Benzoxazole derivatives: design, synthesis and biological evaluation

Abstract

Background: A new series of benzoxazole analogues was synthesized and checked for their in vitro antibacterial, antifungal and anticancer activities.

Results and discussion: The synthesized benzoxazole compounds were confirmed by IR, ¹H/¹³C-NMR, mass and screened for their in vitro antimicrobial activity against Gram-positive bacterium: Bacillus subtilis, four Gram-negative bacteria: Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella typhi and two fungal strains: Candida albicans and Aspergillus niger using tube dilution technique and minimum inhibitory concentration (MIC) was noted in µM and compared to ofloxacin and fluconazole. Human colorectal carcinoma (HCT116) cancer cell line was used for the determination of in vitro anticancer activity (IC₅₀ value) by Sulforhodamine B assay using 5-fluorouracil as standard drug.

Conclusion: The performed study indicated that the compounds 1, 10, 13, 16, 19, 20 and 24 had highest antimicrobial activity with MIC values comparable to ofloxacin and fluconazole and compounds 4, 6, 25 and 26 had best anticancer activity in comparison to 5-fluorouracil.

Keywords: Anticancer; Antimicrobial; Benzoxazole; Characterization; Synthesis.

Fig. 1

Marketed drugs containing benzoxazole

Fig. 2

Design of benzoxazole molecules for antimicrobial and anticancer potential based on literature

Scheme 1

Synthesis of 2-(2-((benzo[d]oxazol-2-ylthio)methyl)-1H-benzo[d]imidazol-1-yl)acetohydrazide derivatives

Fig. 3

Antibacterial screening results against Gram positive and Gram negative species

Fig. 4

Antifungal screening results against fungal species

Fig. 5

Structure activity relationship of the synthesized compounds