Novel Benzoxazoles: Synthesis and Antibacterial, Antifungal, and Antitubercular Activity against Antibiotic-Resistant and -Sensitive Microbes

Abstract

A new series of 5-(p-substituted benzamido/phenylacetamido)-2-(p-tert-butylphenyl)benzoxazole derivatives were synthesized and evaluated for their antibacterial, antifungal, and antimycobacterial activities against antibiotic-resistant and -sensitive Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae, and Mycobacterium tuberculosis as well as against Candida albicans and Candida krusei. The compounds possessed broad-spectrum activity against all of the tested Gram-positive and Gram-negative bacteria and yeasts, their minimum inhibitory concentrations (MICs) ranging between 16 -128 μg/ml. One compound exhibited signifi cant antibacterial activity (16 μg/ml) against an antibioticresistant Enterococcus faecalis isolate, having twice the potency of the compared standard drugs vancomycin and gentamycin sulfate. The compounds also showed moderate antitubercular activity with MIC values between 8 -128 μg/ml against Mycobacterium tuberculosis and its clinical isolate. , dd, J = 8.0, J' = 2.0), 8.01 (1H, s), 7.99 -7.98 (1H, d, J = 2.0), 7.81 -7.79 (2H, d, J = 8.0), 7.66 -7.63 (1H, dd, J = 8.8, J' = 2.4), 7.56 -7.52 (3H, m), 7.29 -7.27 (1H, d, J = 8.4), 3.00 (3H, s), 1.37 (9H, s), -NH invisible 385 (100) [M + + H] Brought to you by | University of Georgia Libraries Authenticated Download Date | 6/15/15 7:02 PM 1269, 952 -567 10.32 (1H, s), 8.26 -8.256 (1H, d, J = 2.0), 8.13 -8.11 (2H, d, J = 8.8), 7.91 -7.89 (2H, d, J = 8.0), 7.73 -7.77 (2H, d, J = 1.2), 7.63 -7.61 (2H, d, J = 8.8), 7.36 -7.34 (2H, d, J = 8.0), 3.31 (2H, t), 2.63 -2.67 (2H, m), 1.61 -1.54 (2H, m), 1.30 (9H, s), 0.91 -0.88 (3H, t) 427 (100) [M + 1250, 950 -613 10.32 (1H, s), 8.13 -8.11 (3H, d, J = 8.8), 7.72 -7.70 (1H, d, J = 8.8), 7.65 -7.62 (2H, d, J = 8.4), 7.54 -7.52 (1H, d, J = 8.4), 7.29 -7.27 (2H, d, J = 8.0), 6.91 -6.89 (2H, d, J = 8.4), 3.74 (3H, s),

Benzoxazole Derivatives as Promising Antitubercular Agents

“…Recently, Temiz‐Arpaci group published two articles describing a series of 2‐phenyl/benzyl substituted benzoxazoles with potent antimicrobial activity ,. Firstly, they described the synthesis of series of benzyl substituted benzoxazoles 5 and their antitubercular activity against MTB and its isolate (Table ) .…”

“…Three years later, Temiz‐Arpaci et al. modified the structure 5 with p ‐ tert ‐butylphenyl moiety giving compounds 6 (Table ) . Again, they expected that a lipophilic p‐tert‐ butylphenyl moiety in the position 2 of the benzoxazole part might improve the penetration through the lipophilic mycobacterial cell wall.…”

Bazı Yeni Benzoksazol Türevlerinin Sentezi ve Antimikrobiyal ve Sitotoksik Aktivite Çalışmaları

“…At the end of the reaction, the reaction medium was filtered, and crystallized from ethanol-water. During the synthesis studies, ethyl acetate: n-hexane (1:1) TLC mobile phase was used to monitor the reaction end and to check the purity of the compound (Alper-Hayta et al, 2008;Arisoy et al, 2012;Arisoy et al, 2013;Arisoy et al, 2008).…”

“…The chloroformed phases were collected, and the solvent was evaporated, and the residue was purified by column chromatography. The list of synthesized compounds was given in Table 1.During the synthesis studies, the TLC/column mobile phase of ethyl acetate: n-hexane (1:3) was used to monitor the end of the reaction, purify the resulting compound and purify the resulting compound by column chromatography (Alper-Hayta et al, 2008;Arisoy et al, 2012;Arisoy et al, 2013;Arisoy et al, 2008).Compounds 11 are not original. The 1 H-NMR, 13 C-NMR spectra, and HRMS results agree with those of the proposed structures.…”