Design, synthesis, and biological activity of novel factor Xa inhibitors: improving metabolic stability by S1 and S4 ligand modification.

Serine protease factor xa (fXa) inhibitor 1 showed good ex vivo anti-fXa activity upon oral administration in rats. However, it has been revealed that 1 had low metabolic stability against human liver microsomes. To improve the metabolic stability, we attempted to modify the S1 and S4 ligands of 1.

Design, synthesis, and biological activity of non-basic compounds as factor Xa inhibitors: SAR study of S1 and aryl binding sites.

Compound 7 was identified as the active metabolite of 6 by HPLC and mass spectral analysis. Modification of lead compound 7 by transformation of its N-oxide 6-6 biaryl ring system and fused aromatics produced a series of non-basic fXa inhibitors with excellent potency in anti-fXa and anticoagulant assays. The optimized compounds 73b and 75b showed sub to one digit micromolar anticoagulant activity (PTCT2).

Design, synthesis, and biological activity of non-amidine factor Xa inhibitors containing pyridine N-oxide and 2-carbamoylthiazole units.

Based on the both of results for X-ray studies of tetrahydrothiazolopyridine derivative 1c and FXV673, we synthesized a series of thiazol-5-ylpyridine derivatives containing pyridine N-oxide and 2-carbamoylthiazole units to optimize the S4 binding element. N-Oxidation of thiazol-5-ylpyridine increased the anti-fXa activity more than 10-fold independent on the position of N-oxide. The 4-pyridine N-oxide derivatives 3a and 3d excelled over the tetrahydrothiazolopyridine 1b in potency.

Synthesis and conformational analysis of a non-amidine factor Xa inhibitor that incorporates 5-methyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridine as S4 binding element.

Our exploratory study was based on the concept that a non-amidine factor Xa (fXa) inhibitor is suitable for an orally available anticoagulant. We synthesized and evaluated a series of N-(6-chloronaphthalen-2-yl)sulfonylpiperazine derivatives incorporating various fused-bicyclic rings containing an aliphatic amine expected to be S4 binding element. Among this series, 5-methyl-4,5,6,7-tetrahydrothiazolo[5,4-c]pyridine type 61 displayed orally potent anti-fXa activity and evident prolongation of prothrombin time (PT) with the moderate bioavailability in rats.

Orally active factor Xa inhibitors: 4,5,6,7-tetrahydrothiazolo[5,4-c]pyridine derivatives.

In our investigation of factor Xa inhibitors, a series of 1-(6-chloronaphthalen-2-yl)sulfonyl-4-(4,5,6,7-tetrahydrothiazolo[5,4-c]pyridine-2-carbonyl)piperazines 3a-i were synthesized. In vitro inhibitory activities of the compounds against factor Xa and coagulation are summarized. Among the compounds, 3c and 3d, possessing a carbamoyl or N-methylcarbamoyl moiety, showed potent inhibitory activities when administered orally to rats.

Design, synthesis and biological activity of amidinobicyclic compounds (derivatives of DX-9065a) as factor Xa inhibitors: SAR study of S1 and aryl binding sites.

Since factor Xa (fXa) plays a pivotal role in the blood coagulation cascade, inhibition of fXa is thought to be an effective treatment for a variety of thrombotic events. (2S)-2-[4-[[(3S)-1-Acetimidoyl-3-pyrrolidinyl]oxy]phenyl]-3-(7-amidino-2-naphthyl)propanoic acid hydrochloride pentahydrate (DX-9065a) was previously found in our laboratory as a novel orally active factor Xa inhibitor. DX-9065a exhibits a strong inhibitory activity toward fXa by occupying the substrate recognition (called S1) sites and aryl binding sites of fXa.