NUTR 3210 Lecture Notes - Lecture 10: Reactive Oxygen Species, Vitamin, Superoxide Dismutase
1 May 2018
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NUTR3210 – Vitamins and Minerals II
Redox Reactions:
Oxidative Defense:
Types of Reactive Oxygen Species (ROS):
ROS Perspectives
• ROS formation is critical for some physiological functions (too much is a problem;
balance is key)
o E.g. Immune Function
▪ Neutrophils and macrophages produce ROS in order to kill some types of
bacteria that they engulf by phagocytosis
▪ ROS formation is part of the inflammatory response
• Problems arise when there is an imbalance between production of ROS and consumption
of antioxidants from food produce more ROS and consume less antioxidants
• ROS/free radials steal an electron from a stable molecules and in turn, generate more
unstable free radicals dangerous chain reaction that can damage or destroy cells
• Cell membranes are highly susceptible to free radical damage
o Disrupting membrane integrality ability to regulate movement of fluids and
nutrients in and out of the cell in lost
• ….
Micronutrients contribute to two types of oxidant defense systems:
• non-enzymatic antioxidant defense – defense molecules that come from diet that work
independently of enzymatic antioxidant defense system
o vitamin E (lipid soluble antioxidant)
o vitamin C (water soluble antioxidant)
o donate their electrons or H+ to free radials to stabilize them and reduce damage
they cause
• enzymatic antioxidant defense: minerals or phytochemicals that act as cofactors within
antioxidant enzymes (need to be consumed in diet)
o copper and zinc – works as part of superoxide dismutase enzyme
o selenium – works as part of glutathione peroxidase enzyme
o other compounds (beta-carotene and other phytochemicals) stabilize free radicals
and prevent damage to cells and tissues
Vitamin E
• fat soluble vitamin
• widely distributed in foods (fats and oi)
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Ros perspectives: ros formation is critical for some physiological functions (too much is a problem; balance is key, e. g. Vitamin e fat soluble vitamin: widely distributed in foods (fats and oi) in plants, mostly come from oils (ex. Tocopherol transfer protein: recognition of alpha-tocopherol as the required form of vitamin e relates to tocopherol transfer protein (made in the liver, carries fat soluble vitamin e for incorporation in to. It is then packaged with ttp complex of vitamin e with ttp vldl extra hepatic tissues and rest of the body. Vitamin e and lipid peroxidation: vitamin e protects lipid membranes from free radical damage. Further metabolism of vitamin e radical: approx. 1/3 is converted to water and soluble quinone and excreted in the urine: approx. 2/3 excreted from the body in bile after 2 vitamin e radicals come together. Selenium & oxidant defense: glutathione peroxidase used glutathione (gsh) as substrate.
