[quote name='health_nutty' post='392419' date='Mar 19 2010, 04:28 PM'][quote name='malbecman' post='392418' date='Mar 19 2010, 09:21 AM']I find this pretty humorous, actually, because when the first in vivo resveratrol studies (Sinclair and Auwerx's 2 papers) came out, there was all this interest on here ImmInst in people getting it and taking it, we were
all actually pretty worried
that it was very unstable and would isomerize to the cis form or oxidize if you sneezed on it.......
[quote name='Hedgehog' post='374961' date='Jan 10 2010, 09:53 AM']Yep very stable.[/quote]
It is kind of humourous, but really we were intentional mislead by un unscrupulous supplement company.
Yes, that was the main source of the misinformation. One might wonder what other disinformation campaigns are still ongoing. It was shown quite a while ago that resveratrol was stable. Max posted this ages ago:
[quote]Resveratrol: Isomeric Molar Absorptivities and Stability
Brent C. Trela and Andrew L. Waterhouse*
Department of Viticulture and Enology, University of California, Davis, California 95616
J. Agric. Food Chem., 1996
, 44 (5), pp 1253–1257
Resveratrol has attracted interest as a wine constituent that may reduce heart disease. Published data on the molar absorptivity and chemical stability of cis- and trans-resveratrol have varied greatly. Accurate values for UV absorbance for trans-resveratrol [UV λmax (EtOH) nm (ε) 308 (30 000)] and cis-resveratrol [UV λmax (EtOH) nm (ε) 288 (12 600)] were determined and are used to improve chromatographic quantitation methods. Trials conducted under a variety of commonly encountered laboratory conditions show that trans-resveratrol is stable for months, except in high-pH buffers, when protected from light
. cis-Resveratrol was stable only near pH neutrality when completely protected from light.
Keywords: Antioxidant; phenolic; wine; grape; stilbene; isomer; UV spectroscopy; absorptivity[/quote]
Trela showed 14 years ago that resveratrol was stable under normal conditions. Not only that, but cis-resveratrol is unstable; it is in all likelihood reverting back to trans resveratrol. Any organic chemist will tell you that the trans substitution pattern on a double bond is the more stable form, barring some unusual case like a stabilizing intramolecular hydrogen bond.
Here is a paper from 2007 showing thermal stability of resveratrol at fairly high (100 C) temps:
[quote]J Chromatogr A. 2007 Jan 26;1140(1-2):29-34. Epub 2006 Dec 1.
Investigation on phenolic compounds stability during microwave-assisted extraction.
Liazid A, Palma M, Brigui J, Barroso CG.
Département de Génie Chimique, Faculté des Sciences et Techniques de Tanger, Université Abdelmalek Essaadi, Tanger, Morocco.
The stability of 22 phenolic compounds of different families (benzoic acids, benzoic aldehydes, cinnamic acids, catechins, coumarins, stilbens and flavonols) has been studied under conditions of microwave-assisted extraction. The influence on the stability affected by the working temperature between 50 and 175 degrees C has been evaluated, and it has been concluded that all the compounds studied are stable up to 100 degrees C
, whereas at 125 degrees C there is significant degradation of epicatechin, resveratrol and myricetin.
Conclusions have been drawn on the relationship between the chemical structure and the stability of the compounds; it has been found that those that have a greater number of hydroxyl-type substituents are more easily degraded under the extraction conditions.
In 2004, there was this paper from a Chinese journal, which might have misled people. It was probably dealing with resveratrol in the solution phase, and all chemicals are more prone to degradation, in some cases a lot more, when they are in solution. That's not obvious from the abstract though, so it might have made people think that resveratrol was touchy.
[quote]Se Pu. 2004 Nov;22(6):583-8.
[Study on thermostability and photo-isomerization of trans-resveratrol by high performance liquid chromatography and liquid chromatography-electrospray ionization-mass spectrometry]
[Article in Chinese]
Liu Y, Wen D, Chen Z, Liao Y, Liu H.
College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
The thermostability and photo-isomerization reaction mechanism of trans-resveratrol were studied by using high performance liquid chromatography (HPLC) and liquid chromatography-electrospray ionization-mass spectrometry ( LC-ESI-MS). A reversed-phase Hypersil-ODS column was used with the mobile phase consisting of 60/40 methanol-water, with addition of 0.05% trifluoroacetic acid for HPLC, and 0.1% formic acid and 5 mmol/L ammonium formate for LC-ESI-MS, at a flow rate of 0.5 mL/min. Diode array detection was set at 300 nm and the injection volume was 20 or 10 microL. Mass spectrometric conditions were in the negative mode. The results of thermostability test under 4, 20 and 40 degrees C indicated that the concentration of trans-resveratrol, after storage for 600 h, was decreased slightly under 4 degrees C, decreased by 5% under 20 degrees C, and 10% under 40 degrees C. In addition, the photo-isomerization reaction of trans- and cis-resveratrol under 254 nm and 365 nm UV irradiation was investigated by LC-ESI-MS, showing that the isomerization is based on p-status, and that some secondary reactions are radical induced.