Effect of chemopreventive agents on glutathione S-transferase P1-1 gene expression mechanisms via activating protein 1 and nuclear factor kappaB inhibition

Glutathione S-transferase P1-1 (GSTP1-1) is a phase II drug metabolism enzyme implicated in carcinogenesis and development of resistance to anti-cancer drugs. It was previously shown that both activating protein 1 (AP-1) and nuclear factor kappaB (NF-kappaB) are involved in its regulation. In the present study we examined the inhibitory effect of several chemopreventive agents on the tumor necrosis factor (TNF) alpha- or 12-O-tetradecanoylphorbol 13 acetate (TPA)-induced promoter activity of GSTP1-1, as demonstrated by transient transfection experiments in K562 and U937 leukemia cells. Our results provide evidence for a differential effect of chemopreventive agents such as beta-lapachone, emodin, sanguinarine and capsaicin, which significantly inhibit reporter gene expression as well as TNFalpha- and TPA-induced binding of AP-1 and NF-kappaB, whereas trans-anethole and silymarin do not produce any inhibitory effect. Our results demonstrate the ability of selected chemopreventive agents to decrease GSTP1-1 gene expression mechanisms and could thus contribute to reduce the incidence of glutathione related drug resistance in human leukemia.     

Synthesis, molecular modeling studies, and selective inhibitory activity against monoamine oxidase of 1-thiocarbamoyl-3,5-diaryl-4,5-dihydro-(1H)- pyrazole derivatives

A novel series of 1-thiocarbamoyl-3,5-diaryl-4,5-dihydro-(1H)-pyrazole derivatives have been synthesized and investigated for the ability to inhibit selectively the activity of the A and B isoforms of monoamine oxidase (MAO). All the synthesized compounds show high activity against both the MAO-A and the MAO-B isoforms with Ki values between 27 and 4 nM and between 50 and 1.5 nM, respectively, except for a few derivatives whose inhibitory activity against MAO-B was in the micromolar range. Knowing that stereochemistry may be an important modulator of biological activity, we performed the semipreparative chromatographic enantioseparation of the most potent, selective, and chiral compounds. The separated enantiomers were then submitted to in vitro biological evaluation. The selectivity of the (-)-(S)-1 enantiomer against MAO-B increases twice and a half, while the selectivity of the (-)-(S)-4 enantiomer against MAO-A triples. Both the MAO-A and MAO-B isoforms respectively of the 1O5W and 1GOS models deposited in the Protein Data Bank were considered in the computational study. The docking study was carried out using several computational approaches with the aim of proposing possible binding modes of the MAO enantioselective compounds 1 and 4.     

1-苯甲酰基-4-(4-氯苄基)哌嗪衍生物的设计、合成以及抗炎活性研究

目的:以1-苯甲酰基-4-(4-氯苄基)哌嗪为先导化合物,经进一步的结构优化,期望获得一类抗炎活性更好的多靶点抑制剂。方法:以取代苯甲酸为起始原料,经取代、酰化反应合成18个目标化合物。测定所有化合物对脂多糖(lipopolysaccharide,LPS)诱导RAW264.7细胞分泌肿瘤坏死因子(tumor necrosis factor,TNF)-α和白细胞介素(interleukin,IL)-6的抑制作用,并对活性较好的化合物进行分子对接。结果:所有化合物均经¹H NMR,¹³C NMR,HRMS确定其结构,化合物3d,8k对TNF-α的分泌具有较好的抑制活性,化合物3b,3d对IL-6的分泌具有较好的抑制活性。结论:化合物3d对LPS诱导RAW264.7细胞分泌TNF-α和IL-6具有较好的抑制活性,有进一步研究的价值。     

新型非共价结合拟肽类蛋白酶体抑制剂的合成及活性评价

目的 设计、合成系列非共价结合拟肽类蛋白酶体抑制剂,并对其进行活性评价。方法 根据非共价结合蛋白酶体抑制剂与蛋白酶体的结合特点,采用氨基酸替换、生物电子等排等经典的药物设计方法,选取邻氯苄胺作为化合物的羧基末端基团,同时在肽骨架结构中引入六元环以增强肽类化合物的稳定性,设计并合成了一系列短肽非共价结合类蛋白酶体抑制剂,并通过体外蛋白酶体活性抑制实验评价该类化合物的活性。结果 共合成了8个具有全新结构的二肽和三肽化合物,其结构经¹H-NMR、ESI-MS确证,该类化合物对蛋白酶体具有中等的抑制活性。结论 肽链的长短及氨基末端不同的取代基对化合物的蛋白酶体抑制活性都有影响,8个化合物在体外对蛋白酶体都具有不同程度的抑制活性。本研究丰富了蛋白酶体抑制剂的结构类型,为该类化合物的深入研究奠定了基础。     

Relationship between genotype and enzyme activity of glutathione S-transferases M1 and P1 in Chinese.

Glutathione S-transferases (GSTs) are the major detoxifying Phase II enzyme for eliminating electrophilic compounds. Mutations in GSTM1, GSTP1 and GSTT1 in Caucasian and GSTA1 in Chinese have been found to reduce enzyme activity. However, data on the impact of common genetic polymorphisms of GSTM1 and GSTP1 on enzyme activity in Chinese is lacking. This study aimed to investigate the effect of common GSTP1 and GSTM1 polymorphisms on erythrocyte GST activity in healthy Chinese (n = 196). GSTM1 null mutation (GSTM1*0) was analyzed by a PCR-Multiplex procedure, whereas GSTP1 313A-->G polymorphism (resulting in Ile105Val at codon 105) was analyzed by PCR-restriction fragment length polymorphism (RFLP) analysis. Erythrocyte GST activity was measured using 1-chloro-2,4-dinitro-bezene (CDNB) as the model substrate. The frequency of GSTM1 null genotype was 54.3% and the frequency of GSTP1-Ile/Ile, -Ile/Val, and -Val/Val genotype was 60.7%, 35.2% and 4.1%, respectively, with a frequency of 21.7% for the 105 valine allele. Age, gender and smoking did not significantly affect the erythrocyte GST activities. The mean erythrocyte GST enzyme activity for GSTP1*-Ile/Val genotype group (3.53 +/- 0.63U/gHb) was significantly lower than that for subjects with GSTP1-Ile/Ile genotype (4.25 +/- 1.07U/gHb, P = 0.004), while subjects with the GSTP1-Val/Val genotype had the lowest enzyme activity (2.44 +/- 0.67U/gHb). In addition, the GST activity in carriers of GSTM1*0/GSTP1-Ile/Ile was significantly higher than that of subjects inherited GSTM1*0/GSTP1-Ile/Val or GSTM1*0/GSTP1-Val/Val. However, there is no association between GSTM1 null mutation and reduced enzyme activity. GSTP1 codon 105 mutation led to reduced erythrocyte GST activity in Chinese. A combined GSTP1 and GSTM1 null mutations also resulted in significantly reduced GST activity. Further studies are needed to explore the clinical implications of GSTM1 and GSTP1 polymorphisms.     

齐墩果酸衍生物的合成及其降血糖活性研究

目的设计合成两个系列齐墩果酸衍生物,并对其进行体外降血糖活性评价。方法以齐墩果酸为先导物,经酰化、取代等反应得到目标化合物,并对目标化合物和阿卡波糖对α-葡萄糖苷酶的抑制活性进行对比。结果与结论合成了11个未见文献报道的新化合物,两个系列化合物的结构均经MS、1H-NMR谱确证。活性测定表明,目标化合物均具有一定的α-葡萄糖苷酶抑制活性,大部分齐墩果酸衍生物的活性高于齐墩果酸(IC50=0.502 mmol·L-1),其中,化合物6d对α-葡萄糖苷酶的抑制活性最高(IC50=0.025 mmol·L-1),为齐墩果酸的21倍。     

Binding mode analysis of topoisomerase inhibitors, 6-arylamino-7-chloro-quinazoline-5,8-diones,within the cleavable complex of human topoisomerase I and DNA

A series of 6-arylamino-7-chloro-quinazoline-5,8-diones have been evaluated as novel human topoisomerase I (TOP1) inhibitors based on the antitumor activity of 1,4-naphthoquinone. Besides their in vitro cytotoxicity, their ability to inhibit human TOP1-DNA in vitro was tested with human TOP1 and a supercoiled (Form I) plasmid substrate DNA (Park et al., 2004). Using the flexible docking program, QXP, we have developed ternary complex models by docking camptothecin and ten 6-arylamino-7-chloro-quinazoline-5,8-dione analogs into the X-ray crystal structure of the human TOP1-DNA binary complex. The compound binding modes substantiated their potential inhibitory activities against TOP1 in the relaxation assay. Compounds whose templates the 6-arylamino-7-chloro-quinazoline-5,8-dione moiety intercalated between the -1 and +1 base pairs of the scissile strand showed good inhibitory activities. The template of compounds with poor inhibitory activities intercalated between the DNA base pairs of the nonscissile strand. The interaction of the compounds and the human TOP1-DNA binary complex were stabilized by an array of hydrogen bonds and hydrophobic interactions with the TOP1 residues, DNA bases, and water molecules. Docking results from the QXP program suggested potential binding modes of each non-CPT type compound in the human TOP1-DNA cleavable complex, which could provide a rational basis for future TOP1 inhibitor development.     

Inhibition of glutathione S-transferase P1-1 in mouse lung epithelial cells by the tumor promoter 2,6-di-tert-butyl-4-methylene-2,5-cyclohexadienone (BHT-quinone methide): protein adducts investigated by electrospray mass spectrometry

Oxidation of the food preservative 2,6-di-tert-butyl-4-methylphenol (BHT) by mouse lung cytochrome P450 produces electrophilic quinone methides thought to promote lung tumors in mice by covalent binding to critical proteins. Specific pulmonary targets of 2,6-di-tert-butyl-4-methylenecyclohexa-2,5-dienone (BHT-QM) have not been identified, however. The present work was undertaken to determine if glutathione S-transferase P1-1 (GSTP1-1) is alkylated by BHT-QM, as this protein is overexpressed in tumors and has important roles in protecting cells from electrophiles and oxidants and in regulating stress kinases. This work was conducted with cell lines C10 and E10 derived from mouse lung epithelia and their spontaneous transformants, the tumorigenic cell lines A5 and E9. Cytosolic GSTs were isolated by affinity chromatography and analyzed by ESI-LC/MS. Ion current chromatograms indicated that GSTP1 predominates over the other isoforms, especially in tumorigenic cells. Treatment with BHT-QM inhibited cytosolic GST activity by 28-44%, and inhibition was exacerbated by depleting intracellular GSH. Alkylation of GSTP1 by BHT-QM was investigated by separating cytosolic proteins with two-dimensional SDS-PAGE and detecting adducts by Western blotting with polyclonal antibodies that recognize the BHT group. The identity of GSTP1 comigrating with immunoreactive material was confirmed by in-gel proteolysis and LC/MS/MS analysis. Human GSTP1 was utilized to investigate the specific residues involved in QM binding. The only peptide adduct detected in digests of monoadducted GSTP1 corresponded to Cys101, whereas adducts at Cys14, Cys47, and Cys101 were identified from the trialkylated protein. Losses of transferase activity were most influenced by alkylation at Cys47, but binding to Cys14 appeared to inhibit the activity further. These findings demonstrate that cytosolic GSTP1 may be a target for BHT-QM resulting in decreased cellular protection from electrophiles and oxidants. Alkylation also may interfere with GSTP1 regulation of stress kinases, thereby influencing phosphorylation and cell growth.     

Inhibition of human glutathione S-transferases by curcumin and analogues

1. Glutathione S-transferases (GSTs) are important phase II drug-metabolizing enzymes that play a major role in protecting cells from the toxic insults of electrophilic compounds. Curcumin, a promising chemotherapeutic agent, inhibits human GSTA1-1, GSTM1-1, and GSTP1-1 isoenzymes.

2. In the present study, the effect of three series of curcumin analogues, 2,6-dibenzylidenecyclohexanone (A series), 2,5-dibenzylidenecyclopentanone (B series), and 1,4-pentadiene-3-one (C series) substituted analogues (n?=?34), on these three human GST isoenzymes, and on human and rat liver cytosolic GSTs, was investigated using 1-chloro-2,4-dinitrobenzene (CDNB) as a substrate.

3. Most of the 34 curcumin analogues showed less potent inhibitory activities towards GSTA1-1, GSTM1-1, and GSTP1-1 than the parent curcumin. Compounds B14 and C10 were the most potent inhibitors of GSTA1-1 and human liver cytosolic GSTs, with IC₅₀ values of 0.2–0.6 μM. The most potent inhibitors of GSTM1-1 were C1, C3 and C10, with IC₅₀ values of 0.2–0.7 μM. Similarly, GSTP1-1 was predominantly strongly inhibited by compounds of the C series C0, C1, C2 C10 and A0, with IC₅₀ values of 0.4–4.6 μM. Compounds in the B series showed no significant inhibition of GSTP1-1.

4. Molecular Operating Environment (MOE) program-based quantitative structure–activity relationship (QSAR) analyses have also suggested the relevance of Van der Waals surface area and compound lipophilicity factors for the inhibition of GSTA1-1 and GSTM1-1 and partial charge factors for GSTP1-1. These results may be useful in the design and synthesis of curcumin analogues with either more or less potency for GST inhibition.

     

Synthesis of novel N-benzyl substituted piperidine amides of 1H-indole-5-carboxylic acid as potential inhibitors of cholinesterases

A series of novel N-benzyl substituted amides of 1H-indole-5-carboxylic acid were synthesized and evaluated for their ability to inhibit acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). The target compounds (6b-6e) displayed moderate potency to inhibit BuChE. One of the compounds tested, i.e., 1-benzylpiperidine amide of 1H-indole-5-carboxylic acid (6a) was a weak, non-selective inhibitor for both enzymes. The highest inhibitory activity towards BuChE (30.06% [10 microM]) was determined for compound (6c) which is 1-(3-chloro)benzylpiperidine amide of 1H-indole-5-carboxylic acid.     

Potent anti-HIV (type 1 and type 2) activity of polyoxometalates: structure-activity relationship and mechanism of action

A series of polyoxometalates have been synthesized and evaluated for their inhibitory effects on HIV-1(III(B)) and HIV-1(ROD) replication in MT-4 cells. All compounds showed activity against HIV-1 and HIV-2, but the antiviral potency of the heteropolytungstates varied considerably depending on their chemical structure. The antiviral activity of single, double, and triple Keggin-type of compounds against HIV-1(III(B)) replication was comparable (IC(50): 0.4-0.5 microgram/mL), whereas HIV-2(ROD) appeared to become less sensitive with the increasing number of Keggin structures per compound. The same trend was observed for single and double Dawson structures. Some of these compounds were examined for their inhibitory effect on the replication of HIV-1(RF) and SIV(MAC(251)) in MT-4 cells. Their anti-HIV-1(RF) and anti-SIV(MAC(251)) potencies were comparable to those for the HIV-1(III(B)) or HIV-2(ROD) strain, respectively. The polyoxometalates represent a class of polyanionic compounds, which block the binding of the envelope glycoprotein gp120 of HIV to CD4(+) cells. The compounds interfered with the binding of anti-CD4 mAb to the OKT4A/Leu3a epitope of the CD4 receptor, compound 24 being the most active in this regard, and inhibited the binding of anti-gp120 mAb to infected MT-4 cells. None of the polyoxometalates inhibited the binding of a specific CXCR4 mAb to SUP-T1 cells, suggesting that they do not interact with CXCR4, the main co-receptor for T-tropic HIV strains, and thus act as virus binding, and not as fusion, inhibitors.     

Synthesis, DNA binding, and biological evaluation of synthetic precursors and novel analogues of netropsin

A series of oligopeptides have been synthesized that are structurally related to the natural agent netropsin. The binding constants to double-stranded polynucleotides as well as the cytostatic activity against both murine human tumor cell lines and the in vitro activity against a range of DNA and RNA viruses have been determined for these novel compounds and some of their synthetic precursors. 1-Methyl-5-nitropyrrole-2-carboxylic acid methyl ester (4), N-[[1-methyl-4-(1-methyl-4-nitropyrrole-2-carboxamido)pyrrol-2- yl]carbonyl]-L-alanine tert-butyl ester (28), and N-[[1-methyl-4-(1-methyl-4-nitropyrrole-2-carboxamido)pyrrol-2- yl]carbonyl]-L-alanyl-L-alanine tert-butyl ester (29) showed modest inhibitory effect on tumor cell proliferation (CD50 = 26-85 micrograms/mL). Of all the compounds that were evaluated, 28 proved the most potent antiviral agent. It was inhibitory to parainfluenza-3 virus and Coxsackie virus B4 in Vero cells at a concentration of 20 micrograms/mL.     

Synthesis,HIV-1 RT inhibitory,antibacterial, antifungal and binding mode studies of some novel N-substituted 5-benzylidine-2,4-thiazolidinediones

Background

Structural modifications of thiazolidinediones at 3^rd and 5^th position have exhibited significant biological activities. In view of the facts, and based on in silico studies carried out on thiazolidine-2,4-diones as HIV-1- RT inhibitors, a novel series of 2,4-thiazolidinedione analogs have been designed and synthesized.

Methods

Title compounds were prepared by the reported method. Conformations of the structures were assigned on the basis of results of different spectral data. The assay of HIV-1 RT was done as reported by Silprasit et al. Antimicrobial activity was determined by two fold serial dilution method. Docking study was performed for the highest active compounds by using Glide 5.0.

Results

The newly synthesized compounds were evaluated for their HIV-1 RT inhibitory activity. Among the synthesized compounds, compound 24 showed significant HIV-1 RT inhibitory activity with 73% of inhibition with an IC₅₀ value of 1.31 μM. Compound 10 showed highest activity against all the bacterial strains.A molecular modeling study was carried out in order to investigate the possible interactions of the highest active compounds 24, 10 and 4 with the non nucleoside inhibitory binding pocket(NNIBP) of RT, active site of GlcN-6-P synthase and cytochrome P450 14-α-sterol demethylase from Candida albicans (Candida P450DM) as the target receptors respectively using the Extra Precision (XP) mode of Glide software.

Conclusion

A series of novel substituted 2-(5-benzylidene-2,4-dioxothiazolidin-3-yl)-N-(phenyl)propanamides (4–31) have been synthesized and evaluated for their HIV-1 RT inhibitory activity, antibacterial and antifungal activities. Some of the compounds have shown significant activity. Molecular docking studies showed very good interaction.     

Structural requirements for the flavonoid-mediated modulation of glutathione S-transferase P1-1 and GS-X pump activity in MCF7 breast cancer cells

The objective of this study was to investigate the structural requirements necessary for inhibition of glutathione S-transferase P1-1 (GSTP1-1) and GS-X pump (MRP1 and MRP2) activity by structurally related flavonoids, in GSTP1-1 transfected MCF7 cells (pMTG5). The results reveal that GSTP1-1 activity in MCF7 pMTG5 cells can be inhibited by some flavonoids. Especially galangin was able to inhibit almost all cellular GSTP1-1 activity upon exposure of the cells to a concentration of 25microM. Other flavonoids like kaempferol, eriodictyol and quercetin showed a moderate GSTP1-1 inhibitory potential. For GSTP1-1 inhibition, no specific structural requirements necessary for potent inhibition could be defined. Most flavonoids appeared to be potent GS-X transport inhibitors with IC(50) values ranging between 0.8 and 8microM. Luteolin and quercetin were the strongest inhibitors with IC(50) values of 0.8 and 1.3microM, respectively. Flavonoids without a C2-C3 double bond like eriodictyol, taxifolin and catechin did not inhibit GS-X pump activity. The results of this study demonstrate that the structural features necessary for high potency GS-X pump inhibition by flavonoids are (1) the presence of hydroxyl groups, especially two of them generating the 3',4'-catechol moiety; and (2) a planar molecule due to the presence of a C2-C3 double bond. Other factors, like lipophilicity and the total number of hydroxyl groups do not seem to be dominating the flavonoid-mediated GS-X pump inhibition. To identify the GS-X pump responsible for the DNP-SG efflux in MCF7 cells, the effects of three characteristic flavonoids quercetin, flavone and taxifolin on MRP1 and MRP2 activity were studied using transfected MDCKII cells. All three flavonoids as well as the typical MRP inhibitor (MK571) affected MRP1-mediated transport activity in a similar way as observed in the MCF7 cells. In addition, the most potent GS-X pump inhibitor in the MCF7 cells, quercetin, did not affect MRP2-mediated transport activity. These observations clearly indicate that the GS-X pump activity in the MCF7 cells is likely to be the result of flavonoid-mediated inhibition of MRP1 and not MRP2. Altogether, the present study reveals that a major site for flavonoid interaction with GSH-dependent toxicokinetics is the GS-X pump MRP1 rather than the conjugating GSTP1-1 activity itself. Of the flavonoids shown to be most active especially quercetin is frequently marketed in functional food supplements. Given the physiological levels expected to be reached upon supplement intake, the IC(50) values of the present study point at possible flavonoid-drug and/or flavonoid-xenobiotic interactions especially regarding transport processes involved in toxicokinetics.     

2-(Hetero(aryl)methylene)hydrazine-1-carbothioamides as Potent Urease Inhibitors

A small series of 2-(hetero(aryl)methylene) hydrazine-1-carbothioamides including two aryl derivatives was synthesized and tested for their inhibitory activity against urease. Compound (E)-2-(Furan-2-ylmethylene) hydrazine-1-carbothioamide (3f) , having a furan ring, was the most potent inhibitor of urease with an IC₅₀ value of 0.58 μm . Molecular modeling was carried out through docking the designed compounds into the urease binding site to predict whether these derivatives have analogous binding mode to the urease inhibitors. The study revealed that all of the tested compounds bind with both metal atoms at the active site of the enzyme. The aromatic ring of the compounds forms ionic interactions with the residues, Ala(440), Asp(494), Ala(636), and Met(637).     

Dicarboxylic acid azacycle l-prolyl-pyrrolidine amides as prolyl oligopeptidase inhibitors and three-dimensional quantitative structure-activity relationship of the enzyme-inhibitor interactions

A series of dicarboxylic acid azacycle l-prolyl-pyrrolidine amides was synthesized, and their inhibitory activity against prolyl oligopeptidase (POP) from porcine brain was tested. Three different azacycles were tested at the position beyond P3 and six different dicarboxylic acids at the P3 position. l-Prolyl-pyrrolidine and l-prolyl-2(S)-cyanopyrrolidine were used at the P2-P1 positions. The IC(50) values ranged from 0.39 to 19000 nM. The most potent inhibitor was the 3,3-dimethylglutaric acid azepane l-prolyl-2(S)-cyanopyrrolidine amide. Molecular docking (GOLD) was used to analyze binding interactions between different POP inhibitors of this type and the POP enzyme. The data set consisted of the novel inhibitors, inhibitors published previously by our group, and well-known reference compounds. The alignments were further analyzed using comparative molecular similarity indices analysis. The binding of the inhibitors was consistent at the P1-P3 positions. Beyond the P3 position, two different binding modes were found, one that favors lipophilic structures and one that favors nonhydrophobic structures.     

Small molecule agonists of the orphan nuclear receptors steroidogenic factor-1 (SF-1, NR5A1) and liver receptor homologue-1 (LRH-1, NR5A2)

The crystal structure of LRH-1 ligand binding domain bound to our previously reported agonist 3-(E-oct-4-en-4-yl)-1-phenylamino-2-phenyl-cis-bicyclo[3.3.0]oct-2-ene 5 is described. Two new classes of agonists in which the bridgehead anilino group from our first series was replaced with an alkoxy or 1-ethenyl group were designed, synthesized, and tested for activity in a peptide recruitment assay. Both new classes gave very active compounds, particularly against SF-1. Structure-activity studies led to excellent dual-LRH-1/SF-1 agonists (e.g., RJW100) as well as compounds selective for LRH-1 (RJW101) and SF-1 (RJW102 and RJW103). The series based on 1-ethenyl substitution was acid stable, overcoming a significant drawback of our original bridgehead anilino-substituted series. Initial studies on the regulation of gene expression in human cell lines showed excellent, reproducible activity at endogenous target genes.     

Comparative study of the inhibition of metallo-beta-lactamases (IMP-1 and VIM-2) by thiol compounds that contain a hydrophobic group

For the purpose of screening of inhibitors that are effective for wide range of metallo-beta-lactamases, the inhibitory effect of two series of compounds, 2-omega-phenylalkyl-3-mercaptopropionic acid (PhenylCnSH (n=1-4)) and N-[(7-chloro-quinolin-4-ylamino)-alkyl]-3-mercapto-propionamide (QuinolineCnSH (n=2-6)), where n denotes the alkyl chain length, on metallo-beta-lactamases IMP-1 and VIM-2 was examined. These inhibitors contain a thiol group and a hydrophobic group linked by variable-length methylene chain. PhenylCnSH (n=1-4) was found to be a potent inhibitor of both IMP-1 and VIM-2. PhenylC4SH was the potent inhibitor of both IMP-1 (IC(50)=1.2 microM) and VIM-2 (IC(50)=1.1 microM) among this study. When the number of methylene units was varied, QuinolineC4SH showed the maximum inhibitory activity against IMP-1 and VIM-2 (IC(50)=2.5 microM and IC(50)=2.4 microM). The relationship between the inhibitory effect of the alkyl chain length was different for both series of inhibitors, suggesting that IMP-1 has a tighter binding site than VIM-2. QuinolineCnSH did not serve as a fluorescence reagent for metallo-beta-lactamases.