Tocopherol Radical Regeneration by Antioxidants

The Durk Pearson & Sandy Shaw®
Life Extension NewsTM
Volume 8 No. 3 • July 2005


Tocopherol Radical Regeneration by Antioxidants

A recent paper1 reports on the ability of various antioxidants to regenerate vitamin E from the vitamin E radical (tocopheroxyl radical). Though vitamin C is a well-known regenerator of the vitamin E radical to its normal nonradical form, there are other antioxidants that can do so, and in some cases even more powerfully than vitamin C. This paper focused on catechins (found in tea): epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC), and epigallocatechin gallate (EGCG). The researchers found that EC, ECG, EGC, and EGCG “have activity similar to or higher than that of vitamin C in vitamin E regeneration at pH 7–12 in micellar solution.”

They also looked at the regeneration capability of other antioxidants. They found that the rate of the regeneration reaction of the tocopheroxyl radical with the natural antioxidants examined increases in the order of: methyl linoleate << rutin < EC < ECG < EGC ~ vitamin C (ascorbate anion) < EGCG < quercetin (pH 8) << CoQ10. The authors suggest that “catechins may function as antioxidants in biological systems.”

It is interesting to note that, in studies of the effect of vitamin E on the course of cardiovascular disease in patients with that condition, most included no regenerators of vitamin E from its radical, leaving excess vitamin E radicals in the circulation. This may have accounted, in full or in part, for the negative impact of vitamin E in those studies. A few studies have used both vitamin E and vitamin C; however, there were no measurements made of the redox state in the circulation, so we don’t know whether the doses of E and C used were adequate to reduce oxidative stress in cardiovascular disease patients.

Moreover, many of the studies of vitamin E and cardiovascular disease with negative results were done on patients with pre-existing cardiovascular disease; most of those patients would have been taking statins. Statins powerfully inhibit the production of both cholesterol and CoQ10, the latter being the most powerful regenerator of the tocopheroxyl radical (see above). All users of statins should take 120–240 mg/day of supplemental CoQ10.

Reference

  1. Mukai et al. Structure-activity relationship of the tocopherol-regeneration reaction by catechins. Free Rad Biol Med 38:1243-56 (2005).

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