Preparation and antirheumatic activity of optically active 2-acetylthiomethyl-4-(4-methylphenyl)-4-oxobutanoic acid (KE-298)

Merger of Visible Light-Driven Chiral Organocatalysis and Continuous Flow Chemistry: An Accelerated and Scalable Access into Enantioselective α-Alkylation of Aldehydes

The electron donor-acceptor complex-enabled asymmetric photochemical alkylation strategy holds potential to attain elusive chiral α-alkylated aldehydes without an external photoredox catalyst. The photosensitizer-free conditions are beneficial concerning process costs and sustainability. However, lengthy organocatalyst preparation steps as well as limited productivity and difficult scalability render the current approaches unsuitable for synthesis on enlarged scales. Inspired by these limitations, a protocol was developed for the enantioselective α-alkylation of aldehydes based on the synergistic combination of visible light-driven asymmetric organocatalysis and a controlled continuous flow reaction environment. With the aim to reduce process costs, a commercially available chiral catalyst has been exploited to achieve photosensitizer-free enantioselective α-alkylations using phenacyl bromide derivates as alkylating agents. As a result of elaborate optimization and process development, the present flow strategy furnishes an accelerated and inherently scalable entry into enantioenriched α-alkylated aldehydes including a chiral key intermediate of the antirheumatic esonarimod.

Highly Chemo- and Enantioselective Hydrogenation of 2-Substituted-4-oxo-2-alkenoic Acids

The highly chemo- and enantioselective hydrogenation of (E)-2-substituted-4-oxo-2-alkenoic acids was established for the first time using the Rh/JosiPhos complex, affording a series of chiral α-substituted-γ-keto acids with excellent results (up to 99% yield and >99% ee) and high efficiency (up to 3000 TON). In addition, the importance of this methodology was further demonstrated by a concise and gram-scale synthesis of the anti-inflammatory drug (R)-flobufen.

The Reaction of Alkyl Isocyanides and Benzylidene Meldrum's Acid Derivatives in the presence of Water: A One-Pot synthesis of 4-(Alkylamino)-3-Aryl-4-Oxobutanoic Acids

The reaction between alkyl isocyanides and substituted-benzylidene Meldrum's acid derivatives in the presence of water produces 4-(alkylamino)-3-aryl-4-oxobutanoic acids in good yields.

Synthesis and antirheumatic activity of the metabolites of esonarimod

We have developed esonarimod, (+/-)-2-acetylthiomethyl-4-(4-methylphenyl)-4-oxobutanoic acid, as a new antirheumatic drug. Now we describe herein the preparation of the enantiomers of (+/-)-deacetylesonarimod, the pharmaceutically active metabolites of esonarimod, and comparison of their antirheumatic activities. No significant difference has been observed between the two enantiomers. In a pre-clinical study of esonarimod, other metabolites were detected in rat blood or urine. We also synthesized these compounds as authentic samples to analyze the human metabolites in clinical studies of esonarimod.

Expression of membrane-type 1 matrix metalloproteinase in rheumatoid synovial cells

Membrane-type 1 matrix metalloproteinase (MT1-MMP) is thought to be a putative regulator of pro-gelatinase A (MMP-2) in the rheumatoid synovium. In this study, we examined the effects of IL-1beta, one of the inflammatory cytokines, on the expression of MT1-MMP and the activation of pro-MMP-2 using rheumatoid synovial cells. We also studied the effects of KE-298 (2-acetylthiomethyl-4-(4-methylphenyl)-4-oxobutanoic acid), a new disease-modifying anti-rheumatic drug (DMARD), on MT1-MMP expression of rheumatoid synovial cells. Type B synovial cells (fibroblast-like synovial cells) were cultured with KE-298 (25-100 microg/ml) in the presence of IL-1beta for 48 h. Activation of pro-MMP-2 secreted from synovial cells was analysed by gelatin zymography. Reverse transcription-polymerase chain reaction (RT-PCR) methods were used to detect MT1-MMP mRNA. MT1-MMP protein expression on synovial cells was examined by anti-MT1-MMP immunoblot. An active form of MMP-2 was demonstrated in the culture media conditioned by IL-1beta-stimulated synovial cells. In addition, MT1-MMP mRNA and protein expression of rheumatoid synovial cells were increased by IL-1beta treatment. KE-298 blocked this IL-1beta-induced pro-MMP-2 activation and MT1-MMP expression, but did not affect IL-1beta-induced tissue inhibitor of metalloproteinase-2 (TIMP-2) secretion from rheumatoid synovial cells. These findings indicate that activation of rheumatoid synovial cells by IL-1beta results in the induction of MT1-MMP expression. Given that MT1-MMP promotes matrix degradation by activating pro-MMP-2, these results suggest a novel mechanism whereby cytokine may contribute to articular destruction in rheumatoid arthritis (RA). KE-298 may prevent this process by down-regulating MT1-MMP expression.

New disease-modifying antirheumatic drug 2 acetylthiomethyl-4-(4-methylphenyl)-4-oxobutanoic acid (KE-298) selectively augments activation-induced T cell death

We examined in this study whether the newly developed disease-modifying antirheumatic drug (DMARD) 2-acetylthiomethyl-4-(4-methylphenyl)-4-oxobutanoic acid (KE-298) augments activation-induced T cell death. Peripheral blood (PB) T cells, isolated from healthy donors, were activated by incubation with interleukin-2 (IL-2) followed by further culture with 12-0-tetradecanoyl phorbol 13-acetate (PMA) and ionomycin in the presence or absence of KE-298. The apoptosis of activated T cells was examined by flow cytometric determination of hypodiploid DNA. Fas expression and caspase-3 activity in activated T cells were also examined by flow cytometry, and expression of Fas ligand (FasL), Bcl-2-related proteins, and X chromosome-linked inhibitor of apoptosis protein (XIAP) was determined by Western blot analysis. Apoptosis was not obvious in resting T cells and was not augmented by KE-298. In contrast, apoptosis was clearly detected in activated T cells (activation-induced T cell death) with the increment of caspase-3 activity, and incubation of these cells with KE-298 further enhanced apoptosis. Treatment of activated T cells with KE-298 increased Bax expression but decreased XIAP expression without affecting the expression of Fas/FasL. Thus caspase-3 activity in activated T cells appeared to be increased by KE-298. Our results suggest that the newly developed DMARD, KE-298, selectively augmented activation-induced T cell death. This finding may contribute to the therapeutic efficacy of KE-298 in rheumatoid arthritis (RA) patients and provide new insight into the pharmacologic action of DMARDs.

Effects of KE-758; an active metabolite of the new anti-rheumatic drug KE-298, D-penicillamine, bucillamine and auranofin on the proliferation of murine lymphocytes, and the production of nitric oxide by murine macrophages

2-Mercaptomethyl-4-(4-methylphenyl)-4-oxobutanoic acid (KE-758), which is the active metabolite of 2-acetylthiomethyl-4-(4-methylphenyl)-4-oxobutanoic acid (KE-298), is a novel sulphydryl anti-rheumatic drug. In this study we analyzed the effect of KE-758 on the proliferation of murine lymphocytes, and on the production of nitric oxide (NO) by RAW264.7 murine macrophage cells. We compared its effect with other sulphydryl drugs such as D-penicillamine, bucillamine and auranofin. The proliferation of lymphocytes was measured by 3H-thymidine incorporation assay. Nitrite was measured using Griess Reagent. In the absence of copper ions, KE-758, D-penicillamine and bucillamine rarely affected the proliferation of concanavarin A (ConA) activated murine splenocytes. However, in the presence of copper, pharmacological concentrations of KE-758 but not D-penicillamine and bucillamine suppressed the proliferation of murine splenocytes through a hydrogen peroxide-dependent mechanism. Auranofin markedly suppressed the proliferation regardless of the presence of copper ions by reducing the cellular viability. Furthermore, only KE-758 markedly suppressed the proliferation of phorbol myristate acetate (PMA) plus ionomycin activated murine whole blood lymphocytes (WBL) even in the absence of exogenous copper ions by a hydrogen peroxide-independent mechanism. Meanwhile, lipopolysaccharide (LPS) or LPS plus interferon-gamma (IFN-gamma) induced NO production by RAW264.7 cells were suppressed by KE-758 and auranofin but not by D-penicillamine and bucillamine. In conclusion, KE-758 is a novel immunosuppressive drug, which inhibits both lymphocyte and macrophage functions and its unique anti-rheumatic profile is distinct from that of D-penicillamine, bucillamine and auranofin.

Stereoselective disposition and chiral inversion of KE-298, a new antirheumatic drug, in rats

The present study was an attempt to elucidate the relationship between stereoselective pharmacokinetics and protein binding of KE-298 and its active metabolites, deacetyl-KE-298 (M-1) and S-methyl-KE-298 (M-2). Metabolic chiral inversion was also investigated. The levels of unchanged KE-298 in plasma after oral administration of (+)-(S)-KE-298 to rats were lower than those of (-)-(R)-KE-298, whereas the levels of M-1 and M-2 after administration of (+)-(S)-KE-298 were higher than after (-)-(R)-KE-298. In vitro, rat plasma protein binding of (+)-(S)-KE-298 was lower than that of (-)-(R)-KE-298. In contrast, the binding of (+)-(S)-M-1 and (+)-(S)-M-2 was higher than that of (-)-(R)-M-1 and (-)-(R)-M-2. Displacement studies revealed that the (+)-(S) and (-)-(R)- enantiomers of KE-298 and their metabolites bound to the warfarin binding site on rat serum albumin. These results suggested that the stereoselective plasma levels in KE-298 and its metabolites were closely related to enantiomeric differences in protein binding attributed to quantitative differences in binding to albumin rather than to the different binding sites. Unidirectional chiral inversion was detected after oral administration of either (-)-(R)-KE-298 or (-)-(R)-M-2 to rats both yielding (+)-(S)-M-2.