International Journal of Molecular Medical Science, 2024, Vol.14, No.6, 342-354 http://medscipublisher.com/index.php/ijmms 346 (ROS), including superoxide anions, hydroxyl radicals, and hydrogen peroxide, are highly reactive molecules that cause cellular damage, contributing to aging and the development of various diseases, such as cancer, cardiovascular diseases, and neurodegenerative disorders. LBPs are known to neutralize these harmful free radicals effectively, thereby preventing oxidative damage. In several studies, LBPs were shown to exhibit significant antioxidant activity in both in vitro and in vivo models. For instance, in assays testing the scavenging ability of LBPs against DPPH and superoxide radicals, LBPs demonstrated dose-dependent activity, efficiently neutralizing these reactive species (Zeng et al., 2023). These effects were further corroborated by research showing that LBPs reduced lipid peroxidation and prevented mitochondrial dysfunction in retinal and hepatic cells exposed to oxidative stress-inducing agents like light and alcohol (Tang et al., 2018; Wang et al., 2020). The mechanisms through which LBPs exert their free radical scavenging properties are primarily attributed to their structure, particularly their ability to donate hydrogen atoms or electrons to neutralize free radicals. The structural composition of LBPs, which includes sugar residues such as arabinose, glucose, and galactose, contributes to their high antioxidant capacity. Additionally, LBPs exhibit dose-dependent scavenging activity against various radical species, including superoxide, hydroxyl, and peroxyl radicals. Studies have demonstrated that LBPs containing triple-helix structures often exhibit enhanced antioxidant activity, as observed in polysaccharide fractions isolated fromLycium barbarum, which displayed higher scavenging capacity compared to lower molecular weight oligosaccharides (Al-Wraikat et al., 2022). This enhanced activity is likely due to the stability provided by the polysaccharide’s conformation, which enables effective neutralization of radicals. As such, LBPs’ ability to scavenge free radicals not only protects cells from oxidative damage but also helps maintain cellular homeostasis, making them a promising natural antioxidant for therapeutic applications. 3.2 Activation of antioxidant enzymes Lycium barbarum polysaccharides (LBPs) are known to play a critical role in enhancing the body’s endogenous antioxidant defense systems. These defense systems include key enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), which work together to neutralize reactive oxygen species (ROS) and prevent oxidative damage. SOD catalyzes the dismutation of superoxide radicals into hydrogen peroxide, which is then broken down by CAT into water and oxygen. GPx reduces hydrogen peroxide and lipid hydroperoxides by using glutathione as a substrate (Dong, 2024). Studies have shown that LBPs can significantly upregulate the activities of these antioxidant enzymes in various cell types and animal models. For instance, in a model of alcohol-induced liver injury, LBP administration resulted in a marked increase in SOD, CAT, and GPx activities, which helped to reduce the accumulation of malondialdehyde (MDA), a key marker of lipid peroxidation and oxidative stress (Wang et al., 2020). The activation of these enzymes by LBPs is not limited to liver cells. In models of oxidative stress-induced damage in other tissues, such as skin fibroblasts and retinal cells, LBPs have been shown to restore antioxidant enzyme activity, thereby providing cellular protection. For example, in skin fibroblasts exposed to UV-induced oxidative stress, LBP treatment significantly enhanced the activities of SOD, CAT, and GPx, which contributed to a reduction in ROS levels and lipid peroxidation. This enzymatic boost was crucial for preventing DNA damage, maintaining cell viability, and promoting skin cell repair (Liang et al., 2018). Additionally, in models of photoreceptor degeneration, LBPs were found to upregulate these antioxidant enzymes, which mitigated mitochondrial dysfunction and oxidative damage in the retina, highlighting the widespread protective effects of LBPs across different organ systems (Tang et al., 2018). Overall, the ability of LBPs to activate endogenous antioxidant enzymes is a central mechanism through which they confer protection against oxidative stress-induced damage in multiple biological systems. 3.3 Nrf2 pathway and cellular protection The Nrf2 (nuclear factor erythroid 2-related factor 2) signaling pathway is a critical mechanism through which Lycium barbarum polysaccharides (LBPs) exert their antioxidant and cytoprotective effects. Nrf2 is a transcription factor that regulates the expression of numerous antioxidant response element (ARE)-dependent genes, which are involved in neutralizing oxidative stress and maintaining cellular homeostasis. Under normal
RkJQdWJsaXNoZXIy MjQ4ODYzNQ==