Critical Role of Zinc as Either an Antioxidant or a Prooxidant in Cellular Systems

Abstract

Zinc is recognized as an essential trace metal required for human health; its deficiency is strongly associated with neuronal and immune system defects. Although zinc is a redox-inert metal, it functions as an antioxidant through the catalytic action of copper/zinc-superoxide dismutase, stabilization of membrane structure, protection of the protein sulfhydryl groups, and upregulation of the expression of metallothionein, which possesses a metal-binding capacity and also exhibits antioxidant functions. In addition, zinc suppresses anti-inflammatory responses that would otherwise augment oxidative stress. The actions of zinc are not straightforward owing to its numerous roles in biological systems. It has been shown that zinc deficiency and zinc excess cause cellular oxidative stress. To gain insights into the dual action of zinc, as either an antioxidant or a prooxidant, and the conditions under which each role is performed, the oxidative stresses that occur in zinc deficiency and zinc overload in conjunction with the intracellular regulation of free zinc are summarized. Additionally, the regulatory role of zinc in mitochondrial homeostasis and its impact on oxidative stress are briefly addressed.

Yield, Growth, Quality, Biochemical Characteristics and Elemental Composition of Plant Parts of Celery Leafy, Stalk and Root Types Grown in the Northern Hemisphere

“…The investigated macro elements and microelements are involved in the plant antioxidant system [25][26][27] and, in this respect, the mineral composition in celery reflects the degree of nutrient supply, tolerance to biotic and abiotic stressors and nutritional value of produce. The data presented in Table 5 show the significant differences in mineral content recorded between the different plant parts and between cultivars, as well as the distribution of the elements analyzed among leaves, petioles and roots.…”

Maternal Serum Concentrations of Selenium, Copper and Zinc during Pregnancy are associated with Risk of Spontaneous Preterm Birth: A case-control study from Malawi

“…However, the elevated free zinc and copper ion in women delivering preterm could have caused the generation of ROS. Free zinc ion damages mitochondria and NADPH oxidases to produce ROS [47]. Copper (I) ion is also capable of producing ROS by itself [48].…”

Increased early enteral zinc intake improves weight gain in hospitalised preterm infants

“…Upon secondary analysis of only infants with enteral Zn intake of 2 mg/kg/day or less, our results remained significant, suggesting that Zn intake in excess of 2 mg/kg/day is not necessary to see the growth benefits of the mineral. In fact, excess Zn intake may lead to deleterious outcomes, such as gastrointestinal upset, ineffective lipoprotein metabolism and oxidative stress due to the suppression of metabolism and mitochondrial functions . Additionally, Zn is highly involved in immune function, and in vitro studies have shown that Zn excess leads to decreased opsonisation and inhibition of nicotinamide adenine dinucleotide phosphate (NAPDH), which regulates superoxide anion production responsible for the destruction of pathogens after phagocytosis .…”