Molecular binding of Salvinorin & more potent analogue

Lego · Thu Jul 07, 2005 2:24 am

Identification of the Molecular Mechanisms by Which the Diterpenoid Salvinorin A Binds to -Opioid Receptors
Feng Yan, Philip D. Mosier, Richard B. Westkaemper, Jeremy Stewart, Jordan K. Zjawiony, Timothy A. Vortherms, Douglas J. Sheffler, and Bryan L. Roth
Biochemistry, 2005, 44, 8643-8651
http://dx.doi.org/10.1021/bi050490d
http://rapidshare.de/files/2855075/Biochemistry__2005__44__8643-8651.pdf.html

Abstract: Salvinorin A is a naturally occurring hallucinogenic diterpenoid from the plant Salvia divinorum that selectively and potently activates -opioid receptors (KORs). Salvinorin A is unique in that it is the only known lipid-like molecule that selectively and potently activates a G-protein coupled receptor (GPCR), which has as its endogenous agonist a peptide; salvinorin A is also the only known non-nitrogenous opioid receptor agonist. In this paper, we identify key residues in KORs responsible for the high binding affinity and agonist efficacy of salvinorin A. Surprisingly, we discovered that salvinorin A was stabilized in the binding pocket by interactions with tyrosine residues in helix 7 (Tyr313 and Tyr320) and helix 2 (Tyr119). Intriguingly, activation of KORs by salvinorin A required interactions with the helix 7 tyrosines Tyr312, Tyr313, and Tyr320 and with Tyr139 in helix 3. In contrast, the prototypical nitrogenous KOR agonist U69593 and the endogenous peptidergic agonist dynorphin A (1-13) showed differential requirements for these three residues for binding and activation. We also employed a novel approach, whereby we examined the effects of cysteine-substitution mutagenesis on the binding of salvinorin A and an analogue with a free sulfhydryl group, 2-thiosalvinorin B. We discovered that residues predicted to be in close proximity, especially Tyr313, to the free thiol of 2-thiosalvinorin B when mutated to Cys showed enhanced affinity for 2-thiosalvinorin B. When these findings are taken together, they imply that the diterpenoid salvinorin A utilizes unique residues within a commonly shared binding pocket to selectively activate KORs.

Synthesis and in vitro pharmacological evaluation of salvinorin A analogues modified at C(2)
Cécile Béguin, Michele R. Richards, Yulin Wang, Yong Chen, Lee-Yuan Liu-Chen, Zhongze Mac, David Y.W. Lee, William A. Carlezon, Jr. and Bruce M. Cohen
Bioorg. Med. Chem. Lett., 2005, 15, 2761-2765
http://dx.doi.org/10.1016/j.bmcl.2005.03.113
http://rapidshare.de/files/2855399/Bioorg._Med._Chem._Lett.__2005__15__2761-2765.pdf.html

Abstract: Salvinorin A is the only known non-nitrogenous and specific κ-opioid agonist. A series of salvinorin A derivatives were prepared and tested for in vitro activity at the κ-opioid receptor. Unsubstituted carbamate 9 was a potent κ-agonist (EC50 = 6.2 nM) and should be more stable than salvinorin A toward metabolic transformations. Compound 10, containing an N-methyl carbamate at C(2), showed partial agonist activity with 81% efficacy when compared with the full agonist U50,488H. No antagonist ligands were observed.

Synthesis and in vitro pharmacological studies of new C(2) modified salvinorin A analogues
David Y.W. Lee, Vishnu V.R. Karnati, Minsheng He, Lee-Yuan Liu-Chen, Leelakrishna Kondareti, Zhongze Ma, Yulin Wang, Yong Chen, Cecile Beguin, William A. Carlezon, Jr. and Bruce Cohen
Bioorg. Med. Chem. Lett., article in press, corrected proof
http://dx.doi.org/10.1016/j.bmcl.2005.05.048
http://rapidshare.de/files/2855450/Bioorg._Med._Chem._Lett.__2005_10.1016_j.bmcl.2005.05.048.pdf.html

Abstract: Salvinorin A is the most potent naturally occurring opioid agonist yet discovered with high selectivity and affinity for κ-opioid receptor. To explore its structure and activity relationships, a series of salvinorin A derivatives modified at the C(2) position were prepared and studied. These salvinorin A derivatives were screened for binding and functional activities at the human κ-opioid receptor. Compound 4, containing a methoxymethyl group at the 2-position, was a full κ-agonist with an EC50 value at 0.6 nM, which is about 7 times more potent than salvinorin A.

scarmani · Wed Jul 13, 2005 7:36 am

Neoclerodane Diterpenes as a Novel Scaffold for mu Opioid Receptor Ligands
Wayne W. Harding, Kevin Tidgewell, Nathan Byrd, Howard Cobb, Christina M. Dersch, Eduardo R. Butelman, Richard B. Rothman, and Thomas E. Prisinzano,
J. Med. Chem., article in press, corrected proof
http://dx.doi.org/10.1021/jm048963m
http://www.streamload.com/scarmani/Research/Opioids/Neoclerodane_Diterpenes_as_a_Novel_Scaffold_for_mu-Opioid_Receptor_Ligands.pdf

Abstract:
Structural modification of salvinorin A, the active component of Salvia divinorum, has resulted in the synthesis of novel neoclerodane diterpenes with opioid receptor affinity and activity. We report in this study a nonnitrogenous neoclerodane diterpene with mu opioid receptor affinity (13) that is an agonist at mu opioid receptors. This represents the identification of a novel structural class of mu opioid receptor agonists.

Lego · Sat Aug 27, 2005 10:06 pm

Synthesis and in vitro pharmacological studies of C(4) modified salvinorin A analogues
David Y.W. Lee, Minsheng Hea, Leelakrishna Kondaveti, Lee-Yuan Liu-Chen, Zhongze Ma, Yulin Wang, Yong Chen, Jian-Guo Li, Cecile Beguin, William A. Carlezon, Jr. and Bruce Cohen
Bioorg. Med. Chem. Lett., 2005, 15(19), 4169-4173
http://dx.doi.org/10.1016/j.bmcl.2005.06.092
http://rapidshare.de/files/4429897/Bioorg._Med._Chem._Lett.__2005__15_19___4169-4173.pdf.html

Abstract: Salvinorin A is the most potent naturally occurring opioid agonist with a high selectivity and affinity for κ-opioid receptor. To explore its structure–activity relationships, modifications at the C(4) position have been studied and a series of salvinorin A derivatives were prepared. These C(4)-modified salvinorin A analogues were screened for binding and functional activities at the human κ-opioid receptor and several potent new agonists have been identified.

New neoclerodane diterpenoids isolated from the leaves of Salvia divinorum and their binding affinities for human κ opioid receptors
David Y.W. Lee, Zhongze Ma, Lee-Yuan Liu-Chen, Yulin Wang, Yong Chen, William A. Carlezon, Jr. and Bruce Cohen
Bioorg. Med. Chem., 2005, 13(19), 5635-5639
http://dx.doi.org/10.1016/j.bmc.2005.05.054
http://rapidshare.de/files/4429960/Bioorg._Med._Chem.__2005__13_19___5635-5639.pdf.html

Abstract: Bioactivity-guided fractionation of the leaves of Salvia divinorum has resulted in the isolation of three new neoclerodane diterpenoids: divinatorin D (1), divinatorin E (2), and salvinorin G (3), together with 10 known terpenoids, divinatorin C (4), hardwickiic acid (5), salvinorin-A (6), -B (7), -C (8), -D (9), -E (10), and -F (11), presqualene alcohol (12), and (E)-phytol (13). The structures of these three new compounds were characterized by spectroscopic methods. All these compounds were evaluated for their binding affinities to the human κ opioid receptors. In comparison with divinatorin D (1), divinatorin E (2), and salvinorin G (3), salvinorin A (6) is still the most potent κ agonist.

Lego · Thu Sep 08, 2005 3:57 pm

Pharmacokinetics of the plant-derived kappa-opioid hallucinogen salvinorin A in nonhuman primates
Schmidt MD, Schmidt MS, Butelman ER, Harding WW, Tidgewell K, Murry DJ, Kreek MJ, Prisinzano TE
Synapse, 2005, 58(3), 208-210
http://dx.doi.org/10.1002/syn.20191
http://rapidshare.de/files/4855316/Synapse__2005__58_3___208-210.pdf.html

Abstract: Salvinorin A, a potent hallucinogen isolated from the leaves of Salvia divinorum, has gained popularity among adolescents in the USA. No detailed study of the pharmacokinetics has been conducted in vivo. The present study investigates the in vivo pharmacokinetics of salvinorin A (0.032 mg/kg, i.v. bolus) in rhesus monkeys (n = 4, 2 male, 2 female). The elimination t(1/2) was rapid (56.6 +/- 24.8 min) for all subjects. Pharmacokinetic differences (distribution t(1/2), elimination t(1/2), and AUC) were observed between males and females, suggesting potential sex differences in its pharmacologic effects. Salvinorin B, the presumed major metabolite, is observed to accumulate ex vivo; however, in this study it never reached the limit of detection.