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Pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate): A primary antioxidant consisting of sterically hindered phenols with para-propionate groups. Primary antioxidants (also known as chain-breaking antioxidants) act as radical scavengers and remove peroxy radicals (ROO•), as well as to a lesser extent alkoxy radicals (RO•), hydroxyl radicals (HO•) and alkyl radicals (R•).
Analyzing the story of "Free Radicals," there is a connection between reality and the world Alice Munro creates. Cindy Daniel's article, she explores the works of Munro and how they blend reality with fiction. She states, "Munro uses this technique with deliberate force to explore the worlds she creates more completely.
After years of frustration over his inability to increase maximum lifespan with antioxidant supplements, Harman came to the conclusion that mitochondria were producing as well as being damaged by free radicals, but that exogenous antioxidants don't enter the mitochondria. And that it is mitochondria that determine lifespan.
Antioxidants that are reducing agents can also act as pro-oxidants. For example, vitamin C has antioxidant activity when it reduces oxidizing substances such as hydrogen peroxide; [93] however, it will also reduce metal ions such as iron and copper [94] that generate free radicals through the Fenton reaction.
Free radical mechanisms in tissue injury. Lipid peroxidation induced by xenobiotics and the subsequent detoxification by cellular enzymes (termination). Antioxidants play a crucial role in mitigating lipid peroxidation by neutralizing free radicals, thereby halting radical chain reactions. Key antioxidants include vitamin C and vitamin E. [8]
The common mechanism is a free radical chain reaction, where the addition of oxygen gives rise to hydroperoxides and their associated peroxy radicals (ROO•). [5] Typically, an induction period is seen at the start where there is little activity; this is followed by a gradually accelerating take-up of oxygen, giving an autocatalytic reaction ...
BHT stops this autocatalytic reaction by converting peroxy radicals to hydroperoxides. It effects this function by donating a hydrogen atom: RO 2 • + ArOH → ROOH + ArO• RO 2 • + ArO• → nonradical products. where R is alkyl or aryl, and where ArOH is BHT or related phenolic antioxidants. Each BHT consumes two peroxy radicals.
The primary factor in antioxidants causing or promoting the aforementioned health issues, is the attenuation or inactivation of reactive oxygen species (ROS), which immune system responders use to kill or destroy pathogens, mainly bacteria and fungi. ROS produce free-radicals as a by-product of the oxygen burst used to kill pathogens.