title: Derivatives of dexanabinol. II. Salts of amino acid esters containing tertiary and quaternary heterocyclic nitrogen with increased water-solubility.
abstract: OBJECTIVE
  Amino acid esters containing tertiary or quaternary nitrogen heterocycles were synthesized for dexanabinol (1) and evaluated as water-soluble prodrugs or congeners.
  
  
  METHODS
  Syntheses were performed by conventional methods; stability studies in water, blood (rat, dog, human) and assay-media were performed by HPLC; NMDA receptor binding was determined by [3H] MK-801 displacement; neuroprotection and neurotoxicity studies were performed in cortical cell cultures.
  
  
  RESULTS
  7-morpholino and N-methylpiperazino acetates and butyrates and the respective N-methylmorpholinium and piperazinium iodides as well as a 3'-N-methyl morpholino butyrate and the corresponding N-methyl quaternary type derivative were synthesized. All compounds were relatively soluble in water or 10% aqueous ethanol. The examined derivatives were stable in water and generally less stable in blood and assay media. Quaternary derivatives of dexanabinol were found to hydrolyze faster. All examined compounds inhibited NMDA receptor and protected neurons against NMDA induced toxicity. Neuroprotection (with one exception) is however attributed to the parent 1 released by hydrolysis during the assay.
  
  
  CONCLUSIONS
  Some of the examined derivatives could be further evaluated as prodrugs on congeners of 1.
authors.affiliation: Pharmos Corporation, Alachua, Florida 32615, USA.
authors.forename: E
authors.initials: E
authors.lastname: Pop
authors.forename: F
authors.initials: F
authors.lastname: Soti
authors.forename: M E
authors.initials: ME
authors.lastname: Brewster
authors.forename: Y
authors.initials: Y
authors.lastname: Barenholz
authors.forename: V
authors.initials: V
authors.lastname: Korablyov
authors.forename: R
authors.initials: R
authors.lastname: Mechoulam
authors.forename: V
authors.initials: V
authors.lastname: Nadler
authors.forename: A
authors.initials: A
authors.lastname: Biegon
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002478:Cells, Cultured; D016291:Dizocilpine Maleate / Q000378:metabolism / Q000494:pharmacology; D004285:Dogs; D013759:Dronabinol / Q000031:analogs & derivatives* / Q000097:blood / Q000737:chemistry / Q000494:pharmacology; D004355:Drug Stability; D018691:Excitatory Amino Acid Antagonists / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D006801:Humans; D006868:Hydrolysis; D009025:Morpholines / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D009422:Nervous System Diseases / Q000139:chemically induced; D009474:Neurons / Q000187:drug effects; D018696:Neuroprotective Agents / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D010879:Piperazines / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D011355:Prodrugs / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000378:metabolism; D012995:Solubility; D013329:Structure-Activity Relationship; D014316:Tritium; D014867:Water / Q000737:chemistry
chemical_list: D018691:Excitatory Amino Acid Antagonists; D009025:Morpholines; D018696:Neuroprotective Agents; D010879:Piperazines; D011355:Prodrugs; D016194:Receptors, N-Methyl-D-Aspartate; D014867:Water; D014316:Tritium; D016291:Dizocilpine Maleate; D013759:Dronabinol; C062018:HU 211