Design, synthesis, and biological evaluation of N-propionylcysteamine-functionalized calix[n]arenes: antioxidant and enzyme inhibitory activities

In this study, calix[n]arenes were functionalized with N-propionylcysteamine via phenolic moieties, followed by ipso-sulfonation to improve water solubility. Sulfonated derivatives calix[4]arene (C4-4) and calix[8]arene (C8-4) were characterized by FT-IR, 1H NMR, and 13C NMR. Antioxidant activities were determined using DPPH, ABTS• radical scavenging, and Fe(II) chelation assays. At a concentration of 1 mM, DPPH scavenging was 36.45% (C4-4) and, 36.02% (C8-4); Fe(II) chelation 33.33% and, 32.65%; ABTS• scavenging 33.41% and, 39.54%. Both compounds moderately inhibited acetylcholinesterase and α-glucosidase. These results indicate that sulfonated cysteamine-calixarenes possess notable antioxidant potential and moderate enzyme inhibition, making them promising scaffolds for multifunctional bioactive molecule development.