A green and simplified approach for the quantitative and sensitive analysis of heavy metal ions in sea and stream waters.

Elimination of the matrix effect is a major challenge in developing a method for the quantification of heavy metals (HMs) in water samples. In this regard, the current research describes the simultaneous analyses of Cu(II), Cd(II), and Ni(II) ions in water matrices through flame atomic absorption spectrophotometry (FAAS) after preconcentration with carrier element-free co-precipitation (CEFC) technique by the help of an organic co-precipitant, 3-{[5-(4-Chlorobenzyl)-3-(4-chlorophenyl)-1H-1,2,4-triazol-1-yl]-methyl}-4-[2,4-(dichlorobenzylidene)amino]-1H-1,2,4-triazole-5(4H)-thione (CCMBATT). Based on our literature research, CCMBATT was employed for the first time in this study as an organic co-precipitant for the preconcentration of HMs. Factors such as solution pH, concentration of co-precipitant, sample volume, standing time, centrifugation rate, and time were thoroughly examined and optimized to achieve the highest efficiency in terms of HM recovery. The limits of detection (LODs) (with 10 number of tests) of 0.54, 0.34, and 1.95 µg L-1 and the relative standard deviations (RSD %) of 2.1, 3.3, and 3.0 were determined for Cu(II), Cd(II) and Ni(II) ions, respectively. Recovery results of HMs for the spiked samples were in the range of 92.8-101.0%, demonstrating the trueness of the method and its applicability to the water samples matrix.

Design and synthesis of new heterocyclic compounds containing 5-[(1H-1,2,4-triazol-1-yl)methyl]-3H-1,2,4-triazole-3-thione structure as potent hEGFR inhibitors.

EGFR is one of the important mediators of the signaling cascade that determines key roles in various biological processes such as growth, differentiation, metabolism and apoptosis in the cell in response to external and internal stimuli. In recent years, it has been proven that although this enzyme activity is tightly regulated in normal cells, if the enzyme activity cannot be controlled, it can lead to malignancy. EGFR is also considered a prominent macromolecule in targeted cancer chemotherapy. For this purpose, a comprehensive modeling studies were conducted against EGFR protein and novel molecules containing 5-[(1H-1,2,4-triazol-1-yl)methyl]-3H-1,2,4-triazole-3-thione structure were suggested to be synthesized. Among the synthesized molecules, compounds 7c, 8c, 8f and 8g were determined to have significant IC50 values. Compound 8g was found to have the IC50 value closest to the very well-known EGFR inhibitor Gefitinib with its noncompetitive inhibition form. Ki value of compound 8g was calculated as 0.00232 µM.Communicated by Ramaswamy H. Sarma.

1,3,4-Thiadiazole and 1,2,4-triazole-5-thione derivatives bearing 2-pentyl-5-phenyl-2,4-dihydro-3H-1,2,4-triazole-3-one ring: Synthesis, molecular docking, urease inhibition, and crystal structure.

Two series of 1,3,4-thiadiazole (40a-o) and 1,2,4-triazole-5-thione (41a-l) derivatives bearing a 2-pentyl-5-phenyl-1,2,4-triazole-3-one ring were synthesized and then studied for their urease inhibitory activities using thiourea as a standard drug. Among the two groups, the first group (40a-o) did not show good activity while the second group (41a-l) showed excellent activity. Compound 41j (1091.24 ± 14.02 µM) of the second series of compounds showed lower activity than thiourea, while the remaining 11 compounds (41a-i, k, and l) showed better activity than thiourea (183.92 ± 13.14 µM). Among the 11 compounds, 41b (15.96 ± 2.28 µM) having the 3-F group on the phenyl ring showed the highest inhibitory activity. Urease kinetic studies of 41b, which is the most active compound, determined it to have an un-competitive inhibition potential. Moreover, in silico analysis against urease from jack bean with 27 new heterocyclic compounds and the reference molecule was carried out to see the necessary interactions responsible for urease activity. The docking calculations of all compounds supported stronger binding to the receptor than the reference molecule, with high inhibition constants. In addition, compound 40m was characterized by single-crystal X-ray diffraction analysis. X-ray analysis reveals that the structures of the compound 40m crystallize in the monoclinic P21/c space group with the cell parameters: a = 10.2155(9) Å, b = 22.1709(18) Å, c = 21.4858(17) Å, ß = 99.677(8)°, V = 4797.0(7) Å3 . X-ray diffraction analyses were also performed to gain insights into the role of weak intermolecular interactions and C-H…X (halogen) interactions in compound 40m that influence the crystal packing.

Monoamine oxidase A and B inhibitory activities of 3,5-diphenyl-1,2,4-triazole substituted [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole derivatives.

Monoamine oxidase (EC 1.4.3.4, MAO) is a flavin adenine dinucleotide-containing flavoenzyme located on the outer mitochondrial membrane and catalyzes the oxidative deamination of monoaminergic neurotransmitters and dietary amines. MAO exists in humans as two isoenzymes, hMAO-A and hMAO-B, which are distinguished by their tertiary structures, preferred substrates and inhibitors, and selective inhibition of these isoenzymes are used in the treatment of different diseases such as Alzheimer's, Parkinson's and depression. In the present study, we report the design, synthesis and characterization of 3,5-diphenyl-1,2,4-triazole substituted [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole derivatives as novel and selective inhibitors of hMAO-B. Twenty one compounds (38, 39a-h, 41a-d, 42a-h) were screened for their inhibitory activity against hMAO-A and hMAO-B by using in vitro Amplex Red® reagent based fluorometric method and all compounds were found to be as selective h-MAO-B inhibitors to a different degree. The compound 42e and 42h displayed the highest inhibitory activity against hMAO-B with IC50 values of 2.51 and 2.81 µM, respectively, and more than 25-fold selectivity towards inhibition of hMAO-B. A further kinetic evaluation of the most potent derivative (42e) was also performed and a mixed mode of inhibition of hMAO-B by the compound 42e was determined (Ki = 0,26 µM). According to our findings the [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole emerged as a promising scaffold for the development of novel and selective hMAO-B inhibitors.

Synthesis of new 1,2,4-triazole-(thio)semicarbazide hybrid molecules: Their tyrosinase inhibitor activities and molecular docking analysis.

Tyrosinase inhibition is very important in controlling melanin synthesis. If melanin synthesis is not controlled in metabolism, an unwanted increase in melanin synthesis occurs. As melanin plays a role in the formation of skin color, its unusual levels cause some skin disorders such as pregnancy scars, age spots, and especially skin cancer (melanoma). However, the tyrosinase activity is also related to Parkinson's disease and some neurodegenerative diseases. For all these reasons, the medicinal as well as the cosmetic industries focus on research on tyrosinase inhibitors for the treatment of skin disorders and some neurodegenerative diseases. In this study, 32 new 1,2,4-triazole-(thio)semicarbazide hybrid molecules (6a-p and 7a-p) were synthesized, starting from 4-amino-1-pentyl-3-phenyl-1H-1,2,4-triazole-5(4H)-one. These compounds were evaluated for their inhibitory activity against mushroom tyrosinase. The results indicated that 6h, 6m, 6n, and 6p exhibited the most effective inhibitory activity, with IC50 values of 0.00162 ± 0.0109, 0.00166 ± 0.0217, 0.00165 ± 0.019, and 0.00197 ± 0.0063 µM, respectively, compared with kojic acid as the reference drug (IC50 = 14.09 ± 0.02 µM). Also, molecular docking analyses were performed to suggest possible binding poses for the ligands. As a result, derivatives 6h, 6m, 6n, and 6p can be used as promising tyrosinase inhibitor candidates in the medicinal, cosmetics, or food industries.

Synthesis and kinetics studies of N'-(2-(3,5-disubstituted-4H-1,2,4-triazol-4-yl)acetyl)-6/7/8-substituted-2-oxo-2H-chromen-3-carbohydrazide derivatives as potent antidiabetic agents.

A novel series of N'-(2-(3,5-disubstituted-4H-1,2,4-triazol-4-yl)acetyl)-6/7/8-substituted-2-oxo-2H-chromen-3-carbohydrazides were synthesized and studied for their α-glucosidase inhibition activity. Most of the synthesized compounds exhibited potential α-glucosidase inhibition activity with IC50 values ranging from 0.96 ± 0.02 to 32.86 ± 0.73 µg/ml. Among them, compounds 3e and 4e, having a methoxy group on the coumarin ring, proved to be the most potent ones, showing an enzyme inhibition activity with IC50 = 0.96 ± 0.02 and 1.44 ± 0.06 µg/ml, respectively. The kinetic study through Lineweaver-Burk plots revealed that the inhibition mechanism of the most active compounds 3d, 3e, 4d, and 4e, on the α-glucosidase activity, was found to be in the competitive mode.

Synthesis of 1,2,4-triazole-5-on derivatives and determination of carbonic anhydrase II isoenzyme inhibition effects.

Carbonic anhydrase (CA) II plays major roles in pH regulation of body, protection of electrolyte balance, transportation of water and some metabolic pathways. Therefore, CA II inhibitors are very important molecules for drug design and have many pharmacological applications. CA II as a target molecule is also important for eliminating some pathological conditions such as glaucoma, cancer, epilepsy, ulcer and obesity. In this study, some 1,2,4-triazole derivatives were synthesized and CA II inhibition potentials of these molecules were examined. It has been found that molecule 7c was the most potent inhibitor with the lowest IC50 value at micromolar level among the examined molecules. The inhibition in the range of 18.41-64.97% was seen in the presence of newly synthesized molecules at their reachable maximum concentration in the reaction mixtures. Kinetic studies showed that the inhibition mechanism of compound 7c on carbonic anhydrase activity was reversible and uncompetitive. Molecular docking studies also indicated that compound 7c could bind to the active site of the enzyme by weakly interacting with especially Gln102, Leu240, Ala241 and Trp243. ADME properties of these newly synthesized (3a-e, 6, 7a-e) were also studied and showed good oral drug candidate like properties.

Synthesis of some novel heterocylic compounds derived from 2-[3-(4-chlorophenyl)-5-(4-methoxybenzyl)-4H-1,2,4-triazol-4-yl]acetohydrazide and investigation of their lipase and α-glucosidase inhibition.

In the present study, 2-[3-(4-chlorophenyl)-5-(4-methoxybenzyl)-4H-1,2,4-triazol-4-yl]acetohydrazide (1) was used as starting compound for the synthesis of 2-{[3-(4-chlorophenyl)-5-(4-methoxybenzyl)-4H-1,2,4-triazol-4-yl]acetyl}-4-thiosemicarbazides (2a-c) and 5-{[3-(4-chlorophenyl)-5-(4-methoxybenzyl)-4H-1,2,4-triazol-4-yl]methyl}-1,3,4-oxadiazole-2-thione (5). The cyclization of compounds 2a-c in the presence of NaOH resulted in the formation of 5-{[3-(4-chlorophenyl)-5-(4-methoxybenzyl)-4H-1,2,4-triazol-4-yl]methyl}-4-alkyl/aryl-2,4-dihydro-3H-1,2,4-triazole-3-thiones (3a-c). Aminomethylation of compounds 3a-c and 5 with formaldehyde and N-methyl/phenylpiperazine furnished Mannich bases (4a-f and 6a-b). The newly synthesized compounds were well-characterized by IR, (1)H NMR, (13)C NMR, elemental analysis and mass spectral studies. They were also screened for their lipase and α-glucosidase inhibition. Among the tested compound 2c (IC50 = 2.50 ± 0.50 µM) showed the best anti-lipase activity and compounds 2c (IC50 = 3.41 ± 0.16 µM) and 6a (IC50 = 4.36 ± 0.10 µM) showed the best anti-α-glucosidase activity.

Synthesis and antioxidant activities of some new triheterocyclic compounds containing benzimidazole, thiophene, and 1,2,4-triazole rings.

Various triheterocyclic compounds containing benzimidazole, thiophene, and 1,2,4-triazole rings (3-6) were synthesized and screened for their antioxidant activities. The structures of the synthesized compounds (2-6) were judged by (1)H NMR, (13)C NMR, elemental analysis, and LC-MS spectral data. Antioxidant activities of the synthesized compounds (2-6) were determined with CUPric Reducing Antioxidant Capacity (CUPRAC), ABTS (2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)/persulfate, and DPPH (1,1-diphenyl-2-picrylhydrazyl) assays. Most of the compounds showed a significant antioxidant activity and especially, compound 5c showed very good SC50 value for DPPH method and compound 5h exhibited very high scavenging activity to ABTS method.

Synthesis of some new 1,2,4-triazole derivatives starting from 3-(4-chlorophenyl)-5-(4-methoxybenzyl)-4H-1,2,4-triazol with anti-lipase and anti-urease activities.

In the present study, starting compound 4 was prepared by deamination of compound 2 in the presence of hypophosphorous acid and sodium nitrite. Treatment of compound 4 with ethyl bromoacetate produced ethyl[3-(4-chlorophenyl)-5-(4-methoxybenzyl)-4H-1,2,4-triazol-4-yl]acetate (5), which was converted to the hydrazide derivative (6) by treatment with hydrazine hydrate. The reaction of compound 6 with aromatic aldehydes resulted in the formation of arylidene hydrazides (7). Treatment of 6 with CS2 in the presence of potassium hydroxide (KOH), followed by cyclization with hydrazine hydrate, afforded 4-amino-5-{[3-(4-chlorophenyl)-5-(4-methoxybenzyl)-4H-1,2,4-triazol-4-yl]methyl}-2,4-dihydro-3H-1,2,4-triazole-3-thione (9). The condensation of 9 with appropriate aldehydes gave Schiff bases (10), which were converted into Mannich bases (11) in the presence of formaldehyde. All the synthesized compounds were screened for their anti-lipase and anti-urease activities. Compounds 7b, 7d, 11b, 11c, and 11d showed moderate-to-good lipase inhibitory effects compared to orlistat. Compounds 7b and 7d exhibited better anti-lipase activity. Furthermore, among the compounds tested, 11a and 11d were found to show high inhibitory effect against urease with IC50 values of 12.39 ± 0.35 and 16.12 ± 1.06 µg/mL, respectively. Compound 11c showed moderate inhibitory activity. The Mannich base containing compound 11 may be a source of good leads for the synthesis of lipase and urease dual inhibitors.

Microwave-assisted synthesis of new benzimidazole derivatives with lipase inhibition activity.

A practical protocol has been used for the synthesis of benzimidazoles. The reaction of iminoester hydrochlorides of phenylacetic with 4,5-dichloro-1,2-phenylenediamine under microwave irradiation leads to the benzimidazole derivatives with good yields and in short reaction times. After the synthesis of benzimidazoles, we synthesized ester and hydrazide derivatives under microwave irradiation with good yields. All compounds were evaluated with regard to pancreatic lipase activity and 3b, 3c, 5a and 6a showed lipase inhibition at various concentrations.

Carrier element-free coprecipitation (CEFC) method for the separation, preconcentration and speciation of chromium using an isatin derivative.

A new, simple, rapid and sensitive separation, preconcentration and speciation procedure for chromium in environmental liquid and solid samples has been established. The present speciation procedure for Cr(III) and Cr(VI) is based on combination of carrier element-free coprecipitation (CEFC) and flame atomic absorption spectrometric (FAAS) determinations. In this method a newly synthesized organic coprecipitant, 5-chloro-3-[4-(trifluoromethoxy) phenylimino]indolin-2-one (CFMEPI), was used without adding any carrier element for coprecipitation of chromium(III). After reduction of chromium(VI) by concentrated H(2)SO(4) and ethanol, the procedure was applied for the determination of total chromium. Chromium(VI) was calculated as the difference between the amount of total chromium and chromium(III). The optimum conditions for coprecipitation and speciation processes were investigated on several commonly tested experimental parameters, such as pH of the solution, amount of coprecipitant, sample volume, etc. No considerable interference was observed from the other investigated anions and cations, which may be found in natural water samples. The preconcentration factor was found to be 40. The detection limit for chromium(III) corresponding to three times the standard deviation of the blank (N=10) was found 0.7 microg L(-1). The present procedure was successfully applied for speciation of chromium in several liquid and solid environmental samples. In order to support the accuracy of the method, the certified reference materials (CRM-TMDW-500 Drinking Water and CRM-SA-C Sandy Soil C) were analyzed, and standard APDC-MIBK liquid-liquid extraction method was performed. The results obtained were in good agreement with the certified values.

Synthesis of Schiff and Mannich bases of isatin derivatives with 4-amino-4,5-dihydro-1H-1,2,4-triazole-5-ones.

Ethyl imidate hydrochlorides 1 were prepared by passing HCl gas through solutions of substituted benzyl cyanides and absolute ethanol. Ethoxycarbonylhydrazones 2 were synthesized from the reaction of compounds 1 with ethyl carbazate. Treatment of 2 with hydrazine hydrate leads to the formation of substituted 4-amino-4,5-dihydro-1H-1,2,4-triazole-5-ones 3. Isatin and 5-chloroisatin were added to 3 to form Schiff bases 4 and N-Mannich bases 5 of these compounds were synthesized by reacting with formaldehyde and piperidine. Their chemical structures were confirmed by means of IR, (1)H- and (13)C-NMR data and by elemental analysis.

Synthesis of new bis-1,2,4-triazole derivatives.

A series of new 1,2/1,3-bis[o-(N-methylidenamino-3-aryl-5-phenyl-4H-1,2,4-triazole-4-yl)phenoxy]ethane/propane derivatives 4 were prepared in good yields by treatment of 4-amino-3-aryl-5-phenyl-4H-1,2,4-triazoles 2 with certain bis-aldehydes 1.Compounds 4 were reduced with NaBH(4) to afford the corresponding 1,2/1,3-bis[o-(N-methylamino-3-aryl-5-phenyl-4H-1,2,4-triazole-4-yl)phenoxy]ethane/propane derivatives 5. All new compounds were characterized by IR, (1)H-NMR, (13)C-NMR and mass spectral data.

Convenient synthesis of fused heterocyclic 1,3,5-triazines from some N-acyl imidates and heterocyclic amines as anticancer and antioxidant agents.

N-Acyl imidates (2), reacting with 5-amino pyrazole (3), 2-aminobenzimidazole (4), 3-amino-1,2,4-triazole (5), 3,5-diamino-1,2,4-triazole (6), and 5-aminotetrazole (7) give pyrazolo[1,5-a][1,3,5]triazine (8), benzo[4,5]imidazo[1,2-a][1,3,5]triazine (9), [1,2,4]triazolo [2,3-a][1,3,5]triazine (10), [1,2,4]tri azolo[2,3-a][1,3,5]triazin-5-ylamine (12), and tetrazolo-[1,5-a][1,3,5]triazine (14) derivatives, respectively. The synthesized compounds were characterized on the basis of IR, (1)H-NMR, (13)C-NMR, and mass spectral data and elemental analyses results. Five of the newly synthesized compounds, 8a, 9a, 10a, 12a, and 14a, were selected by National Cancer Institute and screened for their anticancer activity against three cancer cell lines MCF7, NCI-H460, and SF-268, where 12a exhibited moderate anti-proliferation potential. 12a was, thus, further tested for anticancer activity against 60 human cancer cell lines and showed moderate growth inhibition potency. 12a showed a high growth inhibitory activity against A498 renal cancer cell line. All of the newly synthesized compounds 8-10, 12 and 14 were tested for their antioxidant capacity where they exhibited very high activity, even higher than the widely used reference antioxidants butylated hydroxytoluene and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox). Compound 12a also showed the highest antioxidant activity.