Replication data for chelating ability of: "Natural and Nature-Inspired Catechol Siderophores: A Promising Strategy for Rice Blast Management"

Preparation of CAS Reagent. 100 mL graduated glass cylinder was previously washed with 6 M HCl. Six mL of 10 mM solution of hexadecyltrimethylammonium bromide (HDTMA) (22 mg in 6 mL distilled water) was poured into the cylinder and diluted to 40 mL with distilled water. While stirring, 1.5 mL of 1 mM ferric iron solution (2.7 mg of FeCl3·6 H2O in 10 mL HCl 1 M) was added, whereupon 7.5 mL of 2 mM Chrome Azurol S (CAS) solution (9.1 mg in 7.5 mL distilled water) was slowly added.
In a separate flask, 2.5 M solution of piperazine (4.31 g in 20 mL distilled water) was prepared and cooled to 0 °C and 6.25 mL of concentrated HCl was carefully added. The piperazine solution was added to the CAS/Fe3+ solution in the cylinder and then brought to a final volume of 100 mL with distilled water. Lastly, sulfosalicylic acid (102 mg) was added. The final blue solution was stored in a polyethylene falcon in a cool and dark place.
Compounds. The assay was done in triplicate. EDTA was selected as a positive control, whereas the negative control (N.C.) was the blank solution of H2O:DMSO 9:1 v/v.
Results: The chelating ability of the synthesized compounds was evaluated by the Chrome azurol S (CAS) assay. The tested compounds were dissolved in H2O:DMSO
9:1 v/v at 1 mg/mL concentration. 100 μL of the solution of the tested compound and 100 μL of CAS reagent were added into the same well of the 96 Microwell plate (final
concentration 0.5 mg/mL) and allowed to react for 30 min. The results evidenced that the 2,3-dihydroxy substituted benzamides have a significant chelating capability, comparable to the reference compound EDTA except for aminochelin. Conversely,
3,4-dihydroxy benzamides, with the catechol group shifted away from the amide moiety, had a lower chelating activity.
The results evidenced that the 2,3-dihydroxy substituted benzamides have a significant chelating capability, comparable to the reference compound EDTA. (see compounds 2, 3, 7a−c, 11, 16a−b) except for the natural compound 1. Conversely, 3,4-dihydroxy benzamides, with the catechol group shifted away from the amide moiety, had a lower chelating activity (7d−e, 16c). As expected, compounds 14a−e, lacking the catechol group, did not show any significant ability to chelate iron.