiazole ring systems were synthesized by reaction of the corresponding hydrazide with different aldose sugars. Heterocyclization of the formed hydrazones afforded the derived acyclic nucleoside analogues possessing the 1,3,4-oxadiazoline as modified nucleobase via acetylation followed by the heterocyclization process. The anticancer activity of the synthesized compounds was studied against human liver carcinoma cell (HepG-2) and at human normal retina pigmented epithelium cells (RPE-1). High activities were revealed by compounds 3, 12 and 14 with IC₅₀ values near to that of the reference drug doxorubicin.

Recent Development on Importance of Heterocyclic Amides as Potential Bioactive Molecules: A Review

Background:

Heterocyclic compounds are an integral part of the chemical and life sciences and constitute a considerable quantum of the modern research that is being currently pursued throughout the world.

Methods:

This review was prepared by collecting the available literature reports on various databases and an extract was prepared for each report after thorough study and compiling the recent literature reports on heterocyclic amides from 2007 to 2018.

Results:

This review summarizes the bio-potential of heterocyclic amides as antimicrobial, anticancer, anti-tubercular and antimalarial agents which would be very promising in the field of medicinal chemistry.

Conclusion:

A wide variety of heterocyclic amides have already been reported and some are currently being used as active medicaments for the treatment of disease. Still, the research groups are focusing on the development of newer heterocyclic amide derivatives with better efficacy, potency and lesser side effects. This area has got the tremendous potential to come up with new chemical entities of medicinal importance.

Synthesis and docking studies of N-(5-(alkylthio)-1,3,4-oxadiazol-2-yl)methyl)benzamide analogues as potential alkaline phosphatase inhibitors

A series of N-(5-(alkylthio)-1,3,4-oxadiazol-2-yl)methyl)benzamides 6a-i were synthesized as alkaline phosphatase inhibitors. The intermediate 5-substituted 1,3,4-oxadiazole-2-thione 4 was synthesized starting with hippuric acid. Hippuric acid in the first step was converted into corresponding methyl ester 2 which upon reaction with hydrazine hydrate furnished the formation of hydrazide 3. The hippuric acid hydrazide was then cyclized into 5-substituted 1,3,4-oxadiazole-2-thione 4. The intermediate 4 was then reacted with alkyl or aryl halides 5a-5i to afford the title compounds N-(5-(methylthio)-1,3,4-oxadiazol-2-yl)methyl)benzamides 6a-i. The bioassay results showed that compounds 6a-i exhibited good to excellent alkaline phosphatase inhibitory activity. The most potent activity was exhibited by the compound 6i having IC₅₀ value 0.420 μM, whereas IC₅₀ value of standard (KH₂ PO₄ ) was 2.80 μM. Molecular docking studies was performed against alkaline phosphatase enzyme (PDBID 1EW2) to check binding affinity of the synthesized compounds 6a-i against target protein. The docking results showed that three compounds 6c, 6e, and 6i have maximum binding interactions with binding energy values of -8 kcal/mol. The compound 6i displayed the interactions of oxadiazole ring nitrogen with amino acid His265 having a binding distance 2.13 Ǻ. It was concluded from our results that synthesized compounds, especially compound 6i may serve as lead structure to design more potent inhibitors of human alkaline phosphatase.

A Review Exploring Therapeutic Worth of 1,3,4-Oxadiazole Tailored Compounds

1,3,4-Oxadiazole, a five-membered aromatic ring can be seen in a number of synthetic molecules. The peculiar structural feature of 1,3,4-oxadiazole ring with pyridine type of nitrogen atom is beneficial for 1,3,4-oxadiazole derivatives to have effective binding with different enzymes and receptors in biological systems through numerous weak interactions, thereby eliciting an array of bioactivities. Research in the area of development of 1,3,4-oxadiazole-based derivatives has become an interesting topic for the scientists. A number of 1,3,4-oxadiazole based compounds with high therapeutic potency are being extensively used for the treatment of different ailments, contributing to enormous development value. This work provides a systematic and comprehensive review highlighting current developments of 1,3,4-oxadiazole based compounds in the entire range of medicinal chemistry such as anticancer, antifungal, antibacterial, antitubercular, anti-inflammatory, antineuropathic, antihypertensive, antihistaminic, antiparasitic, antiobesity, antiviral, and other medicinal agents. It is believed that this review will be of great help for new thoughts in the pursuit for rational designs for the development of more active and less toxic 1,3,4-oxadiazole based medicinal agents.

Anti-Cancer Activity of Derivatives of 1,3,4-Oxadiazole

Compounds containing 1,3,4-oxadiazole ring in their structure are characterised by multidirectional biological activity. Their anti-proliferative effects associated with various mechanisms, such as inhibition of growth factors, enzymes, kinases and others, deserve attention. The activity of these compounds was tested on cell lines of various cancers. In most publications, the most active derivatives of 1,3,4-oxadiazole exceeded the effect of reference drugs, so they may become the main new anti-cancer drugs in the future.

Design, synthesis, in vitro anticancer evaluation, kinase inhibitory effects, and pharmacokinetic profile of new 1,3,4-triarylpyrazole derivatives possessing terminal sulfonamide moiety

The present work describes the design and synthesis of a novel series of 1,3-diaryl-4-sulfonamidoarylpyrazole derivatives 1a–q and 2a–q and their in vitro biological activities. The target compounds were evaluated for antiproliferative activity against NCI-60 cell line panel. Compounds 1c, 1g, 1k–m, 1o, 2g, 2h, 2k–m, 2o, and 2q showed the highest mean inhibition percentages at 10 µM single-dose testing and were selected to be tested at 5-dose mode. The ICs₅₀ of the most potent compounds were determined over the 60 cell lines. Compound 2l exhibited the strongest activity against different cell lines with IC₅₀ 0.33 µM against A498 renal cancer cell line. Compound 2l was tested over a panel of 20 kinases to determine its molecular target(s), and its IC₅₀ values over the most sensitive kinases were defined. In vitro stability and in vivo pharmacokinetic profile of compound 2l was also investigated.

Evaluation of WO2017018805: 1,3,4-oxadiazole sulfamide derivatives as selective HDAC6 inhibitors

INTRODUCTION

There are great potential in the development of selective HDAC6 inhibitors for the treatment of infectious diseases, neoplasms, endocrine diseases, and other diseases associated with HDAC6 activity. Areas covered: The application claims 1,3,4-oxadiazole sulfamide derivatives as selective HDAC6 inhibitors for the treatment of infectious diseases, neoplasms, endocrine, nutritional, and metabolic diseases; mental and behavioral disorders; neurological diseases; diseases of the eye and adnexa; cardiovascular diseases; respiratory diseases; digestive diseases; diseases of the skin and subcutaneous tissue; disease of the musculoskeletal system and connective tissue; or congenital malformations, deformations and chromosomal abnormalities. Many of the exemplified compounds showed nanomole potency against HDAC6 and were more than 5000-fold selectivity for HDAC6 over HDAC1. Expert opinion: These 1,3,4-oxadiazole sulfamide derivatives have a unique zinc-binding group (ZBG) that provide good leads for the discovery of potent selective HDAC6 inhibitors for the treatment of a variety of diseases associated with HDAC6 activity.

Synthesis and anticancer activity of new [(Indolyl)pyrazolyl]-1,3,4-oxadiazole thioglycosides and acyclic nucleoside analogs

New [(Indolyl)pyrazolyl]-1,3,4-oxadiazole compounds and their derived thioglycosides as well as the corresponding sugar hydrazones were synthesized. The acyclo C-nucleoside analogs of the oxadiazoline base system were also prepared by reaction of acid hydrazides with aldehydo sugars followed by one pot process encompassing acetylation and cyclization of the synthesized hydrazones. The anticancer activity of the newly synthesized compounds was studied against colorectal carcinoma (HCT116), breast adenocarcinoma (MCF7) and prostate cancer (PC3) human tumor cell lines and a number of compounds showed moderate to high activities.

Experimental (FT-IR, Laser-Raman and NMR) and theoretical spectroscopic analysis of 3-[(N-methylanilino)methyl]-5-(thiophen-2-yl)-1,3,4-oxadiazole-2(3H)-thione

The structure of a potential bioactive agent namely, 3-[([Formula: see text]-methylanilino)methyl]-5-(thiophen-2-yl)-1,3,4-oxadiazole-2(3[Formula: see text]-thione was characterized by proton and carbon-13 nuclear magnetic resonance (NMR) chemical shifts, Fourier transform infrared (FT-IR) and Laser-Raman spectroscopic techniques. The quantum chemical computations of molecular structures (disorder I and disorder II forms), vibrational wavenumbers, carbon-13 and proton chemical shifts and UV-Vis spectroscopic parameters have been performed with DFT/B3LYP method at 6-311[Formula: see text]G(d,p) basis set. The highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), nonlinear optical (NLO) properties and natural bond orbital (NBO) analyses have been theoretically examined with the mentioned calculation level. The calculated values have been compared with the recorded experimental data. The computed molecular geometric parameters, vibrational wavenumbers, NMR chemical shifts, and UV-Vis wavelengths have been found to be in a good harmony with the experimental values and spectral results of similar structures in the literature. We believe that the work will be of considerable interest to anyone working in the area of theoretical chemistry, whether in industry or academics.

Crystal structure of 2-[3,5-bis(trifluoromethyl)benzylsulfanyl]-5-(5-bromothiophen-2-yl)-1,3,4-oxadiazole, C15H7BrF6N2OS2

C15H7BrF6N2OS2, monoclinic, P21/c (no. 14), a = 18.8292(14) Å, b = 11.4568(9) Å, c = 8.3400(6) Å, β = 90.791(3)°, V = 1799.0(2) Å3, Z = 4, R gt(F) = 0.068, wR ref(F 2) = 0.199, T = 296(2).