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.