Scale Up Isolation of Aaptamine for In Vivo Evaluation Indicates Its Neurobiological Activity is Linked to the Delta Opioid Receptor

Opioid receptors belong to the large superfamily of seven transmembrane-spanning (7TM) G protein-coupled receptors (GPCRs). As a class, GPCRs are of fundamental physiological importance mediating the actions of the majority of known neurotransmitters and hormones. The Mu, Delta, and Kappa (MOP, DOP, KOP) opioid receptors are particularly intriguing members of this receptor family as they are the targets involved in many neurobiological diseases such as addiction, pain, stress, anxiety, and depression. Recently we discovered that the aaptamine class of marine sponge derived natural products exhibit selective agonist activity in vitro for the DOP versus MOP receptor. Our findings may explain reports by others that aaptamine demonstrates in vivo anti-depressant effects in mouse models using the Porsolt Forced Swim Test. This project involved the extraction of the sponge Aaptos aaptos (a source of 1), establishing a scale up purification procedure to provide sufficient amounts of 1 (30 mg) for a follow up in vivo evaluation and ultimately confirmation of the structure of 1 using LC-MS and 1H NMR. The results our purification scheme, chemical analysis and in vivo evaluation of 1 using the Marble burying test in rodents are reported here in and suggest that the in vivo anti-depressant effects of 1 are linked directly to its agonist effects on the DOP receptor.https://scholar.dominican.edu/ug-student-posters/1008/thumbnail.jp

Scale up isolation of aaptamine for in vivo evaluation indicates its neurobiological activity is linked to the delta opioid receptor

Opioid receptors belong to the large superfamily of seven transmembrane-spanning (7TM) G protein-coupled receptors (GPCRs). As a class, GPCRs are of fundamental physiological importance mediating the actions of the majority of known neurotransmitters and hormones. The Mu (µ), Delta (δ) and Kappa (MOR, DOR, KOR) opioid receptors are particularly intriguing members of this receptor family as they are the targets involved in many neurobiological diseases such as addiction, pain, stress, anxiety, and depression. To date few marine natural products have been investigated for their neurobiological activities.1 One noteworthy example involves ziconotide (1) from the cone snail Conus magnus.2 Compound 1 was the first marine natural product approved by the FDA and is used for the treatment of pain, marketed under the trade name Prialt® (2004).3 More recently Hamman reported that aaptamine (2) is the first marine natural product to show in vivo anti-depressant activity, however no mechanism of action was proposed.1,4 During a separate collaborative screening project we profiled 96 sponge-derived extracts and discovered that demethyl–aaptamine (3) and demethyl (oxy)–aaptamine (4) were selective DOR agonists using an LC-MS based library of an active methanolic extract coll. no. 92553 FM as shown in Fig. 1. We speculated that the in vivo activity for 2 could thus be linked to the DOR target and to test this hypothesis we conducted the following experiments below.https://scholar.dominican.edu/ug-student-posters/1074/thumbnail.jp

Model Characterization of Pulmonary Arterial Hypertension: Analysis of Lung Pathology with Respect to Human Disease

Pulmonary arterial hypertension (PAH) is a rare multifactorial disease characterized by abnormal high blood pressure in the pulmonary artery, or increased pulmonary vascular resistance (PVR), caused by obstruction in the small arteries of the lung. Increased PVR is also thought to be caused by abnormal vascular remodeling, due to thickening of the pulmonary vascular wall resulting from significant hypertrophy of pulmonary arterial smooth-muscle cells (PASMCs) and increased proliferation/impaired apoptosis of pulmonary arterial endothelial cells (PAECs). Herein, we investigated the mechanisms and explored molecular pathways mediating the lung pathogenesis in two PAH rat models: Monocrotaline (MCT) and Sugen5416/Hypoxia (SuHx). We analyzed these disease models to determine where the vasculature shows the most severe PAH pathology and which model best recapitulates the human disease. We investigated the role vascular remodeling, hypoxia, cell proliferation, apoptosis, DNA damage and inflammation play in the pathogenesis of PAH. Neither model recapitulated all features of the human disease, however each model presented with some of the pathology seen in PAH patients

Identification of the First Marine-Derived Opioid Receptor Balanced Agonist with a Signaling Profile That Resembles the Endorphins.

Opioid therapeutics are excellent analgesics, whose utility is compromised by dependence. Morphine (1) and its clinically relevant derivatives such as OxyContin (2), Vicodin (3), and Dilaudid (4) are biased agonists at the μ opioid receptor (OR), wherein they engage G protein signaling but poorly engage β-arrestin and the endocytic machinery. In contrast, endorphins, the endogenous peptide agonists for ORs, are potent analgesics, show reduced liability for tolerance and dependence, and engage both G protein and β-arrestin pathways as balanced agonists. We set out to determine if marine-derived alkaloids could serve as novel OR agonist chemotypes with a signaling profile distinct from morphine and more similar to the endorphins. Screening of 96 sponge-derived extracts followed by LC-MS-based purification to pinpoint the active compounds and subsequent evaluation of a mini library of related alkaloids identified two structural classes that modulate the ORs. These included the following: aaptamine (10), 9-demethyl aaptamine (11), demethyl (oxy)-aaptamine (12) with activity at the δ-OR (E

Identification of the First Marine-Derived Opioid Receptor “Balanced” Agonist with a Signaling Profile That Resembles the Endorphins

Opioid therapeutics are excellent analgesics, whose utility is compromised by dependence. Morphine (<b>1</b>) and its clinically relevant derivatives such as OxyContin (<b>2</b>), Vicodin (<b>3</b>), and Dilaudid (<b>4</b>) are “biased” agonists at the μ opioid receptor (OR), wherein they engage G protein signaling but poorly engage β-arrestin and the endocytic machinery. In contrast, endorphins, the endogenous peptide agonists for ORs, are potent analgesics, show reduced liability for tolerance and dependence, and engage both G protein and β-arrestin pathways as “balanced” agonists. We set out to determine if marine-derived alkaloids could serve as novel OR agonist chemotypes with a signaling profile distinct from morphine and more similar to the endorphins. Screening of 96 sponge-derived extracts followed by LC-MS-based purification to pinpoint the active compounds and subsequent evaluation of a mini library of related alkaloids identified two structural classes that modulate the ORs. These included the following: aaptamine (<b>10</b>), 9-demethyl aaptamine (<b>11</b>), demethyl (oxy)–aaptamine (<b>12</b>) with activity at the δ-OR (EC₅₀: 5.1, 4.1, 2.3 μM, respectively) and fascaplysin (<b>17</b>), and 10-bromo fascaplysin (<b>18</b>) with activity at the μ-OR (EC₅₀: 6.3, 4.2 μM respectively). An <i>in vivo</i> evaluation of <b>10</b> using δ-KO mice indicated its previously reported antidepressant-like effects are dependent on the δ-OR. Importantly, <b>17</b> functioned as a balanced agonist promoting both G protein signaling and β-arrestin recruitment along with receptor endocytosis similar to the endorphins. Collectively these results demonstrate the burgeoning potential for marine natural products to serve as novel lead compounds for therapeutic targets in neuroscience research