Sulphonamides are biologically important compounds with low toxicity, many bioactivities and cost-effectiveness. Eight sulphonamide derivatives were synthesised and characterised by FT-IR, ¹³C NMR, ¹H NMR, LC-MS and elemental analysis. Their inhibitory effect on AChE, and carbonic anhydrase I and II enzyme activities was investigated. Their antioxidant activity was determined using different bioanalytical assays such as radical scavenging tests with ABTS^•+, and DPPH^•+ as well as metal-reducing abilities with CUPRAC, and FRAP assays. All compounds showed satisfactory enzyme inhibitory potency in nanomolar concentrations against AChE and CA isoforms with K_I values ranging from 10.14 ± 0.03 to 100.58 ± 1.90 nM. Amine group containing derivatives showed high metal reduction activity and about 70% ABTS radical scavenging activity. Due to their antioxidant activity and AChE inhibition, these novel compounds may be considered as leads for investigations in neurodegenerative diseases.

Sulfonamide derivatives exhibit a wide biological activity and can function as potential medical molecules in the development of a drug. Studies have reported that the compounds have an effect on many enzymes. In this study, the derivatives of amine sulfonamide (1i-11i) were prepared with reduced imine compounds (1-11) with NaBH₄ in methanol. The synthesized compounds were fully characterized by spectral data and analytical. The effect of the synthesized derivatives on acetylcholinesterase (AChE), glutathione S-transferase (GST) and α-glycosidase (α-GLY) enzymes were determined. For the AChE and α-GLY, the most powerful inhibition was observed on 10 and 10i series with K _I value in the range 2.26 ± 0.45–3.57 ± 0.97 and 95.73 ± 13.67–102.45 ± 11.72 µM, respectively. K _I values of the series for GST were found in the range of 22.76 ± 1.23–49.29 ± 4.49. Finally, the compounds have a stronger inhibitor in lower concentrations by the attachment of functional electronegative groups such as two halogens (-Br and -CI), -OH to the benzene ring and -SO₂NH₂. The crystal structures of AChE, α-GLY, and GST in complex with selected derivatives 4 and 10 show the importance of the functional moieties in the binding modes within the receptors. Communicated by Ramaswamy H. Sarma