1-R-2-([1,2,4]Triazolo[1,5-c]quinazoline-2-ylthio)etanon(ol)s: Synthesis, Bioluminescence Inhibition, Molecular Docking Studies, Antibacterial and Antifungal Activities.

The increasing mortality due to antibacterial resistance necessitates the search for novel antimicrobial agents. Hence, series of 1-R-2-([1,2,4]triazolo[1,5-c]quinazoline-2-ylthio)etanon(ol)s were synthesized, evaluated by spectral data and studied against St. aureus, M. luteum, E. faecalis, E. aerogenes, P. aeruginosa, C. sakazakii, E. coli, K. pneumonia, hospital Streptococcus spp., C. albicans and A. niger in 100, 500 µg/mL and 100 µg/disk. Substances exhibited moderate toxicity in 0.025, 0.1 and 0.25 mg/mL in bioluminescence inhibition tests of Photobacterium leiognathi. SAR exposed that introduction of 2,4-(Cl)2C6H3-, 2,5-(OMe)2C6H3-, 4-Me-2-iPr-C6H3O- and 3-iPr-C6H4O- fragments and reduction of the pyrimidine ring of R-([1,2,4]triazolo[1,5-c]quinazolin-2-ylthio)alcohols were the best modifications to promote antimicrobial activity. Molecular docking showed their good affinity into the active sites of EcPanK-AMPPNP and hDHFR. Hence, reported results will be used for subsequent QSAR model creation and purposeful antimicrobial modification of the strongest compounds.

1-R-2-([1,2,4]Triazolo[1,5-c]quinazoline-2-ylthio)etanon(ol)s: synthesis, bioluminescence inhibition, molecular docking studies, antibacterial and antifungal activity.

The increasing mortality due to antibacterial resistance necessitates the search for novel antimicrobial agents. Hence, series of 1-R-2-([1,2,4]triazolo[1,5-c]quinazoline-2-ylthio)etanon(ol)s were synthesized, evaluated by spectral data and studied against St. aureus, M. luteum, E. faecalis, E. aerogenes, P. aeruginosa, C. sakazakii, E.coli, K. pneumonia, hospital Streptococcus spp., C. albicans and A. niger in 100, 500 µg/mL and 100 µg/disk. Substances exhibited moderate toxicity in 0.025, 0.1 and 0.25 mg/mL in bioluminescence inhibition tests of Photobacterium leiognathi. SAR exposed that introduction of 2,4-(Cl)2C6H3-, 2,5-(OMe)2C6H3-, 4-Me-2-iPr-C6H3O- and 3-iPr-C6H4O- fragments and reduction of the pyrimidine ring of R-([1,2,4]triazolo[1,5-c]quinazolin-2-ylthio)alcohols were the best modifications to promote antimicrobial activity. Molecular docking showed their good affinity into the active sites of EcPanK-AMPPNP and hDHFR. Hence, reported results will be used for subsequent QSAR model creation and purposeful antimicrobial modification of the strongest compounds.

2-Heteroaryl-[1,2,4]triazolo[1,5-c]quinazoline-5(6 H)-thiones and Their S-Substituted Derivatives: Synthesis, Spectroscopic Data, and Biological Activity.

In the continuing search for novel, biologically effective heterocyclic agents, several methods for the synthesis of 2-heteroaryl-[1,2,4]triazolo[1,5-c]quinazoline-5(6 H)-thiones have been developed: thiolation of oxo derivatives, [5+1] cyclocondensation of [2-(3-heteroaryl-[1,2,4]triazol-5-yl)phenyl]amines with carbon disulfide, potassium ethyl xanthogenate, or aryl isothiocyanates, and in situ reaction of 2-isothiocyanatobenzonitrile with hydrazides. A series of N-R-2-[(2-heteroaryl-[1,2,4]triazole-[1,5-c]quinazoline-5-yl)thio]acetamides were obtained by aminolysis of the corresponding acetic acids and alkylation of potassium thiolates with N-R-2-chloroacetamides. It was established that some potassium thiolates, 4 a-4 d, 4 h, and 4 i, had high antibacterial activity against Staphylococcus aureus with a minimum inhibitory concentration of 12.5 µg mL-1 and minimum bactericidal concentration of 25 µg mL-1 , which exceeded the values for trimethoprim. In addition, {2-[3-(1 H-indole-2-yl)-1 H-1,2,4-triazol-5-yl]phenyl}amine 2 i was investigated in the concentration range 100-0.01 µM at 59 lines of nine cancer cell types, and showed a mean effective concentration at 3.12-7.03 µM and cytotoxic effect at 15.56-67.38 µM. The possible mechanisms of activity were predicted by molecular docking studies to S. aureus dihydrofolate reductase and epidermal growth factor receptor kinase.

Synthesis and Anticancer Activity of 2-(Alkyl-, Alkaryl-, Aryl-, Hetaryl-)-[1,2,4]triazolo[1,5-c]quinazolines.

The combinatorial library of novel potential anticancer agents, namely, 2-(alkyl-, alkaryl-, aryl-, hetaryl-)[1,2,4]triazolo[1,5-c]quinazolines, was synthesized by the heterocyclization of the alkyl-, alkaryl-, aryl-, hetarylcarboxylic acid (3H-quinazoline-4-ylidene)hydrazides by oxidative heterocyclization of the 4-(arylidenehydrazino)quinazolines using bromine, and by the heterocyclization of N-(2-cyanophenyl)formimidic acid ethyl ester. The optimal method for synthesis of the s-triazolo[1,5-c]quinazolines appeared to be cyclocondensation of the corresponding carboxylic acid (3H-quinazoline-4-ylidene)hydrazides. The compounds' structures were established by (1)H, (13)C NMR, LC- and EI-MS analysis. The in vitro screening of anticancer activity determined the most active compound to be 3,4,5-trimethoxy-N'-[quinazolin-4(3H)-ylidene]benzohydrazide (3.20) in micromolar concentrations with the GI50 level (MG_MID, GI50 is 2.29). Thus, the cancer cell lines whose growth is greatly inhibited by compound 3.20 are: non-small cell lung cancer (NCI-H522, GI50=0.34), CNS (SF-295, GI50=0.95), ovarian (OVCAR-3, GI50=0.33), prostate (PC-3, GI50=0.56), and breast cancer (MCF7, GI50=0.52), leukemia (K-562, GI50=0.41; SR, GI50=0.29), and melanoma (MDA-MB-435, GI50=0.31; SK-MEL-5, GI50=0.74; UACC-62, GI50=0.32). SAR-analysis is also discussed.

Design and Evaluation of Novel Antimicrobial and Anticancer Agents Among Tetrazolo[1,5-c]quinazoline-5-thione S-Derivatives.

The novel heterocyclization of 5-(2-aminophenyl)-1H-tetrazole with potassium ethylxanthogenate or carbon disulfide was proposed. The potassium salt of the tetrazolo[1,5-c]quinazoline-5-thione was subsequently modified by alkylation with proper halogen derivatives to (tetrazolo[1,5-c]quinazolin-5-ylthio)alkyls, N,N-dialkylethylamines, 1-aryl-2-ethanones, 1-(alkyl)aryl-2-ethanols, carboxylic acids, and esters. The structures of all newly synthesized compounds were confirmed by FT-IR, UV-vis, LC-MS, (1)H, (13)C NMR, and elemental analysis data. The substances were screened for antibacterial and antifungal activities (100 µg) against Escherichia coli, Staphylococcus aureus, Enterobacter aerogenes, Entrococcus faecalis, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Candida albicans. Preliminary bioluminescence inhibition tests against Photobacterium leiognathi Sh1 showed that substances 5.2-5.4, 6.1, 7.1 with ethanone or carboxylic acid substituents showed toxicity against bacteria cells. The substances chosen by the US National Cancer Institute (NCI) were screened for their ability to inhibit 60 different human tumor cell lines, where 2-(tetrazolo[1,5-c]quinazolin-5-ylthio)-1-(4-tolyl)ethanone (5.2), 3-(tetrazolo[1,5-c]quinazolin-5-ylthio)propanoic and related 3-metyl-butanoic acids (6.2, 6.3), and ethyl tetrazolo[1,5-c]quinazolin-5-ylthio)acetate (7.2) showed lethal antitumor activity (1.0 µM) against the acute lymphoblastic leukemia cell line (CCRF-CEM), and substances 5.2 and 6.3 exhibited moderate anticancer properties inhibiting growth of the leukemia MOLT-4 and HL06-(TB) cell lines. The moderate antitumor activity was demonstrated in 1-(2,5-dimethoxyphenyl)-2-(tetrazolo[1,5-c]quinazolin-5-ylthio)ethanone (5.4) against the CNS cancer cell line SNB-75. Comparing the docking mode of the Gefitinib and synthesised substances on the ATP binding site of EGFR, it could be assumed that these compounds might act in the same way. The results of the investigation could be considered as a useful base for future development of potent antimicrobials and antitumor agents among tetrazolo[1,5-c]quinazoline-5-thione S-derivatives.

Synthesis of New 6-{[ω-(Dialkylamino(heterocyclyl)alkyl]thio}-3-R-2H-[1,2,4]triazino[2,3-c]quinazoline-2-ones and Evaluation of their Anticancer and Antimicrobial Activities.

Several novel 6-thio-3-R-2-oxo-2H-[1,2,4]triazino[2,3-c]quinazoline-based compounds containing an ω-(dialkylamino(heterocyclyl)]alkyl fragment were synthesized to examine their anticancer activity. Some of the 6-{[ω-(hetero-cyclyl)alkyl]thio}-3-R-2H-[1,2,4]triazino[2,3-c]quinazoline-2-ones (3.1-3.10) were obtained by the nucleophilic substitution of 6-[ω-halogenalkyl]thio-3-R-2H-[1,2,4]triazino[2,3-c]quinazoline-2-ones (2.1-2.8) with azaheterocycles. Alternatively, compounds 3.1-3.22 were synthesized by alkylation of 3-R-6-thio-2H-[1,2,4]triazino[2,3-c]quinazoline-2-ones potassium salts (1.1-1.4) with (2-chloroethyl)-N,N-dialkylamine hydrochlorides or 1-(2-chloroethyl)heterocycle hydrochlorides. The structures of compounds were elucidated by (1)H, (13)C NMR, LC-MS and EI-MS analysis. Then anticancer and antibacterial, bioluminescence inhibition of Photobacterium leiognathi Sh1 activities of the substances were tested in vitro. It was found that compound 3.18 possessed a wide range of anticancer activity against 27 cell lines of cancer: non-small cell lung, colon, CNS, ovarian, renal, prostate, breast, melanoma and leukemia (log GI(50) < -5.65). The "structure-activity" relationship was discussed. COMPARE analysis for synthesized anticancer active compounds was performed.