Synthesis and Biological Activities of Aspirin-Azo Derivatives

The improvement of new antibacterial drugs has gained attention due to rise of infectious bacteria which provide resistance to the current antibiotic drugs. Besides, the rise of various diseases due to free radical has also encouraged the search for compounds with antioxidant properties. Chemical modification of medicines from natural product-based molecules such as aspirin 1 has become of interest in recent years. Aspirin 1 is a well-known drug with high medicinal values but possess no antibacterial properties and weak antioxidant properties. Hence, the structure of 1 will be modified and incorporated with an active group and metal to enhance its biological activities. In this research, a series of aspirin-azo derivative 36a-m and its Ag(I) complexes 41a-m bearing different halogen at different position have been successfully synthesised. Aspirin-azo derivatives 36a-m were prepared via diazotisation of halogenated aniline followed by diazo-coupling with aspirin 1. Ag(I) complexes 41a-m were prepared by allowing 36a-m to be coordinated with silver nitrate (AgNO3). The structure of all the synthesised compounds and complexes were elucidated using CHN analysis, FTIR and NMR spectroscopies. The antioxidant activities of 36a-m were screened using DPPH assay and gave half concentration of inhibition (IC50) more than 200 ppm, which indicated weak antioxidant activities. The antibacterial activities of 36a-m and 41a-m were demonstrated against E. coli and S. aureus via Turbidimetric kinetic method with minimum inhibitory concentration (MIC) values in range from 74-200 ppm and 64-125 ppm. Aspirinazo 36k bearing iodine at ortho position exhibited strongest antibacterial activities against both E. coli and S. aureus with MIC values of 75 ppm and 64 ppm, respectively in comparison to the standard ampicillin (MIC = 93 ppm and 124 ppm). Antibacterial screening of Ag(I) complexes 41a-m showed MIC values of 82-105 ppm and 72-131 ppm against both E. coli and S. aureus, respectively compared to its azo ligands. The presence of N=N, COOH and halogen Contributed to the antibacterial properties by inhibit the DNA of bacteria which is responsible for multiplication and growth