Search

A novel series of 7-alkylidenyltetrahydroindazole-based acylsulfonamides were discovered as potent EP3 antagonists. The initial lead compound 7 exhibited potent in vitro EP3 inhibitory activity and good selectivity against other EP receptors. In addition, compound 7 demonstrated in vivo activity in a rat ivGTT model, reversing the suppressive effect of the EP3-specific agonist sulprostone on glucose-stimulated insulin secretion. Further optimization to improve the pharmacokinetic profile led to the discovery of compounds 26 and 28 with potent in vitro activity and significantly lower in vivo clearance and higher oral exposure than compound 7 ., Competing Interests: The authors declare no competing financial interest., (© 2021 American Chemical Society.)

A novel series of pyridone-based EP3 receptor antagonists was optimized for good physical properties and oral bioavailability in rodents. The lead compounds 3h, 3l and 4d displayed good in vitro profiles, moderate to good metabolic stability and good rodent PK profiles with low clearance, high oral exposure and acceptable half-life., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

A novel series of guanidinebenzoate enteropeptidase and trypsin dual inhibitors has been discovered and SAR studies were conducted. Optimization was focused on improving properties for gut restriction, including increased aqueous solubility, lower cellular permeability, and reduced oral bioavailability. Lead compounds were identified with efficacy in a mouse fecal protein excretion study., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The gut hormone PYY 3-36 reduces food intake in humans and exhibits at least additive efficacy in combination with GLP-1. However, the utility of PYY analogs as anti-obesity agents has been severely limited by emesis and rapid proteolysis, a profile similarly observed with native PYY 3-36 in obese rhesus macaques. Here, we found that antibody conjugation of a cyclized PYY 3-36 analog achieved high NPY2R selectivity, unprecedented in vivo stability, and gradual infusion-like exposure. These properties permitted profound reduction of food intake when administered to macaques for 23 days without a single emetic event in any animal. Co-administration with the GLP-1 receptor agonist liraglutide for an additional 5 days further reduced food intake with only one animal experiencing a single bout of emesis. This antibody-conjugated PYY analog therefore may enable the long-sought potential of GLP-1/PYY-based combination treatment to achieve robust, well-tolerated weight reduction in obese patients., (Copyright © 2019 Elsevier Inc. All rights reserved.)

We have discovered a novel series of isothiazole-based phenylpropanoic acids as GPR120 agonists. Extensive structure-activity relationship studies led to the discovery of a potent GPR120 agonist 4x , which displayed good EC 50 values in both calcium and β-arrestin assays. It also presented good pharmaceutical properties and a favorable PK profile. Moreover, it demonstrated in vivo antidiabetic activity in C57BL/6 DIO mice. Studies in WT and knockout DIO mice showed that it improved glucose handling during an OGTT via GPR120. Overall, 4x possessed promising antidiabetic effect and good safety profile to be a development candidate.

MurF catalyzes the last cytoplasmic step of bacterial cell wall synthesis and is essential for bacterial survival. Our previous studies used a pharmacophore model of a MurF inhibitor to identify additional inhibitors with improved properties. We now present the characterization of two such inhibitors, the diarylquinolines DQ1 and DQ2. DQ1 inhibited Escherichia coli MurF (50% inhibitory concentration, 24 microM) and had modest activity (MICs, 8 to 16 microg/ml) against lipopolysaccharide (LPS)-defective E. coli and wild-type E. coli rendered permeable with polymyxin B nonapeptide. DQ2 additionally displayed activity against gram-positive bacteria (MICs, 8 to 16 microg/ml), including methicillin (meticillin)-susceptible and -resistant Staphylococcus aureus isolates and vancomycin-susceptible and -resistant Enterococcus faecalis and Enterococcus faecium isolates. Treatment of LPS-defective E. coli cells with >or=2x MIC of DQ1 resulted in a 75-fold-greater accumulation of the MurF substrate compared to the control, a 70% decline in the amount of the MurF product, and eventual cell lysis, consistent with the inhibition of MurF within bacteria. DQ2 treatment of S. aureus resulted in similar effects on the MurF substrate and product quantities. At lower levels of DQ1 (

MurF is an essential enzyme of bacterial cell wall biosynthesis. Few MurF inhibitors have been reported, and none have displayed measurable antibacterial activity. Through the use of a MurF binding assay, a series of 8-hydroxyquinolines that bound to the Escherichia coli enzyme and inhibited its activity was identified. To derive additional chemotypes lacking 8-hydroxyquinoline, a known chelating moiety, a pharmacophore model was constructed from the series and used to select compounds for testing in the MurF binding and enzymatic inhibition assays. Whereas the original diverse library yielded 0.01% positive compounds in the binding assay, of which 6% inhibited MurF enzymatic activity, the pharmacophore-selected set yielded 14% positive compounds, of which 37% inhibited the enzyme, suggesting that the model enriched for compounds with affinity to MurF. A 4-phenylpiperidine (4-PP) derivative identified by this process displayed antibacterial activity (MIC of 8 microg/ml against permeable E. coli) including cell lysis and a 5-log(10)-unit decrease in CFU. Importantly, treatment of E. coli with 4-PP resulted in a 15-fold increase in the amount of the MurF UDP-MurNAc-tripeptide substrate, and a 50% reduction in the amount of the MurF UDP-MurNAc-pentapeptide product, consistent with inhibition of the MurF enzyme within bacterial cells. Thus, 4-PP is the first reported inhibitor of the MurF enzyme that may contribute to antibacterial activity by interfering with cell wall biosynthesis.

Chemobiosynthesis has been used to prepare analogs of erythromycins having unique functional groups at the 15-position. Using diketide thioester feeding to genetically engineered Streptomyces coelicolor, analogs of 6-deoxyerythronolide B were prepared having 15-fluoro, 15-chloro, and 15-azido groups. Bioconversion using a genetically engineered mutant of Saccharopolyspora erythraea was used to produce 15-fluoroerythromycin A and 15-azidoerythromycin A. These new erythromycin analogs provide antibacterial macrolides with unique physicochemical properties and functional groups that allow for selective derivatization.

Antimicrobial-modifying resistance enzymes have traditionally been class specific, having coevolved with the antibiotics they inactivate. Fluoroquinolones, antimicrobial agents used extensively in medicine and agriculture, are synthetic and have been considered safe from naturally occurring antimicrobial-modifying enzymes. We describe reduced susceptibility to ciprofloxacin in clinical bacterial isolates conferred by a variant of the gene encoding aminoglycoside acetyltransferase AAC(6')-Ib. This enzyme reduces the activity of ciprofloxacin by N-acetylation at the amino nitrogen on its piperazinyl substituent. Although approximately 30 variants of this gene have been reported since 1986, the two base-pair changes responsible for the ciprofloxacin modification phenotype are unique to this variant, first reported in 2003 and now widely disseminated. An intense increase in the medical use of ciprofloxacin seems to have been accompanied by a notable development: a single-function resistance enzyme has crossed class boundaries, and is now capable of enzymatically undermining two unrelated antimicrobial agents, one of them fully synthetic.

An array of 15-amido substituted erythromycin A compounds was synthesized using a chemobiosynthesis approach. It was found that while the in vitro antibacterial activities of aryl amides were inferior to erythromycin A, substituted benzylamides showed equivalent and in some cases improved activity against the macrolide-resistant strains. The 15-amidoerythromycins represent a new class of antibacterial macrolides.

Novel C6-carbamate ketolides with C2-fluorination and C9-oximation have been synthesized. The best compounds in this series displayed MIC values of 0.03-0.12 microg/mL against streptococci containing erm and mef resistance determinants and 2-4 microg/mL against Haemophilus influenzae. Several compounds also showed measurable activity against erm(B)-containing enterococci with MIC values of 2-8 microg/mL. In vivo activity was adversely affected by fluorination, possibly as a result of increased serum protein binding.

In vitro activities of erythromycin A, telithromycin, and two investigational ketolides, JNJ-17155437 and JNJ-17155528, were evaluated against clinical bacterial strains, including selected common respiratory tract pathogens. Against 46 macrolide-susceptible and -resistant Streptococcus pneumoniae strains, the MIC(90) (MIC at which 90% of the isolates tested were inhibited) of the investigational ketolides was 0.25 microg/ml, twofold lower than that of telithromycin and at least 64-fold lower than that of erythromycin A. Against erm(B)-containing pneumococci, the MIC(90) of all the ketolides was 0.06 microg/ml. The MIC(90) of the investigational ketolides against mef(A)-containing pneumococci or pneumococci with both mef(A) and erm(B) was 0.25 microg/ml, two-and fourfold lower, respectively, than that of telithromycin. In contrast, the MICs of the investigational ketolides against macrolide-resistant S. pneumoniae strains with ribosomal mutations were similar to or, in some cases, as much as eightfold higher than those of telithromycin. Against Haemophilus influenzae, MICs of all the ketolides were < or =2 microg/ml. Against three Moraxella catarrhalis isolates, the MIC of the ketolides was 0.25 microg/ml. The ketolides inhibited in vitro protein synthesis, with 50% inhibitory concentrations ranging from 0.23 to 0.27 microM. In time-kill studies against macrolide-susceptible and erm- or mef-containing pneumococci, the ketolides were bacteriostatic to slowly bactericidal, with 24-h log(10) decreases ranging from 2.0 to 4.1 CFU. Intervals of postantibiotic effects for the ketolides against macrolide-susceptible and -resistant S. pneumoniae were 3.0 to 8.1 h.

At least 18 antibacterial agents are currently undergoing clinical trials for the treatment of infections caused by susceptible and resistant bacteria. The beta-lactam class includes new parenteral carbapenems and cephalosporins with varying spectra of activities. The glycopeptides are antibiotics with in vitro activity primarily against Gram-positive bacteria, including multi-resistant strains. Three quinolones are being investigated for use against a variety of Gram-positive and respiratory Gram-negative organisms. Several other classes of antibacterial agents currently in clinical trials are represented by a glycolipodepsipeptide, a dihydrofolate reductase inhibitor, an oxazolidinone, two peptide antibiotics, a glycylcycline, and a peptide deformylase inhibitor, a member of a new antibacterial class.

We have characterized a novel, potent, and selective phosphodiesterase type 5 inhibitor, JNJ-10258859 ((R)-(-)-3-(2,3-dihydro-benzofuran-5-yl)-2-[5-(4-methoxy-phenyl)-pyrimidin-2-yl]-1,2,3,4-tetrahydro-pyrrolo[3,4-b]quinolin-9-one). Its inhibitory effects on phosphodiesterase 1-6 were determined using enzymes partially purified from human tissues. The compound inhibited phosphodiesterase type 5 with a K(i) of 0.23 nM and displayed excellent selectivity versus phosphodiesterase types 1-4 (>/=22,000 fold compared to phosphodiesterase type 5). It had 27-fold selectivity over phosphodiesterase type 6 as well. In a cell-based assay, JNJ-10258859 was more potent than sildenafil in potentiating nitric oxide (NO) induced accumulation of intracellular cGMP. The in vivo effect of JNJ-10258859 was evaluated in an anesthetized dog model via intravenous administration. The compound had similar efficacy to sildenafil in enhancing both the amplitude and duration of intracavernosal pressure increase induced by electrical stimulation to the pelvic nerve. No significant effects on either mean aortic pressure or heart rate were observed during the course of the experiments. This data suggests that JNJ-10258859 could be a useful treatment for erectile dysfunction.

With the continuing development of clinical drug resistance among bacteria and the advent of resistance to the recently released agents quinupristin-dalfopristin and linezolid, the need for new, effective agents to treat multi-drug-resistant Gram-positive infections remains important. This review focuses on agents presently in clinical development for the treatment of serious multidrug-resistant staphylococcal, enterococcal and pneumococcal infections, including methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci and penicillin-resistant Streptococcus pneumoniae. Agents to be discussed that affect the prokaryotic cell wall include the antimethicillin-resistant S. aureus cephalosporins BAL9141 and RWJ-54428, the glycopeptides oritavancin and dalbavancin and the lipopeptide daptomycin. Topoisomerase inhibitors include the fluoroquinolones gemifloxacin, sitafloxacin and garenoxacin. Protein synthesis inhibitors are represented by the ketolides telithromycin and cethromycin, the oxazolidinones and the glycylcycline tigecycline. Although each of these compounds has demonstrated antibacterial activity against antibiotic-resistant pathogens, their final regulatory approval will depend on an acceptable clinical safety profile.

Bacterial two-component regulatory systems (TCS) play a pivotal role in the process of infection. These signal transduction systems enable bacterial pathogens to mount an adaptive response and cope with diverse environmental stresses, including nutrient deprivation, antibiotic onslaught and phagocytosis. Interest in these systems as novel bacterial targets has been rekindled by the recent discovery of several essential systems in important Gram-positive and Gram-negative pathogens. Several series of TCS inhibitors derived from broad screening approaches have been reported in the literature, however, most appear to suffer from poor selectivity, excessive protein binding and/or limited bioavailability. Consequently, pharmaceutical chemists have turned to alternate strategies, such as the design of substrate-based inhibitors, the generation of combinatorial libraries and the isolation of natural products, to identify inhibitors with more desirable properties. Recent structural studies of the histidine protein kinase and response regulator proteins that constitute TCS may provide a foundation for a structure-based design approach to TCS inhibitors.

Recently, several new drugs for the treatment of bacterial infections have been developed. Quinupristin/dalfopristin, moxifloxacin and gatifloxacin have been approved throughout the world for clinical use. Levofloxacin has been approved for the treatment of community-acquired pneumonia caused by penicillin-resistant Streptococcus pnuemoniae. The Food and Drug Administration has approved linezolid for clinical use, and new drug applications for gemifloxacin and telithromycin were filed. Other new targets have surfaced in the quest for novel antibacterial agents.

Motilin was isolated from acid extracts of the small intestine of chickens by a combination of gel filtration chromatography, ion-exchange, and reverse-phase HPLC. The purification was monitored using a radioreceptor assay. The sequence of chicken motilin is FVPFFTQSDIQKMQEK-ERNKGQ. Although the six residues differing from porcine motilin (4, 7-10, and 12) are mostly in the pharmacophore of porcine motilin, the affinity of chicken motilin and of the (1-14) fragment of chicken motilin for the motilin receptor of rabbit antral smooth muscle is not much reduced (pKds of 8.90 and 8.45), compared with the affinity of [Nle13]porcine motilin (pKd 9.12). With smooth muscle tissue of the chicken, however, receptors could not be demonstrated with binding studies. In the tissue bath chicken motilin induced a dose-dependent tonic contraction, which was most pronounced with muscle strips prepared from chicken jejunum. This response was blocked by the Ca2+ antagonist verapamil, but atropine, TTX, L-NNA, guanethidine, prazosin, and yohimbine had no effect. The pEC50 for chicken motilin in the chicken jejunum was 7.41. Motilins from other species had lower potencies, and [Phe3, Leu13]porcine motilin, an antagonist in the rabbit, was an agonist in the chicken. The motilin agonists erythromycin A and EM-523 were almost without effect. Tested against rabbit duodenum, chicken motilin had a smaller potency than mammalian motilins. Thus, chicken motilin and the chicken motilin receptor differ from their mammalian counterparts.

The solid-phase synthesis of two porcine motilin derivatives, specifically biotinylated on the side chain of Lys20, was accomplished by preactivation of the protected amino acids N alpha-(9-fluorenylmethoxycarbonyl)-N epsilon-biotinyl-L-lysine and N alpha-(9-fluorenylmethoxycarbonyl)-N epsilon-[N-(biotinyl)-6-aminohexanoyl]-L-lysine with BOP/HOBt/DIEA (1:1:2.5) followed by coupling to the support-bound peptide substrate. The biotin moiety was stable to TFA cleavage and repetitive cycles of acylation, as evidenced by the high level of purity (> 80%) of the crude peptides. This direct synthetic approach complements existing orthogonal protection strategies for the site-specific biotinylation of peptides. The derivatized peptides were purified by RP-HPLC and characterized by mass spectral and amino acid analysis. In binding studies using a rabbit antral smooth muscle homogenate, both [Leu13, Lys20 (N epsilon-biotinyl)]porcine motilin (3) and [Leu13, Lys20 (N epsilon-[N-(biotinyl)-6-aminohexanoyl])]porcine motilin (4) possessed nearly equal affinities for the motilin receptor (IC50 = 0.89 and 1.2 nM, respectively) as native porcine motilin (1) (IC50 = 0.76 nM). The biotinylated peptides were also highly potent in tissue bath assays employing rabbit duodenal smooth muscle segments. In contrast, commercially available [N alpha-biotinylPhe1]porcine motilin (5) had markedly lower affinity in the binding assay (IC50 = 30 nM). The relative bioactivities of these receptor probes are in accord with previous synthetic studies on motilin which demonstrated the importance of the amino-terminal segment in the high affinity interaction between the peptide and its receptor. Analog 3 retained high affinity for the motilin receptor in the presence of avidin. Therefore, this peptide is expected to be a valuable tool for the isolation and identification of motilin receptors.

Studies on the physiological role of motilin, and more recently, on the relationship between motilin and erythromycin A, have been hampered by the lack of antagonists. We now have discovered such a compound. ANQ-11125 displaces motilin bound to an homogenate of rabbit antral smooth muscle tissue. The dissociation constant (pKd) was 8.16 +/- 0.10. However, ANQ-11125 did not induce contractions of segments of rabbit duodenum, except at high concentrations. In the presence of 1 microM ANQ-11125 the dose response curves of erythromycin-A, De(N-methyl)-N-ethyl-8,9 anhydroerythromycin A 6,9-hemiacetal and motilin were shifted about one log unit to the right, but the responses to ACh and Substance P were unaffected. Schild-analysis showed the competitive nature of the interaction and allowed the calculation of the pA2: 7.03 +/- 0.05 (motilin curves) and 7.55 +/- 0.06 (EM-523 curves). This is the first report of a motilin antagonist. Its properties definitively prove that motilides are motilin agonists.

Several peptide fragments representing N-terminal, C-terminal, and internal sequences of [Leu13]porcine motilin ([Leu13]pMOT) were synthesized using Fmoc solid phase methodology. Peptides were assayed for motilin receptor binding activity in a rabbit antrum smooth muscle preparation and for stimulation of contractile activity in segments of rabbit duodenum. In vitro activity was directly correlated with motilin receptor binding affinity for all [Leu13]pMOT fragments examined. N-Terminal fragments of just over half the length of the native peptide are nearly equipotent as full-length motilin. These results suggest that the N-terminal segment, together with residues from the mid-portion of the molecule, constitutes the bioactive portion of pMOT. The C-terminal segment, in contrast, contributes little to receptor binding affinity or in vitro activity.

Motilin is a gut hormone, which is involved in gastrointestinal motility. Capillary electrophoresis studies were made on 24 peptides that are N-terminal, C-terminal or internal fragments of motilin. The isoelectric point, total charge and hydrophobicity were calculated for all of the peptides. The effects of buffers and pH on migration time and resolution were studied. These included citrate buffer, pH 2.5; phosphate buffer, pH 7.0 and borate buffer, pH 10.0. A capillary zone electrophoresis method was developed to resolve 14 of the motilin peptides. Secondary structure predictions were made using the Chou-Fasman method. Circular dichroism spectra were collected to confirm presence of alpha-helix in several fragments. Effects of charge, hydrophobicity, secondary structure and length of the motilin fragments on migration time were studied.