Pharmacokinetic evaluation,molecular docking and in vitro biological evaluation of 1,3,4-oxadiazole derivatives as potent antioxidants and STAT3 inhibitors

1, 3, 4-Oxadiazole derivatives(4 a–5 f) were previously synthesized to investigate their anticancer properties.However, studies relating to their antioxidant potential and signal transducer and activator of transcription(STAT) inhibition have not been performed. We investigated previously synthesized 1, 3, 4-oxadiazole derivatives(4 a–5 f) for various radical scavenging properties using several in vitro antioxidant assays and also for direct inhibition of STAT3 through molecular docking. The data obtained from various antioxidant assays such as 2, 2,-diphenyl-1-picrylhydrazyl radical(DPPH), nitric oxide, hydrogen peroxide, and superoxide anion radical revealed that among all the derivatives, compound 5 e displayed high antioxidant activities than the standard antioxidant L-ascorbic acid. Additionally, the total reduction assay and antioxidant capacity assay further confirmed the antioxidant potential of compound 5 e. Furthermore, the molecular docking studies performed for all derivatives along with the standard inhibitor STX-0119 showed that binding energy released in direct binding with the SH2 domain of STAT3 was the highest for compound 5 e(-9.91 kcal/mol).Through virtual screening, compound 5 e was found to exhibit optimum competency in inhibiting STAT3 activity. Compound 5 e decreased the activation of STAT3 as observed with Western blot. In brief, compound5 e was identified as a potent antioxidant agent and STAT3 inhibitor and effective agent for cancer treatment.

SYNTHESIS OF DERIVATIVES OF 3-β-D-XYLOPYRANOSYL-1,2,4-OXADIAZOLES

The synthesis of derivatives of 3-β-D-xylopyranosyl-1,2,4-oxadiazoles is accomplished by condensing protected β-D-xylopyranosyl amidoxime with acid anhydrides or various substituted benzoyl chlorides in good yield.The structures of now derivatives were identified by spectra and elemental analysis. The stability of 1,2,4-oxadiazole ring and mechanism of cyclization were. investigated.

Synthesis and Fungicidal Activities of 2-Alkylthio-5-(3,4,5-tribenzyloxyphenyl)-1,3,4-oxadiazoles

Abstract： Ten novel 2-alkylthio-5-（3, 4, 5-tribenzyloxyphenyl）-1, 3, 4-oxadiazole derivatives （5a-j） were synthesized from methyl 3, 4, 5-trihydroxybenzoate by ethedfication, hydrazidation, cyclization and thioetherification reactions. The structures of 5a-j were confirmed by 1HNMR, MS spectra and elemental analysis. The results indicated that most of the compounds 5 exhibited good fungicidal activities. The activity of 5h is higher than 90% against Fusarium oxysporum and Botrytis cinereapers in 50 mg/L.

Structure and Biological Activities of Novel Triazole Compounds Containing 1,3,4-Oxadiazole Ring

Eighteen novel triazole compounds containing 1,3,4-oxadiazole groups were synthesized from 2-（1H-1,2,4-triazol-1-yl）acetohydrazide and carbon disulfide by several step reactions. The target compounds were characterized by elemental analysis, 1H NMR, 13C NMR, IR, MS, and X-ray crystallography. The results of preliminary biological tests show that all the compounds exhibit certain fungicidal activities.

Solvent-free synthesis of some new 2-(3,5-dimethoxy-4-methylphenyl)-5-aryl-1,3,4-oxadiazoles

An expeditious microwave-accelerated one-step synthesis of some new 2-（3,5-dimethoxy-4-methylphenyl）-5-aryl-1,3,4- oxadiazoles by reaction of 3,5-dimethoxy-4-methyl hydrazide with different carboxylic acids in presence of thionyl chloride under neat conditions,has been achieved.

Synthesis of 5,7-Dimethyl-2-(5-Substituted-1,3,4-Oxadiazole-2-yl)- Methylenethio-1,2,4-Triazolo[1,5-a]Pyrimidines as Potential Fungicides

A series of diheterocyclic compounds containing 1,2,4-triazolo [1,5-a]pyrimidine and 1, 3,4-oxadiazole were designed and synthesized starting from 2-mercapto-5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine. The structure of all compounds prepared were confirmed by H-1 NMR spectroscopy and elemental analysis. The preliminary bioassay indicated that the title compounds displayed good fungicidal activity against Rhizoctonia solani.

1,3,4-Oxadiazole as an emerging telomerase inhibitor-a promising anticancer motif

Currently,cancer is the most rapidly growing life-threatening disease after cardiovascular in the world,posing a major threat to human life.Telomerase promotes tumorigenesis and development in most cancers and dyskerin plays a crucial role in telomere maintenance.Cancer molecules are being developed continuously as a result of continuous research.A series of novel anticancer agents have been developed using telomerase inhibitors with improved specificity and pharmacokinetics.As medicinal chemistry advances,heterocyclic-based drugs find increasing applications,including anticancer agents.These properties have led to the development of five-membered aromatic rings of oxadiazoles.In order to enhance their anticancer activity,oxadiazole scaffolds can be modified.In this review,we discuss the functions and mechanism of action of the telomerase enzyme.The paper also summarizes the interaction between 1,3,4-oxadiazole inhibitors and telomerase enzymes.

Synthesis and antitumor activity of N^1-acetylamino-(5-alkyl/aryl-1,3,4-thiadiazole-2-yl)-5-fluorouracil derivatives

A new series of N^1-acetylamino-（5-alkyl/aryl- 1,3,4-thiadiazole-2-yl）-5-fluorouracil derivatives were designed and synthesized. These compounds have not been reported in literature, and their structure chemical were confirmed by IR, ^1H NMR and MS （HRMS）. The results of antitumor inhibitory activity test showed that some compounds possess more potent antitumor inhibitory activity than 5-fluorouracil.

A mild and facile method for one pot synthesis of 2,5-di-substituted 1,3,4-oxadiazoles at room temperature

2,5-Di-substituted 1,3,4-oxadiazoles 3a-n have been synthesized as a one pot procedure from the reaction of acid hydrazide 1, acyl halides 2 and phosphorus pentoxide in acetonitrile at room temperature. High yield, short reaction time （10-15 min）, mild condition, and easy work-up are advantages of this methodology.

An expeditious and one-pot synthesis of unsymmetrical 2,5-disubstituted-1,3,4-oxadiazoles under microwave irradiation and solvent-free conditions

A one-pot synthesis of some unsymmetrical 2,5-disubstituted-1,3,4-oxadiazoles via cyclocondensation of benzoylhydrazines with orthoesters under solvent-free and microwave conditions are described here. The reaction is efficiently catalyzed by silica- supported sulfuric acid as it provided the title compounds in high yields and relatively short times. The catalyst is reusable and can be applied several times without considerable decrease in the yields and rates of the reactions.

一种新型的以三键为桥含1,3,4-Oxadiazole杂环的弯折型有机配体的合成及其结构表征

有机配体的结构及功能是合成具有新奇结构及物化性质的有机-无机配位聚合物的关键。我们通过Sonogashira-Hagihara偶合反应合成一种以三键为桥的含1,3,4-Oxadiazole杂环的纳米级的角型有机配体,并通过红外和1 HNMR表征了它们的结构。

THERMALLY STABLE POLYMERS BASED ON 1,3,4-OXADIAZOLE RINGS

In the present work, new thermally stable polymers containing 1,3,4-oxadiazole units have been synthesized through Huisgen reaction of the aromatic bis-tetrazole compounds with the aromatic/aliphatic bis-acid chlorides in pyridine as solvent. The obtained polymers are insoluble or slightly soluble in polar aprotic solvents such as DMSO and DMF. Thermal analyses of the polymers using DSC and TGA techniques showed that the polymers had improved thermal stabilities. The model reaction was also investigated and the resulting bis-1,3,4-oxadiazole compounds were characterized by conventional spectroscopic methods.

Studies on Amidothiosemicarbazides and Related Hcterocyclic Derivatives ( XIII) --Synthetic Studies on 2-(3-Pyridyl)-5-Arylamino- 1,3, 4-Thiadiazoles and Oxadiazoles

By ring-closure of 1-nicotinyl-4-arylthiosemicarbazides under the catalysis of concentrated sulfuric acid or mercuric acetate, a series of 2-(3-pyridyl)-5-arylarnino-1,3,4-thiadiazoles and 2-(3-pyridyl)-5-ary-lamino-1,3,4-oxadiazoles were synthesized, respectively. All the products were subjected to testing of biological activity. Furthermore, the IR, 1H NMR and MS spectral properties of these new compounds were studied in details and some significant conclusions were drawn.

Photoluminescence and Electroluminescence Properties of 2,5-Bis[2,2′-bis(5-phenyl)-1,3,4-oxadiazole] Thiophene(T-OXD) and T-OXD/Poly(9-vinylcarbazole) Blends

The photoluminescence(PL) and the electroluminescence(EL) properties of a novel organic compound, 2,5-bis(2,2′-bis(5-phenyl)-1,3,4-oxadiazole(T-OXD), were studied in chloroform and in a solid thin film. The PL and the EL properties of T-OXD/poly(9-vinylcarbazole)(PVK) blends were also studied, which contained various contents of T-OXD. The PL maximum emission peaks of T-OXD/PVK blends show gradual bathochromtic-shift with the increase of the T-OXD content. The EL spectra of T-OXD/PVK devices are similar to their PL spectra, and all the EL maximum emission peaks show bathochromtic-shift compared with the corresponding PL spectra, which is ascribed to the formation of electroplex. The turn-on voltages for ITO/T-OXD:PVK/Al devices decreased from 13.5 V of the device cotaining 0.1% T-OXD(mass fraction) to 5 V of the device containing 5% T-OXD, which suggests that T-OXD improves the energy level match between T-OXD and PVK and enhances the emission efficiency. The experimental results indicate that T-OXD can be used as a good electron transporting material.

Synthesis and Crystal Structure of 2-(4-Decarboxydehydroabietyl)-5-p-tolyl-[1,3,4]-oxadiazole

2-（4-Decarboxydehydroabietyl）-5-p-toyl-[1,3,4]-oxadiazole, C28H34N2O, has been synthesized and characterized by IR, NMR, elemental analysis and single-crystal X-ray diffraction method. The crystal belongs to the orthorhombic system, space group P212121 with a = 6.1351（5）, b = 14.8495（19）, c = 25.9050（2） A, V = 2360.0（4） A3, Z = 4, Mr = 414.57, Dc = 1.167 Mg/m^3, 2 = 0.71073 A,μ（MoKa） = 0.070 mm^-1, F（000） = 896, the final R = 0.0452 and wR = 0.1076 for 1647 observed reflections with I 〉 2σ（I）. There are five rings in the crystal structure of the title compound, but the oxadiazole ring is non-coplanar with the benzene ring D.

Synthesis and Crystal Structure of N-(2-(1,3,4-oxadiazol-2-yl)phenyl)-2,3-dimethylaniline

The title compound, N-（2-（1,3,4-oxadiazol-2-yl）phenyl）-2,3-dimethylaniline, was synthesized and studied by single-crystal X-ray diffraction method. The structure of the product was confirmed by IR, ^1H- and ^13C-NMR spectroscopy, elemental analysis and mass spectrometry. These experimental studies were supported by theoretical optimizations.

1,3,4-oxadiazole-a bioactive scaffold for treating major depression-associated cognitive dysfunction

Background:Alzheimer’s disease affects millions of people worldwide,and one of its major characteristics is the accumulation of extracellular Aβpeptides in the human brain,leading to neuronal death and resulting in memory deficits,disorientation,and inappropriate behaviour.Objective and Methodology:This review study aims to develop new molecular targets for major depression-associated cognitive dysfunction and determine the mechanisms of action of 1,3,4-oxadiazole-based drug candidates.It encourages scientists to develop and synthesize drugs with low side effects to treat Alzheimer’s disease.Furthermore,the drug has shown significant improvement in memory function among dementia patients,which is due to the increased production of acetylcholine in the brain.These derivatives show a high affinity to amyloid plaques,which are thought to cause cognitive damage in patients with Alzheimer’s disease.This review study emphasizes newly developed inhibitors of amyloid deposition using the enzymeα-secretase,which cleaves amyloid precursor protein into smaller fragments that are toxic to neurons.1,3,4-Oxadiazole compounds have demonstrated no significant toxicity to the central nervous system.The antioxidant properties of 1,3,4-oxadiazoles can reduce free radicals,which play an active role in cell damage and disease.Conclusion:This review aims to provide readers with an overview of the current state of knowledge about oxadiazole-related drugs,emphasizing their biological importance.Key aspects related to the discovery and development of these drug candidates are discussed in detail,including information on their structure,biological activity,chemistry,and pharmacological properties.In addition,different derivatives discovered for Alzheimer’s disease to enhance the therapeutic efficiency of oxadiazole drugs have been comprehensively discussed in this review.

Design, synthesis, and fungicidal activity of novel 1,3,4-oxadiazole derivatives

Employing the intermediate derivatization method（IDM）, twenty novel 1,3,4-oxadiazole derivatives containing arylpyrazoloxyl moiety were designed and synthesized. The structures of the title compounds were identified by1 H NMR,13 C NMR, MS and elemental analyses, compound 4 was further identified by single-crystal X-ray diffraction. Antifungal activities against rice sheath blight（RSB） and sorghum anthracnose（SA） were evaluated by the mycelium linear growth rate method. Compounds 4, 16 and 20 displayed significant activities against RSB（EC50= 0.88 mg/L, 0.91 mg/L and 0.85 mg/L, respectively）,higher than the reference tebuconazole; While compound 3 exhibited higher activity against SA（EC50= 1.03 mg/L）, equal to commercial pyraclostrobin（EC50= 1.06 mg/L）. The study showed that compound 20 is a promising fungicide for further development.

5-芳基-1,3,4-噻二唑-2-胺衍生物的合成

在冰醋酸催化下,芳香醛(2a~2g)分别和氨基硫脲(3)反应合成得到芳亚胺基硫脲衍生物(4a~4g),中间体4无需经柱层析纯化,然后在三氯化铁作用下反应关环,得到7个目标化合物5-芳基-1,3,4-噻二唑-2-胺(1a~1g)。产物结构经^(1)H NMR、^(13)C NMR和ESI-MS确证。然后分别以中间体(E)-2-苄基肼-1-硫代酰胺(4a)和产物5-苯基-1,3,4-噻二唑-2-胺(1a)的合成为模型反应,考察了反应的主要影响因素,确定中间体4a合成的适宜条件为:n(氨基硫脲3)∶n(苯甲醛2a)=1.2∶1,在70℃下反应时间4 h;产物1a合成的适宜条件为:n(FeCl_(3))∶n(4a)=4∶1,在80℃下反应16 h。

Synthesis, Crystal Structure and Antitumor Activity of 4-(5-(2,6-Difluorophenyl)-1,3,4-oxadiazol-2-ylthio)-2-(trifluoromethyl)thieno[2,3-d]pyrimidine

The title compound 4-(5-(2,6-difluorophenyl)-1,3,4-oxadiazol-2-ylthio)-2-(trifluoromethyl)thieno[2,3-d]pyrimidine(C15H5F5N4OS2, Mr = 416.35) was designed and synthesized as antitumor agent, and its structure was determined by 1H NMR, 13C NMR, MS, elemental analysis and single-crystal X-ray diffraction. The crystal belongs to monoclinic system, space group P21/c with a = 9.904(2), b = 10.057(2), c = 16.595(3) ?, β = 100.000(3)°, V = 1627.9(6) ?3, Z = 4, F(000) = 832, Dc = 1.699 g/cm3, μ = 0.395 mm-1, R = 0.0468 and wR = 0.1255 for 4726 independent reflections(Rint = 0.0336) and 2847 observed ones(I > 2σ(I)). The in vitro antitumor activity of the title compound was preliminarily evaluated by the standard MTT assay.