6450
S. D. Brinkevich, O. I. Shadyro / Bioorg. Med. Chem. Lett. 18 (2008) 6448–6450
Table 2
Effects of AA and compound I on the yields (G) of major products formed in radiolysis of deaerated aqueous solutions of ethylene glycol,
a-methyl glycoside, maltose, 0.1 M a-
glycerophosphate, 0.1 M
a-glucosophosphate at pH 7.
Initial system
Products
G ꢂ 107 (mol/J)
Without additive
AA
I
1 M Ethylene glycol
3 M Ethylene glycol
Acetaldehyde
Acetaldehyde
Methanol
Glucose
Phosphate
Phosphate
3.24 0.19
9.05 1.03
1.72 0.11
1.20 0.10
3.44 0.12
2.63 0.05
1.64 0.15
3.26 0.07
1.10 0.07
0.80 0.10
2.48 0.04
1.78 0.03
2.20 0.37
5.42 0.09
—
0.1 M
a-Methylglucoside
0.1 M Maltose
—
0.1 M
0.1 M
a
a
-Glycerophosphate
-Glucosophosphate
2.53 0.07
2.12 0.06
for products of radiation-induced free-radical fragmentation in
aqueous solutions of ethylene glycol, -methylglycoside, maltose,
-glycerophosphate and -glucose phosphate in the presence of
AA and I are presented in Table 2. As follows from the obtained
data, the test compounds lower the yields of products formed
due to reactions of type (10) on radiolysis of aqueous solutions of
the compounds under study. This fact evidences the capability of
AA to interact with HCR of various structures and to act as a regu-
lator of free-radical processes involving biologically important
compounds.
Thus, the obtained data point to unique properties of ascorbic
acid, which are manifested as the ability to regulate not only oxi-
dation processes of biologically relevant substances, but also
recombination and fragmentation reactions of hydroxyl-contain-
ing biomolecules, induced in biosystems by radiation or other
sources of ROS.
OH
O
HO
a
O
a
a
+ CH3CH2OH
OH
OH
O
ð8Þ
HO
O
O
+
CH3CH2OH
O
O
The low yields of decomposition observed for AA (cf. Table 1) sug-
gest that its regeneration is possible:
OH
O
OH
O
HO
HO
O
OH
OH
esolv ,H
OH
O
O
ð9Þ
OH
O
OH
O
HO
O
O
HO
References and notes
O
O
2
1. Halliwell, B.; Gutteridge, J. M. C. Free Radicals in Biology and Medicine;
University Press: Oxford, 2005.
2. Asard, H.; May, J.; Smirnoff, N. Vitamin C: Function and Biochemistry in Animals
and Plants; BIOS Scientific Publishers: London, 2004.
3. Violi, F.; Cangemi, R.; Loffredo L. In Vitamin C: New Research; Peel, T., Ed.; Nova
Science Publishers: New York, 2006; pp 93–119.
4. Shadyro, O. I. In Free Radicals in Biology and Environment; Minisci, F., Ed.; Kluwer
Academic Publishers: Netherlands, 1997; pp 317–329.
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G.; Sosnovskaya, A. A.; Yurkova, I. L.; Polozov, G. I. Free Radical Res. 2002, 36,
859.
OH
O
Thus, depending on its form (undissociated or mono-anion), AA
is able to act like either donor or acceptor of a hydrogen atom in
reactions with HER.
Unlike HER, its b-substituted analogues, formed in radiolysis of
aqueous ethylene glycol, carbohydrates or organic phosphates
solutions, are able to undergo free-radical fragmentation reactions
according to a general scheme shown below5:
6. Shadyro, O. I.; Sosnovskaya, A. A.; Vrublevskaya, O. N. Int. J. Radiat. Biol. 2003,
79, 269.
X
7. Shadyro, O. I.; Yurkova, I.; Kisel, M.; Brede, O.; Arnhold, J. Free Radical Biol. Med.
2004, 36, 1612.
8. Yurkova, I.; Kisel, M.; Arnhold, J.; Shadyro, O. I. Chem. Phys. Lipids 2005, 134, 41.
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Radiat. Res. 2005, 46, 319.
X
H, OH
- H2,- H2O
- HX
ð10Þ
O
OH
X = OH, OMe, OPO32- etc.
OH
10. Shadyro, O. I.; Kisel, R. M.; Vysotskii, V. V.; Edimecheva, I. P. Bioorg. Med. Chem.
Lett. 2006, 16, 4763.
11. Shadyro, O. I.; Sosnovskaya, A. A.; Edimecheva, I. P.; Ostrovskaya, N. I.; Kazem,
K. M.; Hryntsevich, I. B.; Alekseev, A. V. Bioorg. Med. Chem. Lett. 2007, 17, 6383.
12. Hryntsevich, I. B.; Shadyro, O. I. Bioorg. Med. Chem. Lett. 2005, 15, 4252.
13. Lagutin, P. Yu.; Shadyro, O. I. Bioorg. Med. Chem. Lett. 2005, 15, 3797.
14. Olabisi, A. O.; Wimalasena, K. J. Org. Chem. 2004, 69, 7026.
15. Stafiej, A.; Pyrzynska, K.; Ranz, A.; Lankmayr, E. J. Biochem. Biophys. Methods
2006, 69, 15.
16. Freeman, G. R. Radiation Chemistry of Ethanol; NBS: Washington, 1974.
17. von Sonntag, C. The Chemical Bases of Radiation Biology; Taylor and Francis:
London, 1987.
18. Davies, M. B.; Austin, J.; Partridge, D. A. Vitamin C: Its Chemistry and
Biochemistry; Royal Society of Chemistry: Cambridge, 1991.
19. Eklund, H.; Uhlin, U.; Farnegardh, M.; Logan, D. T.; Nordlund, P. Prog. Biophys.
Mol. Biol. 2001, 77, 177.
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Future Trends; Jonah, C. D.; Rao, B. S. M., Eds.; Elsevier: Amsterdam, 2001; pp.
481–511.
On radiolysis of ethylene glycol, its dehydration takes place, and
this process occurs according to a chain mechanism in concen-
trated solutions (Table 2). Processes of a similar kind are responsi-
ble for modification of carbohydrates and transformation of
ribonucleosides in deoxyribonucleosides.19 Radiolysis of aqueous
solutions of
a-methylglycoside and maltose, where a rupture of
the O-glycoside bond is realized, are a good models for studying
destruction of polysaccharides and cerebrosides under the action
of ROS.9,10 Radiolysis of aqueous solutions of organic phosphates
leads to dephosphorylation. In the case of RNA, reactions of such
kind result in cleavage of phosphodiester bonds,20 and in the case
of phospholipids, the result is formation of phosphatidic acids
playing the role of signaling molecules.7 The yield values obtained