Free radicals are intermediates in many normal and necessary metabolic reactions. Thus, all oxygen-using organisms have had to evolve defensive mechanisms against free radicals: The enzymes catalase and peroxidase break down hydrogen peroxide and other peroxides, superoxide dismutase
(called SOD) controls the superoxide free radical, and glutathione peroxidase also controls peroxides. Antioxidants such as vitamins C, E, and the minerals zinc and selenium also help control free radicals. For example, each molecule of your enzyme glutathione peroxidase must contain four atoms of selenium. Protection is not perfect, however, and free radical
damage proceeds throughout life. Occasionally, a genetic defect results in an individual missing part of his or her enzymatic free radical control system.
One result may be a family of conditions called progeria, which is distinguished by extremely rapid aging, with victims dying at an early age (typically, before puberty), and showing many signs of old age:
wrinkled and sagging skin, bald head, bent and frail body, advanced cardiovascular diseases, arthritis, etc. Dr. Armstrong found that he could control one type of progeria by giving a young male patient doses of the enzyme horseradish peroxidase, extracted from horseradish. This patient is now older than his brother was when he died (at 8) and shows none of the signs of old age, in spite of the progeria syndrome’s appearance just before the start of therapy.
Superoxide radicals have been shown to degrade hyaluronate (the major lubricant in joint fluid), to degrade collagen (the most common protein in the body), to inactivate enzymes, to oxidize polyunsaturated fats, to damage DNA, and to kill viruses, bacteria, and mammalian cells.
Mammals can produce additional SOD (superoxide dismutase, an enzyme which destroys superoxide radicals) as a response to the presence of increased superoxide radicals. For example, rats can adapt to survive in an 85 percent oxygen atmosphere, which then allows them to survive in a 100 percent oxygen atmosphere, which they could not initially withstand. Increased levels of SOD are found in the lungs of these animals. Increased amounts of SOD and other protective antioxidant enzymes produced in the body in response to air pollutants may explain, at least in part, why cities with lots of air pollution (such as Birmingham, Alabama; Pittsburgh,
Pennsylvania; Cleveland, Ohio; Detroit, Michigan; Los Angeles, California; and Newark, New Jersey) do not have higher cancer rates (adjusted for differences in population age distribution) than cities with relatively clean air (such as San Francisco, California).
In a study by the gerontologist Dr. Richard Cutler, the life spans of many mammalian species, including man, were found to be directly proportional to the amount of SOD they contain and inversely proportional to their specific metabolic rate (the number of calories burned per pound of body
weight per day). The animals with the longest life spans, such as man, have the highest levels of SOD when it is expressed as a function of the oxidative metabolic rate. The three charts on the prior page indicate the amount of SOD protection in three tissue types (brain, heart, liver) versus MLP (Maximum Lifespan Potential) for several mammalian species, including
man. There is a bacterium called radiodurans which actually thrives inside nuclear reactors! Radiodurans has the highest levels of the enzymes SOD, peroxidase, and catalase: ever measured. It almost certainly has other antioxidant (anti-free radical) enzymes as well.
Of course, no control system is perfect, and the damage free radicals do is thought to contribute to aging. How do they do this damage? The free radicals are extremely reactive, owing to their unpaired electron, and are likely to attack any molecule found in your body. Free radicals attack the genetic material, DNA and RNA, resulting in mutations and other defects. If genetic blueprints controlling cell divisions are damaged, cancer can result. Free radicals also attack cellular membranes, damaging them with sometimes drastic results. Lysosomes, for example, contain powerful enzymes (acid hydrolases) which break down tissue constituents. When lysosomal membranes are ruptured by free radicals, these enzymes are released, causing severe damage to surrounding tissues. Rheumatoid arthritis is an example of this type of attack. Free radicals can also cause red blood cells to burst (hemolyze) by breaking their cellular membranes. The measurement of the ease of bursting of red blood cells is a common assay for vitamin E bioavailability because vitamin E, an antioxidant, can protect the red blood cell membranes. Peroxidized fats (fats which have combined with oxygen via a free radical catalyzed reaction, a condition you have smelled in rancidity) break down into malonaldehyde, a mutagen and
cross-linker, which oxidizes further to create more free radicals. The great ability of free radicals to damage tissues is due to the chain reactions in which they engage. Free radicals generate other free radicals, as shown below:
Are you interested in life extension products?
mod4all ships all major brands of Modafinil from the UK
All products shipped from the UK by tracked post. We guarantee delivery.
We guarantee delivery, free reshipping.
Any questions at all about payments, shipping, etc. Anything at all, just email us.
Comments (0)