Many clinical studies have evaluated the ability of sulfur-containing antioxidants to prevent oxidative stress, a major cause of cancer, Parkinson's, and Alzheimer's disease. Cysteine complexes of manganese modified with citric acid were synthesized by a one-pot procedure in two molar ratios and at two different temperatures (90°C, 140°C). The synthesized complexes were studied using FT-IR, UV-Vis, NMR, and EDX. At the lower temperature, a hydrogel was formed, and a thiazolopyridine ring was formed at a temperature of 140°C which was complexed with manganese. Infrared and electronic absorption spectroscopy confirmed that manganese binding occurred via the oxygen atoms of COO. The complexes also exhibited strong fluorescence with excitation/emission peak wavelengths of 350/418 nm. The synthesized compounds showed efficient activity for superoxide scavenging (> 70%), which was evaluated