Synthesis and Antioxidant Properties of Two New Derivatives of Indeno-Benzofuran

Abstract

Ninhydrin reacts with poly-phenols in different ratios to produce tetracyclic adducts. Here, pyrogallol was used as a polyphenol compound. In the company of acidic ionic liquid (AIL), there was a selective reaction between the ortho-site of polyphenol and the ninhydrin's carbonyl group. Mono-adduct (1:1) 3 and bis-adduct (2:1) 4 were prepared as a solvent and a catalyst for the reaction of ninhydrin with pyrogallol in 1-(carboxymethyl)-3-methyl-1<em>H</em>-imidazolium chloride (mcmimCl). Purity of the products was approved by ¹H NMR,¹³C NMR, IR and Mass Spectroscopy. Moreover, the antioxidant activity of novel derivatives investigated in this paper by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical assay and butylated hydroxytoluene (BHT) was considered to be standard. The results indicated that mono-adduct showed the strongest antioxidant activity (IC50 = 5.289µg/ml).