Discovery of New Potent Positive Allosteric Modulators of Dopamine D2 Receptors: Insights into the Bioisosteric Replacement of Proline to 3-Furoic Acid in the Melanostatin Neuropeptide

J Med Chem. 2021 May 13;64(9):6209-6220. doi: 10.1021/acs.jmedchem.1c00252. Epub 2021 Apr 16.

Abstract

The control of Parkinson's disease (PD) is challenged by the motor and non-motor fluctuations as well as dyskinesias associated with levodopa long-term therapy. As such, pharmacological alternatives to reduce the reliance on this drug are needed. Melanostatin (MIF-1), a positive allosteric modulator (PAM) of D2 receptors (D2R), is being explored as a novel pharmacological approach focused on D2R potentiation. In this work, 3-furoic acid (3-Fu) was successfully employed as an l-proline (Pro) surrogate, affording two potent MIF-1 analogues, methyl 3-furoyl-l-leucylglycinate (4a) and 3-furoyl-l-leucylglycinamide (6a). In this series, the C-terminal carboxamide moiety was found crucial to enhancing the potency and toxicological profile, yet it is not considered a requisite for the PAM activity. Conformational analysis excludes 4a from adopting the claimed type II β-turn. The discovery and validation of 6a as a lead compound open a new avenue for the development of a novel class of anti-Parkinson therapeutics targeting the D2R.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Allosteric Regulation / drug effects
  • Cell Line
  • Drug Design*
  • Furans / chemistry*
  • Humans
  • MSH Release-Inhibiting Hormone / chemistry*
  • MSH Release-Inhibiting Hormone / pharmacology*
  • Proline / chemistry*
  • Receptors, Dopamine D2 / metabolism*
  • Structure-Activity Relationship

Substances

  • Furans
  • Receptors, Dopamine D2
  • MSH Release-Inhibiting Hormone
  • Proline
  • 2-furoic acid