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INTRODUCTION
Physicochemically, natural waters are complex
nonstationary multicomponent redox system [1, 2]. It
is universally accepted that natural waters, including
seawater, are oxidizing media [3]. However, the redox
state of an aqueous medium is determined by a set of
redox reactions which take place in this medium
(some of these reactions yield reducing substances);
therefore, this state is subject to change, depending on
the time of day, season, and biogenic activity, and
varies up to a quasi-reducing state [3]. The oxidizing
properties of natural water are largely determined by
dissolved atmospheric oxygen. The one-electron re
-
duction of oxygen gives rise to reactive oxygen spe
-
cies, which can cause damage to biological mole
-
cules. Therefore, the necessity of protecting from
such a damage emerges [4]. It was previously shown
that heating activates redox processes in water and
aqueous solutions [5–8]. In pure water saturated with
atmospheric gases, an electron donor can be hydroxyl
ions [7]. The electron donor properties of hydroxyl
942
Biophysics, Vol. 48, No. 6, 2003, pp. 942–949. Translated from Biofizika, Vol. 48, No. 6, 2003, pp. 1022–1029.
Original Russian Text Copyright © 2003 by Bruskov, Chernikov, Gudkov, Massalimov.
English Translation Copyright © 2003 by MAIK “Nauka / Interperiodica” (Russia).
MOLECULAR BIOPHYSICS
Thermal Activation of the Reducing Properties
of Seawater Anions
V. I. Bruskov, A. V. Chernikov, S. V. Gudkov, and Zh. K. Massalimov
Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences,
Pushchino, Moscow Region, 142290 Russia
E-mail: bruskov_v2000@mail.ru
Received June 11, 2003
A tiny atom in this world of troubles
Don’t be the fierce kT’s subordinate
Don’t stumble over everyday life’s hubbles
Hold on your way in your coordinate
L.A. Blumenfeld
AbstractUsing Ellman’s reagent [5,5′-dithiobis(2-nitrobenzoic acid)], it was shown that thermally acti-
vated reducers in seawater are bicarbonate and chloride anions and that their joint effect is superadditive.
Sulfate anions do not exhibit such properties. By studying enhanced chemiluminescence in the
luminol–p-iodophenol–peroxidase system, the formation of hydrogen peroxide and the effect of seawater
anions on the thermally activated hydrogen peroxide production were investigated. In NaCl and NaHCO
3
solutions whose concentrations and pH are close to those for seawater, heating increases the H
2
O
2
produc-
tion more significantly than it increases the H
2
O
2
production in water, with sulfate anions suppressing the
formation of H
2
O
2
. Using coumarin-3-carboxylic acid, a fluorescent probe for hydroxyl radicals, it was
shown that heating considerably increases the OH
.
production in the presence of chloride and bicarbonate
anions. This increase is caused by the electron donor properties of these anions in the decomposition of hy-
drogen peroxide. The results obtained were considered from the standpoint of equivalence between heat and
electromagnetic blackbody radiation. It was assumed that the spectrum of this radiation contains signals of
high-energy quanta causing the dissociation of anions to form a hydrated electron and radicals. These radi
-
cals further recombine to yield various molecular products.
Key words: water; anions, reducing properties; hyperthermia; hydroxyl radicals; hydrogen production; hy
-
drated electron; thermal electromagnetic radiation; radicals, formation and recombination
Abbreviations: TNA, 5-thio-2-nitrobenzoic acid; 7-OH-3-CCA,
7-hydroxycoumarin-3-carboxylic acid.
BIOPHYSICS Vol. 48 No. 6 2003
ions were experimentally discovered for the first time
by EPR spectroscopy by L.A. Blumenfeld and col
-
leagues forty years ago [9]. However, this achieve
-
ment was not properly appreciated at that time, was
disbelieved, and passed into oblivion. Much later, the
fundamental possibility of the formation of an OH
.
–
e
aq
−
electron–radical pair from the hydroxyl ion was theo
-
retically substantiated by Kloss [10] without referring
to Blumenfeld and colleagues [9].
It has recently been shown that heating of sea
-
water gives rise to both hydroxyl radicals and reduc
-
ing substances [8]. It is generally assumed that elec
-
tron donors in biological systems are mainly cations
of transition metals, such as iron and copper. In this
work, we showed that, along with hydroxyl ions
[7–10], the reducing properties are also exhibited by
bicarbonate anions and chloride anions, which are
contained in seawater and can be thermally activated,
acting as electron donors, whereas sulfate anions do
not have such properties. The effect of the reducing
properties of bicarbonate and chloride anions on the
production of hydrogen peroxide and hydroxyl radi-
cals on heating was studied.
EXPERIMENTAL
Artificial seawater was prepared by dissolving
sea salt (Tropical Marine, UK) to a concentration of
34 g/l (pH 8.5) in double distilled water saturated
with air for a day. We also used solutions of the salts
NaCl (special-purity grade, Bio-Chemica, Germany)
and/or NaHCO
3
(USP Grade, Solvey, France),
Na
2
SO
4
(special-purity grade, Reakhim, Russia), and
also p-iodophenol (ICN, USA), peroxidase and super
-
oxide dismutase (Sigma, USA).
As a probe for the formation of electron donors
in a medium, we used Ellman’s reagent (5,5′-dithio
-
bis(2-nitrobenzoic acid), Sigma, USA) [11, 12],
whose reduced form (5-thio-2-nitrobenzoic acid) has
acharacteristic absorption spectrum. The optical
density was measured at a wavelength of 412 nm
with a Uvikon 923 B spectrophotometer (Kontron
Instruments, Italy). The concentration of 5-thio-2-
nitrobenzoic acid was calculated at a molar extinc
-
tion coefficient of 12 000 M
–1
cm
–1
at the wave
-
length 412 nm [12].
To study the reducing properties of anions con
-
tained in seawater, a 1 mM 5,5′-dithiobis(2-nitro
-
benzoic acid) solution in double distilled water was
prepared. In the experiment, this solution was diluted
with double distilled water to a final concentration of
50 µM (pH 4), and NaCl and/or NaHCO
3
was added
to a concentration of 30.97 g/l (0.53 M) or 0.196 g/l
(2.33 M), respectively, which corresponds to its con
-
centration in seawater [12]. Then, 1 M NaOH was
added until the pH of the solution was 8.5–8.7 and the
resultant solution in polypropylene vials was heated
in a U-10 ultrathermostat (Prüfgeräte-Werk Medin
-
gen, Germany).
Hydroxyl radicals were determined using a reac
-
tion with coumarin-3-carboxylic acid (Aldrich, USA).
7-Hydroxycoumarin-3-carboxylic acid, a product of
hydroxylation of coumarin-3-carboxylic acid, is a
convenient fluorescent probe for the formation of
these radicals [8]. The experimental procedure was
described in detail previously [8]. The formation of
hydrogen peroxide was determined by studying en
-
hanced chemiluminescence in the luminol–p-iodophe
-
nol–peroxidase system as described earlier [8]. Fresh
double distilled water had a conductivity of 1.7 µS. In
the experiments, water saturated with atmospheric
gases for a day was used. After saturation, the con-
ductivity was 4 µSand pH was 5.6. To eliminate the
effect of possible trace contaminants of transition
metal compounds, water and the salt solutions were
additionally treated with the chelator Chelex-100
(Bio-Rad, USA). Such treatment did not influence the
experimental results.
RESULTS
Heating of seawater samples containing 5,5′-di
-
thiobis(2-nitrobenzoic acid) in the temperature range
of 40 to 60°Ccauses an increase in the absorption
A
412
, which is caused by the reduction of 5,5′-dithio
-
bis(2-nitrobenzoic acid) to 5-thio-2-nitrobenzoic acid
[8]. The kinetics of this process is described by an
equation of a (pseudo)first-order reaction, which is in
-
dicated by the linearization of the kinetic curves in
semilogarithmic coordinates. The activation energy of
formation of a reducing substance on heating of sea
-
water was 20 kcal/mol. Introduction of 5,5′-dithio
-
bis(2-nitrobenzoic acid) into seawater in various time
intervals after heating allowed us to determine the
half-life of the reducing substance, which was about
4 min. Transition metal ions in seawater are mainly in
their higher oxidation states [14]; therefore, their par
-
ticipation in the observed reaction as electron donors
is unlikely [8]. Seawater contains a significant
THERMAL ACTIVATION OF REDUCING PROPERTIES OF SEAWATER ANIONS 943
BIOPHYSICS Vol. 48 No. 6 2003
amount of carbon dioxide, whose solubility is many
times higher than the solubilities of nitrogen and oxy-
gen. Carbon dioxide dissolved in seawater at pH val-
ues characteristic of seawater is primarily in the form
of the bicarbonate anion
HCO
3
−
[14]. It is supposed
that the
HCO
3
−
ion is capable of one-electron oxida
-
tion and exhibits the properties of a reducer to yield
bicarbonate anion radical [15].
To check the ability of the bicarbonate anion
and also other inorganic anions contained in seawa
-
ter to act as reducers, the reducing properties of its
individual components were studied. The concentra
-
tions of salts in samples (0.53 M NaCl and 2.33 mM
NaHCO
3
)corresponded to their concentrations in
seawater [13], and the pH of the samples (8.5–8.7)
was taken to be equal to the pH of artificial seawater.
Figure 1 shows that the presence of both the chloride
anion (Fig. 1b) and the bicarbonate anion (Fig. 1c)at
the given concentrations in the heated samples of the
aqueous solution of 5,5′-dithiobis(2-nitrobenzoic
acid) leads to the reduction of 5,5′-dithiobis(2-nitro
-
benzoic acid) and to an increase in the 5-thio-2-
nitrobenzoic acid concentration as compared with
reference samples containing no inorganic anions
(Fig. 1a). Under the joint action of sodium chloride
and bicarbonate (Fig. 1d), the concentration of the
forming 5-thio-2-nitrobenzoic acid exceeds its con
-
centration reached in seawater on heating at the same
temperature for the same time (Fig. 1e). Note that
the joint effect of Cl
–
and
HCO
3
−
is superadditive.
Similar experiments with sulfate anions at a concen
-
tration of 28.87 mM, which is characteristic of sea
-
water [13], gave negative results.
We previously showed that heating of water and
aqueous solutions gives rise to hydrogen peroxide
[5–7]. By studying enhanced chemiluminescence in
the luminol–p-iodophenol–peroxidase system [5–7],
the formation of hydrogen peroxide in seawater on
heating and the effect of seawater anions on the hy
-
drogen peroxide production were investigated. The
kinetics of the reaction of formation of H
2
O
2
in sea
-
water has a complex quasi-oscillating character, as in
water [7] and phosphate buffer [5, 6]. In the initial lin
-
ear portion of the kinetic curve, the kinetics is de-
scribed by an equation of a pseudofirst-order reaction.
In this portion at temperatures of 40 to 65°C, the rate
constant varies from 1.42⋅10
–8
to 1.96⋅10
–7
,respec-
tively. The activation energy of this process as deter-
mined from the Arrhenius plot is 21 kcal/mol (Fig. 2).
The half-life of H
2
O
2
at a concentration of 10
–7
Mand
atemperature of 25°Cinseawater is about 2 h. Addi-
tion of superoxide dismutase [5–7] after heating for
4hat50°C increases the H
2
O
2
content by half. This
suggests the formation of superoxide radicals on heat-
ing of seawater. As one would expect, incubation of
heated seawater with catalase decreases the H
2
O
2
con
-
tent to background values.
The results of studying of the effect of individ
-
ual salts on the formation of H
2
O
2
are presented in
Fig. 3. Both 0.53 M NaCl (Fig. 3b)and2.33 mM
NaHCO
3
(Fig. 3c)atpH8.5 increase the hydrogen
peroxide production on heating under standard condi
-
tions by a factor of 2.5–2.6, whereas the joint action
of these salts (Fig. 3d)causes a superadditive increase
in the hydrogen peroxide production up to 80% of the
H
2
O
2
production in seawater (Fig. 3e). Sulfate anions
at a concentration of 28.87 mM, which is characteris
-
tic of seawater [13], at the pH value corresponding to
seawater significantly decrease the standard hydrogen
peroxide production in water down to zero.
It is known that hydrogen peroxide can be re
-
duced to form hydroxyl radicals in the presence of
transition metal ions, such as Fe(II) and Cu(I), which
944 BRUSKOV et al.
Fig. 1. Effect of anions Cl
–
and
HCO
3
−
contained in a
50 µM aqueous solution of 5,5′-dithiobis(2-nitrobenzoic
acid) (pH 8.75) on the formation of 5-thio-2-nitrobenzoic
acid (TNA) as determined from the absorption A
412
after
heating at 50°C for 20 min: (a) reference sample, (b)
0.53 M NaCl, (c) 2.33 mM NaHCO
3
,(d) 0.53 M NaCl
and 2.33 mM NaHCO
3
, and (e) seawater (pH 8.7). Mean
values and their standard errors are presented (n = 4–6).
are electron donors, in the Fenton reaction. Hydroxyl
radicals can also, in principle, be produced by the re-
duction of hydrogen peroxide using the electron do-
nor properties of bicarbonate and chloride anions in
the reaction
HO =OH+OH
22 aq
+
−−
⋅
e
. (1)
To explore such a possibility, we used the highly
efficient OH radical trap coumarin-3-carboxylic acid.
7-Hydroxycoumarin-3-carboxylic acid, a product of
hydroxylation of coumarin-3-carboxylic acid, is a
specific fluorescent probe for these radicals [8]. The
samples studied contained 2.33 mM sodium bicarbon
-
ate and 0.53 M NaCl. Figure 4 illustrates the kinetics
of the reaction in water and solutions containing chlo
-
ride and bicarbonate anions at concentrations charac
-
teristic of seawater at the pH value corresponding to
seawater. Figure 4 shows that, in the presence of chlo
-
ride and bicarbonate anions, the production of hydro
-
xyl radicals significantly (by a factor of 1.75) in
-
creases. Addition of exogenous H
2
O
2
at a concentra
-
tion of 1 mM to a coumarin-3-carboxylic acid solu
-
tion containing NaCl and NaHCO
3
at concentrations
characteristic of seawater at the pH value correspond
-
ing to seawater on heating at 80°C for up to 1 h leads
to an additional increase in the rate of thermal genera-
tion of OH radicals, on the average, by a factor of 1.5.
DISCUSSION
Thus, along with hydroxyl ions [7–10], Cl
–
and
HCO
3
−
anions activated on heating of the solution act
as reducers and their joint effect exceeds the effect
characteristic of seawater. Heating activates the re
-
ducing properties of seawater anions Cl
–
and
HCO
3
−
,
and this increases the production of hydrogen perox
-
ide and hydroxyl radicals. The reducing properties of
the bicarbonate anion is ∼250 times higher than those
of the chloride anion, as indicated by the strength of
the effect and the ratio between the concentrations of
chloride and bicarbonate anions.
Note the nonequilibrium character of the pro
-
cesses studied. On heating, an additional energy is
supplied, and then, as the system is restored to the ini
-
tial temperature, it relaxes to the initial energy state.
As we showed earlier [8], the thermally activated re
-
ducing properties of bicarbonate and chloride anions
are rather brief and has a half-life of about 4 min.
The reducing activity of seawater anions on
heating is high and ranges from 5 to 20 µM (Fig. 1).
BIOPHYSICS Vol. 48 No. 6 2003
THERMAL ACTIVATION OF REDUCING PROPERTIES OF SEAWATER ANIONS 945
Fig. 2. Arrhenius plot of –logk versus inverse tempera
-
ture for determining the activation energy of the early
formation of H
2
O
2
in seawater on heating. k is the
pseudofirst-order reaction rate constant, s
–1
; T is temper-
ature, K.
Fig. 3. Thermally activated formation of H
2
O
2
on heating
solutions for3hat40°CatpHofwaterand the solutions
of 8.5: (a)water (n = 8), (b) 0.53 M NaCl (n = 2), (c)
2.33 mM NaHCO
3
(n = 2), (d)0.53MNaCl and 2.33 mM
NaHCO
3
(n = 3), and (e) seawater (n = 5).
This suggests that this activity cannot be caused by
transition metal impurities in water and the salt solu-
tions we used. Moreover, additional treatment of wa-
ter and the salt solutions with the chelator Chelex-100
did not influence the experimental results.
The previous data on the thermal generation of
hydrogen peroxide in double distilled water are indic
-
ative of the formation of a hydroxyl radical and a hy
-
drated electron from a hydroxyl ion by the reaction
OH
–
OH
.
+
e
aq
−
,and also suggest two interrelated
pathways of formation of H
2
O
2
on heating [7]. The
first pathway is the recombination of OH radicals.
This reaction is favored by the presence of electron
acceptors in water, one of which is usually oxygen
dissolved in water. A necessary step of the formation
of H
2
O
2
on heating is the transition of oxygen into the
singlet state [5–7]. Addition of electron to singlet ox
-
ygen yields superoxide anion radicals, whose dismut
-
ation gives rise to H
2
O
2
. The kinetics of the reaction
of formation of H
2
O
2
has a quasi-oscillating character
[5, 7]. Along with singlet oxygen, another most essen
-
tial acceptor of hydrated electron in water and aque
-
ous solutions is hydrogen ions H
+
in the reaction
2H = 2H H
aq 2
+−
+
⋅
2e=
, (2)
which yields a hydrogen molecule.
It is known that, under the action of light quanta,
a number of anions in polar solutions go into an ex
-
cited state and then dissociate to form a solvated elec
-
tron and anion radicals [16]. It was previously estab
-
lished that the photoexcited state (
A
aq
−
)* of anions
A
aq
⋅
can lead to thermally activated dissociation to
form an electron–radical pair comprising a hydrated
electron
e
aq
−
and an oxidized (radical) product
A
aq
−
[16]:
AA A
aq aq aq aq
−−−
++
⋅
heν ()
*
. (3)
It was shown that a wide variety of anions, such
as Cl
–
,Br
–
,I
–
,OH
–
,
PO
4
2−
,and
CO
3
2−
, produce a hy
-
drated electron in process (3) in their flash photolysis
[17, 18]. Since matter at a given temperature emits
electromagnetic radiation similar to electromagnetic
blackbody radiation throughout the electromagnetic
radiation frequency spectrum [19, 20], one can as
-
sume that heat, much as light quanta, also causes a
similar process:
AAA
aq aq aq aq
−−−
++
⋅
kT e()
, (4)
where kT means thermal electromagnetic radiation. In
their turn, radicals recombine to yield molecular
forms by the reaction
A
aq
⋅
+
A
aq
⋅
=A
2
, and if there are
a number of various radicals, cross recombination
products additionally form. Process (4) of formation
of an electron–radical pair on heating was previously
established for hydroxyl ions [8].
Thus, anions can act as reducers in the reaction
of formation of electron–radical pairs and the subse
-
quent recombination of radicals. The cross recombi
-
nation of radicals of different anions can be the cause
of the synergic superadditive effect observed in our
experiments.
Our results suggest that the formation of radical
products on heating has a universal character and is
qualitatively similar to the effects of UV and ionizing
radiation. We previously [7] demonstrated the simi
-
larity between the effects of heat and ionizing radia
-
tion on water, including the “oxygen effect” in both
cases. It was concluded that water thermolysis gives
rise to the same radicals and molecular products as
radiolysis by ionizing radiation does. Hyperthermia
with allowance for its features can, in some cases, be
regarded as a model of oxidative stress similar to the
effect of ionizing radiation. Note that it is water
thermolysis that causes the formation of ions OH
–
and
H
+
, which is accompanied by the rupture of a covalent
bond in the water molecule: this is suggested by the
BIOPHYSICS Vol. 48 No. 6 2003
946 BRUSKOV et al.
Fig. 4. Kinetics of formation of hydroxyl radicals in
0.5 mM coumarin-3-carboxylic acid solutions (pH 8.7)
obtained by dissolving the acid in (1) double distilled wa
-
ter and (2)asalt solution containing 0.53 M NaCl and
2.33 mM NaHCO
3
on heating at 80°Casdetermined
from the concentration of 7-hydroxycoumarin-3-carbo-
xylic acid (7-OH-3-CCA). Mean values and their stan-
dard errors are presented (n = 3).
strong temperature dependence of this process [21].
The increase in the degree of water dissociation into
ions with an increase in temperature should favor re
-
action (4).
Physically, water thermolysis can be explained
as follows. Thermal electromagnetic radiation, along
with components with averaged energies on the order
of kT, contains small numbers of high-energy quanta
whose energies significantly exceed kT. Since such
quanta are few, their induced high-energy processes,
which can lead to by the rupture of covalent bonds,
are slow. Besides, highly sensitive methods for de
-
tecting products of such reactions are necessary.
Note the well-established existence of a phys
-
icochemical mechanism for energy transformation of
weak influences into high-energy processes using at
-
mospheric air bubbles in water in sonoluminescence
[22–24]. Natural waters contain a significant number
of air microbubbles about 1–30 µmindiameter [2]
because of the hydrophobicity of air bubbles in such a
polar liquid as water.
In sonoluminescence in air bubbles, the ultra-
sonic energy is accumulated, increases by several or-
ders of magnitude, and is released through emission
of visible or UV radiation. Gas bubbles are sensors
and transducers (amplifiers and transformers) of rela-
tively low ultrasonic energy into giant fluctua-
tionselectromagnetic field energy bundles. The in-
stability of air bubbles manifests itself in the initial
expansion and the subsequent implosive compres
-
sioncollapse accompanied by a sharp increase in
the temperature (up to ∼10
5
K) and pressure within
the bubble. In this case, the gas bubble not only emits
photons but also acts as a microreactor, in which radi
-
cal products, such as hydroxyl radicals, form and
there are chemical processes accompanied by the for
-
mation of nitrite ions [24]. Moreover, under certain
conditions, gas bubble collapse leads to such a local
increase in temperature that a thermonuclear reaction
becomes possible [25].
One can assume that a small part of natural gas
microbubbles in solutions are capable of similarly
collapsing on heating to yield the same radical and
molecular products in solution as those produced by
ionizing radiation [7]. Previously, Domrachev et al.
[26] detected mechanochemically activated water de
-
composition by sonication to form hydrogen peroxide
in the absence of cavitation and in pumping air
through a filter and thin capillaries. Potselueva et al.
[27] found that extremely high frequency electromag
-
netic radiation causes the formation of hydrogen per
-
oxide in 50 mM carbonate buffer. It was established
that this process is characterized by the oxygen effect,
which consists in the participation of dissolved atmo
-
spheric oxygen in the formation of H
2
O
2
. Ikeda et al.
[28] showed that, in the presence of simple metal ox
-
ide catalysts, water molecules decompose to form ox
-
ygen and hydrogen on exposure to visible light and
even in the dark under vigorous stirring.
Hodgson and Fridovich [29] demonstrated that
OH radicals interact with carbonate ions to form car
-
bonate radicals. In their turn, carbonate radicals re
-
combine, emitting light quanta. This is indicated by
the quadratic dependence of the intensity of this emis
-
sion on the concentration of carbonate ions [29]. One
can suppose that the products of recombination of
(bi)carbonate radicals are peroxocarbonates [30]. Pre
-
viously, Klimov and Baranov [31] showed that bicar
-
bonate can act as an electron donor in water oxidation
in the water-oxidizing complex of photosystem II of
chloroplasts. It was also supposed bicarbonate is a
more preferable reducer than water and is an integral
component of the evolution of oxygen photosynthesis
in the Archean period [32].
The product of recombination of chloride radi-
cals is molecular chlorine, and the product of cross re-
combination of chloride and hydroxyl radicals is
hypochlorite. The possibility of the oxidation of the
chloride ion by hydrogen peroxide to form hypo
-
chlorite has recently been shown by Voeikov and
Khimich [33]. The electrochemical oxidation of chlo
-
ride ions in NaCl solutions to form molecular chlo
-
rine, hypochlorous acid, and sodium hypochlorite was
shown by Miroshnikov [34]. When considering the
formation of radical products from chloride and bicar
-
bonate anions on heating, account should also be
taken of the possibility of their reaction with super
-
oxide radicals forming by the addition of hydrated
electron to singlet oxygen [5–7].
Chloride ions in oxygenated aqueous solutions
are known to protect DNA from the destructive action
of ionizing radiation [35]. These data are consistent
with recent results [6] showing that the presence of
NaCl in solution decreases the oxidative damage of
guanine in DNA by reactyive oxygen species on heat
-
ing. It was also established that carbon dioxide at a
partial pressure close to the tension in the blood of
homoiothermal animals significantly inhibits the
BIOPHYSICS Vol. 48 No. 6 2003
THERMAL ACTIVATION OF REDUCING PROPERTIES OF SEAWATER ANIONS 947
generation of superoxide anion radicals by cells of
homoiothermal, poikilothermal, and unicellular or
-
ganisms [36]. Among other previously studied anions,
phosphate should be noted. Goncharova et al. [37]
demonstrated the possibility of the participation of in
-
organic phosphate as an electron donor in primary
photosynthetic reactions.
Thermal processes giving rise to radical prod
-
ucts in seawater and the blood plasma of homo
-
iothermal animals can be similar because the compo
-
sitions of these media are quite close. Therefore, pos
-
sible biological consequences of the thermal genera
-
tion of reactive oxygen species, and the effect of vari
-
ous anions on the generation of hydroxyl radicals and
hydrogen peroxide can be significant and diversified.
First of all, these are processes caused by intracellular
oxidative stressenhanced production of reactive ox
-
ygen species, which are associated with many patho
-
physiological consequences for the organism [4], in
-
cluding aging [38]. The thermal generation of reactive
oxygen species is a new convincing argument for the
free-radical theory of aging [6, 38], since for poikilo-
thermal organisms, ambient temperature is the most
significant factor determining the lifetime. The bio-
regulatory, bioenergetic, and information role of reac-
tive oxygen species in a number of biological pro-
cesses and the origin and evolution of life on the
Earth was considered by Voeikov et al. [39]. Hyper-
thermia causes damage to DNA and other cellular
structures and processes, which are mediated by reac-
tive oxygen species [6, 40], in particular, hydroxyl
radicals [41].
It seems topical to study further the reducing
properties of anions contained in seawater, biological
fluids, and intracellular space in the context of their
possible role in various biologically significant redox
processes. On this way, it will probably be possible to
arrive at scientifically substantiated understanding of
the therapeutic and preventive effect of natural min
-
eral waters. The results of this work predicted that
heating of salt solutions gives rise to such molecular
products as chlorine, hypochlorite, peroxocarbonate,
molecular hydrogen, and others. Experimental confor
-
mation of their formation will be the subject of further
studies.
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