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The Scientific World Journal
Volume 2014, Article ID 705973, 11 pages
http://dx.doi.org/10.1155/2014/705973
Research Article

Synthesis and Antimycobacterial and Photosynthesis-Inhibiting Evaluation of 2-[(E)-2-Substituted-ethenyl]-1,3-benzoxazoles

1Institute of Organic Chemistry and Technology, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 532 10 Pardubice, Czech Republic
2Department of Inorganic and Organic Chemistry, Faculty of Pharmacy in Hradec Kralove, Charles University in Prague, Heyrovskeho 1203, 500 05 Hradec Kralove, Czech Republic
3Department of Environmental Ecology, Faculty of Natural Sciences, Comenius University, Mlynska dolina Ch-2, 842 15 Bratislava, Slovakia
4Laboratory for Mycobacterial Diagnostics and TB, Institute of Public Health in Ostrava, Partyzanske namesti 7, 702 00 Ostrava, Czech Republic
5Institute of Chemistry, Faculty of Natural Sciences, Comenius University, Mlynska dolina Ch-2, 842 15 Bratislava, Slovakia
6Department of Chemical Drugs, Faculty of Pharmacy, University of Veterinary and Pharmaceutical Sciences Brno, Palackeho 1/3, 612 42 Brno, Czech Republic

Received 10 March 2014; Accepted 15 July 2014; Published 13 August 2014

Academic Editor: Autar K. Mattoo

Copyright © 2014 Ales Imramovsky et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A series of twelve 2-[(E)-2-substituted-ethenyl]-1,3-benzoxazoles was designed. All the synthesized compounds were tested against three mycobacterial strains. The compounds were also evaluated for their ability to inhibit photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. 2-[(E)-2-(4-Methoxyphenyl)ethenyl]-1,3-benzoxazole, 2-[(E)-2-(2,3-dihydro-1-benzofuran-5-yl)ethenyl]-1,3-benzoxazole and 2-(E)-2-[4-(methylsulfanyl)phenyl]ethenyl-1,3-benzoxazole showed the highest activity against M. tuberculosis, M. kansasii, and M. avium, and they demonstrated significantly higher activity against M. avium and M. kansasii than isoniazid. The PET-inhibiting activity of the most active ortho-substituted compound 2-[(E)-2-(2-methoxyphenyl)ethenyl]-1,3-benzoxazole was IC50 = 76.3 μmol/L, while the PET-inhibiting activity of para-substituted compounds was significantly lower. The site of inhibitory action of tested compounds is situated on the donor side of photosystem II. The structure-activity relationships are discussed.