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Organochalcogen Substituents in Phenolic Antioxidants
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry. (Lars Engman)
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2010 (English)In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 12, no 10, 2326-2329 p.Article in journal (Refereed) Published
Abstract [en]

Little is known about the ED/EW character of organochalcogen substituents and their contribution to the O-H bond dissociation enthalpy (BDE) in phenolic compounds. A series of ortho- and para-(S,Se,Te)R-substituted phenols were prepared and investigated by EPR, IR, and computational methods. Substituents lowered the O-H BDE by >3 kcal/mol in the para position, while the ortho-effect was modest due to hydrogen bonding ( approximately 3 kcal/mol) to the O-H group.

Place, publisher, year, edition, pages
2010. Vol. 12, no 10, 2326-2329 p.
National Category
Chemical Sciences
URN: urn:nbn:se:uu:diva-122483DOI: 10.1021/ol100683uISI: 000277531000040PubMedID: 20405887OAI: oai:DiVA.org:uu-122483DiVA: diva2:310244
Available from: 2010-04-13 Created: 2010-04-13 Last updated: 2011-02-02Bibliographically approved
In thesis
1. Exploring Novel Catalytic Chalcogenide Antioxidants
Open this publication in new window or tab >>Exploring Novel Catalytic Chalcogenide Antioxidants
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis is concerned with the synthesis and evaluation of regenerable chalcogen containing antioxidants. Variously substituted 2,3-dihydrobenzo[b]selenophene-5-ol antioxidants were evaluated in order to gain information about structure/reactivity-relationships. Within the series explored, the most regenerable unsubstituted compound inhibited lipid peroxidation for more than 320 minutes when assayed in a two-phase lipid peroxidation model in the presence of N-acetylcysteine (NAC). α-Tocopherol which could inhibit lipid peroxidation for 90 minutes under similar conditions was therefore easily outperformed. The antioxidant activity of the parent was also documented in an aqueous environment. The best catalyst quenched/inhibited ROS production by neutrophils and PMA-stimulated macrophages more efficiently than Trolox. In addition, over a period of seven days, no disruption in proliferation for the cell lines used was observed when exposed to our synthetic compound or Trolox at a concentration of 60 µM.

3-Pyridinols substituted with alkyltelluro groups in the ortho-position were more regenerable in the two-phase model than their corresponding para-substituted analogues in the presence of NAC and also inhibited autoxidation of styrene in a catalytic fashion in homogenous phase in the presence of N-tert-butoxycarbonyl cysteine methyl ester (LipCys), a lipid-soluble analogue of NAC. The best inhibitors quenched peroxyl radicals more efficiently than α-tocopherol. They could also catalyze reduction of organic hydroperoxides in the presence of thiols and therefore mimic the action of the glutathione peroxidase enzymes. Mechanisms for the catalysis are proposed.

Octylthio, octylseleno and octyltelluro analogues of butylated hydroxyanisole (BHA) were synthesized and evaluated. Among these, the tellurium compound was superior to α-tocopherol in the presence of NAC both when it comes to quenching capacity and regenerability.  Organochalcogen substituent effects in phenolic compounds were studied by using EPR, IR and computational methods.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2010. 71 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 742
antioxidant, tellurium, selenium, catalytic, toxicity, ROS, neutrophil, glutathione peroxidase mimic, macrophage.
National Category
Organic Chemistry
Research subject
Chemistry with specialization in Organic Chemistry
urn:nbn:se:uu:diva-122485 (URN)978-91-554-7803-2 (ISBN)
Public defence
2010-06-03, B41, BMC, Husargatan 3, 751 23, Uppsala, 10:15 (English)
Available from: 2010-05-11 Created: 2010-04-13 Last updated: 2010-05-18

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