Design,synthesis, and structure–activity relationship of novel CCR2 antagonists

A series of novel 1-aminocyclopentyl-3-carboxyamides incorporating substituted tetrahydropyran moieties have been synthesized and subsequently evaluated for their antagonistic activity against the human CCR2 receptor. Among them analog 59 was found to posses potent antagonistic activity.     

Discovery, synthesis and SAR of azinyl- and azolylbenzamides antagonists of the P2X₇ receptor

The discovery, of a series of 2-Cl-5-heteroaryl-benzamide antagonists of the P2X(7) receptor via parallel medicinal chemistry is described. Initial analogs suffered from poor metabolic stability and low Vd(ss). Multi parametric optimization led to identification of pyrazole 39 as a viable lead with excellent potency and oral bioavailability. Further attempts to improve the low Vd(ss) of 39 via introduction of amines led to analogs 40 and 41 which maintained the favorable pharmacology profile of 39 and improved Vd(ss) after iv dosing. But these analogs suffered from poor oral absorption, probably driven by poor permeability.     

Design,synthesis, and structure–activity relationships of dihydrofuran-2-one and dihydropyrrol-2-one derivatives as novel benzoxazin-3-one-based mineralocorticoid receptor antagonists

Dihydrofuran-2-one and dihydropyrrol-2-one derivatives were identified as novel, potent and selective mineralocorticoid receptor (MR) antagonists by the structure-based drug design approach utilizing the crystal structure of MR/compound complex. Introduction of lipophilic substituents directed toward the unfilled spaces of the MR and identification of a new scaffold, dihydropyrrol-2-one ring, led to potent in vitro activity. Among the synthesized compounds, dihydropyrrol-2-one 11i showed an excellent in vitro activity (MR binding IC₅₀ = 43 nM) and high selectivity over closely related steroid receptors such as the androgen receptor (AR), progesterone receptor (PR) and glucocorticoid receptor (GR) (>200-fold for AR and PR, 100-fold for GR).     

Synthesis and structure–activity relationships of novel,substituted 5,6-dihydrodibenzo[a,g]quinolizinium P2X7 antagonists

Iminium quaternary protoberberine alkaloids (QPA) have been found to be novel P2X₇ antagonists. To assess their structure–activity relationships, these compounds were modified at their R¹ and R² groups and assayed for their ability to inhibit the 2′(3′)-O-(4-benzoylbenzoyl)-ATP (BzATP)-induced uptake of fluorescent ethidium by HEK-293 cells stably expressing the human P2X₇ receptor, and their ability to inhibit BzATP-induced IL-1β release by differentiated THP-1 cells. Compounds 15a and 15d, with alkyl groups at the R¹ position, and especially compound 19h, with the 2-NO₂-4,5-dimethoxy-benzyl group at the R² position, had potent inhibitory efficacy as P2X₇ antagonists.     

γ-Lactams as glycinamide replacements in cyclohexane-based CC chemokine receptor 2 (CCR2) antagonists

We describe the design, synthesis, and evaluation, of γ-lactams as glycinamide replacements within a series of di- and trisubstituted cyclohexane CCR2 antagonists. The lactam-containing trisubstituted cyclohexanes proved to be more potent than the disubstituted analogs, as trisubstituted analog, lactam 13, displayed excellent activity (CCR2 binding IC₅₀ = 1.0 nM and chemotaxis IC₅₀ = 0.5 nM) and improved metabolic stability over its parent glycinamide.     

Neonicotinic analogues: Selective antagonists for α4β2 nicotinic acetylcholine receptors

Nicotine is an agonist of nicotinic acetylcholine receptors (nAChRs) that has been extensively used as a template for the synthesis of α4β2-preferring nAChRs. Here, we used the N-methyl-pyrrolidine moiety of nicotine to design and synthesise novel α4β2-preferring neonicotinic ligands. We increased the distance between the basic nitrogen and aromatic group of nicotine by introducing an ester functionality that also mimics acetylcholine (Fig. 2). Additionally, we introduced a benzyloxy group linked to the benzoyl moiety. Although the neonicotinic compounds fully inhibited binding of both [α-¹²⁵I]bungarotoxin to human α7 nAChRs and [³H]cytisine to human α4β2 nAChRs, they were markedly more potent at displacing radioligand binding to human α4β2 nAChRs than to α7 nAChRs. Functional assays showed that the neonicotinic compounds behave as antagonists at α4β2 and α4β2α5 nAChRs. Substitutions on the aromatic ring of the compounds produced compounds that displayed marked selectivity for α4β2 or α4β2α5 nAChRs. Docking of the compounds on homology models of the agonist binding site at the α4/β2 subunit interfaces of α4β2 nAChRs suggested the compounds inhibit function of this nAChR type by binding the agonist binding site.     

Are nectar-robbers mutualists or antagonists?

As exploiters of plant-pollinator mutualisms, nectar-robbers remove rewards (nectar) without providing pollination services. Though one might expect nectar-robbing to be costly to plants, it may instead benefit plants by indirectly increasing pollen dispersal. I investigated the direct effects of nectar-robbing bees (Xylocopa californica) on floral rewards and behaviors of pollinators visiting desert willow (Chilopsis linearis) and indirect effects of robbing on the reproductive success of the plant. Nectar-robbers reduced nectar; while unrobbed and robbed flowers were equally likely to contain nectar, nectar volumes were smaller in robbed flowers with nectar. Apis mellifera (honeybees), ineffective pollinators in terms of pollen deposition, avoided robbed flowers. In contrast, Bombus sonorus (bumblebees), effective pollinators, did not avoid robbed flowers. While bumblebees tended to spend less time in robbed flowers, the time that they spent in flowers was not correlated with pollen deposition. Using powder mimicking pollen, I found that on some days, powder was dispersed farther or to more flowers from robbed flowers, indicating that robbing may sometimes benefit plants by increasing male reproductive success. Powder movement suggested that the effect of robbing on male reproductive success ranged from costly to beneficial. The outcome for flowers that were marked early each morning was a function of prevalence of robbing and abundances of effective pollinators, but not a function of spatial variability among trees in prevalence of robbing or the abundance of ineffective honeybees. Unlike powder dispersal, female reproductive success, measured by fruit set and the number of pollen tubes growing in styles, was not affected by robbing. Thus, robbers did not reduce plants female reproductive success either directly by damaging flowers or indirectly by reducing pollen deposition by pollinators. Overall, this study indicates that nectar-robbers were not often costly to plants, and sometimes even benefited plants.     

Do calcium-mediated cellular signalling pathways, prostaglandin E2 (PGE2), estrogen or progesterone receptor antagonists, or bacterial endotoxins affect bovine placental function in vitro?

The major objective of this experiment was to determine whether the bovine placenta could be stimulated to secrete progesterone, since the bovine placenta secretes little progesterone when the corpus luteum is functional. Secondly, we wanted to determine whether reported abortifacients or progesterone or estrogen receptor antagonists affected bovine placental prostaglandin secretion. The ovine placenta secretes half of the circulating progesterone at day 90 of pregnancy and PGE2 appears to regulate ovine placental progesterone secretion. Calcium has been reported to regulate placental progesterone secretion in cattle. Diced 186-245-day placental slice explants from six Brahman and six Angus cows were incubated in vitro at 39.5 degrees C under 95% air: 5% CO2 at pH 7.2 in 5 ml of M-199 for 1 h in the absence of treatments and for 4 and 8 h in the presence of treatments. Treatments were: vehicle; R24571; compound 48/80; IP3; PGE2; CaCl2; cyclosporin A; lipopolysaccharide (endotoxin) from Salmonella abortus equi., enteriditis, and typhimurium; monensin; ionomycin; arachidonic acid; mimosine; palmitic acid; progesterone, androstenedione; estradiol-17beta; A23187; RU-486; or MER-25. Jugular and uterine venous plasma and culture media were analyzed for progesterone, PGE2 and PGF2alpha by radioimmunoassay (RIA). Plasma hormone data were analyzed by a One-Way Analysis of Variance (ANOVA). Hormone data in culture media were analyzed for breed and treatment effects by a Factorial Design (2 breeds, 2-range of days, 21 treatments) for ANOVA (2 x 2 x 21). Since hormone data secreted by placental tissue in vitro did not differ (P > or = 0.05) by breed or range of days of pregnancy, data were pooled and analyzed by a One-Way ANOVA. Concentrations of PGE2 in uterine venous blood were two-fold greater (P < or = 0.05) in Angus than Brahman cows. PGE2 and PGF2alpha in vehicle controls increased from 4 to 8h (P < or = 0.05), but not progesterone (P > or = 0.05) Progesterone in culture media treated with RU-486 increased (P < or = 0.05) at 4 and 8 h compared to vehicle controls and was not affected by other treatments (P > or = 0.05). Concentrations of PGE2 in media at 4 and 8 h were lower (P < or = 0.05) when compared to controls except treatment with PGE2 at 4 and 8h and RU-486 at 8h (P > or = 0.05). PGF2alpha was increased (P < or = 0.05) by RU-486 at 8h and no other treatment affected PGF2alpha at 4 or 8 h (P < or = 0.05). In conclusion, modulators of cellular calcium signalling pathways given alone do not affect bovine placental progesterone secretion at the days studied and progesterone receptor-mediated events appear to suppress placental progesterone, PGF2alpha, and PGE2 secretion in cattle. In addition, PGE2 does not appear to regulate bovine placental progesterone secretion when the corpus luteum is functional and bacterial endotoxin does not appear to affect bovine placental secretion of PGF2alpha or PGE2.     

Effects of α-adrenoceptor antagonists on ABCG2/BCRP-mediated resistance and transport

Acquired resistance of cancer cells to various chemotherapeutic agents is known as multidrug resistance, and remains a critical factor in the success of cancer treatment. It is necessary to develop the inhibitors for multidrug resistance. The aim of this study was to examine the effects of eight α-adrenoceptor antagonists on ABCG2/BCRP-mediated resistance and transport. Previously established HeLa/SN100 cells, which overexpress ABCG2/BCRP but not ABCB1/MDR1, were used. The effects of the antagonists on sensitivity to mitoxantrone and the transport activity of Hoehst33342, both substrates for ABCG2/BCRP, were evaluated using the WST-1 assay and cellular kinetics, respectively. ABCG2/BCRP mRNA expression and the cell cycle were also examined by real-time RT-PCR and flow cytometry, respectively. Sensitivity to mitoxantrone was reversed by the α-adrenoceptor antagonists in a concentration-dependent manner, although such effects were also found in the parental HeLa cells. Levels of ABCG2/BCRP mRNA expression were not influenced by the antagonists. The transport activity of Hoechst33342 was decreased by doxazosin and prazosin, but unaffected by the other antagonists. In addition, doxazosin and prazosin increased the proportion of S phase cells in the cultures treated with mitoxantrone, whereas the other α-adrenoceptor antagonists increased the percentage of cells in G(2)/M phase. These findings suggested that doxazosin and prazosin reversed resistance mainly by inhibiting ABCG2/BCRP-mediated transport, but the others affected sensitivity to mitoxantrone via a different mechanism.     

Discovery of a series of potent,orally active α,α-disubstituted piperidine NK1 antagonists

Modification of prototype NK₁ antagonist 2 resulted in the synthesis of a series of simple amides 6 and retroamides 9. These compounds were shown to be potent and orally active NK₁ antagonists.     

Rational design, synthesis, biological evaluation, homology and docking studies of coumarin derivatives as α1 -adrenoceptor antagonists

According to a three-point pharmacophore for some uro-selective α(1) -adrenoceptor (AR) antagonists, a novel class of coumarin (=2H-1-benzopyran-2-one) derivatives have been successfully designed and synthesized with high efficacies for α(1) -AR. These synthesized coumarin derivatives exhibited high efficacies towards α(1) -AR in in vitro pharmacological assays. Compared with prazosin (pK(i) value of 8.77), among those coumarins, tolylpiperazine-substituted derivatives, 7 and 8, have comparable pK(i) values of 8.81 and 8.77, respectively. The trend in efficacies of these coumarin derivatives towards α(1A) -adrenoceptor was further rationalized by intensive molecular docking. Our work demonstrated that the designed coumarin derivatives can inhibit α(1) -AR in vitro. These findings will provide a guide for further studies of the medical therapy of benign prostatic hyperplasia (BPH).     

Design,synthesis, and structure–activity relationships of a series of novel N-aryl-2-phenylcyclopropanecarboxamide that are potent and orally active orexin receptor antagonists

Herein we describe the design, synthesis, and structure–activity relationships (SARs) of a novel phenylcyclopropane series represented by 7 and 33b as antagonists of orexin 1 and orexin 2 receptors. With 4 serving as the initial lead for the development of orexin antagonists, exploration of SAR resulted in improved binding affinity for orexin 1 and orexin 2 receptors. Among the synthesized compounds, 33b ((−)-N-(5-cyanopyridin-2-yl)-2-[(3,4-dimethoxyphenyl)oxymethyl]-2-phenylcyclopropanecarboxamide) exhibited potent in vitro activity and oral efficacy in animal sleep measurement experiments. The results of our study suggest that compound 33b may serve as a valuable template for the development of new orexin receptor antagonists.     

Design and synthesis of novel sulfonamide-containing bradykinin hB(2) receptor antagonists. Synthesis and structure-relationships of α,α-tetrahydropyranylglycine

A series of α,α-cycloalkylglycine sulfonamide compounds of general formula 1 has previously been identified by our group as selective human B(2)(hB(2)) receptor antagonists. Here we report the in vitro and in vivo BK antagonist activity of a further evolution of the series, consisting in compounds of the general formula 2, containing either an alkyl piperazine or a 4-alkyl piperidine ring bearing various positively charged groups (R'). These studies unexpectedly revealed quite a flat nanomolar/subnanomolar SAR for the binding affinity, while differences were seen in the in vitro functional activities. We propose that variations in the residence time may explain these results.     

Amine-constrained pyridazinone histamine H₃ receptor antagonists

Pyridazinone 1 was recently reported as a potent H(3)R antagonist with good drug-like properties and in vivo activity. A series of constrained amine analogs of 1 was synthesized to identify compounds with improved pharmacokinetic profiles. From these efforts, a new class of (S)-2-pyrrolidin-1-ylmethyl-1-pyrrolidinyl amides was identified.     

Synthesis and evaluation of bivalent, peptidomimetic antagonists of the αvβ3 integrins

Targeting the integrin α(v)β(3) by directly interfering with its function is considered to be an effective and non-cytotoxic strategy for the treatment of tumor. In this study, a series of bivalent analogs of peptidomimetic integrin antagonists IA 1 and IAC 2 were designed, synthesized, and evaluated for their ability to inhibit the integrin α(v)β(3). All the bivalent ligands exhibited increased potency compared to that of their monomeric counterparts for the integrin α(v)β(3) with low nanomolar range binding affinity. The best bivalent ligand 6 tested in the series has an IC(50)=0.09 nM evaluated by ELISA assay. We conclude that multivalency is providing a useful template for the development novel integrin α(v)β(3) antagonists as potential therapeutics.     

潘庆民1,于振文2,王月福2

采用盆栽和水泥池栽研究了追氮时期对小麦光合作用、14C同化物运转分配和硝酸还原酶(NR)活性的影响.结果表明,拔节(雌雄蕊原基形成)期较起身(二棱)期追施氮肥,显著提高了小麦开花后的旗叶叶绿素含量和单叶光合速率;灌浆期旗叶14C同化物向籽粒转移比例显著提高,而在营养器官的滞留比例显著降低;旗叶和根系中硝酸还原酶(NR)活性亦显著提高.小麦穗粒数、粒重和产量增加,蛋白质含量提高.     

2-Methyltetrahydro-3-benzazepin-1-ols – The missing link in SAR of GluN2B selective NMDA receptor antagonists

The NMDA receptor containing GluN2B subunits represents a promising target for the development of drugs for the treatment of various neurological disorders including neurodegenerative diseases. In order to study the role of CH₃ and OH moieties trisubstituted tetrahydro-3-benzazepines 4 were designed as missing link between tetra- and disubstituted 3-benzazepines 2 and 5. The synthesis of 4 comprises eight reaction steps starting from alanine. The intramolecular Friedel-Crafts acylation to obtain the ketone 12 and the base-catalyzed elimination of trifluoromethanesulfinate (CF₃SO₂^?) followed by NaBH₄ reduction represent the key steps. The GluN2B affinity of the cis-configured 3-benzazepin-1-ol cis-4a with a 4-phenylbutyl side chain (K_i?=?252?nM) is considerably lower than the GluN2B affinity of (R,R)-2 (K_i?=?17?nM) indicating the importance of the phenolic OH moiety for the interaction with the receptor protein. Introduction of an additional CH₃ moiety in 2-position led to a slight decrease of GluN2B affinity as can be seen by comparing the affinity data of cis-4a and 5. The homologous phenylpentyl derivative cis-4b shows the highest GluN2B affinity (K_i?=?56?nM) of this series of compounds. According to docking studies cis-4a adopts the same binding mode as the cocrystallized ligand ifenprodil-keto 1A and 5 at the interface of the GluN2B and GluN1a subunits. The same crucial H-bonds are formed between the C(O)NH₂ moiety of Gln110 within the GluN2B subunit and the protonated amino moiety and the OH moiety of (R,R)-cis-4a.     

Discovery of novel α7 nicotinic receptor antagonists

Two distinct families of small molecules were discovered as novel α7 nicotinic acetylcholine receptor (nAChR) antagonists by pharmacophore-based virtual screening. These novel antagonists exhibited selectivity for the neuronal α7 subtype over other nAChRs and good brain penetration. Neuroprotection was demonstrated by representative compounds 7i and 8 in a mouse seizure-like behavior model induced by the nerve agent diisopropylfluorophosphate (DFP). These novel nAChR antagonists have potential use as antidote for organophosphorus nerve agent intoxication.     

Drug treatments to reduce excitotoxicity in vivo: a potential for α 2-adrenoceptor antagonists?

Summary. It is hypothesized that the locus coeruleus-noradrenergic system controls compensatory and repair mechanisms in the CNS, and that its dysfunction is a critical factor in the progression of central neurodegenerative diseases. Pharmacological activation of locus coeruleus neurons can be achieved with α ₂-adrenoceptor antagonists, and such compounds are protective in vivo in some models of brain injury where excitotoxicity is thought to be a causative factor. To further explore this neuroprotective potential, the effects of a 7-day treatment with the α ₂-antagonists, (+)-efaroxan and (±)-idazoxan, were evaluated in rats undergoing a unilateral lesioning of the striatum with the excitotoxin, quinolinic acid. The α ₂-antagonist treatments reduced both the ipsiversive circling response to apomorphine and the deficit of choline acetyltransferase in the lesioned animals. To elucidate the mechanisms underlying this neuroprotective effect, a modulation of the extracellular levels of amino acids within the striatum was investigated using in vivo microdialysis. Intrastriatal injection of quinolinic acid increased taurine and tyrosine levels by 2–2.5 fold, while most other amino acids were not significantly altered; the effect of (+)-efaroxan on these changes is being investigated. Further research is required to identify which of several possible mechanisms is involved in the neuroprotective action of α ₂-antagonists in vivo. Received August 31, 1999 Accepted September 20, 1999