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1.
ACS Omega ; 6(47): 31831-31842, 2021 Nov 30.
Article in English | MEDLINE | ID: mdl-34870006

ABSTRACT

Antimicrobial peptides that act by disrupting bacterial membranes are attractive agents for treating drug-resistant bacteria. This study investigates a membrane-disrupting peptide mimic made of a cyclic oligosaccharide cyclodextrin scaffold that can be chemically polyfunctionalized. An antibacterial functional group on the peptide was simplified to an alkylamino group that combines cationic and hydrophobic moieties, the former to interact with the anionic bacterial membrane and the latter with the membrane interior. The cyclodextrins equipped with eight alkylamino groups on the molecules using a poly-click reaction exhibited antibacterial activity against Gram-positive and Gram-negative bacteria, including drug-resistant pathogens such as carbapenem-resistant Enterobacteriaceae. Several lines of evidence showed that these agents disrupt bacterial membranes, leading to rapid bacterial cell death. The resulting membrane perturbation was directly visualized using high-speed atomic force microscopy imaging. In Gram-negative bacteria, the membrane-permeabilizing action of these derivatives allowed the entry of co-treated traditional antibiotics, which were then active against these bacteria.

2.
Medchemcomm ; 10(8): 1432-1437, 2019 Aug 01.
Article in English | MEDLINE | ID: mdl-31803397

ABSTRACT

A membrane-active antimicrobial peptide gramicidin S-like amphiphilic structure was prepared from cyclodextrin. The mimic was a cyclic oligomer composed of 6-amino-modified glucose 2,3-di-O-propanoates and it exhibited antimicrobial activity against Gram-positive and Gram-negative bacteria, together with no resistance development and low haemolytic activity against red blood cells.

3.
Medchemcomm ; 9(3): 509-518, 2018 Mar 01.
Article in English | MEDLINE | ID: mdl-30108941

ABSTRACT

The emergence of drug-resistant bacteria has led to the high demand for new antibiotics. In this report, we investigated membrane-active antimicrobial ß-cyclodextrins. These contain seven amino-modified alkyl groups on a molecule, which act as functional moieties to permeabilize bacterial cell membranes. The polyfunctionalization of cyclodextrins was achieved through a click reaction assisted by microwave irradiation. A survey using derivatives with systematically varied functionalities clarified the unique correlation of the antimicrobial activity of these compounds with their molecular structure and hydrophobicity/hydrophilicity balances. The optimum hydrophobicity for the compounds being membrane-active was specific to bacterial strains and animal cells; this led to specific compounds having selective toxicity against bacteria including multidrug-resistant pathogens. The results demonstrate that cyclodextrin is a versatile molecular scaffold for rationally designed structures and can be used for the development of new antibiotics.

4.
Photochem Photobiol Sci ; 17(7): 954-963, 2018 Jul 11.
Article in English | MEDLINE | ID: mdl-29892767

ABSTRACT

We analyzed the structure-activity relationship of porphyrins with the photoinactivation of membrane function in bacteria and erythrocytes. The porphyrins tested were protoporphyrin (PP), mesoporphyrin (MP), deuteroporphyrin (DP), hematoporphyrin (HP), coproporphyrin (CP) and uroporphyrin (UP), along with hematoporphyrin derivative (HPD) and photofrin (PF). These porphyrins dissipated membrane potential of Staphylococcus aureus cells depending on the degrees of respiratory inhibition and K+ leakage. The dysfunction of bacterial membrane was caused within minutes and in the order of PP ∼ MP > DP > HPD ≫ HP > PF > CP ∼ UP. For bovine erythrocytes, these porphyrins induced leakage of K+ and inhibition of the enzyme acetylcholinesterase, which is located on the outer layer of the erythrocyte membrane, in the same order as that observed in bacteria. At high concentrations of PP, MP, DP and HPD, hemolysis (the lysis of erythrocytes with liberation of hemoglobin) was also induced. We found that the degree of photoinactivation of membrane function was closely associated with porphyrin-induced morphological changes in bovine erythrocytes, forming a crenated form from the normal discoid, which is the index of the amount of porphyrins in the outer layer of the cytoplasmic membrane. Furthermore, the degree of morphological changes was related with the octanol/water partition coefficients of porphyrins. These results strongly supported that porphyrins located in the outer layer of cytoplasmic membrane inactivated the cell membrane function by photo-irradiation, and the strength of photoinactivation by porphyrins depended on their affinity to the cell membrane.


Subject(s)
Erythrocytes/drug effects , Membrane Potentials/drug effects , Photosensitizing Agents/pharmacology , Porphyrins/pharmacology , Staphylococcus aureus/drug effects , Animals , Anti-Bacterial Agents/pharmacology , Cattle , Erythrocyte Membrane/drug effects , Erythrocytes/cytology , Humans , Microbial Viability/drug effects , Staphylococcal Infections/drug therapy , Staphylococcus aureus/cytology , Structure-Activity Relationship
5.
Science ; 347(6228): 1362-7, 2015 Mar 20.
Article in English | MEDLINE | ID: mdl-25792327

ABSTRACT

Neuronal excitation is regulated by energy metabolism, and drug-resistant epilepsy can be suppressed by special diets. Here, we report that seizures and epileptiform activity are reduced by inhibition of the metabolic pathway via lactate dehydrogenase (LDH), a component of the astrocyte-neuron lactate shuttle. Inhibition of the enzyme LDH hyperpolarized neurons, which was reversed by the downstream metabolite pyruvate. LDH inhibition also suppressed seizures in vivo in a mouse model of epilepsy. We further found that stiripentol, a clinically used antiepileptic drug, is an LDH inhibitor. By modifying its chemical structure, we identified a previously unknown LDH inhibitor, which potently suppressed seizures in vivo. We conclude that LDH inhibitors are a promising new group of antiepileptic drugs.


Subject(s)
Anticonvulsants/pharmacology , Dioxolanes/pharmacology , Enzyme Inhibitors/pharmacology , L-Lactate Dehydrogenase/antagonists & inhibitors , Safrole/pharmacology , Seizures/drug therapy , Animals , Anticonvulsants/chemistry , Anticonvulsants/therapeutic use , Dioxolanes/chemistry , Dioxolanes/therapeutic use , Disease Models, Animal , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/therapeutic use , Membrane Potentials/drug effects , Mice , Mice, Inbred ICR , Neurons/enzymology , Neurons/physiology , Patch-Clamp Techniques , Safrole/chemistry , Safrole/therapeutic use , Subthalamic Nucleus/enzymology
6.
Nat Chem Biol ; 11(2): 127-33, 2015 Feb.
Article in English | MEDLINE | ID: mdl-25485686

ABSTRACT

To obtain therapeutically effective new antibiotics, we first searched for bacterial culture supernatants with antimicrobial activity in vitro and then performed a secondary screening using the silkworm infection model. Through further purification of the in vivo activity, we obtained a compound with a previously uncharacterized structure and named it 'lysocin E'. Lysocin E interacted with menaquinone in the bacterial membrane to achieve its potent bactericidal activity, a mode of action distinct from that of any other known antibiotic, indicating that lysocin E comprises a new class of antibiotic. This is to our knowledge the first report of a direct interaction between a small chemical compound and menaquinone that leads to bacterial killing. Furthermore, lysocin E decreased the mortality of infected mice. To our knowledge, lysocin E is the first compound identified and purified by quantitative measurement of therapeutic effects in an invertebrate infection model that exhibits robust in vivo effects in mammals.


Subject(s)
Anti-Bacterial Agents/pharmacology , Cell Membrane/drug effects , Drug Discovery/methods , Gram-Positive Bacteria/drug effects , Peptides, Cyclic/pharmacology , Vitamin K 2/antagonists & inhibitors , Animals , Anti-Bacterial Agents/isolation & purification , Anti-Bacterial Agents/therapeutic use , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Bacteriolysis/drug effects , Bombyx/microbiology , Cell Membrane/metabolism , Disease Models, Animal , Gram-Positive Bacteria/genetics , Gram-Positive Bacteria/metabolism , Lysobacter/metabolism , Membrane Potentials/drug effects , Mice , Mice, Inbred ICR , Microbial Sensitivity Tests , Molecular Structure , Peptides, Cyclic/isolation & purification , Peptides, Cyclic/therapeutic use , Staphylococcal Infections/drug therapy , Staphylococcus aureus/drug effects , Staphylococcus aureus/genetics , Staphylococcus aureus/metabolism , Vitamin K 2/metabolism
7.
Bioorg Med Chem ; 22(8): 2529-34, 2014 Apr 15.
Article in English | MEDLINE | ID: mdl-24650702

ABSTRACT

Non-steroidal anti-inflammatory drugs (NSAIDs) achieve their anti-inflammatory effect by inhibiting cyclooxygenase activity. We previously suggested that in addition to cyclooxygenase-inhibition at the gastric mucosa, NSAID-induced gastric mucosal cell death is required for the formation of NSAID-induced gastric lesions in vivo. We showed that celecoxib exhibited the most potent membrane permeabilizing activity among the NSAIDs tested. In contrast, we have found that the NSAID rofecoxib has very weak membrane permeabilizing activity. To understand the membrane permeabilizing activity of coxibs in terms of their structure-activity relationship, we separated the structures of celecoxib and rofecoxib into three parts, synthesized hybrid compounds by substitution of each of the parts, and examined the membrane permeabilizing activities of these hybrids. The results suggest that the sulfonamidophenyl subgroup of celecoxib or the methanesulfonylphenyl subgroup of rofecoxib is important for their potent or weak membrane permeabilizing activity, respectively. These findings provide important information for design and synthesis of new coxibs with lower membrane permeabilizing activity.


Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/chemistry , Cyclooxygenase Inhibitors/chemistry , Lactones/chemistry , Lipid Bilayers/chemistry , Pyrazoles/chemistry , Sulfonamides/chemistry , Sulfones/chemistry , Anti-Inflammatory Agents, Non-Steroidal/chemical synthesis , Anti-Inflammatory Agents, Non-Steroidal/metabolism , Celecoxib , Cyclooxygenase 1/chemistry , Cyclooxygenase 1/metabolism , Cyclooxygenase 2/chemistry , Cyclooxygenase 2/metabolism , Cyclooxygenase Inhibitors/chemical synthesis , Cyclooxygenase Inhibitors/metabolism , Lactones/metabolism , Lipid Bilayers/metabolism , Liposomes/chemistry , Liposomes/metabolism , Protein Binding , Pyrazoles/metabolism , Spectrometry, Fluorescence , Structure-Activity Relationship , Sulfonamides/metabolism , Sulfones/metabolism
8.
Chem Commun (Camb) ; 50(41): 5444-6, 2014 May 28.
Article in English | MEDLINE | ID: mdl-24575430

ABSTRACT

Cyclodextrin derivatives are synthesized as membrane-disrupting agents via a microwave-assisted Huisgen reaction. Their ability to permeabilize bacterial membranes depends on the amino substituents and an appropriate balance of hydrophobicity and hydrophilicity, thus enabling the preparation of derivatives with selective toxicity against bacteria.


Subject(s)
Cell Membrane/drug effects , Click Chemistry , Cyclodextrins/chemical synthesis , Cyclodextrins/pharmacology , Escherichia coli/drug effects , Staphylococcus aureus/drug effects , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Cyclodextrins/chemistry , Escherichia coli/cytology , Staphylococcus aureus/cytology
9.
Biol Pharm Bull ; 36(7): 1197-203, 2013.
Article in English | MEDLINE | ID: mdl-23811569

ABSTRACT

Our recent work has shown that cannabidiol (CBD) exhibits the most potent direct inhibition of human cytochrome P450 1A1 (CYP1A1) among the CYP enzymes examined. However, the mechanism underlying this CBD inhibition remains to be clarified. Thus, to elucidate the structural requirements for the potent inhibition by CBD, the effects of CBD and its structurally related compounds on CYP1A1 activity were investigated with recombinant human CYP1A1. Olivetol, which corresponds to the pentylresorcinol moiety of CBD, inhibited the 7-ethoxyresorufin O-deethylase activity of CYP1A1; its inhibitory effect (IC50=13.8 µM) was less potent than that of CBD (IC50=0.355 µM). In contrast, d-limonene, which corresponds to the terpene moiety of CBD, only slightly inhibited CYP1A1 activity. CBD-2'-monomethyl ether (CBDM) and CBD-2',6'-dimethyl ether inhibited CYP1A1 activity with IC50 values of 4.07 and 23.0 µM, respectively, indicating that their inhibitory effects attenuated depending on the level of methylation on the free phenolic hydroxyl groups in the pentylresorcinol moiety of CBD. Cannabidivarin inhibited CYP1A1 activity, although its inhibitory potency (IC50=1.85 µM) was lower than that of CBD. The inhibitory effects of Δ(9)-tetrahydrocannabinol and cannabielsoin (IC50s ≈10 µM), which contain a free phenolic hydroxyl group and are structurally constrained, were less potent than that of CBDM, which contains a free phenolic hydroxyl group and is rotatable between pentylresorcinol and terpene moieties. These results suggest that the pentylresorcinol structure in CBD may have structurally important roles in direct CYP1A1 inhibition, although the whole structure of CBD is required for overall inhibition.


Subject(s)
Cannabidiol/chemistry , Cannabidiol/pharmacology , Cytochrome P-450 CYP1A1/antagonists & inhibitors , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Resorcinols/chemistry , Cytochrome P-450 CYP1A1/chemistry , Humans , Models, Molecular , Molecular Structure , Protein Conformation , Structure-Activity Relationship
10.
J Microbiol Methods ; 91(3): 497-500, 2012 Dec.
Article in English | MEDLINE | ID: mdl-23046554

ABSTRACT

We introduced a new assay system, combining tyrocidine A and a K(+)-selective electrode, to evaluate the bacterial outer membrane-permeabilizing ability of drugs. Tyrocidine A, in the presence of an outer membrane permeabilizer, increased the permeability to K(+) of the cytoplasmic membrane of Escherichia coli, because this antibiotic could markedly increase the permeability of phospholipid layers constituting the cytoplasmic membrane, while it acted weakly on the outer membrane. Hence, the novel function of agents increasing the permeability of the outer membrane could be examined directly by monitoring the tyrocidine A-induced leakage of K(+) from the bacterial cytoplasm using a K(+)-selective electrode. We found that antiprotozoal diamidines, such as diminazene, pentamidine, and 4',6-diamidino-2-phenylindole (DAPI), can increase the permeability of the bacterial outer membrane and appropriate lipophilicity is important for diamidines to permeabilize the outer membrane.


Subject(s)
Antiprotozoal Agents/pharmacology , Cell Membrane Permeability/drug effects , Cell Membrane/metabolism , Escherichia coli/metabolism , Pentamidine/metabolism , Potentiometry/methods , Anti-Bacterial Agents/pharmacology , Biological Transport/drug effects , Cell Membrane/chemistry , Cell Membrane/drug effects , Escherichia coli/chemistry , Escherichia coli/drug effects , Hydrophobic and Hydrophilic Interactions , Potassium/metabolism , Tyrocidine/pharmacology
11.
Photochem Photobiol ; 88(2): 423-31, 2012.
Article in English | MEDLINE | ID: mdl-22211880

ABSTRACT

We analyzed the photoinactivation of the membrane functions of bacteria and erythrocytes induced by xanthene dyes. The dyes tested were rose bengal, phloxine B, erythrosine B and eosin B. These dyes induced the leakage of K(+) from Staphylococcus aureus cells within minutes of photoirradiation, in the order of rose bengal > phloxine B > erythrosine B > eosin B. The ability of dyes to inhibit respiration was weak, except for rose bengal, and the dyes dissipated the membrane potential in similar time traces with changes in K(+) permeability. The xanthene dyes also induced the leakage of K(+) from bovine erythrocytes upon photoirradiation in the same order as that observed with bacteria. Furthermore, we found that the ability to cause the leakage of K(+) from erythrocytes was associated with dye-induced morphological changes, forming a crenated form from the normal discoid. These results are discussed in connection with the ability of xanthene dyes to generate singlet oxygen and bind to bacterial cells, and further compared with the actions of cationic porphyrins, which induced photoinactivation of bacteria through respiratory inhibition.


Subject(s)
Cell Membrane Permeability/drug effects , Cell Membrane/drug effects , Coloring Agents/metabolism , Staphylococcus aureus/drug effects , Xanthenes/metabolism , Animals , Cattle , Cell Membrane/radiation effects , Cell Membrane Permeability/radiation effects , Coloring Agents/pharmacology , Erythrocytes/cytology , Erythrocytes/drug effects , Erythrocytes/radiation effects , Membrane Potentials/drug effects , Membrane Potentials/radiation effects , Microbial Viability/drug effects , Microbial Viability/radiation effects , Microscopy , Photochemical Processes , Potassium/metabolism , Singlet Oxygen/metabolism , Staphylococcus aureus/physiology , Staphylococcus aureus/radiation effects , Ultraviolet Rays , Xanthenes/pharmacology
13.
Bioorg Med Chem ; 19(11): 3299-311, 2011 Jun 01.
Article in English | MEDLINE | ID: mdl-21570308

ABSTRACT

Non-steroidal anti-inflammatory drugs (NSAIDs) achieve their anti-inflammatory actions through an inhibitory effect on cyclooxygenase (COX). Two COX subtypes, COX-1 and COX-2, are responsible for the majority of COX activity at the gastrointestinal mucosa and in tissues with inflammation, respectively. We previously suggested that both gastric mucosal cell death due to the membrane permeabilization activity of NSAIDs and COX-inhibition at the gastric mucosa are involved in NSAID-induced gastric lesions. We have also reported that loxoprofen has the lowest membrane permeabilization activity among the NSAIDs we tested. In this study, we synthesized a series of loxoprofen derivatives and examined their membrane permeabilization activities and inhibitory effects on COX-1 and COX-2. Among these derivatives, 2-{4'-hydroxy-5-[(2-oxocyclopentyl)methyl]biphenyl-2-yl}propanoate 31 has a specificity for COX-2 over COX-1. Compared to loxoprofen, oral administration of 31 to rats produced fewer gastric lesions but showed an equivalent anti-inflammatory effect. These results suggest that 31 is likely to be a therapeutically beneficial and safer NSAID.


Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/chemical synthesis , Cyclooxygenase 2 Inhibitors/chemical synthesis , Phenylpropionates/chemistry , Phenylpropionates/chemical synthesis , Animals , Anti-Inflammatory Agents, Non-Steroidal/chemistry , Anti-Inflammatory Agents, Non-Steroidal/pharmacology , Binding Sites , Cell Membrane Permeability/drug effects , Computer Simulation , Cyclooxygenase 1/chemistry , Cyclooxygenase 1/metabolism , Cyclooxygenase 2/chemistry , Cyclooxygenase 2/metabolism , Cyclooxygenase 2 Inhibitors/chemistry , Cyclooxygenase 2 Inhibitors/pharmacology , Gastric Mucosa/drug effects , Phenylpropionates/pharmacology , Rats
14.
Photochem Photobiol Sci ; 10(7): 1181-8, 2011 Jul.
Article in English | MEDLINE | ID: mdl-21472187

ABSTRACT

We analysed the porphyrin-induced photodynamic inactivation of the membrane functions of bacteria through the in situ monitoring of changes in respiration rates, membrane permeability and membrane potential, using electrochemical sensors, such as oxygen, K(+) and tetraphenylphosphonium (TPP(+)) electrodes. We used two cationic porphyrins, tetrakis(4-N,N,N-trimethylammoniumphenyl)porphyrin (TTMAPP) and tetrakis(4-N-methylpyridinium)porphyrin (TMPyP), along with an anionic porphyrin, tetrakis(4-sulfonatophenyl)porphyrin (TSPP), as a negative control. TTMAPP and TMPyP inhibited the respiration of bacteria within minutes of photo-irradiation at a concentration of 1 µM, where the survival of bacteria decreased, while TSPP did not affect the bacteria. The respiration of Staphylococcus aureus cells (Gram-positive bacterium) was more strongly inhibited than that of Escherichia coli cells (Gram-negative bacterium). Increasing the concentration of porphyrin strengthened the respiratory inhibition. Although TTMAPP increased the permeability to K(+) of the cytoplasmic membranes of bacteria, the change was relatively slow. Cationic porphyrins, showing the strong respiratory inhibition of S. aureus cells, induced the dissipation of membrane potential within minutes of photo-irradiation, in accord with the time traces of respiratory inhibition. Such a correlation strongly supported that porphyrin-induced photo-inactivation of bacteria involved rapid damage to the energy-producing system of bacteria induced by inhibition of the respiratory chain, leading to a dissipation of membrane potential. These results are discussed in connection with the ability of porphyrins to generate singlet oxygen and bind to the bacterial cell envelope.


Subject(s)
Porphyrins/chemistry , Staphylococcus aureus/drug effects , Cations/chemistry , Cell Membrane Permeability/physiology , Electrochemical Techniques , Electrodes , Escherichia coli/drug effects , Escherichia coli/radiation effects , Light , Membrane Potentials/physiology , Onium Compounds/metabolism , Organophosphorus Compounds/metabolism , Oxygen/metabolism , Potassium/metabolism , Singlet Oxygen/metabolism , Staphylococcus aureus/radiation effects
15.
Biochim Biophys Acta ; 1808(1): 490-7, 2011 Jan.
Article in English | MEDLINE | ID: mdl-20955685

ABSTRACT

The membrane-permeabilizing activities of mastoparans and related histamine-releasing agents were compared through measurements of K(+) efflux from bacteria, erythrocytes, and mast cells. Changes in bacterial cell viability, hemolysis, and histamine release, as well as in the shape of erythrocytes were also investigated. The compounds tested were mastoparans (HR1, a mastoparan from Polistes jadwagae, and a mastoparan from Vespula lewisii), granuliberin R, mast cell-degranulating peptide, and compound 48/80, as well as antimicrobial peptides, such as magainin I, magainin II, gramicidin S, and melittin. We used a K(+)-selective electrode to determine changes in the permeability to K(+) of the cytoplasmic membranes of cells. Consistent with the surface of mast cells becoming negatively charged during histamine release, due to the translocation of phosphatidylserine to the outer leaflet of the cytoplasmic membrane, histamine-releasing agents induced K(+) efflux from mast cells, dependent on their ability to increase the permeability of bacterial cytoplasmic membranes rich in negatively charged phospholipids. The present results demonstrated that amphiphilic peptides, possessing both histamine-releasing and antimicrobial capabilities, induced the permeabilization of the cytoplasmic membranes of not only bacteria but mast cells. Mastoparans increased the permeability of membranes in human erythrocytes at higher concentrations, and changed the normal discoid shape to a crenated form. The structural requirement for making the crenated form was determined using compound 48/80 and its constituents (monomer, dimer, and trimer), changing systematically the number of cationic charges of the molecules.


Subject(s)
Bacteria/metabolism , Erythrocytes/metabolism , Histamine/chemistry , Mast Cells/metabolism , Peptides/chemistry , Wasp Venoms/chemistry , Animals , Anti-Infective Agents/pharmacology , Cell Survival , Cytoplasm/metabolism , Erythrocyte Membrane/metabolism , Humans , Intercellular Signaling Peptides and Proteins , Mast Cells/cytology , Potassium/chemistry , Rats , Rats, Wistar , Staphylococcus aureus/metabolism
16.
Chem Biol Interact ; 189(3): 146-52, 2011 Feb 01.
Article in English | MEDLINE | ID: mdl-21184751

ABSTRACT

Toxic and pharmacokinetic profiles of drug candidates are evaluated in vivo often using monkeys as experimental animals, and the data obtained are extrapolated to humans. Well understanding physiological properties, including drug-metabolizing enzymes, of monkeys should increase the accuracy of the extrapolation. The present study was performed to compare regio- and stereoselectivity in the oxidation of propranolol (PL), a chiral substrate, by cytochrome P450 2D (CYP2D) enzymes among humans, cynomolgus monkeys and marmosets. Complimentary DNAs encoding human CYP2D6, cynomolgus monkey CYP2D17 and marmoset CYP2D19 were cloned, and their proteins expressed in a yeast cell expression system. The regio- and stereoselective oxidation of PL enantiomers by yeast cell microsomal fractions were compared. In terms of efficiency of expression in the system, the holo-proteins ranked CYP2D6=CYP2D17>>CYP2D19. This may be caused by the bulky side chain of the amino acid residue at position 119 (leucine for CYP2D19 vs. valine for CYP2D6 and CYP2D17), which can disturb the incorporation of the heme moiety into the active-site cavity. PL enantiomers were oxidized by all of the enzymes mainly into 4-hydroxyproranolol (4-OH-PL), followed by 5-OH-PL and N-desisopropylpropranolol (NDP). In the kinetic analysis, apparent K(m) values were commonly in the µM range and substrate enantioselectivity of R-PL

Subject(s)
Aryl Hydrocarbon Hydroxylases/metabolism , Cytochrome P-450 CYP2D6/metabolism , Propranolol/chemistry , Propranolol/metabolism , Animals , Callithrix , Catalytic Domain , Humans , Kinetics , Leucine/chemistry , Leucine/metabolism , Macaca fascicularis , Microsomes, Liver/enzymology , Oxidation-Reduction , Propranolol/analogs & derivatives , Stereoisomerism , Substrate Specificity , Valine/chemistry , Valine/metabolism
17.
Anal Sci ; 26(10): 1019-21, 2010.
Article in English | MEDLINE | ID: mdl-20953042

ABSTRACT

The photodynamic inactivation of the membrane functions of bacteria was analyzed in situ, using K(+) and tetraphenylphosphonium (TPP(+)) electrodes, as well as an oxygen electrode. Tetrakis(4-N-trimethylaminophenyl)porphine (TTMAPP) and rose bengal were used, since both dyes act strongly on bacteria, such as Staphylococcus aureus. After a short time lag, they inhibited the respiration of bacteria and increased the permeability of the cytoplasmic membrane to K(+), while dissipating the membrane potential. This combination of sensors is quite useful for visualizing the actions of photosensitizers on the bacterial membrane. TTMAPP and rose bengal impaired the bacterial function by reducing the membrane potential within minutes of photo-irradiation.


Subject(s)
Cell Membrane/drug effects , Photosensitizing Agents/pharmacology , Porphyrins/pharmacology , Rose Bengal/pharmacology , Staphylococcus aureus/drug effects , Anti-Bacterial Agents/pharmacology , Cell Membrane/physiology , Cell Membrane Permeability/drug effects , Electrochemical Techniques , Electrodes , Light , Membrane Potentials/drug effects , Onium Compounds/metabolism , Organophosphorus Compounds/metabolism , Photochemotherapy , Porphyrins/metabolism , Potassium/metabolism , Staphylococcus aureus/physiology
18.
J Med Chem ; 53(21): 7879-82, 2010 Nov 11.
Article in English | MEDLINE | ID: mdl-20954731

ABSTRACT

We previously proposed that membrane permeabilization activity of NSAIDs is involved in NSAID-induced gastric lesions. We here synthesized derivatives of loxoprofen that have lower membrane permeabilization activity than other NSAIDs. Compared to loxoprofen, the derivatives 10a and 10b have lower membrane permeabilization activity and their oral administration produced fewer gastric lesions but showed an equivalent anti-inflammatory effect. These results suggest that 10a and 10b are likely to be therapeutically beneficial as safer NSAIDs.


Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/chemical synthesis , Gastric Mucosa/drug effects , Phenylpropionates/chemical synthesis , Prodrugs/chemical synthesis , Administration, Oral , Animals , Anti-Inflammatory Agents, Non-Steroidal/adverse effects , Anti-Inflammatory Agents, Non-Steroidal/chemistry , Cell Membrane Permeability , Cyclooxygenase Inhibitors/adverse effects , Cyclooxygenase Inhibitors/chemical synthesis , Cyclooxygenase Inhibitors/pharmacology , Gastric Mucosa/pathology , Gastrointestinal Hemorrhage/chemically induced , Gastrointestinal Hemorrhage/pathology , Humans , Phenylpropionates/adverse effects , Phenylpropionates/pharmacology , Prodrugs/adverse effects , Prodrugs/pharmacology , Rats , Structure-Activity Relationship
19.
Anal Sci ; 26(8): 903-6, 2010.
Article in English | MEDLINE | ID: mdl-20702946

ABSTRACT

The ability to scavenge superoxide anion radicals ((*)O(2)(-)) was determined using an oxygen electrode. The method is based on the determination of (*)O(2)(-) generated by the reaction of nitrilotriacetatoiron(III) with hydrogen peroxide and a decrease in the concentration of (*)O(2)(-) by a scavenging reaction, converting into a change in the generation of oxygen molecules through an electron-transfer reaction from (*)O(2)(-) to nitrilotriacetatoiron(III). Oxygen generation, which enhanced proportionally with an increase in the concentration of hydrogen peroxide, was inhibited depending on the concentration of superoxide dismutase. Hence, we applied the present reaction system to evaluate the (*)O(2)(-)-scavenging abilities of an antioxidant, measuring the degree of inhibition of oxygen generation using an oxygen electrode. A good correlation was obtained between the present method and conventional colorimetry, monitoring the formation of blueformazan by the reaction of nitro blue tetrazolium with (*)O(2)(-), to estimate the (*)O(2)(-)-scavenging activities of antioxidants.


Subject(s)
Electrochemistry/methods , Electrodes , Free Radical Scavengers/analysis , Oxygen/metabolism , Superoxides/metabolism , Electrochemistry/instrumentation , Hydrogen Peroxide , Superoxide Dismutase/metabolism
20.
Bioorg Med Chem Lett ; 20(5): 1771-5, 2010 Mar 01.
Article in English | MEDLINE | ID: mdl-20138759

ABSTRACT

A series of cationic cyclic heptapeptides based on polymyxin B have been synthesized for use as permeabilizers of the outer membrane of Gram-negative bacteria. Only analogs with the Dab(2)-d-Phe(3)-Leu(4)-Xxx(5) sequence (Xxx = Dab or Orn) showed a synergistic bactericidal effect when combined with conventional antibiotics, indicating that the Dab(2) residue plays a critical role in permeation of the outer membrane of Gram-negative bacteria.


Subject(s)
Anti-Bacterial Agents/chemistry , Cell Membrane Permeability/drug effects , Escherichia coli/drug effects , Peptides, Cyclic/chemistry , Polymyxin B/analogs & derivatives , Amino Acid Sequence , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/pharmacology , Circular Dichroism , Microbial Sensitivity Tests , Peptides, Cyclic/chemical synthesis , Peptides, Cyclic/pharmacology , Polymyxin B/chemistry , Polymyxin B/pharmacology , Structure-Activity Relationship
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