A POSSIBLE WAY FOR QUANTIFICATION OF SPIN TRAPPING IN BIOLOGY Dezsô Gál Institute of Chemistry. Chemical Research Center, Hungarian Academy of Sciences, Pusztaszeri út 59-67, Budapest 1025, Hungary
It is well known from the corresponding literature [1-3] that analysis of free radicals in biological samples meets serious difficulties mainly because of their very small steady state concentrations and consequently spin trapping procedures (STP) offer a good possibility for such purpose. STP is based on the interaction of spin traps (ST) with free radicals
(Rad ST + Rad Due to the enhanced concentration of A Beyond any doubts STP is very useful if the problem to be solved needs
qualitative proof about the role of free radicals supported by different structures of the
ESR spectra of the adduct depending on the structure of the parent radical, but problems
arise if quantitative data are needed. The reason for this is the fact that the most
appropriate ST-s yield only Therefore it is not by chance, that in many laboratories great efforts have been done to synthesize new ST-s yielding more stable adducts. It is suggested that certain special experimental runs would enable to deduce data leading to reliable quantitative results for free radicals by STP. With respect to the [A (2) where the second member of the right side corresponds to the radical induced decomposition of the adduct, the third and fourth one its monomolecular and bimolecular decomposition, respectively. If the kinetics of accumulation of [A At the same time, measuring the (3) Consequently, the second member of the right side in equ. 2 , that is, the radical induced consumption of the adduct can be calculated. In addition the value of k
(4) For chain reactions with quadratic combination of the radicals the rate
of accumulation of native free radicals d[Rad where W By assuming that at very low conversions the rate of the induced decomposition of the adduct is negligible equations (4) and (5) give: (6) where x (d[ST]/dt) / W Naturally, in order to calculate k Experiments in chemical model systems and at The author expects critical comments concerning above approach. Finally, comments on the importance of spin trapping for photobiology. Photoinitiation of free radicals in live tissues; effect of antioxidants; studies on Photodynamic Therapy [8-9]; chemiluminescence approach of biological processes all require the knowledge of free radicals in living cells quantitatively rendering the development of STP desirable. REFERENCES 1.) Edward G. Janzen, L.Anderson Evans, Yasutaka Nishi : 2.) Georg Buettner, Larry W. Oberley : 3.) D.Griller, K.U.Ingold : 4.) T. Shulyakovskaya, L. Sümegi and D.Gál : 5.) Dezsô Gál, Tamás Kriska, Elena Maltseva : 6.)N.M.Emanuel, E.T.Denisov, Z.K.Maizus : Oxidation Chain Reactions of Hydrocarbons in Liquid Phase („Nauka", Moscow, 1965, in Russian) 7.E.T.Denisov, A.L.Alexandrov : Zh. Fiz. Khim. 8.) T.Kriska, Elena Maltseva and D.Gál :. 9.) Dezsô Gál, Tamás Kriska, Elena Maltseva : |