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.

Substituted 2-[(2-Oxo-2H-[1,2,4]triazino [2,3-c]quinazolin-6-yl)thio]acetamides with Thiazole and Thiadiazole Fragments: Synthesis, Physicochemical Properties, Cytotoxicity, and Anticancer Activity.

The series of novel N-R-2-[(3-R-2-oxo-2H-[1,2,4]triazino[2,3-c]quinazolin-6-yl)thio]acetamides with thiazole and thiadiazole fragments in a molecule were obtained by alkylation of potassium salts 1.1-1.4 by N-hetaryl-2-chloroacetamides and by aminolysis of activated acids 2.1-2.4 with N,N'-carbonyldiimidazole (CDI). The structures of compounds were determined by IR, (1)H NMR, MS, and EI-MS analysis. The results of cytotoxicity evaluated by the bioluminescence inhibition of bacterium Photobacterium leiognathi, Sh1 showed that the compounds have considerable cytotoxicity. The synthesized compounds were tested for anticancer activity in NCI against 60 cell lines. Among the highly active compounds 3.1, 3.2, and 6.5, 2-[(3-methyl-2-oxo-2H-[1,2,4]triazino[2,3-c]quinazolin-6-yl)thio]-N-(1,3-thiazol-2-yl)acetamide (3.1) was found to be the most active anticancer agent against the cell lines of colon cancer (GI(50) at 0.41-0.69 µM), melanoma (GI(50) 0.48-13.50 µM), and ovarian cancer (GI(50) 0.25-5.01 µM). The structure-activity relationship (SAR-analysis) was discussed.

Synthesis, cytotoxicity by bioluminescence inhibition, antibacterial and antifungal activity of ([1,2,4]Triazolo[1,5-c]quinazolin-2-ylthio)carboxylic acid amides.

We report in this work the synthesis, cytotoxicity, and antimicrobial activity of ([1,2,4]triazolo[1,5-c]quinazolin-2-ylthio)carboxylic acid amides 4-7 in connection with our previous research in the preparation of triazoloquinazoline derivatives. Due to simplicity, general availability of starting materials, and high yields, the most reliable method of synthesis appeared to be the one with N,N-carbonyldiimidazole activation stage. The chemical structures of all obtained substances were deduced from FT-IR, (1)H-NMR, EI-MS, and LC-MS spectral data. The results of cytotoxicity evaluated by bioluminescence inhibition of bacterium Photobacterium leiognathi, strain Sh1 showed that compounds 4.1, 4.6, and 6.1 were the most cytotoxic. Investigation of the antimicrobial and antifungal activity of amides 4-7 (concentration 5 mg/mL) was carried out by the stiff-plate agar-diffusion method. We found that the compounds possessed low (4.1, 4.7) antifungal activity against Candida tenuis and strong (4.21, 5.1, 5.9) or inefficient (4.7, 4.12, 4.16) activity against Aspergillus niger. Substances 5.1 and 5.9 slightly affected Mycobacterium luteum. Staphylococcus aureus was resistant to all obtained substances, and only the n-butyramide derivatives 7.1 and 7.5 inhibited the growth of Escherichia coli. Hence, there was no strong correlation between bioluminescence inhibition and antimicrobial activity of the investigated substances.