CAS agar Assay

Chrome Azurol S (CAS) agar plates were prepared according to procedure described by Schwyn and Neilands [53]. The principle of CAS assay is CAS remains blue in color when complexed with iron but turns into orange color halo when iron is chelated by iron chelators. In CAS agar plate, formation of orange halos indicates the iron chelation properties of the given compound. Briefly, 2 μL of EA or UA mixed with or without FeCl₃ at indicated concentrations were placed on CAS plate and monitored for orange-color halo formation. The intensity of halo formation is directly proportional to the concentration of chelated iron. EGCG (Sigma-Aldrich) was used as a positive control [51].