Page 44 - congress

ORAL PRESENTATION / TAM METİN SÖZLÜ SUNUM

evaluated both at the cellular membrane level and by measuring lipid peroxidation
products and antioxidants involved in the defense system against reactive oxygen species

(ROS) (Manivasagam et al., 2020).
Glutathione (GSH) is one of the major intracellular antioxidants, acting as a reducing

agent and protecting cells by neutralizing the harmful effects of ROS (Khaliulin et al.,

2025). Glutathione peroxidase (GPx) is an enzyme that detoxifies peroxides using GSH
and protects cells from oxidative stress (Bjørklund et al., 2020). According to studies by

Meguid et al. (2011) and Frustaci et al. (2012), GPx levels were reported to be lower in
children with ASD compared to control groups. Chauhan et al. (2012) and Rose et al.

(2012) reported impaired GSH homeostasis and decreased GSH antioxidant levels in the
temporal cortex and cerebellum of individuals with ASD. The reduction in GSH levels in

these brain regions was attributed to increased lipid peroxidation and deficiencies in

mitochondrial electron transport chain (ETC) complexes, indicating increased oxidative
damage and mitochondrial dysfunction in autism (Chauhan et al., 2012). Rose et al.

(2012) further suggested that GSH level disturbances in the temporal cortex arise from
increased mitochondrial superoxide production and chronic inflammation. Decreased

GSH availability in the brains of individuals with autism suggests disrupted mitochondrial
redox balance, which may promote mitochondrial damage via elevated ROS, negatively

affecting cellular energy production and leading to cell death (Ayer et al., 2010). In the
present study, decreased GSH and GPX1 levels in the autism group compared to controls

parallel these previous findings.
Malondialdehyde (MDA) is the end product of polyunsaturated fatty acid

peroxidation and serves as a biomarker for lipid peroxidation. Measurement of MDA levels

is one of the most commonly used methods to assess lipid peroxidation (Yui et al., 2020).
Various studies on children diagnosed with ASD have reported increased MDA levels in

plasma (Meguid et al., 2011; Essa et al., 2012; Altun et al., 2018; Yui et al., 2020) and
brain tissue (Bhat et al., 2023). Altun et al. (2018) reported a positive correlation between

elevated MDA levels and the severity of ASD symptoms, suggesting that individuals with
higher MDA may have more severe forms of the disorder (Altun et al., 2018). In the

present study, a significant increase in MDA levels was observed in ASD, consistent with
the literature.

Catalase (CAT) reduces the toxicity of hydrogen peroxide (H₂O₂) by converting it into

water and oxygen, whereas glutathione peroxidase (GPx) reduces hydrogen peroxide and
organic hydroperoxides to water or corresponding alcohols using glutathione (GSH) as an

42