Resveratrol Content
Resveratrol is a phytoalexin produced naturally by several plants when under attack by pathogens such as bacteria or fungi. Resveratrol has also been produced by chemical synthesis and is sold as a nutritional supplement derived primarily from Japanese knotweed.
Anti-cancer, anti-inflammatory, blood-sugar-lowering and other beneficial cardiovascular effects of resveratrol have been reported. Resveratrol was originally isolated by Takaoka from the roots of white hellebore in 1940.
In grapes, resveratrol is found primarily in the skin,and ” in muscadine grapes ” also in the seeds. The amount found in grape skins also varies with the grape cultivar, its geographic origin, and exposure to fungal infection.
Resveratrol (3,5,4′-trihydroxystilbene) is a polyphenolic phytoalexin. It is a stilbenoid, a derivate of stilbene, and is produced in plants with the help of the enzyme stilbene synthase. Resveratrol content also stayed stable in the skins of grapes and pomace taken after fermentation and stored for a long period. It exists as two geometric isomers: cis- (Z) and trans- (E), with the trans-isomer shown in the top image. The trans- form can undergo isomerization to the cis- form when exposed to ultraviolet irradiation.
Trans-resveratrol in the powder form was found to be stable under “accelerated stability” conditions of 75% humidity and 40 degrees C in the presence of air. The mechanisms of resveratrol’s apparent effects on life extension are not fully understood, but they appear to mimic several of the biochemical effects of calorie restriction.
Both the cis- and trans-isomers of resveratrol were detected in all tested samples. cis-Resveratrol levels were comparable to those of the trans-isomer. They ranged from 0.5 mg/L to 1.9 mg/L in red wines and had a maximum of 0.2 mg/L in white wines. A new report indicates that resveratrol activates Sirtuin 1 (SIRT1) and PGC-1 and improves functioning of the mitochondria. Another research calls into question the theory connecting resveratrol, SIRT1, and calorie restriction.