Arch. Pharm. Chem. Life Sci. 2009, 342, 651 – 662 L. N. Antipenko et al. 651 Full Paper Synthesis, Cytotoxicity by Bioluminescence Inhibition, Antibacterial and Antifungal Activity of ([1,2,4]Triazolo[1,5- c]quinazolin-2-ylthio)carboxylic Acid Amides Lyudmila N. Antipenko 1 , Alexander V. Karpenko 1 , Sergey I. Kovalenko 1 , Andrew M. Katsev 2 , Elena Z. Komarovska-Porokhnyavets 3 , and Vladimir P. Novikov 3 1 Department of Pharmaceutical Chemistry, Zaporozhye State Medical University, Zaporozhye, Ukraine 2 Department of Pharmacy, Crimea State Medical University, Simferopol, Ukraine 3 Department of Technology of Biological Active Substances, Pharmacy and Biotechnology, National University “Lviv Polytechnic”, Lviv, Ukraine We report in this work the synthesis, cytotoxicity, and antimicrobial activity of ([1,2,4]tri- azolo[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 avail- ability 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. Investiga- tion of the antimicrobial and antifungal activity of amides 4 – 7 (concentration 5 mg/mL) was car- ried 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 corre- lation between bioluminescence inhibition and antimicrobial activity of the investigated sub- stances. Keywords: Antifungal / Antibacterial / Bioluminescence / Cytotoxicity / 2-Thio-[1,2,4]triazolo[1,5-c]quinazoline / Received: April 9, 2009; Accepted: July 22, 2009 DOI 10.1002/ardp.200900077 Introduction Nowadays, biotesting, a determination of e.g., toxicity, by direct action on a living organism, is widely used as con- trol of the biological system state on different levels of an ecosystem [1]. It is known that certain insects (e.g., beetles known as fireflies) and a few species of bacteria (Photobac- terium phosphoreum, P. leiognathi, Vibrio fischeri, V. harveyi) possess the ability to emit light [2]. The biochemistry and genetics of the light reaction (luciferin oxidation) have been widely studied, and now scientists are exploring other potential applications of luminescence in micro- bial quality control of soil, air, food products, and drink- ing water. Consequently, bioluminescence (BL) inhibi- tion test is a simple rapid in-vitro method for the screen- ing and monitoring of a wide range of organic xenobiot- ics [2]. Still, it should always be kept in mind that rigor- ous testing of the method should be carried out in com- parison to accepted methods. Correspondence: Lyudmila N. Antipenko, Department of Pharmaceuti- cal Chemistry, Zaporozhye State Medical University; 26, Mayakovsky ave., 69035, Zaporozhye, Ukraine. E-mail: antypenko.l@gmail.com Fax: +38 061 234-15-71 Abbreviation: bioluminescence (BL) i 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim