oxidants, antioxidants, and oxidative stress in protozoal infections

Biochemically speaking, an oxidizing agent is recognized for its ability to accept electrons, which can lead to the degradation of biomolecules such as lipids, nucleic acids, and proteins. these agents are highly reactive and are produced through various biological processes. in contrast, antioxidants prevent or slow other compounds oxidation. they interact with reactive oxygen species (ros), effectively neutralizing their potential for biochemical reactivity. oxidative stress (os) refers to a pathological state where the balance between oxidants and antioxidants is compromised, leading to a scenario in which antioxidants fail to counteract the harmful effects of oxidants. oxidants are defined as substances that can oxidize their target molecules and are mainly classified into two types: radical oxidants and non-radical oxidants. in the mitochondrial electron transport chain, which is essential for converting oxygen into water, a minor portion of oxygen may escape this process, generating ros. mitochondrial dna is especially prone to oxidative damage due to its proximity to a primary source of ros and its deficient repair capacity compared with nuclear dna. the increase in oxidants can result from multiple internal mechanisms, such as cellular respiration and neutrophil function, along with external factors like radiation exposure, infections, and environmental contamination. the initiation of lipid peroxidation triggers a series of chain reactions that will continue until termination products are formed. therefore, the resultant end products of lipid peroxidation, which include malondialdehyde (mda), 4-hydroxy-2-nonenal (4-hne), and f2-isoprostanes, accumulate in biological systems. among different markers of os, malondialdehyde (mda) and the natural antioxidants, metalloenzymes cu, zn-superoxide dismutase (cu, zn-sod), and selenium-dependent glutathione peroxidase (gpx), are currently considered to be the most important ones. comprehending these triggers is necessary for establishing effective interventions against os. despite the fluctuations observed in the oxidant-antioxidant indices, extensive research into both naturally occurring and experimental protozoal diseases such as theileriosis, coccidiosis, and cryptosporidiosis indicates that the host experiences oxidative stress, which is essential to the pathogenicity of these diseases.