Mechanism of augmentation of organotin decomposition by ferripyochelin: formation of hydroxyl radical and organotin-pyochelin-iron ternary complex.

Pyochelin (PCH), a kind of siderophore secreted by Pseudomonas aeruginosa, was recently found to have triphenyltin (TPT)-decomposing capacity. In this work, significant augmentation of TPT decomposition by ferripyochelin (FePCH), the chelating compound of PCH with iron, was demonstrated in Tris-HCl buffer (pH 8.0). The generation of hydroxyl radical (HO.) in the presence of FePCH was observed. Inhibition of HO. generation by adding catalase and HO. scavengers (methanol and dimethyl sulfoxide) decreased TPT decomposition, while an increase in HO. formation in the presence of H(2)O(2) enhanced its decomposition. Our findings indicated that HO. generated in the reaction system was responsible for the enhanced TPT decomposition by FePCH versus PCH. The existence of the TPT-pyochelin-iron ternary complex was demonstrated by electron spray ionization-mass spectrometry, tandem mass spectrometry, and (1)H nuclear magnetic resonance. On the basis of the above results, HO. produced in the presence of FePCH was deduced to be in close proximity to TPT and has more opportunity to attack the Sn-C bond, which resulted in the enhanced organotin decomposition. The information obtained may have considerable environmental significance.