Vitamin K Prodrugs: 1. Synthesis of Amino Acid Esters of Menahydroquinone-4 and Enzymatic Reconversion to an Active Form

Jiro Takata, Yoshiharu Karube, Mitsunobu Hanada, Kazuhisa Matsunaga, Yoshikazu Matsushima, Toshiaki Sendo, Toshinobu Aoyama

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)


The efficacy and toxicity of vitamin K depends on the pathway and the extent of enzymatic reductive activation to vitamin K hydroquinone, which is an essential cofactor for the synthesis of clotting factors. Parenteral use of vitamin K is impaired by its water insolubility. With the aim to improve delivery problems associated with menahydroquinone-4 (MKH, 2), an active form of menaquinone-4, N,N-dimethylglycine esters of 2 (1-mono, 4-mono, and 1,4-bis) were synthesized and assessed as potential water-soluble prodrugs for parenteral use. The esters can deliver the hydroquinone to its active site without a quinone reductive activation step. The hydrochloride salts of the esters were found to be quite soluble in water. The hydrolysis of the esters in 20% rat liver homogenate 9000 × g supernatant, rat plasma and phosphate buffer, pH 7.4, at 37°C was kinetically studied in the presence and absence of an esterase inhibitor. The hydrolysis was catalyzed by esterases located in the rat liver and rat plasma and quantitatively yielded 2. These results suggest that esterification of 2 with N,N-dimethylglycine is a promising way for obtaining water-soluble prodrug forms of 2. Based on the high susceptibility to liver esterase, the esters are potential prodrugs for achieving the site-specific delivery of 2.

Original languageEnglish
Pages (from-to)18-23
Number of pages6
JournalPharmaceutical Research: An Official Journal of the American Association of Pharmaceutical Scientists
Issue number1
Publication statusPublished - Jan 1995
Externally publishedYes


  • amino acid ester
  • enzymatic hydrolysis
  • menahydroquinone-4
  • menaquinone-4
  • site-specific delivery
  • water-soluble prodrug

ASJC Scopus subject areas

  • Biotechnology
  • Molecular Medicine
  • Pharmacology
  • Pharmaceutical Science
  • Organic Chemistry
  • Pharmacology (medical)


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