ABSTRACT
The use of local antibiotics to treat bone infections has been questioned due to a lack of clinical efficacy and emerging information about Staphylococcus aureus colonization of the osteocyte-lacuno canalicular network (OLCN). Here we propose bisphosphonate-conjugated antibiotics (BCA) using a "target and release" approach to deliver antibiotics to bone infection sites. A fluorescent bisphosphonate probe was used to demonstrate bone surface labeling adjacent to bacteria in a S. aureus infected mouse tibiae model. Bisphosphonate and hydroxybisphosphonate conjugates of sitafloxacin and tedizolid (BCA) were synthesized using hydroxyphenyl and aminophenyl carbamate linkers, respectively. The conjugates were adequately stable in serum. Their cytolytic activity versus parent drug on MSSA and MRSA static biofilms grown on hydroxyapatite discs was established by scanning electron microscopy. Sitafloxacin O-phenyl carbamate BCA was effective in eradicating static biofilm: no colony formation units (CFU) were recovered following treatment with 800 mg/L of either the bisphosphonate or α-hydroxybisphosphonate conjugated drug (p < 0.001). In contrast, the less labile tedizolid N-phenyl carbamate linked BCA had limited efficacy against MSSA, and MRSA. CFU were recovered from all tedizolid BCA treatments. These results demonstrate the feasibility of BCA eradication of S. aureus biofilm on OLCN bone surfaces and support in vivo drug development of a sitafloxacin BCA.
ABSTRACT
All-trans-retinal, a retinoid metabolite naturally produced upon photoreceptor light activation, is cytotoxic when present at elevated levels in the retina. To lower its toxicity, two experimentally validated methods have been developed involving inhibition of the retinoid cycle and sequestration of excess of all-trans-retinal by drugs containing a primary amine group. We identified the first-in-class drug candidates that transiently sequester this metabolite or slow down its production by inhibiting regeneration of the visual chromophore, 11-cis-retinal. Two enzymes are critical for retinoid recycling in the eye. Lecithin:retinol acyltransferase (LRAT) is the enzyme that traps vitamin A (all-trans-retinol) from the circulation and photoreceptor cells to produce the esterified substrate for retinoid isomerase (RPE65), which converts all-trans-retinyl ester into 11-cis-retinol. Here we investigated retinylamine and its derivatives to assess their inhibitor/substrate specificities for RPE65 and LRAT, mechanisms of action, potency, retention in the eye, and protection against acute light-induced retinal degeneration in mice. We correlated levels of visual cycle inhibition with retinal protective effects and outlined chemical boundaries for LRAT substrates and RPE65 inhibitors to obtain critical insights into therapeutic properties needed for retinal preservation.
Subject(s)
Diterpenes/metabolism , Photic Stimulation/adverse effects , Retinal Degeneration/metabolism , Retinal Degeneration/prevention & control , Retinal Pigment Epithelium/metabolism , Retinal Pigment Epithelium/radiation effects , Retinaldehyde/metabolism , Animals , Cattle , Diterpenes/pharmacology , Diterpenes/therapeutic use , Female , Male , Mice , Mice, Knockout , Retinal Pigment Epithelium/drug effectsABSTRACT
The design, synthesis, and biological studies of a novel class of MCH-R1 antagonists based on an aminotetrahydronaphthalene ketopiperazine scaffold is described. Compounds within this class promoted significant body weight reduction in mouse diet induced obesity studies. The potential for hERG blockage activity and QT interval studies in anesthetized dogs are discussed.
Subject(s)
Piperazines/pharmacology , Receptors, Somatostatin/antagonists & inhibitors , Animals , Dogs , Drug Evaluation, Preclinical , Magnetic Resonance Spectroscopy , Male , Mass Spectrometry , Models, Molecular , Piperazines/chemistry , Structure-Activity RelationshipABSTRACT
Aminomethyl tetrahydronaphthalene biphenyl carboxamide MCH-R1 antagonists with greater selectivity over hERG were identified. SAR studies addressing two distinct alternatives for structural modifications leading to improve hERG selectivity are described.
Subject(s)
Biphenyl Compounds/pharmacology , Ether-A-Go-Go Potassium Channels/drug effects , Naphthalenes/pharmacology , Potassium Channel Blockers/pharmacology , Receptors, Somatostatin/antagonists & inhibitors , Biphenyl Compounds/chemical synthesis , ERG1 Potassium Channel , Ergolines/pharmacology , Humans , Indicators and Reagents , Mianserin/pharmacology , Naphthalenes/chemical synthesis , Receptor, Serotonin, 5-HT2C/drug effects , Serotonin Antagonists/pharmacology , Structure-Activity RelationshipABSTRACT
We have identified a novel series of potent MCH-R1 antagonists based on l-arginine. As predicted by computational methods, there was an activity dependence on the pi-electronic character of the aromatic systems corresponding to the amino-terminus of these molecules. These results have enhanced our understanding of the MCH-R1 receptor and the potential for a predictive homology model.
Subject(s)
Arginine/pharmacology , Receptors, Somatostatin/antagonists & inhibitors , Cell Line , Chromatography, High Pressure Liquid , Humans , Luciferases/genetics , Models, Molecular , Molecular Conformation , Structure-Activity RelationshipABSTRACT
A direct correlation between hERG binding and QTc prolongation was established for a series of aminomethyl tetrahydronaphthalene ketopiperazine MCH-R1 antagonists. Compounds within this class with greater selectivity over hERG were developed. Compound 4h proved to have the best profile, with MCH-R1 Ki = 16 nm and hERG IC50 = 25 microM.
Subject(s)
Ether-A-Go-Go Potassium Channels/drug effects , Naphthalenes/pharmacology , Piperazines/pharmacology , Potassium Channel Blockers/pharmacology , Receptors, Somatostatin/antagonists & inhibitors , Animals , Dogs , ERG1 Potassium Channel , Heart Rate/drug effects , Humans , Indicators and Reagents , Mice , Naphthalenes/chemical synthesis , Piperazines/chemical synthesis , Weight Loss/drug effectsABSTRACT
The synthesis and biological testing of novel classes of potent melanin-concentrating hormone (MCH-R1) antagonists based on pyrazolopiperazinone and pyrrolopiperazinone scaffolds are described.
Subject(s)
Piperazines/chemical synthesis , Pyrazoles/chemical synthesis , Pyrroles/chemical synthesis , Receptors, Somatostatin/antagonists & inhibitors , Caco-2 Cells , Humans , Indicators and Reagents , Models, Molecular , Molecular Conformation , Piperazines/pharmacology , Pyrazoles/pharmacology , Pyrroles/pharmacology , Radioligand Assay , Receptor, Serotonin, 5-HT2C/drug effectsABSTRACT
A substituted 4-aminopiperidine was identified as showing activity in an MCH assay from an HTS effort. Subsequent structural modification of the scaffold led to the identification of a number of active MCH antagonists. 3,5-Dimethoxy-N-(1-(naphthalen-2-ylmethyl)piperidin-4-yl)benzamide (5c) was among those with the highest binding affinity to the MCH receptor (K(i)=27nM), when variations were made at benzoyl and naphthylmethyl substitution sites from the initial HTS hit. Further optimization via piperidine ring contraction resulted in enhanced MCH activity in a 3-aminopyrrolidine series, where (R)-3,5-dimethoxy-N-(1-(naphthalen-2-ylmethyl)-pyrrolidin-3-yl)benzamide (10i) was found to be an excellent MCH antagonist (K(i)=7nM).
Subject(s)
Obesity/drug therapy , Piperidines/pharmacology , Piperidines/therapeutic use , Pyrrolidines/pharmacology , Pyrrolidines/therapeutic use , Receptors, Somatostatin/antagonists & inhibitors , Binding, Competitive/drug effects , Drug Evaluation, Preclinical , Humans , Molecular Structure , Piperidines/chemistry , Pyrrolidines/chemistry , Stereoisomerism , Structure-Activity RelationshipABSTRACT
A novel series of substituted quinoline analogs were designed and synthesized as potent and selective melanin concentrating hormone (MCH) antagonists. These analogs show potent (nM) activity (12a-k) with a moderate selectivity. Conversely, the conformationally constrained thienopyrimidinone analogs (18a-g) showed improved activity in MCH-1R and selectivity over 5HT2C.
Subject(s)
Anti-Obesity Agents/chemical synthesis , Hypothalamic Hormones/antagonists & inhibitors , Melanins/antagonists & inhibitors , Pituitary Hormones/antagonists & inhibitors , Quinolines/chemical synthesis , Quinolines/pharmacology , Anti-Obesity Agents/pharmacology , Drug Design , Humans , Inhibitory Concentration 50 , Ligands , Pyrimidinones , Structure-Activity Relationship , Substrate SpecificityABSTRACT
The design and synthesis of a series of potent 1,3,4-trisubstituted-2-oxopiperazine based MC4 agonists are described. The tripeptidomimetic analogs (12a,b and 23) and the dipeptidomimetic 27 displayed single-nanomolar binding affinity and agonist potency for MC4R and excellent selectivity for MC4R relative to MC1R.
Subject(s)
Drug Design , Guanidines/chemistry , Guanidines/pharmacology , Piperazines/chemistry , Piperazines/pharmacology , Receptor, Melanocortin, Type 4/agonists , Guanidines/chemical synthesis , Molecular Structure , Piperazines/chemical synthesis , Receptor, Melanocortin, Type 4/metabolism , Structure-Activity RelationshipABSTRACT
Novel quinolone antibacterial agents bearing (3S)-amino-(4R)-ethylpiperidines were designed by using low energy conformation analysis and synthesized by applying a conventional coupling reaction of the quinolone nuclei with new piperidine side chains. These compounds were tested in MIC assays and found to be highly potent against Gram-positive and Gram-negative organisms. In particular, the new compounds exhibited high activity against the resistant pathogens Staphylococcus aureus (MRCR) and Streptococcus pneumoniae (PR). Importantly, when the (3S)-amino-(4R)-ethylpiperidinyl quinolones were compared with marketed quinolones sharing the same quinolone nuclei but different side chains at the C-7 position, the new quinolones showed superior activity against Gram-positive organisms, including resistant pathogens.
Subject(s)
Anti-Bacterial Agents/chemical synthesis , Bacteria/drug effects , Drug Resistance, Bacterial , Piperidines/chemical synthesis , Quinolones/chemical synthesis , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , DNA Gyrase/chemistry , DNA Gyrase/drug effects , DNA, Superhelical/chemistry , DNA, Superhelical/drug effects , Escherichia coli/enzymology , Gram-Negative Bacteria/drug effects , Gram-Positive Bacteria/drug effects , Microbial Sensitivity Tests , Models, Molecular , Molecular Conformation , Piperidines/chemistry , Piperidines/pharmacology , Quinolones/chemistry , Quinolones/pharmacology , Stereoisomerism , Structure-Activity RelationshipABSTRACT
Quinolones without the usual 6-fluorine substituent have been recently described as potent antibacterial agents. A series of non-fluorinated analogues of the antibacterial quinolone Levofloxacin were synthesized and tested.
Subject(s)
Anti-Infective Agents/chemical synthesis , Bacteria/drug effects , Levofloxacin , Ofloxacin/analogs & derivatives , Ofloxacin/chemical synthesis , Animals , Anti-Infective Agents/pharmacology , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , Escherichia coli/drug effects , Microbial Sensitivity Tests , Molecular Conformation , Ofloxacin/pharmacology , Structure-Activity Relationship , Topoisomerase II InhibitorsABSTRACT
[reaction: see text] trans-(3S)-Amino piperidines bearing various alkyl and aryl substituents at the C-4 position were synthesized via a ring-closing metathesis reaction. The absolute stereochemistry was controlled using a protected D-serine as a starting material. Stereoselective hydrogenation of allylamines provided trans-(3S)-amino-(4R)-alkyl- and -(4S)-aryl-piperidines. This procedure presents the first method for the asymmetric synthesis of 4-substituted 3-amino piperidines.
ABSTRACT
Palmitoylation of cysteines 3 and 5 is necessary for targeting Lck to lipid rafts and is needed for Lck function in T cell receptor (TCR) signaling. Point mutations of cysteines 3 and 5 result in a form of Lck that fails to associate with the plasma membrane, which limits the usefulness of this genetic approach to address the role of palmitoylation in the distribution of Lck within the plasma membrane. To circumvent this problem, we sought to identify a palmitic acid analogue that would enable plasma membrane association of Lck, but not facilitate its localization within lipid rafts. Here we examined the effects of the heteroatom-substituted analogue of palmitic acid, 13-oxypalmitic acid (13-OP), on Lck subcellular localization and function. 13-OP is similar in chain length to palmitic acid, but possesses reduced hydrophobicity. We found that treatment of cells with 13-OP inhibited incorporation of omega-[(125)I]iodopalmitate into Lck. 13-OP inhibited localization of Lck to lipid rafts without altering its membrane localization. Consistent with the dissociation of Lck from rafts, treatment with 13-OP abolished Lck association with the GPI-anchored protein, CD48, but not the transmembrane glycoprotein CD4. Jurkat T cells treated with 13-OP showed marked reduction in tyrosine phosphorylation and activation of mitogen-activated protein kinase upon TCR stimulation. In conclusion, the less hydrophobic analogue of palmitate, 13-OP, alters the normal acylation of Lck that provides Lck with the necessary hydrophobicity and tight packing order required for inclusion in lipid rafts.