The objectives are to synthesize of 2-mercaptobenzoxazole derivatives with amino acetylenic
side chain as new and possibly with excellent antimicrobial agents, to reach structural
selectivity of higher antifungal activity without or low antibacterial interference. A new series
of 2-{[4-(t-amino-1-yl)but-2-yn-1-yl]sulfanyl}-1,3-benzoxazole derivatives (HZ1-HZ8) were
synthesized, and structural elucidation was confirmed through UV-HPLC, FT-IR,1HNMR,
13C-NMR by the aid of Bruker FT-IRand elemental analyses, by the aid of the Varian
300MHZ spectrometer. An antimicrobial activity evaluation was done by agar diffusion
methods, broth dilution test, and kinetic ofthe killing against Staphylococcus aureus (ATCC
6538p), Escherichia coli (ATCC 8739), Pseudomonas aeruginosa (ATCC 9027), Bacillus
subtilis (ATCC 6633), Candida. albicans (ATCC10231) and Aspergillus. Brasiliensis
(ATCC16404). The minimum inhibitory concentrations (MIC) and the minimum bactericidal
concentration (MBC) were determined and compared to two positive control drugs
(ciprofloxacin 85.51% and fluconazole 99.9%). The synthesized compounds were consistent
with the assigned structures as illustrated by UV-HPLC, FT-IR, DSC, 1H-NMR,13C-NMR
and elemental analysis results. Compounds 2-{[4-(pyrrolidin-1-yl)but-2-yn-1-yl]sulfanyl}-1,3-benzoxazoleHZ2, 2-{[4-(2-methyllindolin-1-yl)but-2-yn-1-yl]sulfanyl}-1,3-benzoxazole
HZ3, 2{[4-(4-methylpiperazine-1-yl)but-2-yn-1-yl]sulfanyl}-1,3-benzoxazoleHZ4, 2-{[4-(2-
methylpiperidin-1-yl)but-2-yn-1-yl]sulfanyl}-1,3-benzoxazole HZ5, 2-{[4-(2-morphline-1-
yl)but-2-yn-1-yl]sulfanyl}-1,3-benzoxazole HZ6, 2-{[4-(piperidin-1-yl)but-2-yn-1-
yl]sulfanyl}-1,3-benzoxazole HZ7 and 2-{[4-(azepane-1-yl)but-2-yn-1-yl]sulfanyl}-1,3-
benzoxazoleHZ8 demonstrated the highest antifungal activity against C. albicanswith MIC
value of 125 ?g/ml. The most active compound against A. brasiliensis was 2-{[4-(2-
morphline-1-yl)but-2-yn-1-yl]sulfanyl}-1,3-benzoxazole HZ6 with zone of inhibition of35
mm. In conclusion these results verified the selectivity of these synthesized compounds to
antifungal activity compared to their antibacterial activity. These data promote our interest
for further structural modification to reach structural selectivity for higher antifungal activity.
Keywords: 2-mercaptobenzoxazole, Aminoacetylenic, antibacterial, antifungal,
ciprofloxacin, fluconazole
https://ijbpas.com/pdf/2018/February/1517811975MS IJBPAS 2018 4379.pdf
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