Nano-sized zinc oxide (ZnO NPs) has become a common food additive in recent years due to its unique physical and chemical properties, such as small size, high reactivity, good antibacterial performance, etc. Casein phosphopeptide (CPP) is a casein fragment that carries some phosphorylated serine residues.CPP has primary and secondary antioxidant capabilities, such as direct scavenging of free radicals and separation of potential metal peroxides. Asccorbic acid, also known as vitamin C(VC), is a water-soluble vitamin that boosts the body's immunity and health by effectively scavenging free radicals, including hydroxyl groups. CPP is a water-soluble vitamin that can enhance human immunity and health.CPP has primary and secondary antioxidant capabilities, such as direct scavenging of free radicals and separation of potential metal peroxides. Ascorbic acid, also known as vitamin C(VC), is effective at scavenging free radicals, including hydroxyl groups. Casein phosphopeptides (CPP) and vitamin C (VC), together with zinc oxide nanoparticles (ZnO NPs), have been used as functional food additives in many commercial foods. Our previous studies have shown that VC can increase ZnO NPs-induced cytotoxicity both in vivo and in vitro, and CPP has a cytoprotective effect on ZnO NPs-induced oxidative stress. However, the combined toxic effects of these three additives in foods are unclear. In this paper, the combined toxicity of ZnO NPs, CPP and VC in the complex system was studied by changing the order of addition, so as to clarify the mechanism of their toxicity in the complex system. When the addition sequence of the three materials changed, the concentration of dissolved Zn ions in different groups was different, leading to the change of ZnO NPS-induced cytotoxicity. Intestinal absorption of zinc ions was also investigated using an inclined intestinal sac model. The intestinal absorption of Zn2+in different complex systems also had different responses to the order of additive addition. The control of VC on the synergistic toxicity induced by ZnO NPs is stronger than the protective effect of CPP in the composite system.
https://pubs.rsc.org/en/content/articlepdf/2018/ra/c8ra03693d
