Resveratrol conjugates

After these in vivo and in situ experiments in animals, the absorption of resveratrol by humans was performed. Soleas et al. [120] was the first to measure free and conjugated resveratrol in plasma and urine. Volunteers were given 25 mg of resveratrol orally in 120 mL of white wine. The plasma concentrations of free resveratrol and glucuronide and sulfate conjugates peaked at 30 min. At this time, the concentration of resveratrol conjugates was 48-fold higher than the free resveratrol (338 pg vs. 7.1 pg L ). Over the 24-h collection period, 24.6% of the resveratrol was recovered in the urine, predominantly in conjugated form. Walle et al. evaluated the absorption after oral administration of 25 mg of C-labeled resveratrol [121]. They determined a peak plasma resveratrol equivalent concentration, based on total radioactivity, of 491 pg at 1 h after the dose. 

In 2007, Boocock et al. [2007] were the first to publish a complete phase I dose pharmacokinetic study in humans. Ten healthy volunteers were recruited to consume single doses of oral resveratrol (0.5, 1, 2.5, or 5 g). Consumption of resveratrol did not cause serious adverse events. Analyses of resveratrol and its metabolites were performed by LC-MS/MS. In plasma in all intake doses resveratrol-3-sulfate (56%) was the highest metabolite, the second and third metabolites were monoglucuronides (17 and 23%, respectively), and, finally, the lowest was free resveratrol (5%). Resveratrol was rapidly absorbed, the 7/nax for all metabolites ranged between 0.8 and 2.4 h, although the half-lives of free resveratrol and the conjugated forms remained for a long time in plasma, between 2.9 and 11.5 h. 

Burkon A, Somoza V. 2008. Quantification of free and protein-bound iraw-s-resveratrol metabolites and identification of traws-resveratrol-C/O-conjugated diglucuronides— Two novel resveratrol metabolites in human plasma. Mol Nutr Food Res 52 549-557. 

Soleas GJ, Yan J, Goldberg DM. 2001b. Ultrasensitive assay for three polyphenols (catechin, quercetin and resveratrol) and their conjugates in biological fluids utilizing gas chromatography with mass selective detection. J Chromatogr B Biomed Sci Appl 757 161-172. 

It may therefore be observed that some of the substances listed in Table 8.2 and Table 8.3 are employed in what may be called medical folklore, that is, in the arena of complementary and alternative medicine (CAM). A listing is as follows camp-tothecin, curcumin, melatonin, vitamin A analogs, colchicines, paclitaxels, several of the vinca alkaloids, and acetylsalicylic acid, as well as ascorbic acid or vitamin C, (3-carotene, a certain gallate compound from green tea, folic acid, lycopene from tomatoes, conjugated linoleic acid, quercetin, resveratrol, sodium selenite, and a-tocopherol or vitamin E. 

The extended conjugated stilbene moiety of 1 has been examined using UV spectroscopy. This chromophore typically presents a UV absorption spectrum with a A,max of approximately 310-320 nm. However, it has been noted that for resveratrol oligomers in which the ethylene bridge has been reduced, such as that seen in (-)-a-viniferin (8b) [100], kobophenol A (9) [43], and tricuspidatol A (71) [89], the A,max is shifted to a lower wavelength of approximately 280-290 nm. 

Figure 9.1 Mean total (free and conjugated) trans-resveratrol in serum of four subjects given 25 mg of trans-resveratrol in various matrices [27. (Reproduced with permission from Elsevier.)...

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