One of the most important sources of reactive
oxygen species (ROS) produced by cell respiration
is mitochondria (Ames et al. 1993). During life,
induced by many pathological stimuli, mitochondrial
respiration produces ATP, but releases ROS
and other reactive species (from nitrogen and
chlorine) that can damage any cell biomolecules.
Overproduction of ROS can damage mitochondrial
DNA from 4.4- to 48.2-fold than nuclear
DNA (Zastawny et al. 1998). This massive oxidative
damage to mitochondria is increased during
cell aging, affecting mitochondrial DNA and
causing mutations that can compromise cell respiration
and induce mitochondrial failure (Cottrell
et al. 2000). Resistance against mitochondrial
failure and free radical damage is determined by
efficient antioxidant and repair systems controlled
by ‘gerontogenes’ (Rattan 2003). However, gene
mutations or heterozigozity can decrease intracellular
antioxidant protection, increasing cell aging
and degeneration. In amyotrophic lateral sclerosis
(ALS) motor neurons have a SOD-1 mutation that
impairs Cu+-binding, causing a failure in the dismutation
of molecular oxygen (O2) to hydrogen
peroxide (H2O2), with accumulation of superoxide
anion (O2
)
) (Estevez et al. 1999). This SOD-1
defect also induces senescence in human fibroblasts
(Blander et al. 2003). SOD-2 heterozigozity
is also associated with decreased capacity to dismutate
superoxide and subsequently increasing
ROS production, culminating with mitochondrial
failure, cell aging and apoptosis (Kokoszka et al.
2001). Mitochondrial failure and massive ROS
production is associated with myocardium ischemic
injury and aging (Lucas and Szweda 1998;
Marı´n-Garcia and Goldenthal 2002) and with
Parkinson’s (PD) and Alzheimer’s diseases (AD