Peningkatan Radikal Bebas pada Eritrosit yang Terinfeksi oleh Plasmodium falciparum
Abstract: Especially in
tropical area, there
is high falciparum
malaria morbidity and
mortality which is caused
by oxidative stress
such as cerebral
malaria. One of the causes
of the oxidative
stress is the process
happening in the
parasitized erythrocytes. Therefore,
it is important
to study the
process that causes the oxidative
stress in parasitized erythrocytes. The oxidative stress in non parasitized
erythrocytes is caused by hemoglobin auto-oxidation. Reactive oxygen species (ROS) production in
the parasite food vacuoles happens because
of a producing
ROS reaction cascade
and the hemoglobin
digestion that produces toxic
heme which should
be biomineralized. Part
of this heme
escapes from the biomineralization and moves from the
parasite food vacuoles into the parasite cytosol which also needs to be
detoxified and sequestrated by using GSH. Parasite mitochondrial activity
produces superoxide anion and hydrogen peroxide, which is then changed to be
water and oxygen by thioredoxin consuming enzyme. However, there
is no thioredoxin
reductase to reduce
thioredoxin. Lipoic acid
protein ligase (LplA) metabolites ligates lipoic acid to
E2-subunit of KADH (mitochondrial α keto acid dehydrogenase), which then
reduces thioredoxin by using NADH. Part of this H2O2 also escapes from the detoxification and is exported to
the parasite cytosol.
The antioxidant system
in the parasite
cytosol includes superoxide dismutase, glutathione reductase,
and thioredoxin reductase. The detoxification of H2O2 is carried out by using GST
(glutathione S transferase)
and 1 cys
peroxyredoxin with GSH
as cofactor, and
by 2 cys peroxyredoxin with thioredoxin as
cofactor. Plasmodium has neither glutathione peroxydase nor catalase. Part of
GSSG as redox
product in Plasmodium
is exported to
the erythrocyte cytosol
and it causes oxidative stress in this cell. Hence, antioxidant supplementation must be
considered in treating malaria especially in serious cases.
Penulis: Susy Tjahjani
Kode Jurnal: jpkedokterandd090088
