Lactam-Conformationally Restricted Analogs of N.ALPHA.-Arylsulfonyl Arginine Amide: Design, Synthesis and Inhibitory Activity toward Thrombin and Related Enzymes.

Authors:
  • SSSumie Seki
    Sumie Seki
  • HIHajime Ito
    Hajime Ito
  • TTTomoko Takeshima
    Tomoko Takeshima
  • MHMasaki Hagiwara
    Masaki Hagiwara
  • TMTadanori Morikawa
    Tadanori Morikawa
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Abstract
Three new lactam-conformationally restricted arginine derivatives, 1-butyl-3-(6,7-dimethoxy-2-naphthylsulfonyl)-3-(3-guanidinoprop yl)-substituted gamma-, delta-, and epsilon-lactams (2-4), were synthesized on the basis of backbone modification of the lead structure, 6,7-dimethoxy-2-naphthylsulfonylarginine n-butylmethylamide (1). We tested these compounds for inhibitory activity toward thrombin and other trypsin-like enzymes (trypsin, factor Xa, plasmin, and kallikrein). All the compounds synthesized (1-4) potently inhibited thrombin with IC50 values of 0.75, 0.70, 0.92, and 3.2 microM, respectively; they inhibited thrombin over 40-fold more effectively than the other enzymes tested. The gamma-lactam (2) with the most profound inhibitory activity toward thrombin was a reversible inhibitor with a Ki of 0.26 microM. Compound 2 also showed better thrombin selectivity than the lead compound (1). The lactam-conformational restriction of arylsulfonylarginine amides, especially gamma-lactam, has thus proved to be a useful device for the improvement of antithrombotic activity.