Oxidative Damage and Suppression: an Experimental Approach to Teaching Biochemistry

Resumo

Experimental Biochemistry is a challenging and worthy didactical  task:  a vast field with many different techniques.   Radical mediated biooxidative processes, implied in aging and accompanying various pathologies,  have an enormous  appeal  to public in general and particularly to students in the science field.   The  Fenton  reaction,   first  reported by  the 22-year  old Cambridge  chemistry  undergraduate Henry J. H. Fenton  (Chemical  news vol. 33 page 190, 1876), is a useful in vitro system for generating hydroxyl radicals generally implied in biooxidation.  When coupled with the 2-deoxyribose (DR)- thiobarbituric acid (TBA)  method,  provides  a most  resourceful  tool for studying  oxidative  processes that may  provide  insights  to  in  vivo  processes.    In  this  communication  a  classical  experiment of quantification of thiobarbituric reactive  substances  (TBARS) resulting  from breakage  of DR (5 mM) in aqueous buffered media (5mM, pH 7.2) by 0,100 mM H2O2 and ferrous ion (up to 0,150 mM) is the base for the demonstration of oxidative damage suppressive ability of known hydroxyl radical quenchers as ethanol,  dimethylsulfoxide (DMSO)  and  thiourea (1mM  each).   The  results  of the  experiments, developed  to  be worked  in experimental classes for senior  undergraduate biochemistry students of biomedical  sciences, show a very mild but  consistent  suppressive  capacity  for ethanol  (reduction in2 percent  of TBARS  measured  at  0,150 mM ferrous ion concentration).  Thiourea  and  DMSO show very similar  suppressive  abilities:  reduction  in 19 and  18 percent  in measured  TBARS,  respectively (at  0,150 mM ferrous ion).