Salvinorin C, a new neoclerodane diterpene from a bioactive fraction of the hallucinogenic Mexican mint Salvia divinorum

Design of κ-Opioid Receptor Agonists for the Development of Potential Treatments of Pain with Reduced Side Effects

The κ-opioid receptor (KOR) has recently emerged as an alternative therapeutic target for the development of pain medications, without deleterious side effects associated with the μ-opioid receptor (MOR). However, modulation of KOR is currently under investigation for the treatment of depression, mood disorders, psychiatric comorbidity, and specific drug addictions. However, KOR agonists also trigger adverse effects including sedation, dysphoria, and hallucinations. In this respect, there is currently much debate on alternative paradigms. Recent effort has been devoted in search of biased ligands capable of selectively activating favorable signaling over signaling associated with unwanted side effects. On the other hand, the use of partial agonists is expected to allow the analgesia to be produced at dosages lower than those required to produce the adverse effects. More empirically, the unwanted central effects can be also avoided by using peripherally restricted agonists. In this review, we discuss the more recent trends in the design of KOR-selective, biased or partial, and finally, peripherally acting agonists. Special emphasis is given on the discussion of the most recent approaches for controlling functional selectivity of KOR-specific ligands.

A Review on the Ethnopharmacology and Phytochemistry of the Neotropical Sages (Salvia Subgenus Calosphace; Lamiaceae) Emphasizing Mexican Species

Salvia is the most diverse genus within the mint family (Lamiaceae), many of its species are well-known due to their medicinal and culinary uses. Most of the ethnopharmacological and phytochemical studies on Salvia are centred on species from the European and Asian clades. However, studies about the most diverse clade, the Neotropical sages (Salvia subgenus Calosphace; 587 spp.), are relatively scarce. This review aims to compile the information on the traditional medicinal uses, pharmacological and phytochemistry properties of the Neotropical sages. To do so, we carried out a comprehensive review of the articles available in different online databases published from the past to 2022 (i.e., PubMed, Scopus, and Web of Science, among others) and summarized the information in tables. To uncover phylogenetic patterns in the distribution of four different groups of metabolites (mono-, sesqui-, di-, and triterpenes), we generated presence-absence matrices and plotted the tip states over a dated phylogeny of Salvia. We found several studies involving Mexican species of Salvia, but only a few about taxa from other diversity centres. The main traditional uses of the Mexican species of Calosphace are medicinal and ceremonial. In traditional medicine 56 species are used to treat diseases from 17 categories according to the WHO, plus cultural-bound syndromes. Pharmacological studies reveal a wide range of biological properties (e.g., antinociceptive, anti-inflammatory, anxiolytic, cytotoxic, and antidiabetic, etc.) found in extracts and isolated compounds of 38 Neotropical sages. From extracts of these species, at least 109 compounds have been isolated, identified and evaluated pharmacologically; 73 of these compounds are clerodanes, 21 abietanes, six flavonoids, five sesquiterpenoids, and four triterpenoids. The most characteristic metabolites found in the Neotropical sages are the diterpenes, particularly clerodanes (e.g., Amarisolide A, Tilifodiolide), that are found almost exclusively in this group. The Neotropical sages are a promising resource in the production of herbal medication, but studies that corroborate the properties that have been attributed to them in traditional medicine are scarce. Research of these metabolites guided by the phylogenies is recommended, since closely related species tend to share the presence of similar compounds and thus similar medicinal properties.

Natural Products for the Treatment of Pain: Chemistry and Pharmacology of Salvinorin A, Mitragynine, and Collybolide

Pain remains a very pervasive problem throughout medicine. Classical pain management is achieved through the use of opiates belonging to the mu opioid receptor (MOR) class, which have significant side effects that hinder their utility. Pharmacologists have been trying to develop opioids devoid of side effects since the isolation of morphine from papaver somniferum, more commonly known as opium by Sertürner in 1804. The natural products salvinorin A, mitragynine, and collybolide represent three nonmorphinan natural product-based targets, which are potent selective agonists of opioid receptors, and emerging next-generation analgesics. In this work, we review the phytochemistry and medicinal chemistry efforts on these templates and their effects on affinity, selectivity, analgesic actions, and a myriad of other opioid-receptor-related behavioral effects.

Pharmacokinetics and Pharmacodynamics of Salvinorin A and Salvia divinorum: Clinical and Forensic Aspects

Salvia divinorum Epling and Játiva is a perennial mint from the Lamiaceae family, endemic to Mexico, predominantly from the state of Oaxaca. Due to its psychoactive properties, S. divinorum had been used for centuries by Mazatecans for divinatory, religious, and medicinal purposes. In recent years, its use for recreational purposes, especially among adolescents and young adults, has progressively increased. The main bioactive compound underlying the hallucinogenic effects, salvinorin A, is a non-nitrogenous diterpenoid with high affinity and selectivity for the κ-opioid receptor. The aim of this work is to comprehensively review and discuss the toxicokinetics and toxicodynamics of S. divinorum and salvinorin A, highlighting their psychological, physiological, and toxic effects. Potential therapeutic applications and forensic aspects are also covered in this review. The leaves of S. divinorum can be chewed, drunk as an infusion, smoked, or vaporised. Absorption of salvinorin A occurs through the oral mucosa or the respiratory tract, being rapidly broken down in the gastrointestinal system to its major inactive metabolite, salvinorin B, when swallowed. Salvinorin A is rapidly distributed, with accumulation in the brain, and quickly eliminated. Its pharmacokinetic parameters parallel well with the short-lived psychoactive and physiological effects. No reports on toxicity or serious adverse outcomes were found. A variety of therapeutic applications have been proposed for S. divinorum which includes the treatment of chronic pain, gastrointestinal and mood disorders, neurological diseases, and treatment of drug dependence. Notwithstanding, there is still limited knowledge regarding the pharmacology and toxicology features of S. divinorum and salvinorin A, and this is needed due to its widespread use. Additionally, the clinical acceptance of salvinorin A has been hampered, especially due to the psychotropic side effects and misuse, turning the scientific community to the development of analogues with better pharmacological profiles.

Cutting-Edge Search for Safer Opioid Pain Relief: Retrospective Review of Salvinorin A and Its Analogs

Over the years, pain has contributed to low life quality, poor health, and economic loss. Opioids are very effective analgesic drugs for treating mild, moderate, or severe pain. Therapeutic application of opioids has been limited by short and long-term side effects. These side effects and opioid-overuse crisis has intensified interest in the search for new molecular targets and drugs. The present review focuses on salvinorin A and its analogs with the aim of exploring their structural and pharmacological profiles as clues for the development of safer analgesics. Ethnopharmacological reports and growing preclinical data have demonstrated the antinociceptive effect of salvinorin A and some of its analogs. The pharmacology of analogs modified at C-2 dominates the literature when compared to the ones from other positions. The distinctive binding affinity of these analogs seems to correlate with their chemical structure and in vivo antinociceptive effects. The high susceptibility of salvinorin A to chemical modification makes it an important pharmacological tool for cellular probing and developing analogs with promising analgesic effects. Additional research is still needed to draw reliable conclusions on the therapeutic potential of salvinorin A and its analogs.

Screening of Hallucinogenic Compounds and Genomic Characterisation of 40 Anatolian Salvia Species

INTRODUCTION

Salvia, an important and widely available member of Lamiaceae family. Although comparative analysis on secondary metabolites in several Salvia species from Turkey has been reported, their hallucinogenic chemicals have not been screened thoroughly.

OBJECTIVE

This study provides LC-MS/MS analysis of 40 Salvia species for screening their psychoactive constituents of salvinorin A and salvinorin B. 5S-rRNA gene non-coding region of Salvia plants was sequenced, aligned and compared with that sequence of Salvia divinorum plant.

METHODOLOGY

Targeted molecules of salvinorin A and salvinorin B were quantified, using LC-MS/MS, from all aerial parts of 40 Salvia species, collected from different parts of Turkey. Regions of 5S-rRNA gene from different species were amplified by polymerase chain reaction and DNA sequences were aligned with Salvia divinorum DNA sequences.

RESULTS

Very few of the Salvia species (S. recognita, S. cryptantha and S. glutinosa) contained relatively high levels of salvinorin A (212.86 ± 20.46 μg/g, 51.50 ± 4.95 μg/g and 38.92 ± 3.74 μg/g, respectively). Salvinorin B was also found in Salvia species of S. potentillifolia, S. adenocaulon and S. cryptantha as 2351.99 ± 232.22 μg/g, 768.78 ± 75.90 μg/g and 402.24 ± 39.71 μg/g, respectively. The sequences of 5S-rRNA gene of 40 different Salvia species were presented and it was found that none of the Salvia species in Turkey had similar DNA sequence to Salvia divinorum plant.

CONCLUSION

This is the first report of screening 40 Salvia species in Turkey according to their psychoactive constituents, salvinorin A and salvinorin B and their genomic structures. It is possible that some of these Salvia species may exhibit some psycho activity. Thus, they need to be screened further. Copyright © 2017 John Wiley & Sons, Ltd.

An immunochromatographic assay for rapid etection of salvinorin A

We developed an immunochromatographic assay (ICA) that enables rapid analysis of salvinorin A (Sal A) in Salvia divinorum within 10 min. The result shows that no Sal A in other samples of Lamiaceae plants was detected, but it could recognize Sal A among other substances in complex samples. The main advantage of the ICA is its high performance in combination with low cost, simplicity, and speed. Our newly developed combined ICA/indirect competitive ELISA(icELISA) system enables analysis of large numbers of samples over short periods of time without cumbersome pretreatments in complex mixtures. This method can complement other instrumental analyses for salvinorins, and could be used to deter S. divinorum abuse.

A unique natural selective kappa-opioid receptor agonist, salvinorin A, and its roles in human therapeutics

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 μg 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.

22-azidosalvinorin A exhibits antidepressant-like effect in mice

The increasing cases of depression has made the searches for new drugs and understanding of the underligning neurobiology of this psychiatric disorder a necessity. Here, we modified the structure of salvinorin A (a known halucinogen) and investigated antidepressant-like activity of its four derivatives; 22-methylsulfanylsalvinorin A(SA1), 2-O-cinnamoylsalvinorin B (CSB), 22-azidosalvinorin A (SA2), and 2-O-(4^'-azidophenylsulfonyl)salvinorin B (SA3). Prior to behavioural tests (Irwin test, open field test - OFT, forced swimming test - FST and tail suspension test - TST), SA1 was prepared by reacting salvinorin B and methylthioacetic acid with 89% yield; CSB was obtained from the reaction of salvinorin B and cinnamic acid with 92% yield; SA2 was obtained from the reaction of salvinorin B and azidoacetic acid with 81% yield; and SA3 was prepared by reacting salvinorin B with 4-azidophenylsulfonyl chloride with 80% yield. Oral treatment of mice with these derivatives (1-1000mg/kg) did not elicit toxic sign or death. Unlike SA, SA1, CSB and SA3, treatment with SA2 (5, 10 and 20mg/kg) decreased the immobility (TST and FST) and swimming time (FST) without altering locomotor activity in OFT. A decrease in the immobility time in TST and FST confirmed antidepressant-like property of SA2. Although p-chlorophenylalanine (serotonin depletor) or WAY100635 (selective 5-HT_1A receptor antagonist) did not attenuate effect of SA2, alpha-methyl-para-tyrosine (catecholamine depletor) and prazosin (selective α₁-receptor antagonist) attenuated this effect. SA2 mildly inhibited monoamine oxidase and showed affinity for α₁A, α₁B, α₁D and κ-opioid receptor subtypes. In summary, SA2 induced monoamine-mediated antidepressant-like effect.

A (-)-kolavenyl diphosphate synthase catalyzes the first step of salvinorin A biosynthesis in Salvia divinorum

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.

Clerodane diterpenes: sources, structures, and biological activities

Covering: 1990 to 2015The clerodane diterpenoids are a widespread class of secondary metabolites and have been found in several hundreds of plant species from various families and in organisms from other taxonomic groups. These substances have attracted interest in recent years due to their notable biological activities, particularly insect antifeedant properties. In addition, the major active clerodanes of Salvia divinorum can be used as novel opioid receptor probes, allowing greater insight into opioid receptor-mediated phenomena, as well as opening additional areas for chemical investigation. This article provides extensive coverage of naturally occurring clerodane diterpenes discovered from 1990 until 2015, and follows up on the 1992 review by Merritt and Ley in this same journal. The distribution, chemotaxonomic significance, chemical structures, and biological activities of clerodane diterpenes are summarized. In the cases where sufficient information is available, structure activity relationship (SAR) correlations and mode of action of active clerodanes have been presented.

Salvia divinorum: toxicological aspects and analysis in human biological specimens

The identification and quantitation of the main psychoactive component of Salvia divinorum (salvinorin A) in biological specimens are crucial in forensic and clinical toxicology. Despite all the efforts made, its uncontrolled abuse has increased quickly, exposing its users' health to serious risks both in the short and long term. The use of alternative biological matrices in toxicological analyzes can be advantageous as complementary postmortem samples, or in situations when neither blood nor urine can be collected; they may be useful tools in those determinations, providing important information about prior exposure. The aim of this article is to present a brief summary of legal aspects of Salvia divinorum and salvinorin A, including the methods used for the determination of the latter in biological matrices.

Salvia divinorum: An overview of the usage, misuse, and addiction processes

Salvia divinorum, a sage plant with leaves that can produce a psychoactive high, has been used for hundreds of years for its psycho-mimetic effects in religious rituals in South America. Salvia has now become popular mainly with adolescents and young adults for the short-lived relatively pleasant experiences many consider a "legal high" and its ready availability through Internet purchases. The main (psycho)active compound in salvia is Salvinorin A, a potent κ-opioid agonist and although the short and long-term effects have not been examined in sufficient detail, it is widely believed to have low addictive potential and low toxicity. Recent findings, however, seem to suggest that Salvinorin A can precipitate psychiatric symptoms and negatively affect cognition. Its ready availability and increasingly widespread use requires clinicians to have knowledge and awareness of its effects.

From local to global-fifty years of research on Salvia divinorum

ETHNOPHARMACOLOGICAL RELEVANCE

In 1962 ethnopharmacologists, Hofmann and Wasson, undertook an expedition to Oaxaca, Mexico. These two researchers were the first scientists to collect a flowering specimen of Salvia divinorum allowing the identification of this species. While the species' traditional use is confined to a very small region of Mexico, since Hofmann and Wasson's expedition 50 years ago, Salvia divinorum has become globally recognized for its main active constituent, the diterpene salvinorin A, which has a unique effect on human physiology. Salvinorin A is a kappa-opioid agonist and the first reported psychoactive diterpene.

METHODS

This review concentrates on the investigation of Salvia divinorum over the last 50 years including ethnobotany, ethnopharmacology, taxonomy, systematics, genetics, chemistry and pharmacodynamic and pharmacokinetic research. For the purpose of this review, online search engines were used to find relevant research. Searches were conducted between October 2011 and September 2013 using the search term "Salvia divinorum". Papers were excluded if they described synthetic chemical synthesis of salvinorin A or analogues.

RESULTS

Ethnobotanically there is a comprehensive body of research describing the traditional Mazatec use of the plant, however, the modern ethnobotanical use of this plant is not well documented. There are a limited number of botanical investigations into this plant and there are still several aspects of the botany of Salvia divinorum which need further investigation. One study has investigated the phylogenetic relationship of Salvia divinorum to other species in the genus. To date the main focus of chemistry research on Salvia divinorum has been salvinorin A, the main active compound in Salvia divinorum, and other related diterpenoids. Finally, the effects of salvinorin A, a KOR agonist, have primarily been investigated using animal models.

CONCLUSIONS

As Salvia divinorum use increases worldwide, the emerging cultural use patterns will warrant more research. More botanical information is also needed to better understand this species, including germination, pollination vector and a better understanding of the endemic environment of Salvia divinorum. As well there is a gap in the genetic knowledge of this species and very little is known about its intra-species genetics. The terpenes in Salvia divinorum are very well documented, however, other classes of constituents in this species warrant further investigation and identification. To date, the majority of the pharmacology research on Salvia divinorum has focused on the effects of salvinorin A using animal models. Published human studies have not reported any harmful effects when salvinorin A is administered within the dose range of 0.375-21µg/kg but what are the implications when applied to a larger population? More data on the toxicology and safety of Salvia divinorum are needed before larger scale clinical trials of the potential therapeutic effects of Salvia divinorum and salvinorin A are undertaken.

Salvinorin A analogs and other κ-opioid receptor compounds as treatments for cocaine abuse

Acute activation of kappa-opioid receptors produces anti-addictive effects by regulating dopamine levels in the brain. Unfortunately, classic kappa-opioid agonists have undesired side effects such as sedation, aversion, and depression, which restrict their clinical use. Salvinorin A (Sal A), a novel kappa-opioid receptor agonist extracted from the plant Salvia divinorum, has been identified as a potential therapy for drug abuse and addiction. Here, we review the preclinical effects of Sal A in comparison with traditional kappa-opioid agonists and several new analogs. Sal A retains the anti-addictive properties of traditional kappa-opioid receptor agonists with several improvements including reduced side effects. However, the rapid metabolism of Sal A makes it undesirable for clinical development. In an effort to improve the pharmacokinetics and tolerability of this compound, kappa-opioid receptor agonists based on the structure of Sal A have been synthesized. While work in this field is still in progress, several analogs with improved pharmacokinetic profiles have been shown to have anti-addictive effects. While in its infancy, it is clear that these compounds hold promise for the future development of anti-addictive therapeutics.

Development of an enzyme immunoassay using a monoclonal antibody against the psychoactive diterpenoid salvinorin A

Salvinorin A (1), the main active constituent in Salvia divinorum, is a highly selective kappa-opioid receptor agonist with hallucinogenic effects, which is regulated in several countries. In the present study, a monoclonal antibody (mAb) against 1 was prepared, and an indirect competitive enzyme-linked immunosorbent assay (icELISA) system was developed for the detection of salvinorins. To raise mAbs against 1, salvinorin B (2) hemisuccinate was synthesized and used to prepare the immunogen 2-bovine serum albumin conjugate. This technique was used to prepare a hybridoma cell line, 3D5, which secreted a mAb that recognized 1. The mAb was shown to have specificity for 1 and other salvinorins in cross-reactivity tests. The intra-assay calibration range by icELISA using the mAb against 1 was 0.0195-0.625 μg/mL. After validating the icELISA using intra- and interassays, a recovery experiment and analysis of several plants in the family Lamiaceae, including S. divinorum, confirmed that the analytical method based on ELISA is not only simple but also precise, accurate, sensitive, and sufficiently reliable. The results indicate that icELISA is a useful tool in the identification of S. divinorum.

Neoclerodanes as atypical opioid receptor ligands

The neoclerodane diterpene salvinorin A is the major active component of the hallucinogenic mint plant Salvia divinorum Epling and Játiva (Lamiaceae). Since the finding that salvinorin A exerts its potent psychotropic actions through the activation of opioid receptors, the site of action of morphine and related analogues, there has been much interest in elucidating the underlying mechanisms behind its effects. These effects are particularly remarkable because (1) salvinorin A is the first reported non-nitrogenous opioid receptor agonist and (2) its effects are not mediated through the previously investigated targets of psychotomimetics. This Perspective outlines our research program, illustrating a new direction to the development of tools to further elucidate the biological mechanisms of drug tolerance and dependence. The information gained from these efforts is expected to facilitate the design of novel agents to treat pain, drug abuse, and other central nervous system disorders.

Dose-related effects of salvinorin A in humans: dissociative, hallucinogenic, and memory effects

RATIONALE

Salvinorin A is a kappa opioid agonist and the principal psychoactive constituent of the plant Salvia divinorum, which has increased in popularity as a recreational drug over the past decade. Few human studies have examined salvinorin A.

OBJECTIVE

This double-blind, placebo-controlled study evaluated the dose-related effects of inhaled salvinorin A in individuals with histories of hallucinogen use.

METHODS

Eight healthy hallucinogen-using adults inhaled up to 16 doses of salvinorin A (0.375-21 μg/kg) in ascending order. Physiological, behavioral, and subjective effects were assessed every 2 min for 60 min after administration. Qualitative subjective effects were assessed retrospectively via questionnaires at the end of sessions. Persisting effects were assessed 1 month later.

RESULTS

Orderly dose-related effects peaked at 2 min and then rapidly dissipated, replicating previous findings. Subjective effects were intense, with maximal drug strength ratings or unresponsiveness frequently observed at high doses. Questionnaires assessing qualitative effects (Hallucinogen Rating Scale, Pharmacological Class Questionnaire) suggested some overlap with serotonergically mediated classic hallucinogens. Salvinorin A also produced dose-related dissociative effects and impairments in recall/recognition memory. At 1-month follow-up, there was no evidence of persisting adverse effects. Participants reported that salvinorin A effects were qualitatively different from other drugs.

CONCLUSIONS

Salvinorin A produces a unique profile of subjective and cognitive effects, including strong dissociative effects and memory impairment, which only partially overlap with classic hallucinogen effects. Along with nonhuman studies of salvinorin A, these results are important for understanding the neurobiology of the kappa opioid system and may ultimately have important therapeutic applications.

Salvia divinorum use and phenomenology: results from an online survey

Salvia divinorum is a hallucinogenic plant with ethnopharmacological and recreational uses. It differs from classic serotonergic hallucinogens such as LSD and psilocin in both phenomenology and potent agonist activity of the active component salvinorin A at κ-opioid receptors. Awareness of S. divinorum has grown recently, with both an increase in its public representation and concern over its potential harmful effects. This discussion is particularly relevant as S. divinorum is legal to use in many countries and regions and easily available through online retailers. Drawing upon previous investigations of S. divinorum and other hallucinogens, this study surveyed 154 recent users and questioned them on their use behaviours, consequences of use and other attitudinal measures. Although reporting an extensive substance use history, and considering the limitations of online surveys, there was little evidence of dysfunctional S. divinorum use, and few reports of troubling adverse consequences of use. Furthermore, there was no evidence that users exhibited increased schizotypy. Respondents reported that S. divinorum produced mixed hallucinogenic and dissociative effects, which lends support to assertions that it phenomenologically differs from other hallucinogens with primary serotonergic activity. The functions of use changed with greater experiences with the drug, and although many respondents reported use of S. divinorum as an alternative to illegal drugs it, was apparent that legal proscription would be unlikely to dissuade them from use. These results are discussed with reference to psychopharmacologically informed public health responses to substance use.

Synthesis of neoclerodane diterpenes and their pharmacological effects

Salvinorin A is a neoclerodane diterpene that has been shown to be an agonist at kappa opioid receptors. Its unique structure makes it an attractive target for synthetic organic chemists due to its seven chiral centers and diterpene scaffold. This molecule is also interesting to pharmacologists because it is a non-serotonergic hallucinogen, and the first opioid ligand discovered that lacks a basic nitrogen. There have been several total synthesis approaches to salvinorin A, and these will be detailed within this chapter. Additionally, research efforts have concentrated on structure modification of the salvinorin A scaffold through semi-synthetic methods. Most modifications have focused on the manipulation of the acetate at C-2 and the furan ring. However, chemistry has also been developed to generate analogs at the C-1 ketone, the C-4 methyl ester, and the C-17 lactone. The synthetic methodologies developed for the salvinorin A scaffold will be described, as well as specific analogs with interesting biological activities.

Neuropharmacology of the naturally occurring kappa-opioid hallucinogen salvinorin A

Salvia divinorum is a perennial sage native to Oaxaca, Mexico, that has been used traditionally in divination rituals and as a treatment for the "semimagical" disease panzón de borrego. Because of the intense "out-of-body" experiences reported after inhalation of the pyrolized smoke, S. divinorum has been gaining popularity as a recreational hallucinogen, and the United States and several other countries have regulated its use. Early studies isolated the neoclerodane diterpene salvinorin A as the principal psychoactive constituent responsible for these hallucinogenic effects. Since the finding that salvinorin A exerts its potent psychotropic actions through the activation of KOP receptors, there has been much interest in elucidating the underlying mechanisms behind its effects. These effects are particularly remarkable, because 1) salvinorin A is the first reported non-nitrogenous opioid receptor agonist, and 2) its effects are not mediated by the 5-HT(2A) receptor, the classic target of hallucinogens such as lysergic acid diethylamide and mescaline. Rigorous investigation into the structural features of salvinorin A responsible for opioid receptor affinity and selectivity has produced numerous receptor probes, affinity labels, and tools for evaluating the biological processes responsible for its observed psychological effects. Salvinorin A has therapeutic potential as a treatment for pain, mood and personality disorders, substance abuse, and gastrointestinal disturbances, and suggests that nonalkaloids are potential scaffolds for drug development for aminergic G-protein coupled receptors.

First Total Synthesis of the Neo-Clerodane Diterpenoid Salvinorin F

The total synthesis of the neoclerodane diterpenoid salvinorin F was accomplished for the first time.

Absorption, distribution, metabolism and excretion pharmacogenomics of drugs of abuse

Pharmacologic and toxic effects of xenobiotics, such as drugs of abuse, depend on the genotype and phenotype of an individual, and conversely on the isoenzymes involved in their metabolism and transport. The current knowledge of such isoenzymes of frequently abused therapeutics such as opioids (oxycodone, hydrocodone, methadone, fentanyl, buprenorphine, tramadol, heroin, morphine and codeine), anesthetics (γ-hydroxybutyric acid, propofol, ketamine and phencyclidine) and cognitive enhancers (methylphenidate and modafinil), and some important plant-derived hallucinogens (lysergide, salvinorin A, psilocybin and psilocin), as well as of nicotine in humans are summarized in this article. The isoenzymes (e.g., cytochrome P450, glucuronyltransferases, esterases and reductases) involved in the metabolism of drugs and some pharmacokinetic data are discussed. The relevance of such data is discussed for predicting possible interactions with other xenobiotics, understanding pharmacokinetic behavior and pharmacogenomic variations, assessing toxic risks, developing suitable toxicological analysis procedures, and finally for interpretating drug testing results.

Natural products from the hallucinogenic sage

The isolation, structures and biological activity of the neoclerodane and other natural products obtained from the Mexican hallucinogenic sage, Salvia divinorum are reviewed.

New therapeutic potential for psychoactive natural products

Much of our knowledge in neuroscience was discovered through the study of mind-altering natural products. However, although much has been learned about human physiology and basic biological processes, the underlying causes of CNS disorders and other disease states are still elusive. Based on its main past successes, the continued study of mind-altering compounds promises to yield novel agents that may be developed into medications and to identify new targets for the treatment of diseases. This Highlight describes the history of investigations into several classes of mind-altering natural products and relates recent and potential therapeutic uses for these agents.

Evaluation of the transport, in vitro metabolism and pharmacokinetics of Salvinorin A, a potent hallucinogen

Salvinorin A is an unregulated potent hallucinogen isolated from the leaves of Salvia divinorum. It is the only known non-nitrogenous kappa-opioid selective agonist, and rivals synthetic lysergic acid diethylamide (LSD) in potency. The objective of this study was to characterize the in vitro transport, in vitro metabolism, and pharmacokinetic properties of Salvinorin A. The transport characteristics of Salvinorin A were assessed using MDCK-MDR1 cell monolayers. The P-glycoprotein (P-gp) affinity status was assessed by the P-gp ATPase assay. In vitro metabolism studies were performed with various specific human CYP450 isoforms and UGT2B7 to assess the metabolic characteristics of Salvinorin A. Cohorts (n = 3) of male Sprague Dawley rats were used to evaluate the pharmacokinetics and brain distribution of Salvinorin A (10 mg/kg, intraperitoneal (i.p.) over a 240-min period. A validated UV-HPLC and LC/MS/MS method was used to quantify the hallucinogen concentrations obtained from the in vitro and in vivo studies, respectively. Salvinorin A displayed a high secretory transport in the MDCK-MDR1 cells (4.07 +/- 1.34 x 10(-)5 cm/s). Salvinorin A also stimulated the P-gp ATPase activity in a concentration (5 and 10 microM)-dependent manner, suggesting that it may be a substrate of (P-gp). A significant decrease in Salvinorin A concentration ranging from 14.7 +/- 0.80% to 31.1 +/- 1.20% was observed after incubation with CYP2D6, CYP1A1, CYP2C18, and CYP2E1, respectively. A significant decrease was also observed after incubation with UGT2B7. These results suggest that Salvinorin A maybe a substrate of UGT2B7, CYP2D6, CYP1A1, CYP2E1, and CYP2C18. The in vivo pharmacokinetic study showed a relatively fast elimination with a half-life (t1/2) of 75 min and a clearance (Cl/F) of 26 L/h/kg. The distribution was extensive (Vd of 47.1 L/kg); however, the brain to plasma ratio was 0.050. Accordingly, the brain half-life was relatively short, 36 min. Salvinorin A is rapidly eliminated after i.p. dosing, in accordance with its fast onset and short duration of action. Further, it appears to be a substrate for various oxidative enzymes and multi-drug resistant protein, P-gp.

Salvinorins J from Salvia divinorum: mutarotation in the neoclerodane system

A search for biosynthetic precursors of salvinorin A (1) led to the isolation of a new neoclerodane diterpenoid hemiacetal mixture, salvinorins J (2), from the chloroform extract of Salvia divinorum. A leaf surface extraction method was used on S. divinorum, affording a chlorophyll-free extract containing predominantly neoclerodane diterpenoids, including the new salvinorins J (2) and 14 known analogues. Salvinorins J (2) represent an example of a neoclerodane hemiacetal (lactol) susceptible to mutarotation with the formation of an equilibrium mixture of C-17 epimers.

Natural products as tools for neuroscience: discovery and development of novel agents to treat drug abuse

Much of what we know about the neurosciences is the direct result of studying psychoactive natural products. Unfortunately, there are many gaps in our understanding of the basic biological processes that contribute to the etiology of many CNS disorders. The investigation of psychoactive natural products offers an excellent approach to identify novel agents to treat CNS disorders and to find new chemical tools to better elucidate their biological mechanisms. This review will detail recent progress in a program directed toward investigating psychoactive natural products with the goal of treating drug abuse by targeting kappa opioid receptors.

Synthesis of deacetyl-1,10-didehydrosalvinorin G

To unambiguously confirm the actual product in autoxidation of salvinorin A under basic conditions, deacetyl-1,10-didehydrosalvinorin G was synthesized from salvinorin C via intermediate salvinorin H. Furthermore, oxidation of salvinorin D with manganese dioxide gave salvinorin G in good yield.

Total synthesis of the hallucinogenic neoclerodane diterpenoid salvinorin A

Total synthesis of salvinorin A (1), a neoclerodane diterpenoid having the most potent hallucinogenic activity and a selective kappa-opioid agonist, was completed in 20 steps starting from enantiomerically pure hydroxy-Wieland-Miescher ketone 5.

Short synthesis of a novel class of salvinorin A analogs with hemiacetalic structure

Novel semisynthetic analogs of salvinorin A, a full agonist having extraordinary affinity as well as selectivity for the κ-opioid receptor (KOR), were obtained in good yields. The derivatives are remarkable for their unusual and unique hemiacetal structure in the salvinorin series of compounds. The formation of the hemiacetal occurs with epimerization at C-12, thus preserving the original configuration of salvinorin A. The dimethyl ester derivative of the hemiacetal was found to have an affinity for both KOR and MOR (μ-opioid receptor).

Isolation and Chemical Modification of Clerodane Diterpenoids fromSalvia Species as Potential Agonists at theκ-Opioid Receptor

The clerodane diterpenoid salvinorin A (1), the main active component of the psychotropic herb Salvia divinorum, has been reported to be a potent agonist at the kappa-opioid receptor. Computer modeling suggested that splendidin (2) from S. splendens, as well as related compounds, might possess similar activities. In the present study, this hypothesis was tested by determination of the binding properties of a series of structural congeners, compounds 2-8, at the mu-, delta-, and kappa-opioid receptors. However, none of these compounds showed significant binding to any of the opioid-receptor subtypes, thus disproving the above hypothesis. The novel compounds 7 and 8 were obtained semi-synthetically by selective modification of salvifarin (5), isolated from Salvia farinacea, upon epoxide-ring opening with AcOH in the presence of indium(III) triflate. Also, the X-ray crystal structure of salvifaricin (6; Fig.), obtained from S. farinacea, was determined for the first time and used, in combination with in-depth NMR experiments, to elucidate the absolute configurations of the new products. Our experiments demonstrate that the relatively well-accessible diterpenoid 6 could be used as starting material for future studies into the structure-activity relationship at the kappa-opioid receptor.

Revised structure of deacetyl-1,10-didehydrosalvinorin G

In comparison with the NMR data of salvinorin A and its 8-epimer, the published structure of deacetyl-1,10-didehydrosalvinorin G was revised to its 8-epimer. The stereochemistry of 8-epi-deacetyl-1,10-didehydrosalvinorin G was further confirmed by NOESY and chemical synthesis.

Convenient synthesis and in vitro pharmacological activity of 2-thioanalogs of salvinorins A and B

To study drug-receptor interactions, new thio-derivatives of salvinorin A, an extremely potent natural kappa-opioid receptor (KOR) agonist, were synthesized. Obtained compounds were examined for receptor binding affinity. Analogs with the same configuration at carbon atom C-2 as in natural salvinorin A showed higher affinity to KOR than their corresponding epimers.

8-epi-Salvinorin B: crystal structure and affinity at the kappa opioid receptor

There have been many reports of epimerization of salvinorins at C-8 under basic conditions, but little evidence has been presented to establish the structure of these compounds. We report here the first crystal structure of an 8-epi-salvinorin or derivative: the title compound, 2b. The lactone adopts a boat conformation with the furan equatorial. Several lines of evidence suggest that epimerization proceeds via enolization of the lactone rather than a previously proposed indirect mechanism. Consistent with the general trend in related compounds, the title compound showed lower affinity at the kappa opioid receptor than the natural epimer salvinorin B (2a). The related 8-epi-acid 4b showed no affinity.

Neo-clerodane diterpenes from the hallucinogenic sage Salvia divinorum

Seven new neo-clerodane diterpenes, salvidivins A (2), B, (3), C (4), and D (5), salvinorins H (6) and I (7), and divinatorin [corrected] F (8), along with eight known neo-clerodane diterpenes, salvinorins A (1)-F, divinatorins A and B, and seven other constituents, were isolated from the hallucinogenic sage Salvia divinorum. The structures of 1-7 were elucidated on the basis of 2D NMR spectroscopic studies.

Autoxidation of salvinorin A under basic conditions

[reaction: see text] Treatment of salvinorin A (1a) with KOH in MeOH gave the enedione 3, for which the dienone structure 7 was recently proposed. Also isolated, after methylation, were the secotriesters 4a-c. A mechanism for this unusual series of autoxidations is proposed. Surprisingly, 4a showed weak affinity at the kappa-opioid receptor. Divinatorins A-C (2a-c) showed no affinity at opioid receptors. Attempted reduction of 3 to a novel salvinorin diol (9d) was unsuccessful, but careful deacetylation of salvinorin C (9a) provided a viable route to this compound. A general method for identifying salvinorin 8-epimers by TLC is also presented.

Salvinicins A and B, new neoclerodane diterpenes from Salvia divinorum

[reaction: see text] Two new neoclerodane diterpenes, salvinicins A (4) and B (5), were isolated from the dried leaves of Salvia divinorum. The structures of these compounds were elucidated by spectroscopic techniques, including (1)H and (13)C NMR, NOESY, HMQC, and HMBC. The absolute stereochemistry of these compounds was assigned on the basis of single-crystal X-ray crystallographic analysis of salvinicin A (4) and a 3,4-dichlorobenzoate derivative of salvinorin B.

New Drugs of Abuse in North America

The term "drugs of abuse" usually brings to mind traditional street drugs, such as cocaine, heroin, marijuana, and methamphetamine. The drug scene, however, is constantly evolving. As various law enforcement agencies pursue and dismantle distribution and pro-duction organizations of the usual drugs of abuse, dealers and users are turning to less known, more accessible, and often currently licit substances. The widespread growth of the Internet with its vast distribution of information has increased the accessibility ofa host of substances and facilitated synthesis and production of various substances by individuals. This article discusses several new and emerging abused substances, including new synthetic variations, plants, and pharmaceuticals diverted for abuse.

Concise Synthesis of theneo-Clerodane Skeleton of Teucrolivin A Using a Pericyclic Reaction Cascade

Herein, we describe the synthesis of advanced intermediate 39 on the path towards the total synthesis of teucrolivin A (3) in 16 steps from commercially available 1,3-cyclohexadiene. We have constructed the trans-decalin core of the natural product 3 as a single diastereomer using a tandem oxy-Cope/Claisen/ene cascade and in doing so have incorporated sufficient functionality to allow completion of the total synthesis.

Studies Towards the Synthesis of Salvinorin A

Salvinorin A 1, a psychoactive neoclerodane diterpenoid from the Mexican sage S. divinorum, has gained interest as a selective κ-opioid receptor agonist. Non-racemic 3-furylamines 9a and 9b have been prepared from (+)-pseudoephedrine and (–)-ephedrine for application in the stereoselective synthesis of the ketone ring of 1. Diels–Alder reaction of 9b with methyl acrylate in aqueous media, followed by selective ether bridge cleavage, has allowed access to the cyclohexenone 17 with preservation of stereochemistry at C2. A model route to the lactone ring has also been achieved through a one-pot deconjugation/esterification procedure of 2-bromocrotonyl chloride 20 to the furyl alcohol 19 followed by Reformatski-mediated ring closure.

Determination of salvinorins and divinatorins in Salvia divinorum leaves by liquid chromatography/multistage mass spectrometry

Salvinorin A is the most potent naturally occurring hallucinogen known and rivals synthetic LSD in potency. Structurally it belongs to the neoclerodane diterpenoids, and it is the only known non-nitrogenous kappa-opioid-selective agonist. Salvia divinorum (Diviner's sage) is a member of the mint family that was used in ancient Mexican traditional practices. Today it is widely cultivated in Europe as a recreational marijuana substitute; it is illegal to buy, sell or possess the plant or the active principle in some countries. Six different salvinorins and three divinatorins have been isolated from Salvia divinorum leaves. The ion fragmentation, separation and quantitation of these diterpenes by liquid chromatography/electrospray ionization multistage mass spectrometry (LC/ESI-MS(n)) are described. The importance of LC in herbal extract determination and the chemical diagnostic power of MS(n) in the analysis of classes of natural organic products are discussed.