| In the previous study three compounds of semicarbazones (namely, 2: 1-Naphthalen- 1-yl-etylidene-urea, 7a: 1-{4[6-(4-Acetyl-phenoxy)-hexacyloxy]-phenyl}-ethanone Bis, 7b: 1-{4[12-Acetyl-phenoxy)–dodecyloxyl-phenyl}-ethanone Bis) were used to prepare three novel 1,2,3-seleniadiazole heterocyclic ring compounds respectively (namely: (3) :4-naphthalene-1-yl-[1,2,3]selenadiazole, (8a) : 1,6-Bis[4-(1,2,3-seleniadiazol-4-yl) phenoxy] hexane, (8b): 1,12-Bis[4-(1,2,3-seleniadiazol-4-yl) phenoxy] dodecane). We described here the antibacterial activity of semicarbazones compounds and the new series of compounds containing 1,2,3-seleniadiazole heterocyclic ring. The compounds 2, 7a, 7b, 3, 8a, 8b were evaluated in vitro for their antibacterial activity against three genera of Gram negative bacteria; Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and two of Gram positive bacteria, Staphylococcus aureus, S. epidermidis. The novel 1,2,3-seleniadiazole heterocyclic ring compounds (3,8a, 8b) showed very good activity against gram positive bacteria (Staphylococcus aureus, S. epidermidis) and showed moderate antibacterial effect against gram negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia), whereas the semicarbazones compounds (2, 7a, 7b) had not any effect on all types of bacteria in this study. |