In:
Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 121, No. 14 ( 2024-04-02)
Abstract:
It is well-known that highly reactive hydroxyl radicals (HO • ) can be produced by the classic Fenton system and our recently discovered haloquinone/H 2 O 2 system, but rarely from thiol-derivatives. Here, we found, unexpectedly, that HO • can be generated from H 2 O 2 and thiourea dioxide (TUO 2 ), a widely used and environmentally friendly bleaching agent. A carbon-centered radical and sulfite were detected and identified as the transient intermediates, and urea and sulfate as the final products, with the complementary application of electron spin-trapping, oxygen-18 isotope labeling coupled with HPLC/MS analysis. Density functional theory calculations were conducted to further elucidate the detailed pathways for HO • production. Taken together, we proposed that the molecular mechanism for HO • generation by TUO 2 /H 2 O 2 : TUO 2 tautomerizes from sulfinic acid into ketone isomer (TUO 2 -K) through proton transfer, then a nucleophilic addition of H 2 O 2 on the S atom of TUO 2 -K, forming a S-hydroperoxide intermediate TUO 2 -OOH, which dissociates homolytically to produce HO • . Our findings represent the first experimental and computational study on an unprecedented new molecular mechanism of HO • production from simple thiol-derived sulfinic acids, which may have broad chemical, environmental, and biomedical significance for future research on the application of the well-known bleaching agent and its analogs.
Type of Medium:
Online Resource
ISSN:
0027-8424
,
1091-6490
DOI:
10.1073/pnas.2302967120
Language:
English
Publisher:
Proceedings of the National Academy of Sciences
Publication Date:
2024
detail.hit.zdb_id:
209104-5
detail.hit.zdb_id:
1461794-8
SSG:
11
SSG:
12
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