Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: smart on 24/12/2016 13:33:07
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Phytocannabinoids may exists beyond the Cannabis sativa plant:
The dietary polyphenols trans-resveratrol and curcumin (Table 1) were reported to bind selectively to the human CB1 cannabinoid receptor with low nM Ki values (5.9 nM and 45 nM respectively) and to exert potent pharmacological effects in mice similar to those induced by the CB1 receptor inverse agonist rimonabant (Seely et al., 2009). Intrigued by this unexpected finding, our research groups independently measured the binding affinities of these compounds for CB1 and CB2 receptors in our laboratories. In our experiments, trans-resveratrol and curcumin only displaced [3H]CP55 940 from cannabinoid receptors at high µM concentrations, suggesting that they lack significant affinity for these receptors. Also polydatin, a glycosilated form of resveratrol, was inactive in these binding assays. Recently, the senior author of the original report retracted the paper (Prather et al., 2009). Hence, neither trans-resveratrol nor curcumin interact functionally with the CB1 receptor, despite the fact that these compounds appear to share the ability of the CB1 receptor inverse agonist, rimonabant, to induce weight loss in mice.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2931553/
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No. As that quote says :
"curcumin only displaced [3H]CP55 940 from cannabinoid receptors at high µM concentrations, suggesting that they lack significant affinity for these receptors. "
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No.
This
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The dietary polyphenols trans-resveratrol and curcumin (Table 1) were reported to bind selectively to the human CB1 cannabinoid receptor with low nM Ki values (5.9 nM and 45 nM respectively)
This...
Does the low binding affinity of curcumin (45nM) to CB1 receptors may act as a selective partial agonist
and second messenger to GABAergic synapses?
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Does the low binding affinity of curcumin (45nM) to CB1 receptors may act as a selective partial agonist
As demonstrated in the study, curcumin lacks the affinity to displace the full CB1/CB2 agonist CP 55,940 - unless they reach high concentrations [as in µM]. These levels aren't even achievable in vivo, so any appreciable affects by curcumin at these receptors would be highly improbable.
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Does the low binding affinity of curcumin (45nM) to CB1 receptors may act as a selective partial agonist
As demonstrated in the study, curcumin lacks the affinity to displace the full CB1/CB2 agonist CP 55,940 - unless they reach high concentrations [as in µM]. These levels aren't even achievable in vivo, so any appreciable affects by curcumin at these receptors would be highly improbable.
"significant specific binding to either human or mouse CB1 receptors could not be observed below 3 µM concentrations of trans-resveratrol or curcumin."
"although potential weak allosteric effects at the CB1 receptor cannot be excluded, the in vivo data demonstrating antiobesity effects of trans-resveratrol and curcumin reported in our initial report may be completely independent of CB1 and CB2 receptor binding interactions. As such, we are retracting our article from publication in the Journal of Pharmacology and Experimental Therapeutics (JPET)."
J Pharmacol Exp Ther. 2009 Dec;331(3):1147.
Notice of retraction.
Prather PL, Seely KA, Levi MS.
Retraction of: The dietary polyphenols trans-resveratrol and curcumin selectively bind human CB1 cannabinoid receptors with nanomolar affinities and function as antagonists/inverse agonists.