Salvinorin A

A (-)-kolavenyl diphosphate synthase catalyzes the first step of salvinorin A biosynthesis in Salvia divinorum.[Pubmed:28204567]

J Exp Bot. 2017 Feb 1;68(5):1109-1122.

Salvia divinorum (Lamiaceae) is an annual herb used by indigenous cultures of Mexico for medicinal and ritual purposes. The biosynthesis of Salvinorin A, its major bioactive neo-clerodane diterpenoid, remains virtually unknown. This investigation aimed to identify the enzyme that catalyzes the first reaction of Salvinorin A biosynthesis, the formation of (-)-kolavenyl diphosphate [(-)-KPP], which is subsequently dephosphorylated to afford (-)-kolavenol. Peltate glandular trichomes were identified as the major and perhaps exclusive site of Salvinorin Accumulation in S. divinorum. The trichome-specific transcriptome was used to identify candidate diterpene synthases (diTPSs). In vitro and in planta characterization of a class II diTPS designated as SdKPS confirmed its activity as (-)-KPP synthase and its involvement in Salvinorin A biosynthesis. Mutation of a phenylalanine into histidine in the active site of SdKPS completely converts the product from (-)-KPP into ent-copalyl diphosphate. Structural elements were identified that mediate the natural formation of the neo-clerodane backbone by this enzyme and suggest how SdKPS and other diTPSs may have evolved from ent-copalyl diphosphate synthase.

A unique natural selective kappa-opioid receptor agonist, salvinorin A, and its roles in human therapeutics.[Pubmed:28190678]

Phytochemistry. 2017 May;137:9-14.

Until the mid-60s, only the Mazatecs, an indigenous group from Oaxaca, Mexico, used Salvia Divinorum (S. divinorum) due to its hallucinogen properties. Later it was found that the hallucinogen effects of this plant were caused by the presence of a neoclerodane diterpene Salvinorin A (Salvinorin A), which is a highly selective agonist of kappa-opioid receptor (KOR) that cause more intense hallucinations than the common hallucinogens as lysergic acid, mushrooms, ecstasy and others. In fact, smoking of only 200-500 mug of S. divinorum leaves is enough to produce these effects thus making it the most potent natural occurring hallucinogen known. Due to its legal status in various countries, this compound has gained a worldwide popularity as a drug of abuse with an easy access through smartshops and internet. Furthermore, Salvinorin A gathered an increased interest in the scientific community thanks to its unique structure and properties, and various studies demonstrated that Salvinorin A has antinociceptive, antidepressant, in some circumstances pro-depressant and anti-addictive effects that have yielded potential new avenues for research underlying Salvinorin A and its semi-synthetic analogs as therapeutic agents.

Addressing Structural Flexibility at the A-Ring on Salvinorin A: Discovery of a Potent Kappa-Opioid Agonist with Enhanced Metabolic Stability.[Pubmed:28376298]

J Med Chem. 2017 May 11;60(9):3866-3878.

Previous structure-activity studies on the neoclerodane diterpenoid Salvinorin A have demonstrated the importance of the acetoxy functionality on the A-ring in its activity as a kappa-opioid receptor agonist. Few studies have focused on understanding the role of conformation in these interactions. Herein we describe the synthesis and evaluation of both flexible and conformationally restricted compounds derived from Salvinorin A. One such compound, spirobutyrolactone 14, was synthesized in a single step from salvinorin B and had similar potency and selectivity to Salvinorin A (EC50 = 0.6 +/- 0.2 nM at kappa; >10000 nM at mu and delta). Microsomal stability studies demonstrated that 14 was more metabolically resistant than Salvinorin A. Evaluation of analgesic and anti-inflammatory properties revealed similar in vivo effects between 14 and Salvinorin A. To our knowledge, this study represents the first example of bioisosteric replacement of an acetate group by a spirobutyrolactone to produce a metabolically resistant derivative.

Synergistic blockade of alcohol escalation drinking in mice by a combination of novel kappa opioid receptor agonist Mesyl Salvinorin B and naltrexone.[Pubmed:28263712]

Brain Res. 2017 May 1;1662:75-86.

Mesyl Salvinorin B (MSB) is a potent selective kappa opioid receptor (KOP-r) agonist that has potential for development as an anti-psychostimulant agent with fewer side-effects (e.g., sedation, depression and dysphoria) than classic KOP-r agonists. However, no such study has been done on alcohol. We investigated whether MSB alone or in combination with naltrexone (mu-opioid receptor antagonist) altered voluntary alcohol drinking in both male and female mice. Mice, subjected to 3weeks of chronic escalation drinking (CED) in a two-bottle choice paradigm with 24-h access every other day, developed rapid escalation of alcohol intake and high preference. We found that single, acute administration of MSB dose-dependently reduced alcohol intake and preference in mice after 3-week CED. The effect was specific to alcohol, as shown by the lack of any effect of MSB on sucrose or saccharin intake. We also used the drinking-in-the-dark (DID) model with limited access (4h/day) to evaluate the pharmacological effect of MSB after 3weeks of DID. However, MSB had no effect on alcohol drinking after 3-week DID. Upon investigation of potential synergistic effects between naltrexone and MSB, we found that acute administration of a combination of MSB and naltrexone reduced alcohol intake profoundly after 3-week CED at doses lower than those individual effective doses. Repeated administrations of this combination showed less tolerance development than repeated MSB alone. Our study suggests that the novel KOP-r agonist MSB both alone and in combination with naltrexone shows potential in alcoholism treatment models.