Restricted Rotation in α-Carbonyl Radicals

1974 ◽  
Vol 52 (3) ◽  
pp. 524-526 ◽  
Author(s):  
Terry Foster ◽  
Dieter Klapstein ◽  
Paul Ronald West
Keyword(s):  
Aqueous Solution ◽  
Electron Spin Resonance ◽  
Electron Spin ◽  
Reductive Elimination ◽  
Restricted Rotation ◽  
Radical Intermediates ◽  
Spin Resonance ◽  
Radical Fragmentation ◽  
Direct Abstraction

Electron spin resonance spectra of tertiary α-carbonyl radicals, R1R2ĊCOR3 (R1R2R3 = H, alkyl), at 24 °C in aqueous solution show fully restricted rotation about the Ċ—CO bond. The effect is identified by differing h.f.s. constants for equivalent substituents R1 and R2. The radical intermediates are generated by direct abstraction, radical fragmentation, and reductive elimination processes.

scholarly journals Antioxidant activity of Induna apple pomace extract

2005 ◽  
pp. 239-246 ◽  
Author(s):  
Sladjana Savatovic ◽  
Sonja Djilas ◽  
Vesna Tumbas ◽  
Jasna Canadanovic-Brunet ◽  
Gordana Cetkovic
Keyword(s):  
Aqueous Solution ◽  
Antioxidant Activity ◽  
Acetic Acid ◽  
Electron Spin Resonance ◽  
Hydroxyl Radicals ◽  
Electron Spin ◽  
Esr Spectroscopy ◽  
Methanol Extract ◽  
Apple Pomace ◽  
Spin Resonance

Different concentrations ofmethanol aqueous solution with or without 0.5% acetic acid and 80% acetone were used to achieve the highest yield of extraction of phenolics from Induna apple pomace. The highest content of phenolics (6.38 mg/g) was detected in the 80% methanol extract. The influence of 80% methanol extract of Induna apple pomace on stable l,l-diphenyl-2-picrylhydrazyl (DPPH) and reactive hydroxyl radicals has been investigated by electron spin resonance (ESR) spectroscopy. Based on the obtained results it can be concluded that the investigated extract is more effective in the DPPH test than on the DMPO-OH scavenging. In both cases antioxidant activity increased with increasing concentration of the investigated extract. The high contents ofphenolics (6.38 mg/g), flavonoids (1.01 mg/g) and flavan-3-ols (0.70 mg/g) in 80% methanol extract indicated that these compounds contributed to the antioxidant activity of Induna apple pomace.

scholarly journals ESR and Optical Studies on the Interaction between Cu(II) and Pepsin

1978 ◽  
Vol 33 (5-6) ◽  
pp. 321-325 ◽  
Author(s):  
L. Sportelli ◽  
H. Neubacher ◽  
W. Lohmann
Keyword(s):  
Aqueous Solution ◽  
Electron Spin Resonance ◽  
Reaction Time ◽  
Conformational Change ◽  
Optical Spectroscopy ◽  
Electron Spin ◽  
Molar Ratio ◽  
Optical Studies ◽  
Spin Resonance

Abstract The interaction of Cu (II) with the protein pepsin has been investigated by means of electron spin resonance (ESR) and optical spectroscopy. Depending on the molar ratio of Cu(II) and pepsin in aqueous solution two different complexes are formed. A third complex can be detected after a reaction time of several days, attributed to a complex with a conformationally changed pepsin. The presence of inhibitors 1,2-epoxy-3-phenoxypropane (EPP) or diazoacetyl-ethylester (DAE) seems to hinder the conformational change. The structure of the three complexes is discussed.

Sign in / Sign up

Export Citation Format

Share Document