1-Deaminopenicillamine,4-threonine]oxytocin, a potent inhibitor of oxytocin

[1-Deaminopenicillamine,4-threonine]oxytocin was prepared in duplicate from S-benzyl-3-mercapto-3,3-dimethylpropanoyl-Tyr(Bzl)-Ile-Thr(Bzl)-Asn-Cys(Bzl)-Pro-Leu-Gly-NH2 (I) by removal of the Bzl-protecting groups with Na-NH3, followed by cyclization of the resulting disulfhydryl compound with K3Fo(CN)6. The analogue was purified by desalting on Sephadex G-15 in 50% acetic acid and gel filtration of Sephadex G-15. The protected peptide I was synthesized (a) by the solid-phase method and (b) by a combination of solid-phase synthesis and an [8 + 1] coupling in solution. The analogue has no detectable agonist activity in rat vasopressor or isolated rat uterus assays. It has an antivasopressor pA2 of 6.67 +/- 0.09. It is a potent inhibitor of the in vitro oxytocic response to oxytocin and has a pA2 value of 7.46 +/- 0.04. (Material from the repeat synthesis has a pA2 value of 7.59 +/- 0.08.) Thus the substitution of threonine for glutamine in the antagonist [1-deaminopenicilliamine]oxytocin (pA2, 7.14 +/- 0.05) has effected a twofold increase in inhibitory potency. [1-deaminopenicillamine,4-threonine]oxytocin is one of the most potent inhibitors of oxytocin known to date.     

苯乙烯基萘类化合物的合成及其CYP1B1酶抑制活性研究

目的寻找CYP1B1酶的高活性高选择性抑制剂。方法以α-萘黄酮为先导物,结合二苯乙烯类CYP1B1酶抑制剂的结构特征,设计了先导物的结构类似物α-(E)-苯乙烯基萘类(Ⅰ)及β-(E)-苯乙烯基萘类(Ⅱ、Ⅲ)化合物。目标化合物通过萘甲醛(6、7或8)及苄基膦酸酯(Ⅴ1～Ⅴ10)的Horner-Wadsworth-Em-mons反应制备。利用7-乙氧基-3H-吩口恶嗪-3-酮-脱乙基(EROD)试剂评价目标化合物对人重组CYP1A1和CYP1B1酶的抑制活性。结果合成了26个新型苯乙烯基萘类化合物,其结构通过1H-NMR确证。酶抑制活性试验表明,与阳性对照物白藜芦醇相比,大多数目标化合物对CYP1B1酶表现出较强的抑制活性及选择性。化合物Ⅰ2、Ⅰ8、Ⅲ2、Ⅲ4较α-萘黄酮显示更强的酶抑制活性及选择性。其中,化合物Ⅰ2对CYP1B1酶的抑制活性最强(IC50为0.31 nmol.L-1)。结论合成了新型苯乙烯基萘类CYP1B1酶抑制剂,并初步分析了其构效关系,为进一步的结构优化及新抑制剂的研究提供依据。     

Synthesis and some pharmacological properties of [4-threonine,7-sarcosine]oxytocin, a peptide with high oxytocic potency, and of [4-threonine,7-N-methylalanine]oxytocin

Two analogues of oxytocin, [Thr4,Sar7]- and [Thr4,MeAla7]oxytocin, were synthesized and their pharmacological properties investigated. [Thr4,Sar7]oxytocin was found to exhibit high biological activity (uterotonic activity of 1174 +/- 104 and milk ejection activity of 731 +/- 57 units/mg) and high selectivity for oxytocin-like relative to vasopressin-like activities (antidiuretic activity of 0.037 +/- 0.012 unit/mg, undetectable pressor activity). [Thr4,MeAla7]oxytocin was characterized by markedly lower biological activities. In both analogues, the additivity of the effects of the residues in positions 4 and 7 of oxytocin on the biological activity of the analogues was ascertained.     

(1-Beta-mercaptopropionic acid, 2-(3,5-dibromo-L-tyrosine))oxytocin, a potent inhibitor of oxytocin.

[1-Beta-Mercaptopropionic acid,2-(3,5-dibromo-L-tyrosine)]oxytocin was synthesized from a protected polypeptide intermediate that had been prepared by the condensation of S-ethylcarbamoyl-beta-mercaptopropionyl-3,5-dibromotyrosine with H-Ile-Gln-Asn-Cys(Ec)-Pro-Leu-Gly-NH2, using dicyclohexylcarbodiimide in dimethylformamide. The ethylcarbamoyl (Ec) protecting groups were removed by refluxing NH3, and the resulting disulfhydryl peptide was oxidatively cyclized to the corresponding disulfide by ICH2CH2I. Purification of the analog was effected by partition chromatography and gel filtration. The analog possesses antioxytocic (pA2 = 7.05) and antiavian vasodepressor (pA2 = 7.44) activities but has neither agonist nor antagonist activity in the rat pressor assay.     

Synthesis,structure-activity relationship,and biological studies of indolocarbazoles as potent cyclin D1-CDK4 inhibitors

Novel substituted indolocarbazoles were synthesized, and their kinase inhibitory capability was evaluated in vitro. 6-Substituted indolocarbazoles 4 were found to be potent and selective D1/CDK4 inhibitors. 4d and 4h exhibited potent and ATP-competitive D1/CDK4 activities with IC50 values of 76 and 42 nM, respectively. Both compounds had high selectivity against the other kinases. These D1/CDK4 inhibitors inhibited tumor cell growth, arrested tumor cells at the G1 phase, and inhibited pRb phosphorylation.     

Synthesis, flow cytometric evaluation, and identification of highly potent dipyridamole analogues as equilibrative nucleoside transporter 1 inhibitors

Dipyridamole (Persantine) is a clinically used vasodilator with equilibrative nucleoside transporters 1 and 2 (ENT1 and ENT2) inhibitory activity albeit less potent than the prototype ENT1 inhibitor nitrobenzylmercaptopurine riboside (NBMPR). Dipyridamole is a good candidate for further exploration because it is a non-nucleoside and has a proven record of safe use in humans. A series of dipyridamole analogues were synthesized with systematic modification and evaluated as ENT1 inhibitors by flow cytometry. Compounds with much higher potency were identified, the best being 2,6-bis(diethanolamino)-4,8-diheptamethyleneiminopyrimido[5,4-d]pyrimidine (13) with a K(i) of 0.49 nM compared to a K(i) of 308 nM for dipyridamole. Compound 13 is similar in potency to the prototype potent ENT1 inhibitor NBMPR (0.43 nM). For the first time, a dipyridamole analogue has been identified that is equipotent with NBMPR. The SAR indicated that diethanolamine substituted analogues were more active than monoethanolamine compounds. Also, free hydroxyl groups are not essential for activity.     

Synthesis and biological activity of potent,low molecular weight renin inhibitors*

A series of renin inhibitors containing the dipeptide transition state mimics (2R, 4S, 5S)-5-amino-4-hydroxy-2-methyl-6-cyclohexyl hexanoic acid (Cha-Ψ[CH(OH)CH₂]Ala) and (2R, 45, 5S)-5-amino-4-hydroxy-2-isopropyl-6-cyclohexyl hexanoic acid (Cha-Ψ[CH(OH)CH₂]Val) were prepared. A structure-activity study, using pseudopeptide (Boc-Phe-His-Leu-Ψ[CH(OH)CH₂]Val-Ile-His-OH) as our lead structure, led to a new series of inhibitors, which correspond to tripeptides and contain no natural amino acids. For example, R, S-Bpma-Ape-Cha-Ψ[CH(OH)CH₂]Ala-NH₂ (IC₅₀= 1.26 nM against human plasma renin at pH 6.0; molecular weight = 564) has only two thirds of the molecular weight but twice the potency of our original lead. This new class of low molecular weight renin inhibitor displays excellent specificity toward human renin versus the related aspartic proteinase pepsin and angiotensin-1-converting enzyme. Examples are given of selected inhibitors showing encouraging evidence for intestinal absorption after intracolonic and oral administration in male Sprague-Dawley rats.     

Synthesis of some novel potent and selective catechol O-methyltransferase inhibitors

A series of disubstituted catechol derivatives was synthesized and tested as potential COMT inhibitors. The most active compounds were more than 1000 times more potent (IC50 = 3-6 nM) in vitro than the known COMT inhibitor, 3',4'-dihydroxy-2-methylpropiophenone (U 0521, IC50 = 6000 nM). The new compounds were also highly selective COMT inhibitors with no activity against other essential enzymes involved in the synthesis and metabolism of catecholamines.     

Synthesis and biological activity of potent HIV-1 protease inhibitors based on Phe-Pro dihydroxyethylene isosteres

Peptidomimetic inhibitors of HIV-1 PR are still a key resource in the fight against AIDS. Here we describe the synthesis and biological activity of HIV-1 PR inhibitors based on four novel dihydroxyethylene isosteres of the Phe-Pro and Pro-Pro dipeptides. The isosteres, containing four stereogenic centers, were synthesized in high yield and excellent stereoselectivity via the cyclization of epoxy amines derived from α-amino acids. The inhibitors were assembled by coupling the isosteres with suitable flanking groups and were screened against recombinant HIV PR showing activities in the subnanomolar to micromolar range. Two Phe-Pro-based inhibitors active at the nanomolar level were further investigated: both inhibitors combine the ability to suppress HIV-1 replication in infected MT-2 cells with low cytotoxicity against the same cells, thereby displaying a high therapeutic index. These results demonstrate the potential of the new Phe-Pro dihydroxyethylene isostere as a core unit of powerful HIV-1 PR inhibitors.     

Synthesis of triazole- and tetrazole-xyloside analogues as potent hyaluronidase inhibitors

Hyaluronidase is one of the most important enzymes in the development of many diseases. In this study, a series of xyloside analogues bearing a triazole and tetrazole at the anomeric position were prepared from xylosylthioureas and evaluated their inhibitory effects on the hyaluronidase. Triazole and tetrazole skeletons were formed via the Hg(OAc)₂-mediated desulfurizative cyclization through carbodiimide intermediates. According to in vitro anti-hyaluronidase assay, tetrazole-xylosides having p-chloro- or p-nitro-substitution exhibited the high inhibition rates, whereas the compound having p-trifluoromethyl group on the structure did not show the potency. Our results demonstrated the importance of tetrazole-xylosides as hyaluronidase inhibitors.     

Discovery of potent, selective, orally bioavailable stearoyl-CoA desaturase 1 inhibitors

Stearoyl-CoA desaturase 1 (SCD1) catalyzes the committed step in the biosynthesis of monounsaturated fatty acids from saturated, long-chain fatty acids. Studies with SCD1 knockout mice have established that these animals are lean and protected from leptin deficiency-induced and diet-induced obesity, with greater whole body insulin sensitivity than wild-type animals. In this work, we have discovered a series of potent, selective, orally bioavailable SCD1 inhibitors based on a known pyridazine carboxamide template. The representative lead inhibitor 28c also demonstrates excellent cellular activity in blocking the conversion of saturated long-chain fatty acid-CoAs (LCFA-CoAs) to monounsaturated LCFA-CoAs in HepG2 cells.     

2,5-diketopiperazines as potent, selective, and orally bioavailable oxytocin antagonists. 2. Synthesis, chirality, and pharmacokinetics

A short stereoselective synthesis of a series of chiral 7-aryl-2,5-diketopiperazines oxytocin antagonists is described. Varying the functionality and substitution pattern of substituents in the 7-aryl ring and varying the chirality of this exocyclic ring have produced potent oxytocin antagonists (pK(i) > 8.5). SAR and pharmacokinetic profiling of this series of (3R,6R,7R)-2,5-diketopiperazines together with the introduction of an ortho F group in the 7-aryl ring to improve rat pK has culminated in the 2',4'-difluorophenyldiketopiperazine derivative 37, a highly potent oxytocin antagonist against the human oxytocin receptor (pK(i) = 8.9) that has >1000-fold selectivity over all three vasopressin receptors V1a, V2, and V1b. It has good bioavailability (46%) in the rat and moderate bioavailability (13-31%) in the dog and is more active in vivo in the rat than atosiban (rat DR(10) = 0.44 mg/kg iv).     

Bradykinin agonist activity of a novel, potent oxytocin antagonist

From a series of potent cyclic hexapeptide oxytocin (OT) antagonists, a compound that exhibited significant bradykinin (BK) agonist activity was identified. L-366,811 (cyclo[L-proline-D-tryptophan-L-isoleucine-D-pipecolic acid-L-piperazine-2-carboxylic acid-N-Me-D-phenylalanine]) stimulated phosphatidylinositol (PI) turnover in rat uterine slices in vitro (approximately EC50, 2 microM) with a maximal effect (15-fold increase over basal) greater than that obtained for either BK or OT. L-366,811 also elicited dose-related contractions of the isolated rat uterus, producing measurable effects at 100 nM. Several other equally potent OT antagonists from the cyclic hexapeptide structural class were either less potent or inactive as activators of uterine PI turnover or contractility. The stimulatory effects of L-366,811 on uterine PI turnover and contractions were blocked by BK antagonists but not by an arginine vasopressin (AVP)/OT antagonist. In radioligand binding studies, L-366,811 exhibited moderate affinity (IC50, 360 nM) for the [3H]BK binding site in rat uterus, consistent with its potency in the functional models. These results indicate that L-366,811 exhibits BK agonist activity in rat uterus in vitro.     

Synthesis and biological evaluation of novel dasatinib analogues as potent DDR1 and DDR2 kinase inhibitors

Novel dasatinib analogues as DDR1 and DDR2 inhibitors were designed and synthesized. The synthesized compounds were screened for DDR1 and DDR2 kinase inhibitory and cancer cell proliferation inhibitory activities. Some of the compounds showed the potent inhibitory activities against both DDR1 and DDR2, as well as anticancer activity in low nanomolar range against K562 cell line; especially, compound 3j demonstrated significantly better inhibitory potency than the parental dasatinib against both DDRs and also demonstrated the potent inhibitory activity against K562 cell lines (IC₅₀ values of 2.26±0.46 nm for DDR1, 7.04±2.90 nm for DDR2, and 0.125±0.017 nm for K562 cell line).     

Novel and potent 17beta-hydroxysteroid dehydrogenase type 1 inhibitors

Structure-based drug design using the crystal structure of human 17beta-hydroxysteroid dehydrogenase type 1 (17beta-HSD1) led to the discovery of novel, selective, and the most potent inhibitors of 17beta-HSD1 reported to date. Compounds 1 and 2 contain a side chain with an m-pyridylmethyl-amide functionality extended from the 16beta position of a steroid scaffold. A mode of binding is proposed for these inhibitors, and 2 is a steroid-based 17beta-HSD1 inhibitor with the potential for further development.     

Arylcyclopropanecarboxyl guanidines as novel, potent, and selective inhibitors of the sodium hydrogen exchanger isoform-1

A novel series of arylcyclopropanecarboxyl guanidines was synthesized and evaluated for activity against the sodium hydrogen exchanger isoform-1 (NHE-1). In biological assays conducted in an AP1 cell line expressing the human NHE-1 isoform, the starting cyclopropane 3a (IC(50) = 3.5 microM) shows inhibitory activity comparable to cariporide (IC(50) = 3.4 microM). Structure-activity relationships are used to optimize the affinity of various acyl guanidines for NHE-1 by screening the effect of substituents at both aryl and cyclopropyl rings. It is demonstrated that introduction of appropriate hydrophobic groups at the phenyl ring and a gem-dimethyl group at the cyclopropane ring enhances the NHE-1 inhibitory activity by up to 3 orders of magnitude (compound 7f, IC(50) = 0.003 microM). In addition, the gem-dimethyl series of analogues seem to display improved oral bioavailability and longer plasma half-life in rats. Furthermore, the lead benzodihydrofuranyl analogue 1 (BMS-284640) shows over 380-fold increased NHE-1 inhibitory activity as well as improved selectivity for NHE-1 over NHE-2 compared to cariporide.     

Identification of imidazo-pyrrolopyridines as novel and potent JAK1 inhibitors

A therapeutic rationale is proposed for the treatment of inflammatory diseases, such as rheumatoid arthritis (RA), by specific targeting of the JAK1 pathway. Examination of the preferred binding conformation of clinically effective, pan-JAK inhibitor 1 led to identification of a novel, tricyclic hinge binding scaffold 3. Exploration of SAR through a series of cycloamino and cycloalkylamino analogues demonstrated this template to be highly tolerant of substitution, with a predisposition to moderate selectivity for the JAK1 isoform over JAK2. This study culminated in the identification of subnanomolar JAK1 inhibitors such as 22 and 49, having excellent cell potency, good rat pharmacokinetic characteristics, and excellent kinase selectivity. Determination of the binding modes of the series in JAK1 and JAK2 by X-ray crystallography supported the design of analogues to enhance affinity and selectivity.