Effect of a trifluoromethyl ketone on the motility of proton pump-deleted mutant of Escherichia coli strain and its wild-type

We have recently found that 1-(2-benzoxazolyl)-3,3,3-trifluoro-2-propanone [TF18] exhibited the most potent antibacterial activity among 30 trifluoromethyl ketones against various prokaryotes, such as Escherichia coli (E. coli). In the present study, the inhibition of E. coli motility by TF18 was investigated. TF18 showed the lowest minimum inhibitory concentration (MIC) and highest inhibitory effect on the motility of E. coli strains. The wild-type E. coli was more sensitive to inhibition of motility than its proton pump-deleted mutant strain at subinhibitory concentrations. These data suggest that one of the targets of the antibacterial effect of the trifluoromethyl ketone is the proton pump system.     

Inhibitory action of a new proton pump inhibitor, trifluoromethyl ketone derivative, against the motility of clarithromycin-susceptible and-resistant Helicobacter pylori

We previously reported that a trifluoromethyl ketone derivative, 1-(2-benzoxazolyl)-3,3,3-trifluoro-2-propanone (TF18), exhibited the potent antibacterial activity against Helicobacter pylori, but had no urease activity. In order to clarify the mechanism of anti-H. pylori action of TF18, we evaluated the growth and motility of TF18 on clarithromycin-susceptible H. pylori (CSHP) and -resistant H. pylori (CRHP). An effective proton pump inhibitor (TF18) had remarkable dose-dependent antibacterial activity and was able to inhibit the flagellar motor of both CSHP and CRHP isolates. The antimotility effect of TF18 was more pronounced at subinhibitory concentration in CRHP than in CSHP. The swimming (the forward motion) was more sensitive to the inhibition than the tumbling. Based on the results, it is supposed that TF18 works as an uncoupler similar to the ‘clutch’ in a biological motor, in which counterclockwise rotation is more sensitive to the effect of TF18 than the clockwise rotation.     

Effects of trifluoromethyl ketones on the motility of Proteus vulgaris

In the present study, we showed the inhibition of motility by trifluoromethyl ketone (TF) derivatives (1-8) in Proteus vulgaris (P. vulgaris) cultures. Among them, 1-(2-benzoxazoyl)-3,3,3-trifluoro-2-propanone (1) showed a much stronger inhibitory effect on the motility of P. vulgaris than other TF compounds at 10% MIC. Our results suggest the possibility of an inhibitory action of TF compounds on the proton motive forces by affecting the action of biological motor and proton efflux in the membranes, resulting in a reduction of the ratio of running and the increased number of tumbling and non-motile cells.     

Synergistic interaction between proton pump inhibitors and resistance modifiers: promoting effects of antibiotics and plasmid curing

A proton pump-deleted mutant E. coli, AG100 A, had greater sensitivity to ampicillin, tetracycline and erythromycin than the wild-type parent E. coli AG100 containing the proton pump. This antibiotic sensitivity was further increased by resistance modifiers such as the Ca2+ channel blocker (+/-) verapamil (VP) and the calmodulin antagonist promethazine (PMZ). Whereas the newly-synthesized trifluoromethyl-ketone (TF) enhanced the activity of these antibiotics against the wild-type strain, it did not enhance the activity of ampicillin against the proton pump-deleted mutant. These results suggested that TF14 had an inhibitory effect on the proton pump. Elimination of plasmids from another strain of E. coli, K12, was promoted by PMZ and 9-amino-acridine (9-AA), but not by TF14 alone. However, combinations of TF14 with either PMZ or 9-AA enhanced the plasmid elimination capacity of the latter compounds. The combination of TF14, PMZ and VP proved that the Ca2+ channel blocker was not effective by itself These results collectively suggest that TF14 inhibited the proton pump of E. coli and that it was this pump which, when inhibited by TF14, allowed more PMZ to reach its plasmid elimination target.     

Trifluoromethyl ketones show culture age-dependent inhibitory effects on low K(+)-induced apoptosis in cerebellar granule neurons

We previously reported that two trifluoromethyl ketones, 3,3,3-trifluoro-1-phenyl-1,2-propanedione (TF1) and 1,1,1-trifluoro-3-phenyl-2-propanone (TF2), have neuroprotective effects against low K(+)-induced apoptosis in cerebellar granule neurons (CGNs) exposed at 12-13 days in vitro (DIV). On the other hand, these compounds showed weak neuroprotective potency against 7 DIV CGNs. It is reported that actinomycin D (Act-D), cycloheximide (CHX), and caspase-3 inhibitors prevent the apoptosis of CGNs induced by K+ deprivation. However, these experiments are generally performed using 7 DIV CGNs. We investigated and compared the antiapoptotic efficacy of these drugs and newly-discovered TF1 and TF2 to protect DIV 7 and 12-13 CGNs from death induced by K+ deprivation. Apoptosis of CGNs induced by K+ withdrawal at 13 DIV was potently inhibited by Act-D and CHX similar to those at 7 DIV. Caspase-3 inhibitors moderately suppressed cell death during low K(+)-induced apoptosis both exposed 7 and 13 DIV. Serine protease inhibitor N-tosyl-L-phenylalanyl chloromethylketone (TPCK) had no effect on K(+)-deprivation-induced apoptosis of CGNs at both 7 and 12 DIV. This study showed that there are different pathways of apoptosis in CGNs depending on the culture age.     

Expedient synthesis of [18F]‐labeled α‐trifluoromethyl ketones

Several [¹⁸F]‐labeled α‐trifluoromethyl ketones have been synthesized. Reactions of 2,2‐difluoro‐1‐aryl‐1‐trimethylsiloxyethenes ( 1a–d ) with [¹⁸F]‐F₂ at low temperature produced [¹⁸F]‐labeled α‐trifluoromethyl ketones ( 2a–d ). Radio‐labeled products were isolated by purification with column chromatography in 22–28% yields, decay corrected (d.c.) in three runs per compound. Radiochemical purity was >99% with specific activities 15–20 GBq/mmol at the end of synthesis (EOS). The synthesis time was 35–40 min from the end of bombardment (EOB). This one‐step simple method is highly useful for the radiochemical synthesis of potential biologically active [¹⁸F]‐labeled α‐trifluoromethyl ketones for PET imaging. Copyright © 2003 John Wiley & Sons, Ltd.     

Heterocyclic derivatives of 3-substituted-1,1,1-trifluoro-2-propanones as inhibitors of esterolytic enzymes

A series of (alkylthio)trifluoropropanones containing a heterocyclic moiety was synthesized. The compounds were tested for in vitro inhibition of four hydrolytic enzymes including insect juvenile hormone esterase (JHE), eel acetylcholinesterase (AChE), yeast lipase (LP), and bovine alpha-chymotrypsin. The I50 values ranged from 10(-3) to 10(-7) M. 3-(2-Pyridylthio)-1,1,1-trifluoro-2-propanone was found to be the most potent inhibitor as compared to the other tested heterocyclic analogues with an I50 value of 98 nM against JHE from the fifth-instar larvae of Trichoplusia ni. Results from X-ray crystallography showed that the compound exists in a tetrahedral gem-diol form stabilized by an intramolecular hydrogen bond in the solid state. X-ray crystallography of a less potent inhibitor, 3-(4-pyridylthio)-1,1,1-trifluoro-2- propanone, showed that it also exists in the hydrated form, but it lacks an intramolecular hydrogen bond. These results provide indirect support that trifluoromethyl ketones are transition-state mimic inhibitors of esterases, and the bearing of the results on the transition-state mimic theory is discussed. The I50 values against AChE were in the micromolar range. Compounds containing a imidazolyl, triazolyl, and pyrimidyl moiety showed the highest inhibition of this enzyme. Differential selectivity of inhibition was associated with the bond distances between the nitrogen and the carbonyl group as in the natural substrate, when measured in the molecules in their minimal energy conformations. Inhibition of LP was moderate to weak, when compared to JHE and AChE. None of the tested compounds showed significant inhibition of alpha-chymotrypsin.(ABSTRACT TRUNCATED AT 250 WORDS)     

Synthesis of (E)-5-(3,3,3-trifluoro-1-propenyl)-2'-deoxyuridine and related analogues: potent and unusually selective antiviral activity of (E)-5-(3,3,3-trifluoro-1-propenyl)-2'-deoxyuridine against herpes simplex virus type 1

Syntheses of (E)-5-(3,3,3-trifluoro-1-propenyl)-2'-deoxyuridine (TFPe-dUrd) (1), 5-(3,3,3-trifluoro-1-propyl)-2'-deoxyuridine (11), 5-(3,3,3-trifluoro-1-methoxy-1-propyl)-2'-deoxyuridine (8), and 5-(3,3,3-trifluoro-1-hydroxy-1-propyl)-2'-deoxyuridine (10) from 5-chloromercuri-2'-deoxyuridine are described. The antiviral activity of TFPe-dUrd was determined in cell culture against herpes simplex virus type 1 (HSV-1), herpes simplex virus type 2 (HSV-2), and vaccinia virus and compared concurrently with 5-(1-propenyl)-2'-deoxyuridine, 5-(2-bromovinyl)-2'-deoxyuridine, 5-iodo-2'-deoxyuridine, and 5-(trifluoromethyl)-2'-deoxyuridine. TFPe-dUrd demonstrated a potent and unusually selective activity against HSV-1, with a 2-log reduction in virus yield at 0.03 micrograms/mL (0.09 microM); L-1210 cell growth was inhibited by 50% only at 290 micrograms/mL. Isopycnic centrifugation of 32P-labeled DNA indicated that if 0.5 or 2 microM TFPe-dUrd was present for 0-6 h postinfection, viral DNA synthesis was reduced by ca. 50 and 85%, respectively; concomitantly, a new DNA band appeared at lower density than normal cellular or viral DNA.     

Synthesis, structure investigations, and antimicrobial activity of selected s-trans-6-aryl-4-isopropyl-2-[2-[(E)-1-phenylalkylidene]-(E)-hydrazino]-1,4-dihydropyrimidine hydrochlorides.

A series of 6-aryl-4-isopropyl-2-[2-(1-phenylalkylidene)hydrazino]-1,4-dihydropyrimidine hydrochlorides was prepared and tested for antibacterial and antifungal effects. The title compounds were synthesized by cyclocondensation of N(2)-(1-phenylalkylideneamino)guanidines with 1-aryl-4-methyl-2-penten-1-ones. Structure analyses of the prepared compounds were accomplished by means of 1D and 2D NMR spectroscopy. The analyses showed that the ring closure reaction took place regioselectively in all cases and generated exclusively 2-(phenylalkylidenehydrazino)dihydropyrimidines. According to the NOE experiments, the applied N(2)-(1-phenylalkylideneamino)guanidines exist in [D(6)]DMSO solution as s-trans-(E)- and the title compounds as s-trans-(E,E)-isomers. The antimicrobial activity was evaluated against representative Gram-negative and Gram-positive bacteria, and against the pathogenic yeast Candida albicans. The tested title compounds showed weak antibacterial activity against Gram-positive bacteria, and one compound was active against Candida albicans.     

Synthesis and Antimicrobial Evaluation of Dibenzo[b,e]oxepin-11(6H)-one O-Benzoyloxime Derivatives

A series of dibenzo[b,e]ox(thi)epin-11(6H)-one O-benzoyloximes has been synthesized and structurally elucidated by means of IR, (1)H-NMR, (13)C-NMR, MS, and elemental analysis. The newly developed compounds were screened at concentrations of 200-25 μg/mL for their antibacterial activity against Gram+ve organisms such as Methicillin-Resistant Staphylococcus Aureus (MRSA), Gram-ve organisms such as Escherichia coli (E. coli), and at the same concentration range for their antifungal activity against fungal strain Aspergillus niger (A. niger) by the cup plate method. Ofloxacin and ketoconazole (10 μg/mL) were used as reference standards for antibacterial and antifungal activity, respectively. The dibenzo[b,e]oxepines 6a-c and 6e-h showed low antimicrobial activity (MIC 125-200 μg/mL) compared to the reference substances, whereas a major improvement (MIC 50-75 μg/mL) was achieved with the synthesis of the corresponding bromomethyl derivative 6d. Moreover, replacement of oxygen by its bioisosteric sulfur led to isomeric dibenzo[b,e]thi-epine derivatives 6g,h which significantly exhibited higher antimicrobial activity (MIC 25-50 μg/mL) against all tested culture strains used in the present study, demonstrating that a change of chemical class from dibenzo[b,e]oxepine to dibenzo[b,e]thiepine significantly improves the antimicrobial activity. Further variation, such as the oxidation of the thiepine sulfur to the corresponding isomeric dibenzo[b,e]thiepine 5,5-dioxide derivative 9, comparatively failed to exhibit high activity (MIC 200 μg/mL) against S. aureus, E. coli or A. niger.     

国产头孢拉宗钠对临床分离致病菌的体内外抗菌作用研究

目的 研究国产注射用头孢拉宗钠(CFB)的体内外抗菌效果.方法 体外实验采用琼脂二倍稀释法计算细菌的最低抑菌浓度(MIC),体内实验用临床分离大肠埃希菌和金黄色葡萄球菌,小鼠腹腔注射最小致死量菌液造成全身感染,静脉注射不同剂量的受试药物,观察7d或14 d内小鼠的死亡情况,用NDST程序的Bliss法计算ED50.结果 CFB对G-菌中的大肠埃希菌、肺炎克雷伯菌抗菌作用良好,MIC50为0.25～0.5 μg·mL-1,对G+菌中的金黄色葡萄球菌、表皮葡萄球菌呈强抗菌作用,MIC50均为0.5 μg· mL-1,对不动杆菌和铜绿假单胞菌无抗菌活性,体内保护实验显示:国产CFB对大肠埃希菌、金黄色葡萄球菌的ED50为5.71、45.00 mg·kg-1.结论 国产注射用CFB对体外多数G+菌效果良好,对金黄色葡萄球菌有强抗菌作用,对G-菌大肠埃希菌、肺炎克雷伯菌有较强抗菌作用.对腹腔感染大肠埃希菌、金黄色葡萄球菌的小鼠也有显著抗菌效果.     

Synthesis and antibacterial activity of thiazolo-, oxazolo-, and imidazolo[3,2-a][1,8]naphthyridinecarboxylic acids

It is known that thiazolo[3,2-a][1,8]naphthyridine derivatives (3a) exhibit good antibacterial activity. Accordingly, several analogues of 3a, viz. oxazolo- and imidazolo[3,2-a][1,8]naphthyridine derivatives 3b and 3c, were synthesized and evaluated for antibacterial activity in vitro and for inhibitory activity against DNA gyrase of Escherichia coli K-12 C600. Compound 3a exhibited antibacterial activity comparable to that of ofloxacin and enoxacin against Gram-positive and Gram-negative bacteria and displayed antibacterial activity superior to that of 3b and 3c. The antibacterial activities of 3b and 3c decreased in that order. DNA gyrase inhibitory activities of 3a-c in E. coli K-12 C600 paralleled their in vitro antibacterial activity. It was found that enhancement of the DNA gyrase inhibitory activity of 3a was dependent on a certain feature of the sulfur atom of the thiazole ring.     

舒巴坦与第三代头孢菌素联合对第三代头孢菌素耐药菌的体外抗菌作用研究

目的：探讨舒巴坦与头孢他啶、头孢噻肟、头胞呋辛1：1联合对头孢他啶或头孢呋辛耐药的革兰阴性杆菌及金葡球菌的体外抗菌增效作用。方法：用平皿二倍稀释法测定了舒巴坦与头孢他啶、头孢噻肟、头孢呋辛1：1联合的体外抗菌作用。结果：舒巴坦可以增强头孢他啶、头孢噻肟及头孢呋辛对革兰阴性杆菌的体外抗菌活性。舒巴坦可以使头孢他啶对大肠杆菌、阴沟肠杆菌、弗劳地枸橼酸杆菌、不动杆菌属、铜绿假单胞菌的MIC90降低4倍;使头孢噻肟对大肠杆菌、阴沟肠杆菌、弗劳地枸橼酸杆菌、不动杆菌属的MIC90降低2－4倍,但对金葡球菌、肠球菌及嗜麦芽窄食单胞菌无明显的增效作用。38.4%的头孢他啶耐药的大肠杆菌、45.3%的对头孢他啶耐药的阴沟肠杆菌、66.6%的对头孢他啶耐药的弗劳地枸橼酸杆菌及60％的对头孢他啶耐药的不动杆菌属对舒巴坦与头孢他啶（1：1）的联合制剂敏感。结论：舒巴坦与头孢他啶联合对头孢他啶耐药菌有30％－40％的抗菌增效作用。     

Studies on condensed-heterocyclic azolium cephalosporins. IV. Synthesis and antibacterial activity of 7 beta-[2-(5-amino-1,2,4-thiadiazol-3-yl)-2(Z)- alkoxyiminoacetamido]-3-(condensed-heterocyclic azolium)methyl cephalosporins including SCE-2787.

The synthesis and in vitro antibacterial activity of 7 beta-[2-(5-amino-1,2,4-thiadiazol-3-yl)-2(Z)-alkoxyiminoacetami do] cephalosporins bearing various condensed-heterocyclic azolium groups at the 3 position in the cephalosporin nucleus are described. The thiadiazolyl cephalosporins showed good antibacterial activity against both Gram-positive and Gram-negative bacteria and the MICs of the thiadiazolyl cephalosporins against Pseudomonas aeruginosa was more potent than that of the corresponding 7 beta-[2-(2-aminothiazol-4-yl)-2(Z)-alkoxyiminoacetamido]-3- (condensed-heterocyclic azolium)methyl cephalosporins. Also, the thiadiazolyl cephalosporins bearing (imidazo[1,2-b]-pyridazinium-1-yl)methyl groups at the 3 position showed antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). Among the cephalosporins tested, 7 beta-[2-(5- amino-1,2,4-thiadiazol-3-yl)-2(Z)-methoxyiminoacetamido]-3-(imidaz o[1,2- b]pyridazinium-1-yl)methyl-3- cephem-4-carboxylate (4, SCE-2787) which exhibited the most potent antibacterial activity and the broadest antibacterial spectrum was selected as a parenteral cephalosporin candidate for further biological evaluation.     

Antimicrobial evaluation of cefoxitin: a new semisynthetic cephamycin. Comparative studies with cefazolin and cefalotin

Antimicrobial activity of 3-carbamoyloxymethyl-7-alpha-methoxy-7-[2-(2-thienyl)-acetamido]-3-cephem-4-carboxylic acid (cefoxitin), a new semisynthetic cephamycin antibiotic, was studied in comparison with that of cefazolin and cefalotin. Cefoxitin exhibited antibacterial activity against both gramnegative and gram-positive bacteria, and its action was bactericidal. Against gram-negative bacteria, cefoxitin was highly active as well as cefazolin, and more active than cefalotin. Especially, cefoxitin was highly active not only against strains of clinical isolates of indole-positive Proteus and S. marcescens but also against those of E. coli and P. mirabilis which were resistant to cefazolin and/or cefalotin, respectively. In addition, cefoxitin was effective against the strains resistant to beta-lactam antibiotics including cefazolin and cefalotin. Cefoxitin was hardly active against the strains of E. cloacae and P. aeruginosa, similar to cefazolin and cefalotin. Against gram-postive bacteria, cefoxitin was less active than cefazolin and cefalotin. In protection tests in mice, cefoxitin and cefazolin were more effective against infection with E. coli than cefalotin. Furthermore, cefoxitin was more active against infections with S. marcescens and P. morgani than the other antibiotics. Cefoxitin, like cefalotin, was less effective against infection with S. aureus than cefazolin. Cefoxitin was highly resistant to hydrolysis by beta-lactamases derived from the organisms insusceptible to the antibiotic. This fact revealed that the resistance of the organisms to cefoxitin may be in part due to factors other than beta-lactamase inactivation.     

Synthesis of new 2-substituted-[1,3,4]-oxadiazino-[6,5-b]-indoles with H1-antihistaminic,antimuscarinic and antimicrobial activity [corrected

New 2-substituted-[1,3,4]-oxadiazino-[5,6-b]-indoles have been prepared and tested for their antibacterial, antifungal, H1-antihistaminic and antimuscarinic activities. Among them, compounds 5b, 5d, 5k exhibited higher H1-antihistaminic activity than pheniramine maleate. Compounds 5c, 5d showed higher antibacterial activity than ampicillin against Staphylococcus aureus and E. coli, respectively.     

巴洛沙星对泌尿道病原菌的体外抗菌活性

目的:评价巴洛沙星对泌尿道病原菌的体外抗菌活性。方法:收集泌尿道感染病人尿液中所分离到的249株病原菌,其中革兰阳性菌90株(金黄色葡萄球菌30株、表皮葡萄球菌27株、粪肠球菌18株、B溶血性链球菌15株)、革兰阴性菌159株(大肠埃希菌84株、肺炎克雷伯菌20株、肠杆菌属25株、奇异变形杆菌15株、铜绿假单胞菌15株),采用琼脂二倍稀释法,测定巴洛沙星与左氧氟沙星对该249株泌尿道病原菌的最低抑菌浓度(MIC)。结果:巴洛沙星对革兰阳性菌的MIC_(90)(2～8 mg·L~(-1))是左氧氟沙星MIC_(90)(2～16 mg·L~(-1))的1/4～1/2或相等,对革兰阴性菌的MIC_(90)(4～32 mg·L~(-1))是左氧氟沙星MIC_(90)(2～16 mg·L~(-1))的2～4倍或相等。结论:巴洛沙星对革兰阳性菌和革兰阴性菌均具有抗菌活性,其中对革兰阳性菌的作用稍强于或等于左氧氟沙星,对革兰阴性菌的作用等于或稍弱于左氧氟沙星。     

Synthesis and antibacterial activity of 3-(2-arylvinylen)-2-isoxazolines

3-[2-(5-Nitro-2-furyl)vinylen]-2-isoxazoline (VIII) and 3-nitro-, 3-amino- and 3-acylaminostyryl-2-isoxazolines have been synthesized and tested for antibacterial activity. Compound (VIII) showed potent antibacterial activity in vitro against several strains of S. aureus and E. coli (two to eight times more active than furazolidone). None of the styryl derivatives exhibited significant activity.     

Semisynthetic beta-lactam antibiotics. I. Synthesis and antibacterial activity of new ureidopenicillin derivatives having catechol moieties

The synthesis and antibacterial activity of new ureidopenicillin derivatives having catechol moieties in the 6-acyl side chain are described. These compounds showed remarkably strong activities against Pseudomonas aeruginosa. Especially, 6-[(R)-2-[3-(3,4-dihydroxybenzoyl)-3-methyl-1-ureido]-2- phenylacetamido]penicillanic acid (7a) had the most potent activity in vitro against Gram-negative bacteria, its activity being 30 approximately 60-fold greater than that of piperacillin against most strains of P. aeruginosa.     

Efficacy of six frog skin-derived antimicrobial peptides against colistin-resistant strains of the Acinetobacter baumannii group

The emergence of Acinetobacter sp. strains resistant to all antibacterial agents including colistin necessitates the development of new types of antimicrobial agents. Six cationic α-helical frog skin-derived peptides (CPF-AM1, PGLa-AM1, B2RP-ERa, [E4K]alyteserin-1c, [D4K]B2RP and [G4K]XT-7) were selected for this study on the basis of potent growth-inhibitory activity against Gram-negative bacteria and low haemolytic activity against human erythrocytes. All peptides were active against a range of colistin-susceptible [minimum inhibitory concentration (MIC)≤2 μg/mL] and colistin-resistant (MIC≥64 μg/mL) clinical isolates of multidrug-resistant strains of Acinetobacter baumannii and Acinetobacter nosocomialis. The most potent peptides against the colistin-resistant strains were [D4K]B2RP and [E4K]alyteserin-1c (MIC=4-16 μg/mL for both). The MIC values of these peptides against the colistin-susceptible strains were in the same range. The frog peptides show potential for development into drugs to treat infections caused by pandrug-resistant Gram-negative pathogens.