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Wed Jan 25, 2017, 10:22 PM

Free Radicals, pro and con

Last edited Fri Jan 27, 2017, 10:03 PM - Edit history (1)

Apparently free radicals and oxidants are vital to cell health. In short, cellular defense systems respond to viral and bacterial infection by releasing free radicals to destroy the intruders. Additionally, oxidizers play a vital role in cell metabolism, key to many energy and synthesis pathways, to wit, the familiar redox equation of basic college chemistry. Not entirely coincidentally, these powerful elements or compounds are capable of damaging ells and components as well. They've been implicated in various types of inflammatory and cancer disorders. They also may accelerate or catalyze the degradation of nutrients, for example, the polymerization of polyunsaturated fats into viscous and probably unhealthy structures.

Not entirely coincidentally, the potential for harm from free radicals and oxidants elicited a search for ways to defeat them, especially since lab experiments seemed to show a protective action of substances loosely grouped into the category of antioxidants seemed to counteract the oxidizing action. But the results to epidemiological studies have been mixed, which may actually be in part because free radicals and oxidizers are so vital to life - in the right places at the right times - to begin with. This conundrum should not be confused with "pseudoscience". Rather, it's indicative of a situation far more complex than a shotgun approach with attempted neutralizing modalities can effectively address.

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Response to Rollo (Original post)

Wed Jan 25, 2017, 10:43 PM

1. Antioxidants as a dietary suppliment is pseudo-science.

 

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Response to Dr Hobbitstein (Reply #1)

Thu Jan 26, 2017, 12:00 AM

2. Not quite

None of your links deal with reservatrol or Pterostilbene. They discuss popular anti-oxidant supplements such as vitamins C and A, and beta carotene. I do not dispute that these vitamins have been overhyped in the popular press, on the internet, and by outfits standing to make a profit off them.

However we would be remiss if we were to conclude that other proposed anti-oxidants, such as reservatrol, are worthless if even harmful in excess based solely on studies of entirely different chemicals. Let's see some research papers on reservatrol and Pterostilbene before we dismiss them entirely.

Your fourth link is well written and although it doesn't discuss reservatrol et. al., it gives a good background on how free radicals are essential to normal bodily function and metabolism. This is the sort of info I was looking for.

Now we just need some peer-reviewed studies on reservatrol and/or Pterostilbene...

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Response to Rollo (Reply #2)

Thu Jan 26, 2017, 12:16 AM

3. Psuedo-Science.

 

Antioxidants have ZERO impact on health.

You may want to post your topic here, where pseudoscience is discussed:
http://www.democraticunderground.com/?com=forum&id=1231

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Response to Dr Hobbitstein (Reply #3)

Thu Jan 26, 2017, 01:41 AM

4. Oh, please

I never claimed they were proved to be beneficial.

I'm not sure you can say they have zero impact. That precludes the possibility that mass quantities might negatively impact health.

I prefer not to indulge in didactic pomposity.

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Response to Rollo (Reply #4)

Thu Jan 26, 2017, 09:45 AM

5. Psuedo-Science. Nt

 

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Response to Dr Hobbitstein (Reply #5)

Thu Jan 26, 2017, 04:52 PM

7. I see...

Last edited Fri Jan 27, 2017, 07:58 PM - Edit history (1)

nt

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Response to Rollo (Reply #7)

Fri Jan 27, 2017, 08:19 AM

8. Take your personal attacks elsewhere. Nt

 

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Response to Dr Hobbitstein (Reply #8)

Fri Jan 27, 2017, 11:27 AM

9. How about posting something relevant?

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Response to Rollo (Reply #9)

Fri Jan 27, 2017, 12:03 PM

10. You were asked to continue your discussion of this in the Health group. nt

 

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Response to Dr Hobbitstein (Reply #10)

Fri Jan 27, 2017, 04:26 PM

11. Please take your attacks on what you view as pseudoscience somewhere else.

To wit:

Please do not post threads about pseudoscience (astrology, homeopathy, crop circles, bigfoot, alien abductions, and the like), which is not science. Don't even post threads bashing pseudoscience, because most people here in the science forum don't need to be convinced, but more importantly because such topics are bait for people to come here and argue the opposing viewpoint -- and then all hell breaks loose. If you want to discuss pseudoscience there are plenty of other places on DU where you can do so.


This thead is about free radicals, a topic which is not "pseudoscience". You've repeatedly tried to bait me by claiming it is pseudoscience. Please stop that.

Now, I AM interested in a discussion about the scientific aspects of free radicals. If you don't want to participate, that's fine with me.

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Response to Rollo (Reply #11)

Fri Jan 27, 2017, 05:24 PM

18. No, your topic was about antioxidants and health.

 

You CHANGED it to free radicals after you were asked to post this topic elsewhere.

Trolololol, as they say.

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Response to Rollo (Original post)

Thu Jan 26, 2017, 11:33 AM

6. Please post further discussion in the Health Group.

While antioxidants have been the subjects of epidemiological studies, such studies do not provide much in the way of mechanistic explanation of any effects observed. Thus the matter of the benefits, or otherwise, of deliberate medication with antioxidants before the evidence is fully analyzed is at present one of judgment and/or policy, and is more appropriately discussed under Health.

It is certainly true that touting the benefits of antioxidants has been overhyped, and become something of a fad in some quarters, but this only came about *after* some studies suggested AOs were beneficial in some respects. It was, of course, a matter of no time at all before AOs were being touted as "cures" for everything from cancer to aging to impotence. Hopefully, after more studies are in, the pendulum will swing back the other way, in the usual fashion.

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Response to eppur_se_muova (Reply #6)

Fri Jan 27, 2017, 04:27 PM

12. The thread title is now about Free Radicals, which more closely conforms to the original content.

Thanks.

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Response to Rollo (Original post)

Fri Jan 27, 2017, 04:34 PM

13. Synthesis and free-radical polymerization of water-soluble acrylamide monomers

Synthesis and free-radical polymerization of water-soluble acrylamide monomers

Water-soluble acrylamide monomers N-(hydroxymethyl)acrylamide, N-(hydroxymethyl)methacrylamide, N,N-diethanolacrylamide, N,N-diethanolmethacrylamide, N,N-methylethanolacrylamide, and N,N-methylethanolmethacrylamide have been synthesized and characterized. The kinetics and thermodynamics of the free-radical polymerization of these monomers and of the model compounds N-isopropylacrylamide and acrylamide have been studied by the methods of isothermal and scanning calorimetry. The structure and the solubility of the said polymers in water and organic solvents have been investigated and their molecular-mass characteristics and temperatures of glass transition (Tg) and melting (Tm) have been examined by DSC, liquid chromatography, 1H NMR and IR spectroscopy, and chemical analysis of functional groups. Hydrogels and amphiphilic network polymers based on acrylamide monomers have been prepared and characterized.

Original Russian Text © L.L. Gur’eva, A.I. Tkachuk, Ya.I. Estrin, B.A. Komarov, E.A. Dzhavadyan, G.A. Estrina, L.M. Bogdanova, N.F. Surkov, B.A. Rozenberg, 2008, published in Vysokomolekulyarnye Soedineniya, Ser. A, 2008, Vol. 50, No. 3, pp. 446–455.

This work was supported by the Russian Foundation for Basic Research (project no. 04-03-32674a), the program of Basic Sciences of the Division of Chemistry and Materials Sciences, Russian Academy of Sciences (project no. 4), and the International Science and Technology Center (project 1918).

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Response to Rollo (Original post)

Fri Jan 27, 2017, 04:36 PM

14. Free radical polymerization and lipid binding of lysozyme reacted with peroxidizing linoleic acid

Free radical polymerization and lipid binding of lysozyme reacted with peroxidizing linoleic acid

Insolubilization and polymerization of proteins exposed to peroxidizing lipids may be due either to cross-linking with incorporation of fragments of the lipid oxidation products, or to free radical transfer from lipid to protein and subsequent free radical polymerization of protein. The second mechanism which has been proposed was inferred from measurements of electron spin resonance signals in proteins. In this study, uniformly labeled linoleic acid, [14C(U)] LA, was reacted with lysozyme. Volatile oxidation products of LA were also used in some experiments. Incubation was done in the absence of water. Oligomers of lysozyme, as well as the monomer, were isolated after incubation, and the [14C] label incorporated into each fraction was determined. The results show that the dominant mechanism of protein polymerization after exposure to peroxidizing linoleic acid is the transfer of free radical from lipid to protein, and subsequent free radical polymerization.

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Response to Rollo (Original post)

Fri Jan 27, 2017, 04:38 PM

15. A Perspective on Free Radical Autoxidation: The Physical Organic Chemistry of Polyunsaturated Fatty

A Perspective on Free Radical Autoxidation: The Physical Organic Chemistry of Polyunsaturated Fatty Acid and Sterol Peroxidation

This Perspective describes advances from the author’s laboratory on the free radical reactions of organic compounds with molecular oxygen. Polyunsaturated fatty acids (PUFAs) and sterols are particularly prone to undergo radical chain oxidation and evidence suggests that this process, known as lipid peroxidation, occurs in vivo under a variety of conditions that are the result of an oxidative stress. Cyclic peroxides, hydroperoxides, and epoxy-alcohols are major products formed from peroxidation and the basic mechanisms of product formation are now reasonably well understood. These mechanisms include reversible addition of oxygen to carbon radicals, rearrangement and cyclization of allyl and pentadienyl peroxyl radicals and homolytic substitution of carbon radicals on the peroxide bond. A physical organic approach to the problem of free radicals in biology and medicine is highlighted in this Perspective with stereochemical, kinetic and extrathermodynamic probes applied to the study of mechanism. A radical clock permits the determination of free radical propagation rate constants and 7-dehydrocholesterol, the immediate biosynthetic precursor of cholesterol, is found by this clock to be one of the most oxidizable lipids known. The consequences of the extreme reactivity of 7-dehydrocholesterol on human health is the focus of a current research theme in the author’s laboratory....

The reaction of oxygen with organic free radicals has been one of the continuing themes of research that has been of interest to me over the past forty years. There were several ongoing projects in free radical chemistry in the Bartlett research group at Harvard during the mid to late ‘60s when my interests were developing. Mike McBride, the TA in a first-year graduate course I took from Bartlett, and other members of the Bartlett group were unraveling the free radical chemistry of azo compounds.6–8 Radical and bi-radical chemistry was part of Bartlett’s research in step-wise cycloadditions,9–12 and he also had an interest in peroxide, tetroxide and singlet oxygen chemistry during that time.13–16 My project was on bi-radical chemistry and the “spin correlation” effect of singlet and triplet bi-radicals formed from direct and sensitized photolysis of cyclic azo compounds.17 The project hinged on being able to separate diastereomeric product cyclobutanes formed in azo decomposition and a capillary GC column, new to the lab in those days, solved the problem after months of futile work packing 75 foot GC columns in the stairwell of the Converse Labs at Harvard.

The mechanism of azo compound decomposition was a topic of general interest when I started my work at Duke in 1969 and my first independent publications used stereochemistry as a probe, an approach borrowed directly from my thesis research.18,19 The azo compounds we prepared were of interest for a number of reasons and they provided an opportunity to collaborate with Gerhard Closs at an early stage of his work on the theory of 1H and 13C CIDNP.20 We independently carried out some of the first experiments on 15N CIDNP,21,22 all of which showed unequivocally that unsymmetrically substituted azo compounds decompose one bond at a time, the reactions proceeding via a nitrogen containing radical.

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Response to Rollo (Original post)

Fri Jan 27, 2017, 04:43 PM

16. Chemistry of Deep-Fat Frying Oils

[link:nfscfaculty.tamu.edu/talcott/courses/FSTC605/...2015/Frying%20Oils.pdf|Chemistry of Deep-Fat Frying Oils]

Deep-fat frying produces desirable or undesirable flavor compounds and changes the flavor stability and
quality of the oil by hydrolysis, oxidation, and polymerization. Tocopherols, essential amino acids, and fatty acids in
foods are degraded during deep-fat frying. The reactions in deep-fat frying depend on factors such as replenishment
of fresh oil, frying conditions, original quality of frying oil, food materials, type of fryer, antioxidants, and oxygen
concentration. High frying temperature, the number of fryings, the contents of free fatty acids, polyvalent metals,
and unsaturated fatty acids of oil decrease the oxidative stability and flavor quality of oil. Antioxidant decreases the
frying oil oxidation, but the effectiveness of antioxidant decreases with high frying temperature. Lignan compounds
in sesame oil are effective antioxidants in deep-fat frying.

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Response to Rollo (Original post)

Fri Jan 27, 2017, 04:50 PM

17. FREE RADICAL PATHOPHYSIOLOGY

FREE RADICAL PATHOPHYSIOLOGY

Oxidative modification of collagen influences breast cancer stem cell response to HNE

Breast cancer represents leading cause of mortality and morbidity in women, mostly due to property of primary tumor to metastasize. It was revealed recently that metastases comprise a fraction of stem-like cells, denoted as cancer stem cells (CSCs), usually located in the bone marrow. CSCs are of great importance in cancer biology as they are involved in blood vessel formation, promotion of cell motility and resistance to therapies and especially to metastasis development. One of the important factors influencing the stem cell destiny is their microenvironment and their interaction with extracellular matrix (ECM). Taking together the role of ECM in determining cell destiny and the involvement of lipids, lipid metabolism and lipid peroxidation in breast cancer development, we wanted to investigate the interactions between ECM and the growth regulating lipid peroxidation product 4-hydroxynonenal (HNE) on breast cancer stem cells. Our results indicate that oxidative modification of ECM collagen influences CSC growth, morphology and reaction to extracellular oxidative stress mediated by HNE and the growth inhibiting effects of this aldehyde. This is of importance as oxidative modification of ECM proteins could occur during local inflammation and during chemotherapies which cause lipid peroxidation. These modifications could be toxic for cancer and change gene expression, motility or stage

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