Mitragynine/Corynantheidine Pseudoindoxyls As Opioid Analgesics with Mu Agonism and Delta Antagonism, Which Do Not Recruit beta-Arrestin-2.

Natural products found in Mitragyna speciosa, commonly known as kratom, represent diverse scaffolds (indole, indolenine, and spiro pseudoindoxyl) with opioid activity, providing opportunities to better understand opioid pharmacology. Herein, we report the pharmacology and SAR studies both in vitro and in vivo of mitragynine pseudoindoxyl (3), an oxidative rearrangement product of the corynanthe alkaloid mitragynine. 3 and its corresponding corynantheidine analogs show promise as potent analgesics with a mechanism of action that includes mu opioid receptor agonism/delta opioid receptor antagonism. In vitro, 3 and its analogs were potent agonists in [35S]GTPgammaS assays at the mu opioid receptor but failed to recruit beta-arrestin-2, which is associated with opioid side effects. Additionally, 3 developed analgesic tolerance more slowly than morphine, showed limited physical dependence, respiratory depression, constipation, and displayed no reward or aversion in CPP/CPA assays, suggesting that analogs might represent a promising new generation of novel pain relievers

Synthesis and Pharmacology of Halogenated δ-Opiod Selective [\u3csub\u3eD\u3c/sub\u3eAla\u3csup\u3e2\u3c/sup\u3e] Deltorphin II Peptide Analogs

Deltorphins are naturally occurring peptides produced by the skin of the giant monkey frog (Phyllomedusa bicolor). They are δ-opioid receptor-selective agonists. Herein, we report the design and synthesis of a peptide, Tyr-d-Ala-(pI)Phe-Glu-Ile-Ile-Gly-NH2 3 (GATE3-8), based on the [d-Ala2]deltorphin II template, which is δ-selective in in vitro radioligand binding assays over the μ- and κ-opioid receptors. It is a full agonist in [35S]GTPγS functional assays and analgesic when administered supraspinally to mice. Analgesia of 3 (GATE3-8) is blocked by the selective δ receptor antagonist naltrindole, indicating that the analgesic action of 3 is mediated by the δ-opioid receptor. We have established a radioligand in which 125I is incorporated into 3 (GATE3-8). The radioligand has a KD of 0.1 nM in Chinese hamster ovary (CHO) cells expressing the δ receptor. Additionally, a series of peptides based on 3 (GATE3-8) was synthesized by incorporating various halogens in the para position on the aromatic ring of Phe3. The peptides were characterized for binding affinity at the μ-, δ-, and κ-opioid receptors, which showed a linear correlation between binding affinity and the size of the halogen substituent. These peptides may be interesting tools for probing δ-opioid receptor pharmacology

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Amphetamine Analogs Methamphetamine and 3,4-Methylenedioxymethamphetamine (MDMA) Differentially Affect Speech

Rationale: Most reports of the effects of methamphetamine and 3,4-methylenedioxymethamphetamine (MDMA) on speech have been anecdotal. Objectives: The current study used a within-participant design to assess the effects of methamphetamine and MDMA on speech. Materials and methods: Eleven recreational users of amphetamines completed this inpatient, within-participant, double-blind study, during which they received placebo, methamphetamine (20, 40 mg), and MDMA (100 mg) on separate days. Following drug administration, study participants described movies viewed the previous evening and completed mood scales. Results: Methamphetamine increased quantity of speech, fluency, and self-ratings of talkativeness and alertness, while it decreased the average duration of nonjuncture unfilled pauses. MDMA decreased fluency and increased self-ratings of inability to concentrate. To determine if methamphetamine- and MDMA-related effects were perceptible, undergraduates listened to the participants\u27 movie descriptions and rated their coherence and the speaker\u27s mood. Following methamphetamine, descriptions were judged to be more coherent and focused than they were following MDMA. Conclusions: Methamphetamine improved verbal fluency and MDMA adversely affected fluency. This pattern of effects is consistent with the effects of these drugs on functioning in other cognitive domains. In general, methamphetamine effects on speech were inconsistent with effects popularly attributed to this drug, while MDMA-related effects were in agreement with some anecdotal reports and discordant with others

Tetrapeptide Endomorphin Analogs Require Both Full Length and Truncated Splice Variants of the Mu Opioid Receptor Gene <i>Oprm1</i> for Analgesia

The mu opioid receptor gene undergoes extensive alternative splicing. Mu opioids can be divided into three classes based on the role of different groups of splice variants. Morphine and methadone require only full length seven transmembrane (7TM) variants for analgesia, whereas IBNtxA (3′-iodobenzyol-6β-naltrexamide) needs only truncated 6TM variants. A set of endomorphin analogs fall into a third group that requires both 6TM and 7TM splice variants. Unlike morphine, endomorphin 1 and 2, DAPP (Dmt,d-Ala-Phe-Phe-NH₂), and IDAPP (3′-iodo-Dmt-d-Ala-Phe-Phe-NH₂) analgesia was lost in an exon 11 knockout mouse lacking 6TM variants. Restoring 6TM variant expression in a knockout mouse lacking both 6TM and 7TM variants failed to rescue DAPP or IDAPP analgesia. However, re-establishing 6TM expression in an exon 11 knockout mouse that still expressed 7TM variants did rescue the response, consistent with the need for both 6TM and 7TM variants. In receptor binding assays, ¹²⁵I-IDAPP labeled more sites (<i>B</i>_max) than ³H-DAMGO ([d-Ala²,N-MePhe⁴,Gly­(ol)⁵]-enkephalin) in wild-type mice. In exon 11 knockout mice, ¹²⁵I-IDAPP binding was lowered to levels similar to ³H-DAMGO, which remained relatively unchanged compared to wild-type mice. ¹²⁵I-IDAPP binding was totally lost in an exon 1/exon 11 knockout model lacking all <i>Oprm1</i> variant expression, confirming that the drug was not cross labeling non-mu opioid receptors. These findings suggested that ¹²⁵I-IDAPP labeled two populations of mu binding sites in wild-type mice, one corresponding to 7TM variants and the second dependent upon 6TM variants. Together, these data indicate that endomorphin analogs represent a unique, genetically defined, and distinct class of mu opioid analgesic

Synthesis and Characterization of a Dual Kappa-Delta Opioid Receptor Agonist Analgesic Blocking Cocaine Reward Behavior

3-Iodobenzoyl naltrexamine (IBNtxA) is a potent analgesic belonging to the pharmacologically diverse 6β-amidoepoxymorphinan group of opioids. We present the synthesis and pharmacological evaluation of five analogs of IBNtxA. The scaffold of IBNtxA was modified by removing the 14-hydroxy group, incorporating a 7,8 double bond and various N-17 alkyl substituents. The structural modifications resulted in analogs with picomolar affinities for opioid receptors. The lead compound (<b>MP1104</b>) was found to exhibit approximately 15-fold greater antinociceptive potency (ED₅₀ = 0.33 mg/kg) compared with morphine, mediated through the activation of kappa- and delta-opioid receptors. Despite its kappa agonism, this lead derivative did not cause place aversion or preference in mice in a place-conditioning assay, even at doses 3 times the analgesic ED₅₀. However, pretreatment with the lead compound prevented the reward behavior associated with cocaine in a conditioned place preference assay. Together, these results suggest the promise of dual acting kappa- and delta-opioid receptor agonists as analgesics and treatments for cocaine addiction

Synthesis of Carfentanil Amide Opioids Using the Ugi Multicomponent Reaction

We report a novel approach to synthesize carfentanil amide analogues utilizing the isocyanide-based four-component Ugi multicomponent reaction. A small library of bis-amide analogues of carfentanil was created using <i>N</i>-alkylpiperidones, aniline, propionic acid, and various aliphatic isocyanides. Our lead compound showed high affinity for mu (MOR) and delta opioid receptors (DOR) with no appreciable affinity for kappa (KOR) receptors in radioligand binding assays. The compound was found to be a mixed MOR agonist/partial DOR agonist in [³⁵S]­GTPγS functional assays, and it showed moderate analgesic potency in vivo. The compound showed no visible signs of physical dependence or constipation in mice. In addition, it produced less respiratory depression than morphine. Most mixed MOR/DOR opioids reported in the literature are peptides and thereby systemically inactive. Our approach utilizing a multicomponent reaction has the promise to deliver potent and efficacious small-molecule analgesics with potential clinical utility