Synthesis, antioxidant activity of novel sulfonamide and sulfonate organic salts bearing various heterocyclic moieties.

Abstract

Aim: The reactions of various heterocyclic primary amines with sulfonyl chloride derivatives or with sulfosalicylic acid results in the first case to the formation of sulfonamide derivatives and in the second case to the formation of sulfonate organic salts which are both hybrid molecule that integrate multiple pharmacophores into a single scaffold.

Materials and methods: The novel sulfonamide derivatives 3 were obtained through mono-nucleophilic addition reactions of the corresponding primary amines to the appropriate sulfonyl derivative. In contrast, the sulfonate organic salts 5, 7 and 8 were formed as the result of an acid-base neutralization reaction, during which a molecule of amine captures the acid proton from the sulfosalicylic acid molecule. The antioxidant activity of the synthesized compounds is evaluated by determining their DPPH (2,2-Diphenyl-1-picrylhydrazyl) free radical scavenging activity as well as gallic acid equivalent antioxidant capacity (GEAC).

Results and conclusion: The structures of compounds 3, 5, 7 and 8 were confirmed through elemental analysis, IR (Infrared), UV-Vis (ultraviolet-visible), ¹H-NMR (Proton nuclear magnetic resonance), ¹³C-NMR (Carbon-13 nuclear magnetic resonance) and HRMS (High-Resolution Mass Spectrometry) spectroscopic data. Organic salt 7a was characterized by single-crystal and X-ray diffraction. Organic sulfonate salts were found to be more active than covalent sulfonamide derivatives.