Additional file 1: Figure S1. of Gastrointestinal delivery of propofol from fospropofol: its bioavailability and activity in rodents and human volunteers

Absolute latency of ipsilateral paw in CCI rats before and after fospropofol or vehicle treatment

Selective CNS Uptake of the GCP-II Inhibitor 2-PMPA following Intranasal Administration

<div><p>Glutamate carboxypeptidase II (GCP-II) is a brain metallopeptidase that hydrolyzes the abundant neuropeptide N-acetyl-aspartyl-glutamate (NAAG) to NAA and glutamate. Small molecule GCP-II inhibitors increase brain NAAG, which activates mGluR3, decreases glutamate, and provide therapeutic utility in a variety of preclinical models of neurodegenerative diseases wherein excess glutamate is presumed pathogenic. Unfortunately no GCP-II inhibitor has advanced clinically, largely due to their highly polar nature resulting in insufficient oral bioavailability and limited brain penetration. Herein we report a non-invasive route for delivery of GCP-II inhibitors to the brain via intranasal (i.n.) administration. Three structurally distinct classes of GCP-II inhibitors were evaluated including DCMC (urea-based), 2-MPPA (thiol-based) and 2-PMPA (phosphonate-based). While all showed some brain penetration following i.n. administration, 2-PMPA exhibited the highest levels and was chosen for further evaluation. Compared to intraperitoneal (i.p.) administration, equivalent doses of i.n. administered 2-PMPA resulted in similar plasma exposures (AUC_{0-t, i.n}./AUC_{0-t, i.p.} = 1.0) but dramatically enhanced brain exposures in the olfactory bulb (AUC_{0-t, i.n}./AUC_{0-t, i.p.} = 67), cortex (AUC_{0-t, i.n}./AUC_{0-t, i.p.} = 46) and cerebellum (AUC_{0-t, i.n}./AUC_{0-t, i.p.} = 6.3). Following i.n. administration, the brain tissue to plasma ratio based on AUC_0-t in the olfactory bulb, cortex, and cerebellum were 1.49, 0.71 and 0.10, respectively, compared to an i.p. brain tissue to plasma ratio of less than 0.02 in all areas. Furthermore, i.n. administration of 2-PMPA resulted in complete inhibition of brain GCP-II enzymatic activity <i>ex-vivo</i> confirming target engagement. Lastly, because the rodent nasal system is not similar to humans, we evaluated i.n. 2-PMPA also in a non-human primate. We report that i.n. 2-PMPA provides selective brain delivery with micromolar concentrations. These studies support intranasal delivery of 2-PMPA to deliver therapeutic concentrations in the brain and may facilitate its clinical development.</p></div

Ex vivo GCP-II enzymatic activity following 2-PMPA i.n. administration.

<p>Enzyme activity was measured in olfactory bulb, cortex and cerebellum collected 1 h post dose following 30 mg/kg i.n. administration. Percent inhibition was calculated in all tissue samples relative to brain tissues collected from untreated control rats.</p

Chemical structures and IC₅₀ values of DCMC, 2-MPPA, 2-PMPA.

<p>Chemical structures and IC₅₀ values of DCMC, 2-MPPA, 2-PMPA.</p

Mean concentrations of 2-PMPA, 2-MPPA and DCMC in different brain regions.

<p>Concentration were measured in olfactory bulb, cortex and cerebellum following 30mg/kg intranasal administration in rats. Tissues were collected 1h post dose and evaluated via LC/MS/MS.</p

Discovery of Orally Available Prodrugs of the Glutamate Carboxypeptidase II (GCPII) Inhibitor 2‑Phosphonomethyl­pentanedioic Acid (2-PMPA)

2-Phosphonomethylpentanedioic acid (<b>1</b>, 2-PMPA) is a potent inhibitor of glutamate carboxypeptidase II which has demonstrated robust neuroprotective efficacy in many neurological disease models. However, <b>1</b> is highly polar containing a phosphonate and two carboxylates, severely limiting its oral bioavailability. We strategized to mask the polar groups via a prodrug approach, increasing the likelihood of passive oral absorption. Our initial strategy was to cover the phosphonate with hydrophobic moieties such as <u>p</u>ivaloyl<u>o</u>xy<u>m</u>ethyl (POM) and iso<u>p</u>ropyl­<u>o</u>xy<u>c</u>arbonyl­oxymethyl (POC) while keeping the α- and γ-carboxylates unsubstituted. This attempt was unsuccessful due to the chemical instability of the bis-POC/POM derivatives. Addition of α,γ-diesters and α-monoesters enhanced chemical stability and provided excellent oral exposure in mice, but these mixed esters were too stable in vivo, resulting in minimal release of <b>1</b>. By introducing POC groups on both the phosphonate and α-carboxylate, we synthesized Tris-POC-2-PMPA (<b>21b)</b>, which afforded excellent release of <b>1</b> following oral administration in both mice and dog

Structure–Activity Relationship Studies on a Series of 3α-[Bis(4-fluorophenyl)methoxy]tropanes and 3α-[Bis(4-fluorophenyl)methylamino]tropanes As Novel Atypical Dopamine Transporter (DAT) Inhibitors for the Treatment of Cocaine Use Disorders

The development of medications to treat cocaine use disorders has thus far defied success, leaving this patient population without pharmacotherapeutic options. As the dopamine transporter (DAT) plays a prominent role in the reinforcing effects of cocaine that can lead to addiction, atypical DAT inhibitors have been developed that prevent cocaine from binding to DAT, but they themselves are not cocaine-like. Herein, a series of novel DAT inhibitors were synthesized, and based on its pharmacological profile, the lead compound <b>10a</b> was evaluated in phase I metabolic stability studies in mouse liver microsomes and compared to cocaine in locomotor activity and drug discrimination paradigms in mice. A molecular dynamic simulation study supported the hypothesis that atypical DAT inhibitors have similar binding poses at DAT in a conformation that differs from that of cocaine. Such differences may ultimately contribute to their unique behavioral profiles and potential for development as cocaine use disorder therapeutics

6‑Hydroxy-1,2,4-triazine-3,5(2<i>H</i>,4<i>H</i>)‑dione Derivatives as Novel d‑Amino Acid Oxidase Inhibitors

A series of 2-substituted 6-hydroxy-1,2,4-triazine-3,5­(2<i>H</i>,4<i>H</i>)-dione derivatives were synthesized as inhibitors of d-amino acid oxidase (DAAO). Many compounds in this series were found to be potent DAAO inhibitors, with IC₅₀ values in the double-digit nanomolar range. The 6-hydroxy-1,2,4-triazine-3,5­(2<i>H</i>,4<i>H</i>)-dione pharmacophore appears metabolically resistant to <i>O</i>-glucuronidation unlike other structurally related DAAO inhibitors. Among them, 6-hydroxy-2-(naphthalen-1-ylmethyl)-1,2,4-triazine-3,5­(2<i>H</i>,4<i>H</i>)-dione <b>11h</b> was found to be selective over a number of targets and orally available in mice. Furthermore, oral coadministration of d-serine with <b>11h</b> enhanced the plasma levels of d-serine in mice compared to the oral administration of d-serine alone, demonstrating its ability to serve as a pharmacoenhancer of d-serine

Structure–Activity Relationship Studies on a Series of 3α-[Bis(4-fluorophenyl)methoxy]tropanes and 3α-[Bis(4-fluorophenyl)methylamino]tropanes As Novel Atypical Dopamine Transporter (DAT) Inhibitors for the Treatment of Cocaine Use Disorders

The development of medications to treat cocaine use disorders has thus far defied success, leaving this patient population without pharmacotherapeutic options. As the dopamine transporter (DAT) plays a prominent role in the reinforcing effects of cocaine that can lead to addiction, atypical DAT inhibitors have been developed that prevent cocaine from binding to DAT, but they themselves are not cocaine-like. Herein, a series of novel DAT inhibitors were synthesized, and based on its pharmacological profile, the lead compound <b>10a</b> was evaluated in phase I metabolic stability studies in mouse liver microsomes and compared to cocaine in locomotor activity and drug discrimination paradigms in mice. A molecular dynamic simulation study supported the hypothesis that atypical DAT inhibitors have similar binding poses at DAT in a conformation that differs from that of cocaine. Such differences may ultimately contribute to their unique behavioral profiles and potential for development as cocaine use disorder therapeutics

Synthesis and SAR of 1‑Hydroxy‑1<i>H</i>‑benzo[<i>d</i>]imidazol-2(3<i>H</i>)‑ones as Inhibitors of d‑Amino Acid Oxidase

A series of 1-hydroxy-1<i>H</i>-benzo­[<i>d</i>]­imidazol-2­(3<i>H</i>)-ones were synthesized and evaluated for their ability to inhibit human and porcine forms of d-amino acid oxidase (DAAO). The inhibitory potency is largely dependent on the size and position of substituents on the benzene ring with IC₅₀ values of the compounds ranging from 70 nM to greater than 100 μM. Structure–activity relationships of this new class of DAAO inhibitors will be presented in detail along with comparisons to previously published SAR data from other classes of DAAO inhibitors. Two of these compounds were given to mice orally together with d-serine to assess their effects on plasma d-serine pharmacokinetics