Regenerable Antioxidants - Introduction of Chalcogen Substituents into Tocopherols
2015 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, no 6, 2447-2457 p.Article in journal (Refereed) Published
To improve the radical-trapping capacity of the natural antioxidants, alkylthio-, alkylseleno-, and alkyltelluro groups were introduced into all vacant aromatic positions in β-, γ- and δ-tocopherol. Reaction of the tocopherols with electrophilic chalcogen reagents generated by persulfate oxidation of dialkyl dichalcogenides provided convenient but low-yielding access to many sulfur and selenium derivatives, but failed in the case of tellurium. An approach based on lithiation of the appropriate bromo-tocopherol, insertion of chalcogen into the carbon-lithium bond, air-oxidation to a dichalcogenide, and final borohydride reduction/alkylation turned out to be generally applicable to the synthesis of all chalcogen derivatives. Whereas alkylthio- and alkylseleno analogues were generally poorer quenchers of lipid peroxyl radicals than the corresponding parents, all tellurium compounds showed a substantially improved radical-trapping activity. Introduction of alkyltelluro groups into the tocopherol scaffold also caused a dramatic increase in the regenerability of the antioxidant. In a two-phase lipid peroxidation system containing N-acetylcysteine as a water-soluble co-antioxidant the inhibition time was up to six-fold higher than that recorded for the natural antioxidants.
Place, publisher, year, edition, pages
2015. Vol. 21, no 6, 2447-2457 p.
IdentifiersURN: urn:nbn:se:uu:diva-243231DOI: 10.1002/chem.201405895ISI: 000348510400023OAI: oai:DiVA.org:uu-243231DiVA: diva2:786459
De två första författarna delar förstaförfattarskapet.2015-02-052015-02-052016-09-04Bibliographically approved