Impact of antioxidants on PM2.5 oxidative potential, radical level, and cytotoxicity

• Published in: The Science of the total environment 2024-02, Vol.912, p.169555-169555, Article 169555
• Main Authors: Wang, Yixiang, Xing, Chunbo, Cai, Baohua, Qiu, Wenhui, Zhai, Jinghao, Zeng, Yaling, Zhang, Antai, Shi, Shao, Zhang, Yujie, Yang, Xin, Fu, Tzung-May, Shen, Huizhong, Wang, Chen, Zhu, Lei, Ye, Jianhuai
• Format: Article
• Language: English
• Subjects: Antioxidants; Cytotoxicity; Oxidative potential; PM2.5; PM2.5 components; Pro-oxidative and anti-oxidative effects
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2023.169555

Antioxidants are typically seen as agents that mitigate environmental health risks due to their ability to scavenge free radicals. However, our research presents a paradox where these molecules, particularly those within lung fluid, act as prooxidants in the presence of airborne particulate matter (PM2.5), thus enhancing PM2.5 oxidative potential (OP). In our study, we examined a range of antioxidants found in the respiratory system (e.g., vitamin C, glutathione (GSH), and N-acetylcysteine (NAC)), in plasma (vitamin A, vitamin E, and β-carotene), and in food (tert-butylhydroquinone (TBHQ)). We aimed to explore antioxidants' prooxidant and antioxidant interactions with PM2.5 and the resulting OP and cytotoxicity. We employed OH generation assays and electron paramagnetic resonance assays to assess the pro-oxidative and anti-oxidative effects of antioxidants. Additionally, we assessed cytotoxicity interaction using a Chinese hamster ovary cell cytotoxicity assay. Our findings revealed that, in the presence of PM2.5, all antioxidants except vitamin E significantly increased the PM2.5 OP by generating more OH radicals (OH generation rate: 0.16–24.67 pmol·min−1·m−3). However, it's noteworthy that these generated OH radicals were at least partially neutralized by the antioxidants themselves. Among the pro-oxidative antioxidants, vitamin A, β-carotene, and TBHQ showed the least ability to quench these radicals, consistent with their observed impact in enhancing PM2.5 cytotoxicity (PM2.5 LC50 reduced to 91.2 %, 88.8 %, and 75.1 % of PM2.5's original level, respectively). Notably, vitamin A and TBHQ-enhanced PM2.5 OP were strongly associated with the presence of metals and organic compounds, particularly with copper (Cu) contributing significantly (35 %) to TBHQ's pro-oxidative effect. Our study underscores the potential health risks associated with the interaction between antioxidants and ambient pollutants. [Display omitted] •Most antioxidants showed both anti- and pro-oxidative effects when mixed with PM2.5.•PM2.5 OP augmentation was observed among many antioxidants.•Antioxidants' impact on PM2.5 OP affects PM2.5 cytotoxicity.•TBHQ and vitamin A's pro-oxidative effect is driven by metals (Cu) and organics.•Excessive use of antioxidants may have an adverse impact on the health.