New high-throughput screening assay to reveal similarities and differences in inhibitory sensitivities of multidrug ATP-binding cassette transporters.

Cdr1p is the major ATP-binding cassette multidrug transporter conferring resistance to azoles and other antifungals in Candida albicans. In this study, the identification of new Cdr1p inhibitors by use of a newly developed high-throughput fluorescence-based assay is reported. The assay also allowed monitoring of the activity and inhibition of the related transporters Pdr5p and Snq2p of Saccharomyces cerevisiae, which made it possible to compare its performance with those of previously established procedures. A high sensitivity, resulting from a wide dynamic range, was achieved upon high-level expression of the Cdr1p, Pdr5p, and Snq2p transporters in an S. cerevisiae strain in which the endogenous interfering activities were further reduced by genetic manipulation. An analysis of a set of therapeutically used and newly synthesized phenothiazine derivatives revealed different pharmacological profiles for Cdr1p, Pdr5p, and Snq2p. All transporters showed similar sensitivities to M961 inhibition. In contrast, Cdr1p was less sensitive to inhibition by fluphenazine, whereas phenothiazine selectively inhibited Snq2p. The inhibition potencies measured by the new assay reflected the ability of the compounds to potentiate the antifungal effect of ketoconazole (KTC), which was detoxified by the overproduced transporters. They also correlated with the 50% inhibitory concentration for inhibition of Pdr5p-mediated transport of rhodamine 6G in isolated plasma membranes. The most active derivative, M961, potentiated the activity of KTC against an azole-resistant CDR1-overexpressing C. albicans isolate.

Tumor-specific cytotoxicity and type of cell death induced by benzo[b]cyclohept[e][1,4]oxazine and 2-aminotropone derivatives.

A total of twenty benzo[b]cyclohept[e] [1,4]oxazines and their S-analogs, and 2-aminotropone derivatives were investigated for their cytotoxicity against three human normal cells and four tumor cell lines. These compounds showed moderate tumor-specific cytotoxicity. The cytotoxicity was enhanced by bromination at the tropone ring and replacement by formylbenzene. The cytotoxicity of 2-(2-hydroxyanilino) tropone was enhanced by introduction of bromine or isopropyl group to the tropone ring. The presence of a hydroxyl group at ortho or para-position should be necessary for the appearance of cytotoxicity and tumor-specificity. The highly active derivatives, 7-bromo-2-(4-hydroxyanilino)tropone [16] and 4-isopropyl-2-(2-hydroxyanilino)tropone [20], induced internucleosomal DNA fragmentation and caspase-3, -8 and -9 activation in human promyelocytic leukemia HL-60 cells, but only at concentrations twice or four times higher than CC(50) values. These compounds induced no discernible DNA fragmentation, and activated caspases much more weakly in human oral squamous cell carcinoma HSC-2 cells. Both [16] and [20] failed to induce the production of acidic organelles, a marker of autophagy, in contrast to the nutritional starvation. These data demonstrated that 2-aminotropones showed relatively higher tumor-specificity than benzo[b]cyclohept[e] [1,4]oxazine, and that 2-aminotropones induced little or no apoptotic cell death in oral squamous cell carcinoma, in contrast to HL-60 cells.

Tumor-specific cytotoxicity and type of cell death induced by naphtho[2,3-b]furan-4,9-diones and related compounds in human tumor cell lines: relationship to electronic structure.

A total of thirty-nine naphtho[2,3-b]furan-4,9-diones and related compounds were tested for their cytotoxicity against three human normal oral cells (gingival fibroblast, HGF, pulp cell, HPC, periodontal ligament fibroblast, HPLF) and four human tumor cell lines (oral squamous cell carcinoma HSC-2, HSC-3, HSC-4, promyelocytic leukemia HL-60). 2-Acetylnaphtho[2,3-b]furan-4,9-dione [1] was highly cytotoxic to both normal and tumor cells, yielding low tumor-specificity. 2-Acetyl-4,9-dimethoxynaphtho[2,3-b]furan [4], the 2-(3-furanoyl) benzoic acids [5, 6] and the 1,4-naphthoquinones [7, 8] showed much reduced cytototoxicity and low tumor-specificity. The introduction of phenoxy [18], isopropylamino [23] or 2-methylpiperidino [33] groups to the 2-position of naphtho[2,3-b]furan-4,9-dione yielded compounds that showed the greatest tumor-specificity. These compounds, at twice or four times higher concentrations than CC50, induced the activation of caspase-3, caspase-8 and caspase-9 in the HSC-2 and HL-60 cells, but not so apparently in the HSC-4 cells. However, they did not induce internucleosomal DNA fragmentation in the HSC-2 and HSC-4 cells even after 24 hours incubation and only slightly induced DNA fragmentation in the HL-60 cells. Compound [18] induced the production of annexin-positive cells, but did not induce microtubule-associated protein light chain 3 (LC3) accumulation in autophagosomes in LC3-green fluorescent protein (GFP)-transfected HSC-2 cells. These data suggested that naphtho[2,3-b]furan-4,9-diones may induce the early apoptotic marker, without induction of caspase activation and DNA fragmentation in oral squamous cell carcinoma cell lines. Quantitative structure-activity relationship (QSAR) analysis suggests the applicability of the theoretical calculations such as frontier molecular orbital, dipole moments and hydrophobicity in predicting their cytotoxic activity.

Inhibition of LPS-stimulated NO production in mouse macrophage-like cells by benzocycloheptoxazines.

Twenty-six benzocycloheptoxazine derivatives were investigated for their effect on nitric oxide (NO) production by lipopolysaccharide (LPS)-stimulated mouse macrophage-like RAW 264.7 cells. Benzo[b]cyclohepta[e][1,4]thiazine most effectively inhibited the LPS-stimulated NO production at noncytotoxic concentrations. 6H-Benzo[b]cyclohepta[e][1,4]-diazine cation, and benzo[b]cyclohepta[e][1,4]oxazine and its 6-bromo derivative also efficiently inhibited the LPS-stimulated NO production. Another sixteen benzo[b]cyclohepta[e]-[1,4]oxazine derivatives, 14H-[1,4]benzoxazino[3',2' :3,4]-cyclohepta[1,2-b][1,4]benzoxazine and its 7-bromo- and 7-isopropyl derivatives were slightly less active (selectivity index (SI)=83-66). Bromination of benzo[b]cyclohepta[e][1,4]-thiazine, benzo[b]cyclohepta[e][1,4]oxazine and 2-methylbenzo[b]cyclohepta[e][1,4]oxazine at C-6, C-8 or C-10 positions resulted in the significant reduction of the inhibitory activity. The observed inhibitory activity of benzo[b]cyclohepta-[e][1,4]thiazine and its 6,8-dibromo derivatives were not due to the reduction of the intracellular level of inducible NO synthase protein (based on Western blot analysis), nor to NO scavenging activity (based on ESR spectroscopy). These results suggest the possible anti-inflammatory action of benzocyclo-heptoxazines via inhibition of LPS-activated macrophages.

Inhibition of NO production in LPS-stimulated mouse macrophage-like cells by trihaloacetylazulene derivatives.

The effect of 20 trihaloacetylazulene derivatives with one halogen atom, on nitric oxide (NO) production by mouse macrophage-like cells Raw 264.7 was investigated. 2-Methoxyazulenes and 2-ethoxyazulenes exhibited comparable cytotoxicity. Trichloroacetylazulenes generally exhibited higher cytotoxicity, as compared with the corresponding trifluoroacetylazulenes. Substitution of chloride, bromide or iodine at the C-3 position further enhanced their cytotoxicity. All of these compounds failed to stimulate the Raw 264.7 cells to produce detectable amounts of NO, but did inhibit NO production by LPS-activated Raw 264.7 cells to different extents. 1-Trichloroacetyl-2-methoxyazulene and 1-trichloroacetyl-2-ethoxyazulene, with less cytotoxic activity, inhibited NO production to the greatest extent, producing the highest selectivity index (SI) of >24.7 and >28.7, respectively. This was accompanied by the efficient inhibition of inducible NO synthase (iNOS) mRNA expression, but not by iNOS protein abundance. Electron spin resonance (ESR) spectroscopy showed that neither of these compounds produced radicals, nor scavenged NO, superoxide anion or diphenyl-2-picrylhydrazyl radicals. The present study suggests that the inhibitory effects of trifluoroacetylazulenes and trichloroacetylazulenes on NO production by activated macrophages might be derived from the perturbation of NO anabolism (inhibition of iNOS mRNA expression and possibly the inactivation of iNOS protein) rather than NO catabolism (NO scavenging).

Tumor-specific cytotoxicity and type of cell death induced by benzocycloheptoxazines in human tumor cell lines.

Twenty-six benzocycloheptoxazine derivatives were investigated for their tumor-specific cytotoxicity and apoptosis-inducing activity against three human normal cells (gingival fibroblast HGF, pulp cell HPC, periodontal ligament fibroblast HPLF) and four human tumor cell lines (squamous cell carcinoma HSC-2, HSC-3, HSC-4, promyelocytic leukemia HL-60). Benzo[b]cyclohepta[e][1,4]thiazine [1] exhibited very weak cytotoxicity, whereas its 6,8,10-tribromo derivative [3] exhibited higher cytotoxicity and tumor specificity (TS = 5.6). 6H-Benzo[b]cyclohepta[e][1,4]diazine [4] and its cation [5] exhibited no tumor specificity. Among eighteen benzo[b]cyclohepta[e][1,4]oxazine derivatives [6-23], 6,8,10-triboromo- [9], 6-bromo-2-methyl- [20], and 6-bromo-2-chloro- [21] derivatives showed the highest tumor-specific cytotoxicity (TS = 12.5, 9.1 and 11.5, respectively). 14H-[1,4]Benzoxazino[3',2':3,4]cyclohepta[1, 2-b][1,4]benzoxazine [24] and its 7-bromo- [25] and 7-isopropyl- [26] derivatives had much lower cytotoxicity and tumor-specificity. Compounds [9, 20, 21] at 50% cytotoxic concentration (CC50) induced internucleosomal DNA fragmentation and caspase activation in HL-60 cells. On the other hand, these compounds induced apoptosis only at concentrations higher than CC50 in HSC-2 cells and failed to induce apoptosis in HSC-4 cells. Compounds [9, 20, 21] induced the formation of acidic organelles as measured by acridine orange staining. Transmission electron microscopy demonstrated the induction of moderate enlargement of mitochondria, the endoplasmic reticulum and nuclear membrane, and the vacuolation of the endoplasmic reticulum and the presence of a number of lamellar body-like organelles. These results indicate the diversity of the type of cell death induced by benzocycloheptoxazine derivatives in human tumor cell lines.

3,5-dibenzoyl-4-(3-phenoxyphenyl)-1,4-dihydro-2,6-dimethylpyridine (DP7): a new multidrug resistance inhibitor devoid of effects on Langendorff-perfused rat heart.

Cardiac effects of 3,5-dibenzoyl-4-(3-phenoxyphenyl)-1,4-dihydro-2,6-dimethylpyridine (DP7), a novel multidrug resistance (MDR) inhibitor, in Langendorff-perfused rat heart have been investigated and compared to that of nifedipine. Nifedipine decreased concentration-dependently (IC50=8.89+/-1.09x10(-8) M) left ventricular pressure leaving unaltered coronary perfusion pressure, whereas DP7 did not affect both parameters. Nifedipine did not modify both QRS and QT intervals of electrocardiogram (ECG). Second-degree atrioventricular block or ventricular rhythm occurred in presence of nifedipine, however, in 4 out of 6 hearts. DP7, up to 30 microM, failed to alter ECG parameters. In conclusion, DP7, may represent a lead compound for the development of potent dihydropyridine MDR chemosensitizers devoid of cardiac effects.

Quantitative structure-cytotoxicity relationship analysis of phenoxazine derivatives by semiempirical molecular-orbital method.

A semiempirical molecular-orbital method (CAChe) was applied to delineate the relationship between the cytotoxicity (evaluated by 50% cytotoxic concentration, CC50) of fifteen phenoxazine derivatives and eleven physical parameters (descriptors). Most of the phenoxazine derivatives had extended and planar structure. The cytotoxic activity of phenoxazines against the human oral squamous cell carcinoma HSC-2 and HSC-4 cells correlated to electron affinity, absolute hardness (eta), absolute electron negativity (chi) and octanol-water distribution coefficient (log-P). However, only log-P was correlated to CC50 in the HSC-3 cells, whereas only heat of formation and log-P were correlated to CC50 in the human promyelocytic leukemia HL-60 cells. The cytotoxic activity of the phenoxazine derivatives became maximum at the log-P = 5.9. Their cytotoxicity strongly depended on the chi value, but not on the eta value. Compounds with relatively higher cytotoxicity showed higher chi value (chi > 5.28), whereas compounds with relatively lower cytotoxicity showed lower chi value (chi < 4.27). These data suggest that appropriate chemical descriptors should be selected to estimate the cytotoxicity of phenoxazines, depending on the target cells.

Tumor-specificity and type of cell death induced by phenoxazines.

Phenoxazines have shown diverse biological activities, but tumor-specific cytotoxic activity has not been investigated. A total of 24 phenoxazine derivatives (WM1-24) was investigated for their relative cytotoxicity against human tumor cell lines vs. normal cells. WM7 and WM8 showed the highest tumor-specificity index of 4.3 and 4.8, respectively. Considerable difference in drug-sensitivity was found among these tumor cell lines. Human promyelocytic leukemia HL-60 cells showed the highest sensitivity to both WM7 and WM8, followed by human oral squamous cell carcinoma (HSC-2, HSC-3, HSC-4), and human gingival fibroblast (HGF), pulp cell (HPC) and periodontal ligament fibroblast (HPLF) were the most resistant. WM7 and WM8 induced little or no internucleosomal DNA fragmentation, and activated caspase-3 in HSC-2, HSC-4 and human glioblastoma T98G cells. These compounds failed to induce autophagic cell death, as judged by acridine orange and microtubule-associated protein 1 light chain 3 (LC3)-GFP assays. These results suggested that the higher cytotoxicity of WM7 and WM8 are derived from the positively-charged quaternary nitrogen substituents on the phenoxazine ring and the electron density of nitrogen at N12, and that inhibition of autophagy is not always coupled with apoptosis induction.

Tumor-specificity and type of cell death induced by trihaloacetylazulenes in human tumor cell lines.

Twenty trihaloacetylazulene derivatives with one atom of fluorine, chlorine, bromine or iodine was investigated for their tumor-specific cytotoxicity and apoptosis-inducing activity against three human normal cells (gingival fibroblast, HGF; pulp cell, HPC; periodontal ligament fibroblast, HPLF) and four human tumor cell lines (squamous cell carcinoma, HSC-2, HSC-3, HSC-4; promyelocytic leukemia, HL-60). There was no apparent difference in the cytotoxic activity between 2-methoxyazulenes [1a-1e, 2a-2e] and 2-ethoxyazulenes [3a-3e, 4a-4e]. Trichloroacetylazulenes [2a-2e, 4a-4e] generally showed higher cytotoxicity and tumor-specificity (expressed as a TS value) as compared with the corresponding trifluoroacetylazulenes [1a-1e, 3a-3e]. Substitution of chloride [1c, 2c, 3c. 4c], bromide [1d, 2d, 3d, 4d] or iodine [1e, 2e, 3e, 4e] at the C-3 position further enhanced cytotoxic activity against four tumor cell lines, especially HL-60 cells. Among twenty trihaloacetylazulene derivatives, two compounds [2d] and [4c] showed the highest tumor specificity (TS = > 3.5 and > 2.5, respectively). Compounds [2d] and [4c] induced apoptotic cell death characterized by caspase-3, -8 and -9 activation and internucleosomal DNA fragmentation in HL-60 cells. On the other hand, compounds [2d] and [4c] induced autophagic cell death characterized by lower activation of caspases, lack of DNA fragmentation, vacuolization and autophagosome formation detected by acridine orange and LC3-GFP fluorescence, without the decline of the intracellular concentration of three major polyamines in HSC-4 cells. The cytotoxic activity of [4c], but not [2d], was slightly reduced by 3-methyladenine, an inhibitor of autophagy. These results suggest the diversity of cell death type induced in human tumor cell lines by trihaloacetylazulene derivatives.

Relationship between electronic structure and cytotoxic activity of azulenequinones and trihaloacetylazulenes.

The relationship between the structure and cytotoxic activity of azulenequinones and trihaloacetylazulenes was investigated based on theoretical calculations. Four different dipole moments (mu(G), mu(ESP-G), mu(W) and mu(ESP-W)) and heats of formation (DeltaH(f)) of the azulenequinones [1-27] and trihaloacetylazulenes [28a,b-40a,b] were separately calculated in gas phase and aqueous solution using the conductor-like screening model/parametric method 3 (COSMO/PM3) method. The cytotoxic activity of azulenequinones was well correlated to DeltaDeltaH(f) HOMO energy and mu(ESP-w). The cytotoxic activity of trihaloacetylazulenes was correlated to DeltaDeltaH(f) LUMO energy and mu(ESP-W). QSAR may be applicable to predict the cytotoxicity of azulenequinones and trihaloacetylazulenes.

Studies on the antimicrobial potential of the cardiovascular drug lacidipine.

The cardiovascular drug lacidipine was screened in vitro for possible antibacterial activity with respect to 389 Gram-positive and Gram-negative bacterial strains. It was noticed that most bacteria (233) failed to grow at 50-200 microg/mL concentrations of the drug. Some strains were inhibited at even lower concentrations. The bacteria could be arranged according to their decreasing order of sensitivity as follows: Staphylococcus aureus, Vibrio cholerae, Salmonella spp., Shigellae, Escherichia coli, Bacillus spp., Klebsiellae and Pseudomonas spp. Lacidipine was found to be bacteriostatic in nature against S. aureus and V cholerae. When administered to Swiss strain of white mice at doses of 30 and 60 microg/mouse, lacidipine significantly protected the animals challenged with 50 MLD of S. typhimurium NCTC 74. According to the chi-square test, the in vivo data were highly significant (p<0.001).

Phenothiazine maleates stimulate MRP1 transport activity in human erythrocytes.

The expression of multidrug resistance-associated protein (MRP1) results in ATP-dependent reduction of drugs' concentration in cancer cells, i.e., multidrug resistance (MDR). Since the majority of projects are concentrated on the search of the new MDR modulators, there are very few reports on drug-induced stimulation of MDR transporters activity. In the present work, by means of functional fluorescence assay we have shown that MRP1-mediated efflux of 2',7'-bis-(3-carboxypropyl)-5-(and-6)-carboxyfluorescein (BCPCF) out of human erythrocytes is stimulated by phenothiazine maleates that have been already identified as P-glycoprotein inhibitors. Phenothiazine maleates-induced stimulation of ATP-dependent uptake of 2',7'-bis-(3-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF) into inside-out membrane vesicles prepared from erythrocyte membranes has been also demonstrated. Moreover, it was shown that phenothiazine maleates exerted stimulating effect on ATPase activity measured in erythrocyte membranes. To our best knowledge, this report is the first one demonstrating that compounds able to inhibit transport activity of P-glycoprotein can stimulate MRP1 transporter. We conclude that phenothiazine maleates probably exert their stimulatory effect on MRP1 by direct interaction with the protein at the site different from the substrate binding site.

Resveratrol oligomers are potent MRP1 transport inhibitors.

BACKGROUND: Knowledge of the structure-activity relationships of multidrug resistance protein 1 (MRP1, ABCC1) inhibitors may aid in developing potent inhibitors that can be used to circumvent MRP1-mediated multidrug resistance. MATERIALS AND METHODS: Six stilbenes were examined for their ability to inhibit MRP1-mediated transport of 2',7'-bis-(carboxypropyl)-5(6)-carboxyfluorescein (BCPCF) from human erythrocytes and into inside-out erythrocyte membrane vesicles (IOVs). The concentrations of stilbenes decreasing BCPCF transport by 50% during 60 min of incubation at 37 degrees C (IC50) were determined from dose-response curves. RESULTS: Stilbenes inhibited BCPCF transport in cells in the rank order (+)-alpha-viniferin (IC50 = 0.8 microM) > sophorastilbene A (IC50 = 3.1 microM) > (-)-epsilon-viniferin (IC50 = 8.9 microM) > piceatannol (IC50 = 57 microM). Resveratrol and rhaponticin were ineffective. (+)-alpha-Viniferin (IC50 = 0.8 microM), sophorastilbene A (IC50 = 3.7 microM) and (-)-epsilon-viniferin (IC50 = 3.5 microM) were also efficient BCPCF transport inhibitors in IOVs. CONCLUSION: Stilbenes may efficiently inhibit MRP1-mediated organic anion transport. This inhibitory potency of stilbenes increases with oligomerisation. The membrane is not a strong barrier for the inhibitory activity of the trimeric stilbenes.

Inhibition of NO production in LPS-stimulated mouse macrophage-like cells by trihaloacetylazulenes.

The effects of 26 trihaloacetylazulene derivatives on nitric oxide (NO) production by the mouse macrophage-like Raw 264.7 cells was investigated. The trichloroacetylazulenes [1b-13b] generally showed higher cytotoxicity as compared with the corresponding trifluoroacetylazulenes [1a-13a]. All the compounds inhibited NO production by lipopolysaccharide (LPS)-activated Raw 264.7 cells to various extents. 3-Trifluoroacetylguaiazulene [8a], 1-trifluoroacetyl-4,6,8-trimethylazulene [10a], 3-methyl-l-trichloroacetylazulene [2b] and 3-ethyl-1-trichloroacetylazulene [3b] showed lower cytotoxic activity and most effectively inhibited NO production. Western blot analysis revealed that compounds [8a, 1Oal dose-dependently reduced the intracellular concentration of inducible NO synthase (iNOS), whereas compounds [2b, 3b] only marginally affected the iNOS protein expression. RT-PCR analysis showed that compounds [8a, 2b] reduced the iNOS mRNA expression by approximately 50%. These compounds affected cyclooxygenase-2 protein and mRNA expression, depending on the concentrations. ESR spectroscopy revealed that compounds [8a, 10a, 2b, 3b] neither produced radical, nor scavenged NO, superoxide anion or diphenyl-2-picrylhydrazyl radicals. The present study showed the inhibitory effects of trifluoroacetylazulenes and trichloroacetylazulenes on NO production by activated macrophages.

Apoptosis-inducing activity of trihaloacetylazulenes against human oral tumor cell lines.

Twenty-six trihaloacetylazulene derivatives were investigated for their tumor-specific cytotoxicity and apoptosis-inducing activity against three human normal cells (HGF, HPC, HPLF) and four human tumor cell lines (HSC-2, HSC-3, HSC-4, HL-60). The trichloroacetylazulenes [1b-13b] generally showed higher cytotoxicity as compared to the corresponding trifluoroacetylazulenes [1a-13a]. The trichloroacetylazulenes [1b-13b] also showed higher tumor-specific cytotoxicity (expressed as TS value) than the corresponding trifluoroacetylazulenes [1a-13a]. Especially, 2,3-dimethyl-1-trichloroacetylazulene [5b] and 1,3-ditrichloroacetyl-4,6,8-trimethylazulene [11b] showed the highest cytotoxicity and tumor specificity (TS > 35.6 and > 44.1, respectively). These compounds induced internucleosomal DNA fragmentation in HL-60 cells, but not in HSC-2 and HSC-3 cells, but activated caspase-3, -8 and -9 in all of these cells, suggesting the activation of both mitochondria-independent (extrinsic) and dependent (intrinsic) pathways. Western blot analysis showed that two compounds [5b, 11b] slightly increased the intracellular concentration of pro-apoptotic proteins (Bad, Bax) in HSC-2 cells. None of the 26 compounds showed anti-HIV activity. These results suggest [5b] and [11b] as possible candidates for future cancer chemotherapy.

Diclofenac in the management of E. coli urinary tract infections.

E. coli is the main agent of uncomplicated urinary tract infections (UTIs) and accounts for more than 85% of recurrent cystitis and at least 35% of recurrent pyelonephritis. Despite the widespread availability of antibiotics, UTIs remain the most common bacterial infection in the human population. It is currently advised that the clinical administration of antibiotics against the pathogenic bacteria should be prohibitted due to the emergence of multidrug resistant (MDR) bacterial strains. Therefore, newer and more effective antimicrobials are in demand to treat such cases. One hundred and thirty six urine samples were collected from UTI patients. E. coli was isolated from 85 samples, out of which 33% were resistant to common antibiotics. The isolates were decreasingly resistant to ampicillin, tobramycin, augmentin, nalidixic acid, cefuroxime, nitrofurantoin, kanamycin, pipemidic acid, chloramphenicol, cefotaxime, cefamendol, ofloxacin, ceftizoxime, norfloxacin and amikacin. The anti-inflammatory drug diclofenac exhibited significant antibacterial activity against common bacterial strains both in vitro and in vivo. The present work was conducted to evaluate the in vitro inhibitory effect of this drug on the clinically isolated strains of E. coli in hospitals. All the isolates were sensitive to diclofenac, with MIC values ranging from 5-50 microg/mL. The MIC90 value of the drug was 25 microg/mL. Therefore, it may be suggested that diclofenac has the capacity to treat UTI caused by E. coli.

Relationship between electronic structure and cytotoxic activity of azulenes.

The structure-activity relationship of the cytotoxic activity of azulene and azulene derivatives was discussed, using theoretically calculated results. In order to clearly divide the azulenes into three groups according to their functional groups, the CC50, four different dipole moments (muG, muESP-G, muwand muESP-W) and heats of formation (deltaHf) of the azulenes [1-24] were separately calculated in two states, gas-phase and water, by the conductor-like screening model/parametric method 3 (COSMO/PM3). For the halogenated azulenes and isopropyl azulenes, the cytotoxic activity might follow the three quantitative structure-activity relationship (QSAR) parameters: deltadeltaHf, HOMO energy and muw Whereas, for the other ten compounds [3-5, 7-8, 10, 15-18], the cytotoxic activity might be related to the three QSAR parameters, deltadeltaHf, LUMO energy and muG

Relationship between electronic structure and cytotoxic activity of tropolones.

A structure-activity relationship of the cytotoxic activity of tropolone derivatives was discussed, using theoretical calculations. In order to clearly divide the tropolones into two structurally analogous groups, four different dipole moments (muG, muESP-G, muW and muESP-W) and heats of formation (deltaHf) of the tropolones [1-21] were calculated in the gas-phase and in water-solution by the conductor-like screening model/parametric method 3 (COSMO/PM3). The cytotoxic activities of the tropolones and 2-methoxytropones seem to be related to the three QSAR parameters deltadeltaHf, HOMO energy (EH) and muw. The cytotoxic activity of the five tropone derivatives [17-21] might depend on the QSAR parameters deltadeltaHf, LUMO energy (EL) and muESP-G. The results of the present study suggest the applicability of theoretical calculations such as frontier molecular orbital, dipole moments and deltadeltaHf in the prediction of the cytotoxic activity of tropolone derivatives.

Benzo[a]phenoxazines: a new group of potent P-glycoprotein inhibitors.

The ability of fifteen novel phenoxazine derivatives (four phenoxazines and eleven benzo[a]phenoxazines) to modulate multidrug resistance (MDR) in a P-gp-overexpressing mouse T lymphoma cell line (L5178 MDR) was studied. A flow cytometric functional test, based on the differential accumulation of rhodamine 123 by sensitive and multidrug-resistant cells, was employed. Seven benzo[a]phenoxazines were observed to increase the amount of rhodamine 123 accumulated by resistant cells, i.e. to be new effective MDR modulators. The results allowed us to draw preliminary conclusions about the structural features of benzo[a]phenoxazines which are important for MDR modulation.