Synthesis and DPPH radical-scavenging effect of novel heterocyclic derivatives of 2-amino-4-(1-benzoylindol-3-yl)selenophene-3-carbonitrile

Background and objectives Selenophene moiety is one of the heterocyclic compounds with a selenium atom that plays a vital role in biological fields such as antioxidant, antidepressant, anticonvulsant, antimicrobial, and anticancer activities. The aim of this study was to describe the synthesis of some new heterocycles derived from 2-amino-4-(1-benzoylindol-3-yl)selenophene-3-carbonitrile derivatives and to evaluate their 2,2Ͳ-diphenyl-1-picrylhydrazyl radical-scavenging activity. Materials and methods 2-Amino-4-(1-benzoylindol-3-yl)selenophene-3-carbonitrile ( 3 ) was prepared and allowed to react with each of formic acid, formamide, carbon disulfide, urea, thiourea, malononitrile, or ethyl cyanoacetate to yield selenolo[2,3-d]pyrimidines 4-7 and selenolo[2,3-b]pyridine derivatives 8 and 9 , respectively. Moreover, reaction of compound 3 with hydrochloric acid or acetic anhydride in glacial acetic acid yielded selenolo[2,3-d]pyrimidin-4-one 10 and selenoacetamide derivative 11 , respectively. In contrast, reaction of Schiff base 12 with thioglycolic acid, phenacyl bromide, or chloroacetyl chloride yielded thiazolidine 13 and azidatine derivatives 14 and 15 , respectively. Reaction of compound 3 with some substituted benzenesulfonyl chlorides yielded sulfonamide derivatives 16a, b, c , respectively. Moreover, 2-amino-1,3,4-thiadiazole 19 and 4-oxo-2-iminothiazolidine derivatives 21 were prepared through cyclization of hydrazinecarbothioamide 18 or chloroacetamido derivative 20, respectively. The fusion of 3 with succinic anhydride yielded pyrrolidine-2,5-dione 23 , whereas heating of 3 with succinic anhydride in ethanol yielded succinamic acid derivative 24 . The newly synthesized compounds were screened for their 2,2Ͳ-diphenyl-1-picrylhydrazyl radical-scavenging activity. Results and conclusion Compound 8 showed promising activity with a radical-scavenging effect (IC 50 ) of 166.40 μg/ml compared with ascorbic acid (an IC 50 of 129.64 μg/ml) as a reference standard.