Authors
Abstract
Background and objectives
Heterocyclic systems with thiadiazole nucleus show a wide spectrum of biological activities such as antioxidant, analgesic, antitumor, and anti-inflammatory activities. The aim of this study is to describe the synthesis of some new 5-(-substituted-1-indol-3-yl)-5-thiazolo[4,3-]-1,3,4-thiadiazole derivatives and to evaluate their antioxidant activity using 2,2º-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity.
Materials and methods
A one-pot reaction of -substituted-1-indol-3-carboxaldehyde , with thioglycolic acid and thiosemicarbazide in concentrated sulfuric acid yielded novel 2-amino-5-(-substituted-1-indol-3-yl)-5-thiazolo[4,3-]-1,3,4-thiadiazoles ,. The reaction of , with some benzenesulfonyl chlorides and/or benzoyl chlorides yielded sulfonamides , and , and benzamide , and , derivatives, respectively, whereas, the reaction of , with chloroacetyl chloride yielded chloroacetamide derivatives ,, which, on cyclization with potassium thiocyanate, yielded thiazolidinone derivatives ,. The reaction of , with sodium azide yielded tetrazole derivatives ,. However, the reaction of , with benzaldehyde yielded Schiff bases ,, which cyclized with chloroacetyl chloride and/or phenacyl bromide to yield azetidinone derivatives , and ,, respectively. However, the reaction of , with sodium cyanide, followed by acid hydrolysis yielded the α-amino acid derivatives ,. Diazotization of , yielded diazonium salt , which, on coupling with sodium azide, yielded the azido derivatives ,. Cyclization of , with ethylacetoacetate yielded tetrazole derivatives ,, whereas the coupling reaction of with malononitrile yielded dicyano derivatives ,, which, on cyclization with hydrazine hydrate, yielded 3,5-diaminopyrazole derivatives ,. The newly synthesized compounds were screened for their antioxidant activity using 2,2º-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity.
Results and conclusion
4-{5-[(1-Indol-3-yl)-5-thiazolo[4,3-]-1,3,4-thiadiazol-2-yl]diazo}-1-pyrazole-3,5-diamine () was highly active with radical-scavenging activity (IC of 69.14 μg/ml) compared with ascorbic acid (IC of 6.50 μg/ml).
Keywords
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