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Antiviral effects of ascorbic and dehydroascorbic acids
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ReCverin Joined: Mon Dec 27, 2010 1:44 pm Posts: 6	Antiviral effects of ascorbic and dehydroascorbic acids Quote: In the present study, ascorbic acid weakly inhibited the multiplication of viruses of three different families: herpes simplex virus type 1 (HSV-1), influenza virus type A and poliovirus type 1. Dehydroascorbic acid, an oxidized form of ascorbic acid and hence without reducing ability, showed much stronger antiviral activity than ascorbic acid... Furuya A. et al. Antiviral effects of ascorbic and dehydroascorbic acids in vitro. Int J Mol Med 22(4) 541-545 (2008)
Thu Jun 23, 2011 10:38 am

ofonorow Ascorbate Wizard Joined: Tue Nov 22, 2005 3:16 pm Posts: 8145 Location: Lisle, IL	Re: Antiviral effects of ascorbic and dehydroascorbic acids Thank you. This is a very interesting report, and while in vitro (test tube) it may have some validity in the body, as large amounts of ascorbic acid will become DHA during the normal course of events. (It is interesting that at least one function of glutathione in cells is supposedly to recylce DHA back to ascorbate.) There is some reason vitamin C is effective against viruses, and increased vitamin C leading to higher serum levels is more effective. My own theory was that the vitamin C was helping to replenish glutathione levels (GSH) in cells, and that this known property of vitamin C was perhaps the primary avenue in which vitamin C acts (through GSH) to inactivate and cure viral infections. This report seems to open up the possibility that increased levels of the oxidized DHA may be playing a role. _________________ Owen R. Fonorow, Orthomolecular Naturopath
Thu Jun 23, 2011 2:53 pm

majkinetor Vitamin C Expert Joined: Fri Sep 10, 2010 8:36 am Posts: 883	Re: Antiviral effects of ascorbic and dehydroascorbic acids Quote: In this study, we showed that ascorbic acid inhibits the multiplication of several viruses of widely different structures and replication strategies. Characterization of the mode of action of ascorbic acid and dehydroascorbic acid suggests that either free radical formation or direct binding, or both, is responsible for the antiviral activity of these two reagents. The effect of these reagents on cell viability suggests that the antiviral effect of ascorbic acid is, at least in part, a secondary result of the cytotoxic effect of the reagent. The antiviral effect of dehydroascorbic acid is possibly due to its binding to the virus or molecules involved in viral replication Quote: Fig. 2 shows the effects of ascorbic acid on the relative virus yields of these three viruses, when the cells infected with either of the viruses were incubated in the medium containing various concentrations of the reagent. The multiplication of all three viruses was similarly sensitive to the reagent. The virus yield decreased as the reagent concentration was ncreased and, in the presence of 30 mM of the reagent, the yields of these viruses were approximately one tenth of those n the absence of the reagent. These results clearly show that ascorbic acid inhibits the multiplication of viruses of widely different structures, i.e., regardless of enveloped or non- enveloped, double-stranded DNA or single-stranded RNA genome, and regardless whether the replication and tran- scription of the viral genome occur in the nucleus or in the cytoplasm of the infected cells. It is noteworthy that the antiviral activity of the reagent was apparently independent of the type of cells since the multiplication of influenza virus was examined on MDCK cells (derived from canine kidney cells) while that of HSV-1 and PV-1 was on HEp-2 cells (derived from human cervical carcinoma). Reducing activity vs. oxidizing activity of ascorbic acid.
Thu Jun 23, 2011 3:09 pm

ofonorow Ascorbate Wizard Joined: Tue Nov 22, 2005 3:16 pm Posts: 8145 Location: Lisle, IL	Re: Antiviral effects of ascorbic and dehydroascorbic acids Yes, I think this is important, however it is a test tube study, and as we have seen, different results are observed depending on whether blood, instead of water is used, etc. By the way, according to Sherry Lewin, the half-life of DHA is very short, "only a few minutes in aqueous solution." Section 1.2.5.4 Stability of the dehydroascorbic entity (page 17, Vitamin C: Its Molecular Biology and Medical Potential.) I am not a chemist. Given her diagrams, it seems that if GSH isn't available to recycle DHA "quickly" back to ascorbic acid, that it breaks down per the diagram. If it is DHA working its magic against viruses, then its very short half-life might help explain why so much vitamin C as ascorbic acid is necessary for the effect. _________________ Owen R. Fonorow, Orthomolecular Naturopath
Fri Jun 24, 2011 7:54 am

ReCverin Joined: Mon Dec 27, 2010 1:44 pm Posts: 6	Re: Antiviral effects of ascorbic and dehydroascorbic acids I agree with you, Dr. Fonorow, that too much weight should not be placed on an in vitro study such as this. I wanted to share this just because of my personal interest in dehydroascorbic acid and the fact that this forum has a section on the effects of vitamin C in infectious diseases. It is interesting, though, that these researchers showed strong antiviral activity of DHAA and suggested a mechanism of action that is quite different than has been speculated to date. One thing that I find particularly interesting about this study: they showed that a solution of ascorbic acid, with iron to catalyze the conversion to DHAA, had stronger antiviral effect than did a solution of DHAA prepared from commercially available, powdered DHAA. Presumably these solutions were of equal concentration. They attribute the stronger effect of the AA + iron solution to the possibility of a pro-oxidant, cytotoxic effect. But there is a very interesting, alternate explanation that they did not mention and of which they were possibly not aware. It is known that the commercially prepared, powdered DHAA is a dimer. Wechtersbach et al have shown that when this product is dissolved in pure water (exactly as these researchers describe), the solution contains substantial proportions of various dimer forms in addition to the naturally-occurring monomer form. Therefore the solution actually has a considerably lower concentration of the monomer than expected based on the weighed-in amount. It is entirely conceivable that the AA + iron solution actually produced a substantially higher concentration of the naturally-occurring monomer form than did the solution they prepared from the powdered DHAA. If that is true, then it would argue even more strongly in favor of the anti-viral activity of natural DHAA.
Sun Jun 26, 2011 11:13 pm

majkinetor Vitamin C Expert Joined: Fri Sep 10, 2010 8:36 am Posts: 883	Re: Antiviral effects of ascorbic and dehydroascorbic acids I think this is valuable study, no matter its in-vitro setup. It would be very hard to do such study in vivo given the different kinds of viruses used. The in vitro concentrations of ascorbate used are to my knowledge physiological. About iron + AA, they say that it turns AA to pro-oxidant role and it might be that antiviral activity is due to cytotoxic effect. I think Levy noted the same thing in Optimal Nutrition for Optimal Health or Curing the Incurable.
Mon Jun 27, 2011 4:24 am

ofonorow Ascorbate Wizard Joined: Tue Nov 22, 2005 3:16 pm Posts: 8145 Location: Lisle, IL	Re: Antiviral effects of ascorbic and dehydroascorbic acids Thank you for this contribution. Very interesting. Quote: One thing that I find particularly interesting about this study: they showed that a solution of ascorbic acid, with iron to catalyze the conversion to DHAA, had stronger antiviral effect than did a solution of DHAA prepared from commercially available, powdered DHAA. Presumably these solutions were of equal concentration. They attribute the stronger effect of the AA + iron solution to the possibility of a pro-oxidant, cytotoxic effect. But there is a very interesting, alternate explanation that they did not mention and of which they were possibly not aware. It is known that the commercially prepared, powdered DHAA is a dimer. Wechtersbach et al have shown that when this product is dissolved in pure water (exactly as these researchers describe), the solution contains substantial proportions of various dimer forms in addition to the naturally-occurring monomer form. Therefore the solution actually has a considerably lower concentration of the monomer than expected based on the weighed-in amount. It is entirely conceivable that the AA + iron solution actually produced a substantially higher concentration of the naturally-occurring monomer form than did the solution they prepared from the powdered DHAA. If that is true, then it would argue even more strongly in favor of the anti-viral activity of natural DHAA. p.s., I don't know if you have any interest, but if you wrote this up as a letter to the Editor (your original idea as far as I can tell), I can help you get it published in the Townsend Letter. Send me PM if interested. _________________ Owen R. Fonorow, Orthomolecular Naturopath
Mon Jun 27, 2011 8:38 am

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Antiviral effects of ascorbic and dehydroascorbic acids

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