Capacity of Ascorbyl Palmitate to Produce
the Ascorbyl Radical in Vitro: an Electron Spin Resonance Investigation
M. POKORSKI1, B. GONET2
1Department of Respiratory Research, Medical Research Center,
Polish Academy of Sciences, Warsaw, and 2Department of Medical
Physics, Pomeranian Academy of Medicine, Stettin, Poland
Received February 21, 2003
Accepted May 19, 2003
Summary
This study aims to compare the electron spin resonance (ESR) spectra
emitted by human blood loaded with either ascorbyl-6-palmitate (AP), a
lipid-soluble derivative of ascorbic acid (AA), or with AA. Whole blood of
a healthy male individual was equilibrated with equimolar concentrations
of AP and AA of 200, 400, and 800 μmol/l. The intensity of the ESR signal,
expressed as the peak-to-peak amplitude, reflects the amount of unpaired
spins that are created due to the reducing action of AA and is
proportional, in relative terms, to the amount of the ascorbyl radical
formed. We found that the blood with AP emitted an ESR signal whose
singlet shape, width, and location precisely correlate with the known
characteristics of the ascorbyl radical in vitro. The signal magnitude
increased linearly with increasing concentrations of AP and was similar to
that of AA. We conclude that AP is biologically active, as it generates
the ascorbyl radical, an action that also underlies the scavenging process
by ascorbic acid. To this end, ascorbyl-6-palmitate might have potential
advantages, due to its ability to penetrate biomembranes and to act at the
lipid-related molecular target sites.
Key words
Ascorbate • Ascorbyl palmitate • Ascorbyl radical • Electron spin
resonance spectroscopy • ESR signal
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