Tuesday, August 14, 2012

Polymerizing Antioxidants

The various defense labs run by the military get to work on some really cool stuff at times, such as hypersonic jets that cruise along at Mach 6. But sometimes, the cool stuff is more mundane, such as preserving food. Napoleon long ago recognized that "an army marches on its stomach" and offered a prize for invention of a safe food preservation process. The winning technology is still around today - canning. While modern soldiers ride more and march less than in the past, keeping them fed is still as much of a concern as in the past, and food preservation is just as important.

A few weeks ago, the US military announced that researchers at the Natick Soldier Research, Development and Engineering Center had discover that polymerization of a natural antioxidant, hydroxytyrosol, allowed it to become an even more effective antioxidant. A quick review of the patent shows that horseradish peroxidase, an enzyme that as you might guess is extracted from horseradish, [*] is used as the initiator - hence it is a free radical polymerization, and in this case, a green, water-based approach as well. Sadly, the details of the polymers structure are not provided at all, although the PR release hints at a conjugated backbone in the product. That would certainly be helpful in providing increased antioxidation potential.

I've never worked with horseradish peroxidase, but others have, such as to polymerize methylmethacrylate (free access) or as was seen here today, polyphenols ($). The general approach is that the enzyme catalyzes a reaction (as enzymes have a tendency to do) between some substrate (not necessarily the monomers) and hydrogen peroxide. That generates a free radical which then starts the whole polymerization. A little biochemistry never hurt anyone, did it?

[*] The enzyme however, is not what gives horseradish its pungency. That comes from allyl isothiocyanate instead.


Anonymous said...

Here's an interesting tidbit - those pungent compounds from horseradish (and other species in the allium genus, such as onion, garlic, and shallot) is where the "allyl" group got its name.

John said...

I didn't know that but it does makes sense.