Free radicals in biology and medicine
General Pharmacology The Vascular System · 1991
Abstract
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First line defence antioxidants-superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX): Their fundamental role in the entire antioxidant defence grid
The body encloses a complex antioxidant defence grid that relies on endogenous enzymatic and non-enzymatic antioxidants. These molecules collectively act against free radicals to resist their damaging effects to vital biomolecules and ultimately body tissues. Based on their response to general free radical invasion, they can be categorized into first, second, third and even fourth line defense antioxidants. The role and effectiveness of the first line defense antioxidants which basically include superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) is important and indispensable in the entire defense strategy of antioxidants, especially in reference to super oxide anion radical (*O2) which is perpetually generated in normal body metabolism, particularly through the mitochondrial energy production pathway (MEPP). A lot has been published concerning antioxidants and their significance in preventing oxidative stress and the attendant cellular damage, howbeit with paucity of awareness on the fundamental role of SOD, CAT and GPX. The present review tends to articulate important information on SOD, CAT and GPX as first line defense antioxidant enzymes.
The Biological Activities of Vitamin D and Its Receptor in Relation to Calcium and Bone Homeostasis, Cancer, Immune and Cardiovascular Systems, Skin Biology, and Oral Health
Vitamin D plays an important role in calcium homeostasis and bone metabolism, with the capacity to modulate innate and adaptive immune function, cardiovascular function, and proliferation and differentiation of both normal and malignant keratinocytes. 1,25(OH) 2 D, the biologically active form of vitamin D, exerts most of its functions through the almost universally distributed nuclear vitamin D receptor (VDR). Upon stimulation by 1,25(OH) 2 D, VDR forms a heterodimer with the retinoid X receptor (RXR). In turn, VDR/RXR binds to DNA sequences termed vitamin D response elements in target genes, regulating gene transcription. In order to exert its biological effects, VDR signalling interacts with other intracellular signalling pathways. In some cases 1,25(OH) 2 D exerts its biological effects without regulating either gene expression or protein synthesis. Although the regulatory role of vitamin D in many biological processes is well documented, there is not enough evidence to support the therapeutic use of vitamin D supplementation in the prevention or treatment of infectious, immunoinflammatory, or hyperproliferative disorders. In this review we highlight the effects of 1,25(OH) 2 D on bone and calcium homeostasis, on cancer, and refer to its effects on the cardiovascular and immune systems.