Quercetin, a plant-derived flavonoid in Chinese herbs, fruits and wine, displays antioxidant properties in many pathological processes associated with oxidative stress. However, the effect of quercetin on the development of preimplantation embryos under oxidative stress is unclear. The present study sought to determine the protective effect and underlying mechanism of action of quercetin against hydrogen peroxide (H2O2)-induced oxidative injury in mouse zygotes. H2O2 treatment impaired the development of mouse zygotes in vitro, decreasing the rates of blastocyst formation and hatched, and increasing the fragmentation, apoptosis and retardation in blastocysts. Quercetin strongly protected zygotes from H2O2-induced oxidative injury by decreasing the reactive oxygen species level, maintaining mitochondrial function and modulating total antioxidant capability, the activity of the enzymatic antioxidants, including glutathione peroxidase and catalase activity to keep the cellular redox environment. Additionally, quercetin had no effect on the level of glutathione, the main non-enzymatic antioxidant in embryos.

Enzyme‐mimicking nanomaterials for antioxidative therapy is a promising star to treat more than 200 diseases or control their progressions through scavenging excessive reactive oxygen species (ROS), such as O2•− and H2O2. However, they can inversely produce stronger ROS (e.g., •OH) under many disease conditions (e.g., low pH for myocardial ischemia). Herein, a biocompatible ‐Cu‐O‐Zn‐ bimetallic covalent doped carbon dots (CuZn‐CDs) processing both catalase (CAT) and superoxide dismutase activities are reported, mainly because of their abundant electrons and the excellent electron transfer abilities. In addition, Cu dopant helps to balance the positive charge at Zn dopant resulting from low pH, enabling CuZn‐CDs to still process CAT ability rather than peroxidase ability. Benefiting from it, CuZn‐CDs exhibit sufficient in vitro ROS scavenging ability and cardiomyocyte protective effect against ROS‐induced damage. In vivo results further demonstrate that CuZn‐CDs can protect the heart from ischemia‐reperfusion injury. In addition to antioxidative therapy, the rapid renal clearance and low toxicity properties of CuZn‐CDs in animal model reveal high biocompatibility which will facilitate clinical use.

No abstract