Synthesis and Biological Activities of Mono Aspirinate Thiourea-Azo Derivatives

Ferlicia, Rasin (2021) Synthesis and Biological Activities of Mono Aspirinate Thiourea-Azo Derivatives. Masters thesis, Universiti Malaysia Sarawak.

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Abstract

The emergence of bacterial resistance diseases has triggered researchers to search for a precursor derived from natural product-based molecules. Modification of natural product-based molecules such as aspirin has been extensively studied for pharmacological purposes. In this study, a series of new halogenated azo derivatives (55a-i, 56a-i) and mono aspirinate thiourea-azo derivatives (57a-i) have been successfully synthesised using aspirin as a precursor. Halogenated azo derivatives precursors (55a-i) were prepared via coupling reaction of 4-acetamidophenol with commercially available halogenated aniline derivatives with 14-37% yield while aspirinate thiourea-azo derivatives (57a-i) were synthesised via nucleophilic substitution reaction of acetoxybenzoyl isothiocyanate intermediate with synthesised halogenated amine derivatives (56a-i) with 70-90% yield. The structures of all the synthesised compounds were analysed using elemental analysis (CHNS) and characterised via Nuclear Magnetic Resonance (1H and 13C NMR) and Fourier Transform Infrared (FTIR) spectroscopy which correspond to the synthesised compounds. All compounds with concentration of 10 mg/mL were evaluated for antibacterial activities against Escherichia coli (ATCC 25922) and Staphylococcus aureus (S48/81) via disc diffusion assay. Halogenated azo derivatives series (55a-i, 56a-i) showed no inhibition against both bacteria strains. Interestingly, the aspirinate thiourea-azo derivatives (57a-i) showed good antibacterial activity against S. aureus and no inhibition against E. coli. Among all the aspirinate thiourea-azo derivatives (57a-i), only 2-(((3-((2-bromophenyl)diazenyl)-4-hydroxyphenyl)carbamothioyl) carbamoyl)phenyl acetate (57g) showed excellent antibacterial activity with a larger zone of inhibition (10 mm) and comparable to the standard drug, ampicillin. The synthesised hybrid aspirinate thiourea-azo derivatives has the potential in pharmaceutical industries as new drugs with the bacteriostatic property.

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