Some Aryl Sulfonyl Ester-Based Heterocyclic Schiff Bases: Synthesis, Structure Elucidation and Antioxidant Activity

Abstract

In this research work, a series of heterocyclic Schiff base compounds bearing arylsulfonyl ester moiety (2a-i) were designed, synthesized, characterized by spectral techniques such as 1D NMR (1H and 13C), 2D NMR (COSY and HMQC), and FT-IR; and then examined their antioxidant activity was by using four different methods as DPPH, ABTS, CUPRAC, and β-carotenelinoleic acid assays. According to the results obtained, it determined that all synthesized molecules had antioxidant activity. In the DPPH assay, it was found that compound 2e (IC50: 96.23±0.02 μM/mL) demonstrated the antioxidant activity among all synthesized molecules. In ABTS assay, compounds 2e (IC50: 41.88±0.21 μM/mL) and 2g (IC50: 50.75±0.32 μM/mL) were determined to be the molecules with the activity, respectively. Compound 2e (IC50:73.49±0.00 μM/mL) indicated the best antioxidant activity in the CUPRAC assay compared to other synthesize molecules. In the β-carotene-linoleic acid assay, compound 2e (IC50: 58.79±0.58 μM/mL) displayed antioxidant activity than all other synthesized molecules. Compounds 2d (IC50: 74.17±0.22 μM/mL) and 2g (IC50: 66.06±0.13 μM/mL) indicated higher antioxidant activity than the remaining molecules in this series, except for compound 2e. In conclusion, it is thought that this study will contribute to the ongoing studies on the design and synthesis of new antioxidant agents.