PMID- 23876337
OWN - NLM
STAT- MEDLINE
DCOM- 20140318
LR  - 20171116
IS  - 1464-3391 (Electronic)
IS  - 0968-0896 (Linking)
VI  - 21
IP  - 17
DP  - 2013 Sep 1
TI  - Tocopheramines and tocotrienamines as antioxidants: ESR spectroscopy, rapid 
      kinetics and DFT calculations.
PG  - 5039-46
LID - S0968-0896(13)00581-6 [pii]
LID - 10.1016/j.bmc.2013.06.050 [doi]
AB  - Tocopheramines (TNH2) and tocotrienamines (T3NH2) are analogues of tocopherols 
      (TOH) and tocotrienols in which phenolic OH is replaced by NH2. It was shown in 
      previous studies that TNH2 and T3NH2 act as potent antioxidants. In this study we 
      compared the one-electron oxidation of TNH2/T3NH2 by diphenyl picryl hydrazyl 
      (DPPH) and galvinoxyl (GOX) radicals with the one of alpha-TOH as a reference 
      compound using ESR spectroscopy, stopped flow spectrophotometry and density 
      functional theory (DFT) calculations. ESR spectroscopy revealed the presence of 
      tocopheramine radicals during electrochemical oxidation of alpha-TNH2. Kinetic 
      measurements demonstrated that in apolar n-hexane TNH2/T3NH2 derivatives reacted 
      two to three orders of magnitude slower than alpha-TOH with the model radicals. DFT 
      calculations indicated that this correlates well with the higher bond 
      dissociation energy (BDE) for N-H in TNH2 than for O-H in alpha-TOH in pure H-atom 
      transfer (HAT). In the more polar medium ethanol TNH2/T3NH2 derivatives partially 
      reacted faster than alpha-TOH depending on the reaction partner. DFT calculations 
      suggest that this is due to reaction mechanisms alternative to HAT. According to 
      thermochemistry data sequential proton loss and electron transfer (SPLET) is more 
      favored for alpha-TOH in ethanol than for TNH2. Therefore, for TNH2 a contribution of 
      the alternative mechanism of sequential electron transfer-proton transfer 
      (SET-PT) could be a possible explanation. These data show that the antioxidant 
      reactivity strongly depends on the structure, reaction partners and environment. 
      According to these findings TNH2/T3NH2 should be superior as antioxidants over 
      alpha-TOH in polar head group regions of membranes but not in the apolar core of 
      lipid bilayers.
CI  - Copyright (c) 2013 Elsevier Ltd. All rights reserved.
FAU - Bamonti, Luca
AU  - Bamonti L
AD  - Dept. of Internal Medicine, Laboratory of Clinical and Nutritional Biochemistry, 
      University of Perugia, I-06123 Perugia, Italy.
FAU - Hosoya, Takashi
AU  - Hosoya T
FAU - Pirker, Katharina F
AU  - Pirker KF
FAU - Bohmdorfer, Stefan
AU  - Bohmdorfer S
FAU - Mazzini, Francesco
AU  - Mazzini F
FAU - Galli, Francesco
AU  - Galli F
FAU - Netscher, Thomas
AU  - Netscher T
FAU - Rosenau, Thomas
AU  - Rosenau T
FAU - Gille, Lars
AU  - Gille L
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20130702
PL  - England
TA  - Bioorg Med Chem
JT  - Bioorganic & medicinal chemistry
JID - 9413298
RN  - 0 (Antioxidants)
RN  - 0 (Tocotrienols)
RN  - R0ZB2556P8 (Tocopherols)
SB  - IM
MH  - Antioxidants/*chemistry
MH  - Electron Spin Resonance Spectroscopy
MH  - Kinetics
MH  - Oxidation-Reduction
MH  - Tocopherols/*chemistry
MH  - Tocotrienols/*chemistry
OTO - NOTNLM
OT  - DFT calculations
OT  - ESR spectroscopy
OT  - Radicals
OT  - Stopped flow spectrophotometry
OT  - Tocopheramines
EDAT- 2013/07/24 06:00
MHDA- 2014/03/19 06:00
CRDT- 2013/07/24 06:00
PHST- 2013/05/07 00:00 [received]
PHST- 2013/06/19 00:00 [revised]
PHST- 2013/06/20 00:00 [accepted]
PHST- 2013/07/24 06:00 [entrez]
PHST- 2013/07/24 06:00 [pubmed]
PHST- 2014/03/19 06:00 [medline]
AID - S0968-0896(13)00581-6 [pii]
AID - 10.1016/j.bmc.2013.06.050 [doi]
PST - ppublish
SO  - Bioorg Med Chem. 2013 Sep 1;21(17):5039-46. doi: 10.1016/j.bmc.2013.06.050. Epub 
      2013 Jul 2.