Design and synthesis of peptidomimetic factor VIIa inhibitors

Selective factor VIIa-tissue factor complex (FVIIa/TF) inhibition is regarded as a promising target for developing new anticoagulant drugs. In previous reports, we described a S3 subsite found in the X-ray crystal structure of compound 2 that bound to FVIIa/soluble tissue factor (sTF). Based on the X-ray crystal structure information and with the aim of improving the inhibition activity for FVIIa/TF and selectivity against other serine proteases, we synthesized derivatives by introducing substituents at position 5 of the indole ring of compound 2. Among them, compound 16 showed high selectivity against other serine proteases. Contrary to our expectations, compound 16 did not occupy the S3-subsite; X-ray structure analysis revealed that compound 16 improved selectivity by forming hydrogen bonds with Gln217, Thr99 and Asn100.

Structure of human factor VIIa/tissue factor in complex with a peptide-mimetic inhibitor: high selectivity against thrombin by introducing two charged groups in P2 and P4

The crystal structure of human factor VIIa/soluble tissue factor (FVIIa/sTF) in complex with a highly selective peptide-mimetic FVIIa inhibitor which shows 1670-fold selectivity against thrombin inhibition has been solved at 2.6 A resolution. The inhibitor is bound to FVIIa/sTF at the S1, S2 and S3 sites and at the additional S1 subsite. Two charged groups, the amidino group in P2 and the carboxylate group in P4, form ionic interactions with Asp60 and Lys192 of FVIIa, respectively. Structural comparisons between factor VIIa and thrombin show that thrombin has oppositely charged residues, Lys60F and Glu192, in the S2 site and the S1 subsites, respectively. These data suggest that the utilization of the differences of charge distribution in the S2 site and the S1 subsites between FVIIa and thrombin is critical for achieving high selectivity against thrombin inhibition. These results will provide valuable information for the structure-based drug design of specific inhibitors for FVIIa/TF.

Novel interactions of large P3 moiety and small P4 moiety in the binding of the peptide mimetic factor VIIa inhibitor

Selective factor VIIa-tissue factor complex (FVIIa/TF) inhibition is seen as a promising target for developing new anticoagulant drugs. A novel peptide mimetic factor VIIa inhibitor, ethylsulfonamide-d-biphenylalanine-Gln-p-aminobenzamidine, shows 100-fold selectivity against thrombin in spite of its large P3 moiety, unlike previously reported FVIIa/TF selective inhibitors. X-ray crystal structure analysis reveals that the large P3 moiety, d-biphenylalanine, and the small P4 moiety, ethylsulfonamide, make novel interactions with the 170-loop and Lys192 of FVIIa/TF, respectively, accompanying ligand-induced conformational changes of the 170-loop, Gln217, and Lys192. Structural comparisons of FVIIa with thrombin and amino acid sequence comparisons among coagulation serine proteases suggest that these interactions play an important role in achieving selective inhibition for FVIIa/TF.

Discovery and structure-activity relationship of coumarin derivatives as TNF-alpha inhibitors

The discovery and structure-activity relationship of a novel series of coumarin-based TNF-alpha inhibitors is described. Starting from the initial lead 1a, various derivatives were prepared surrounding the coumarin core structure to optimize the in vitro inhibitory activity of TNF-alpha production by human peripheral blood mononuclear cells (hPBMC), stimulated by bacterial lipopolysaccharide (LPS). Selected compounds also demonstrated in vivo inhibition of TNF-alpha production in rats.

Crystal structure of human factor VIIa/tissue factor in complex with peptide mimetic inhibitor

The 3D structure of human factor VIIa/soluble tissue factor in complex with a peptide mimetic inhibitor, propylsulfonamide-D-Thr-Met-p-aminobenzamidine, is determined by X-ray crystallography. As compared with the interactions between thrombin and thrombin inhibitors, the interactions at S2 and S3 sites characteristic of factor VIIa and factor VIIa inhibitors are revealed. The S2 site has a small pocket, which is filled by the hydrophobic methionine side chain in P2. The small S3 site fits the small size residue, D-threonine in P3. The structural data and SAR data of the peptide mimetic inhibitor show that these interactions in the S2 and S3 sites play an important role for the improvement of selectivity versus thrombin. The results will provide valuable information for the structure-based drug design of specific inhibitors for FVIIa/TF.

Design and Efficient Synthesis of 2α-(ω-Hydroxyalkoxy)-1α,25-dihydroxyvitamin D3 Analogues, Including 2-epi-ED-71 and Their 20-Epimers with HL-60 Cell Differentiation Activity

A concise and efficient synthetic approach to 2 alpha-(omega-hydroxyalkoxy)-1 alpha,25-dihydroxyvitamin D(3) (4a-c), including 2-epi-ED-71, was developed starting from D-glucose as a chiral template for the construction of the 2 alpha-modified A-ring precursors (11a-c). It was found that the best ligand for the bovine thymus vitamin D receptor (VDR) in this series is 4b, which has 1.8 times greater binding affinity for the bovine thymus VDR than that of the natural hormone 1. Interestingly, potency in the induction of HL-60 cell differentiation for 4a-c was almost the same or weaker than that of 1 despite the strong binding affinity for the VDR. Next, we were interested in the "double modification"of 1 based on 4a-c with C20-epimerization, affording 2 alpha-(omega-hydroxyalkoxy)-20-epi-1 alpha,25-dihydroxyvitamin D(3) (20-epi-4a-c). All three 2 alpha-substituted 20-epi analogues of 1 (20-epi-4a-c) exhibited stronger binding affinities for the VDR, and their conformations in the ligand binding domain of VDR were analyzed by molecular modeling. Double-modified analogues of 20-epi-4a-c showed marked HL-60 cell differentiation activity, and 20-epi-4a possesses an activity 58-fold higher than that of the natural hormone 1.

Design and synthesis of novel tetra-peptide motilin agonists

A series of novel tetra-peptide motilin agonists, having the general structure H-Phe-Val-X-Ile-NH(2), were designed, on the basis of structure-activity relationship studies of motilin. Peptides, in which X is a side chain substituted tryptophan residue, have agonistic activity. H-Phe-Val-Trp(2'-CH(2)CH(2)OH)-Ile-NH(2)(7), H-Phe-Val-Trp(2'-SCH(3))-Ile-NH(2)(8), and H-Phe-Val-Trp(2'-SCH(2)CH(2)CH(3))-Ile-NH(2)(9), showed an EC(50) for contractile activity in the rabbit smooth muscle of 14.1+/-3.2, 12.9+/-4.1, and 4.6+/-1.6 microM, respectively. Interaction of the tryptophan aliphatic side chain with motilin receptor appears to influence the signal transduction via motilin receptor.

Design and synthesis of motilin antagonists derived from the [1-4] fragment of porcine motilin

A series of cyclic peptides having the general structure H-Phe-c[-N(epsilon)-Lys-X-NH-(CH(2))(n)-CO-] were designed on the basis of structure-activity relationship studies of motilin. All were motilin antagonists. The cyclic peptides, in which X is a 3-tert-butyl-substituted tyrosine residue (H-Phe-c[-N(epsilon)-Lys-Tyr(3-tBu)-beta Ala-] (3), H-Phe-c[-N(epsilon)-Lys-Tyr(3-tBu)-Gly-] (6), H-Phe-c[-N(epsilon)-Lys-Tyr(3-tBu)-Abu-] (7), and H-Phe-c[-N(epsilon)-Lys-Tyr(3-tBu)-Ahx-] (8)) showed potent motilin receptor antagonistic activity in the rabbit smooth muscle (pA(2) > 7). The 3-tert-butyl Tyr was found to be the moiety responsible for enhanced binding to the motilin receptor, while the size of the ring had little importance.

Design and synthesis of N-terminal cyclic motilin partial peptides: a novel pure motilin antagonist

Motilin antagonist was designed and synthesized on the basis of the structure-activity relationship analysis of porcine motilin that we reported recently. The drug design was performed on a specific concept to reduce a flexibility of peptide conformation of porcine motilin partial peptide by its cyclization. The cyclic peptide was synthesized using Boc (tert-butyloxycarbonyl) solid phase methodology, followed by cyclization using the azide procedure, and tested for the binding activity to motilin receptor and smooth muscle contractile activity. The cyclic peptides 3, 4, and 5 showed antagonistic property on contraction assay (pA2 [the negative logarithm of molar concentration of antagonist causing a 2-hold shift to the right of the concentration-response curve for motilin]: 4.5, 4.34, and 4.04, respectively, in rabbit duodenum) and no contractile activity even at high concentration.

[Usefulness of rapid bedside cardiac troponin T assay for the diagnosis of acute myocardial infarction]

Cardiac troponin T(cTnT) is one of the most myocardial-specific markers for the diagnosis of acute myocardial infarction(AMI). Recently, the rapid bedside cTnT assay(Trop T rapid assay sensitive version), which can provide qualitative determinations within 15 min, has been developed for the emergency clinical setting. To evaluate the usefulness of rapid bedside cTnT assay, we performed the Trop T test and measured serum levels of myoglobin(Mb), creatine kinase MB isoenzyme(CK-MB) and cTnT in 256 consecutive emergency patients with suspected AMI(65 found to have AMI and 191 without AMI). The diagnostic sensitivities for AMI of Trop T, Mb and CK-MB measurements were 66%, 92% and 52%, respectively, whereas the specificities were 80%, 18% and 74%, respectively. The diagnostic accuracy for AMI of Trop T(77%) was significantly higher than that of Mb(37%, p < 0.001) and CK-MB(69%, p < 0.05). The sensitivity for AMI of Mb(86%) was significantly(p < 0.001) higher than that of Trop T (31%) and CK-MB(31%) in patients admitted < or = 3 hr after the onset of AMI. In contrast, the sensitivities of Trop T(80% and 100%) in patients admitted at 3-6 hr and > 6 hr showed no significant differences from those of Mb(100% and 96%). Furthermore, Trop T in patients admitted > 6 hr had significantly(p < 0.01) higher sensitivity compared with CK-MB(69%). The mortality rate in the non-AMI group during hospitalization in patients with positive Trop T test(39%) was significantly(p < 0.001) higher than that in patients with negative test(9%). When the positive Trop T test was regarded as > or = 0.10 ng/ml of serum cTnT, Trop T test had the best concordance of 92% with a quantitative of cTnT assay.

Structure-activity study of intact porcine motilin

Biologically important sites on intact porcine motilin (pMTL) were explored using its partial peptides. The partial peptides were synthesized using Fmoc (9-fluorenylmethyloxycarbonyl) solid phase methodology, and tested for the binding activity to motilin receptor and the smooth muscle contractile activity. The results were as follows: important residues for the contractile activity were found to be Phe1, Ile4, and Tyr7, and an open space existed beyond the N-terminus between motilin and its receptor. On the model of interaction between motilin and motilin receptor evolved from these results, the three points of interaction, due to Phe1, Ile4, and Tyr7, and the presence of an open space were expected. The motilin agonist and antagonist, designed on this model, will help the inquiry into motilin associated diseases.

Synthesis and biological activity of KCB-328 and its analogues: novel class III antiarrhythmic agents with little reverse frequency dependence

A series of 3,4-dimethoxyphenethylamine derivatives was prepared, and their prolongation effects on effective refractory period of contractile response (ERPc) and action potential duration (APD) in isolated guinea-pig papillary muscles at 1 Hz and 3 Hz were examined. SAR studies led to the identification of KCB-328 (51) which is a novel class III antiarrhythmic agent with little reverse frequency dependence.

Differential expression of Hox genes in multistage carcinogenesis of mouse skin

We surveyed expression of Hox genes in multiple carcinogenesis of mouse skin by RT-PCR cloning. According to the sequences of the amplified DNA fragments within the homeobox of Hox genes, 25 of the 39 known Hox genes were amplified in the normal dorsal skin of adult mice. In the papilloma and carcinoma, clones of Hox A7 and Hox B7 were preferentially isolated among others. The entire Hox D locus was silent in both papilloma and carcinoma. Our present results suggest that the majority of Hox gene family members are expressed in normal mouse skin, while the repertoire is substantially limited in the papilloma and carcinoma.

KCB-328: a novel class III antiarrhythmic agent with little reverse frequency dependence in isolated guinea pig myocardium

The effects of 1-(2-amino-4-methanesulfonamidophenoxy)-2-[N-(3,4-dimethoxypheneth yl)-N-methylamino] ethane hydrochloride (KCB-328), in comparison with those of dofetilide, were studied on the action potentials (APs) of isolated guinea pig papillary muscles. KCB-328 (0.003-3 microM) concentration-dependently prolonged the AP duration at 90% repolarization (APD90) at 1- and 3-Hz pacing, and the concentration-response relations at 1 and 3 Hz resemble each other. Dofetilide (0.001-1 microM) also produced the concentration-dependent prolongation of APD90 but more pronouncedly at 1 than at 3 Hz, demonstrating the reverse frequency-dependent effect. KCB-328 at 0.03, 0.1, 0.3, and 1 microM increased APD90 by 11 +/- 1, 19 +/- 1, 25 +/- 1, and 29 +/- 1% at 3 Hz and by 9 +/- 1, 19 +/- 2, 27 +/- 2, and 33 +/- 2% at 1 Hz, respectively. Prolongation of the effective refractory period (ERP) by each drug is parallel to those of APD90 at each pacing frequency. KCB-328 modified neither the maximal velocity of depolarization, amplitude of AP, and resting membrane potential in the fast APs, nor any parameters of the slow APs. In a separate experiment, the effects of KCB-328 on the ERP of contractile response (ERPc) of excised guinea-pig papillary muscles also were studied at 1 and 3 Hz. KCB-328 (0.01-10 microM) lengthened the ERPc in a concentration-dependent and frequency-independent manner as in the electrophysiologic results. This frequency-independent ERPc prolongation by KCB-328 was not influenced by increased extracellular K+ concentration from 4 to 10 mM. These results suggest that KCB-328 might be a selective class III agent with effects that are relatively frequency independent.

Flat revertant inducers, styryl diphenylamine derivatives, inhibit growth and metastasis of murine tumor cells in vivo

Previously, we reported that a novel styryl diphenylamine derivative, RX-465, reverts the transformed phenotype of human fibrosarcoma HT1080 cells in vitro. To determine whether agents inducing such phenotypic reversion show antitumor and/or antimetastatic effects in vivo, we assessed tumor growth and metastasis in mice inoculated with either murine B16-, B16BL6 melanoma or M5076 reticulosarcoma. These mice received orally our new derivatives of RX-465, namely RX-512 and RX-549. We found that these-derivatives inhibited B16 melanoma and M5076 reticulosarcoma growth by greater than 80% in vivo. RX-512 also inhibited the metastatic dissemination of B16BL6 melanoma into the lung and that of M5076 reticulosarcoma into the liver by 98% and 100% at doses of 60 and 40 mg/kg/day, respectively. These treatments did not cause significant decreases in body weight. Our data strongly demonstrate that styryl diphenylamine derivatives that revert transformed phenotype in vitro potentially inhibit tumor growth and metastasis in mice with negligible toxicity at effective doses.

[Cell morphology and surface markers in three patients with granular lymphocyte proliferative disorders of the T-cell type]

We studied the relationship between cell morphology and surface markers in three patients with granular lymphocyte proliferative disorders. In the two patients with CD3+ CD4-CD8+ cells, there were no atypical cells, and the granules were uniformly fine: In the third patient, who had CD3+ CD4+ CD8- cells, atypical nuclei and the irregular granules in in size were observed. The granules were stained with beta-glucuronidase showing localized coarse features and made clumps, in the staining pattern characteristic of granular lymphocytes. The patient with CD4- CD8+ cells showed cytotoxic T cell phenotype, and the other DN cells type (usually associated with a CD3+ CD4- CD8- phenotype). We obtained conflicting data about OK-NK and Leu 11 antibodies, which recognized CD16 antigen.

A chimeric analog of human and salmon calcitonin eliminates antigenicity and reduces gastrointestinal disturbances

The minimum region in salmon calcitonin (sCT) which induces antigenicity and gastrointestinal disturbances has been identified by examining the cross-reactivity of several sCT fragments and CT analogs with antisera from sCT-treated patients, and by examining inhibition of gastrointestinal motility of these sCT fragments and CT analogs in conscious dogs. Sixteen residues at the N-terminus of sCT comprised the minimum fragment capable of inducing both activities. Human CT (hCT) showed no antigenicity and a four-order weaker inhibition of gastrointestinal motility than sCT. Based on these data, we synthesized the human and salmon chimeric CT, ACT-15, in which the 16 N-terminal residues were those of hCT and the 16 C-terminal residues were those of sCT. ACT-15 had no cross-reactivity with the antisera and had almost the same weak gastrointestinal inhibition effect as hCT in dog and rat models. Nevertheless, it retained a hypocalcemic activity and an analgesic activity comparable to sCT. These results suggest that the amino acid residues in the N-terminal half of CT are responsible for the formation of antibodies and the induction of gastrointestinal disturbances, but may not influence calcium metabolism or analgesia. Clinical studies of ACT-15 will be needed to confirm this hypothesis.