Abstract
The antioxidant activity of two synthesized coumarins namely, N-(4,7-dioxo-2- phenyl-1,3-oxazepin-3(2H,4H,7H)-yl)-2-(2-oxo-2H-chromen-4-yloxy)acetamide 5 and N-(4-oxo-2-phenylthiazolidin-3-yl)-2-(2-oxo-2H-chromen-4-yloxy)acetamide 6 were studied with the DPPH, hydrogen peroxide and nitric oxide radical methods and compared with the known antioxidant ascorbic acid. Compounds 5 and 6 were synthesized in a good yield from the addition reaction of maleic anhydride or mercaptoacetic acid to compound 4, namely N′-benzylidene-2-(2-oxo-2H-chromen-4-yloxy)acetohydrazide. Compound 4 was synthesized by the condensation of compound 3, namely 2-(2-oxo-2H-chromen-4-yloxy) acetohydrazide, with benzaldehyde. Compound 3, however, was synthesized from the addition of hydrazine to compound 2, namely ethyl 2-(2-oxo-2H-chromen-4-yloxy)acetate, which was synthesized from the reaction of ethyl bromoacetate with 4-hydroxycoumarin 1. Structures for the synthesized coumarins 2–6 are proposed on the basis of spectroscopic evidence.
Highlights
Coumarin and its derivatives represent one of the most active classes of compound possessing a wide spectrum of biological activity [1,2,3,4]
Coumarins are widely used as additives in food, perfumes, cosmetics [13], pharmaceuticals and optical brighteners [14] and would dispersed fluorescent and laser dyes [15]
Classical routes to coumarins incorporate Pechmann, Knoevenagel, Perkin, Reformatsky, and Wittig condensation reactions [21,22,23,24]. To make these classical reactions efficacious, several variations in terms of catalyst and reaction conditions have been introduced [25,26]. 4-Hydroxycoumarin and its derivatives have been effectively used as anticoagulants for the treatment of disorders in which there is excessive or undesirable cloterting, such as thrombophlebitis [27], pulmonary embolism [28], and certain cardiac conditions [29]
Summary
Coumarin and its derivatives represent one of the most active classes of compound possessing a wide spectrum of biological activity [1,2,3,4]. Coumarins have the super thermal stability and outstanding optical properties including extended spectral response, high quantum yields and superior photo stability. Optical applications of these compounds, such as laser dyes, nonlinear optical chromophores, fluorescent whiteners, fluorescent probes, polymer science, optical recording and solar energy collectors have been widely investigated [16,17,18,19,20]. The in vitro antioxidant activities were investigated for the synthesized compounds 5 and 6
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