Mosquitoes are the major vectors of parasites and pathogens affecting humans and domestic animals. The widespread development of insecticide resistance and negative environmental effects of most synthetic compounds support an interest in finding and developing alternative products against mosquitoes. Natural coumarins and synthetic coumarin analogues are known for their several pharmacological properties, including being insecticidal. In the present study halogenated coumarins (3-mono/dibromo acetyl, 6-halogenated coumarin analogues) were screened for larvicidal, adulticidal, and repellent properties against Anopheles arabiensis, a zoophilic mosquito that is one of the dominant vectors of malaria in Africa. Five compounds exerted 100% larval mortality within 24 h of exposure. All coumarins and halogenated coumarins reversibly knocked down adult mosquitoes but did not kill them after 24 h of exposure. Repellent properties could not be evidenced. Five compounds were considered potential larvicidal agents for further research and development, while adulticidal activity was considered only mild to moderate.

No abstract

No abstract

Pathogens frequently display resistance to current drugs, which frequently lack selectivity/efficacy and have detrimental side effects. Thus, there is a constant need for novel therapeutic agents. Coumarins belong to the family of lactones, having a benzopyrone system that can be isolated from plants as well as total synthesis that can be carried out in the laboratory. To date, many chemical reactions have been established that can be used to synthesize coumarins. The synthesis of coumarins and their derivatives has attracted the attention of organic and medicinal chemists, as these are widely used as fragrances, pharmaceuticals and agrochemicals. In the present study, the antimicrobial and antioxidant activities of substituted coumarin analogue compounds have been screened. 3-(2-bromoacetyl)-2H-chromen-2-one (CMRN3) and 3-(2, 2-dibromoacetyl)-2H-chromen-2-one (CMRN6) showed bacterial growth inhibition for all the tested species except Klebsiella pneumonia and Bacillus stearothermophilus. CMRN4 and CMRN5 displayed moderate bacterial inhibition against Bacillus cereus, Micrococcus luteus, Staphylococcus aureus. CMRN3 and CMRN6 had a minimum inhibition concentration at 0.75 mg/ml against B. cereus, Bacillus coagulans, and Streptococcus faecalis. They displayed a minimum inhibitory concentration (MIC) of 1.5 mg/ml against Escherichia coli and S. aureus. (CMRN5) displayed an MIC at 0.75 mg/ml against M. luteus and 1.5 mg/ml against S. aureus. Compounds3-(2-bromoacetyl)-6-chloro-2H-chromen-2-one (CMRN4), 3-(2-aminothiazol-4-yl)-6-bromo-2H-chromen-2-one(CMRN7), 3-acetyl-6-bromo-2H-chromen-2-one (CMRN1) exhibited potent antioxidant activity at 85, 61 and 56%, respectively, as evaluated by the DPPH free radical method.

Compounds CMRN1, CMRN2, CMRN4 and CMRN5 can be considered as lead compounds to arrive at a promising anticancer agents.