Synthesis and antitumor activity of 1-substituted-2-methyl-5-nitrobenzimidazoles

Different substituents were introduced in position 1 of 2-methyl-5(6)-nitro-1H-benzimidazole (2) in order to obtain different side chains having different heterocyclic compounds, for example, thiadiazoles (5-7), tetrazoles (8, 9a, b), triazoles (11-13), thiazoles (14a-e), triazines (10, 16, 17), and imidazoles (18a-c). The antitumor effect of compounds 1, 2, 2a, 4, 5, 7, 8, 9a, 10, 13, 14a, 15, 16, and 18c was studied against breast cancer (MCF7) and compounds 2 [IC(50)=4.52 microg] and 7 [IC(50)=8.29 microg] were found to be active.     

Design, synthesis, and antiviral evaluation of 2-deoxy-D-ribosides of substituted benzimidazoles as potential agents for human cytomegalovirus infections

Stereoselective glycosylation of 2,5,6-trichlorobenzimidazole (1b), 2-bromo-5,6-dichlorobenzimidazole (1c), 5,6-dichlorobenzimidazole (1d), 5,6-dichlorobenzimidazole-2-thione (1e), 5,6-dichloro-2-(methylthio)benzimidazole (1f), 2-(benzylthio)-5,6-dichlorobenzimidazole (1g), and 2-chloro-5,6-dimethylbenzimidazole (1h) with 2-deoxy-3,5-di-O-p-toluoyl-alpha-D-erythro-pentofuranosyl chloride was achieved to give the desired beta nucleosides 2b-h. Subsequent deprotection afforded the corresponding free beta-D-2-deoxyribosides 3b-h. The 2-methoxy derivative 3i was synthesized by the treatment of 2b with methanolic sodium methoxide. Displacement of the 2-chloro group of 2b with lithium azide followed by a removal of the protective groups gave the 2-azido-5,6-dichlorobenzimidazole derivative (5). The 2-amino derivative (6) was obtained by hydrogenolysis of 5 over Raney nickel. 5,6-Dichloro-2-isopropylamino-1-(2-deoxy-beta-D-erythro- pentofuranosyl)benzimidazole (10) was prepared using 2'-deoxyuridine (7), N-deoxyribofuranosyl transferase and 1d followed by functionalization of the C2 position. Antiviral evaluation of target compounds established that compounds 3b and 3c were active against human cytomegalovirus (HCMV) at non-cytotoxic concentrations. The activity of these 2-deoxy ribosides, however, was less than the activity of the parent riboside, 2,5,6-trichloro-1-beta-D-ribofuranosylbenzimidazole (TCRB). Compared to TCRB, 3b and 3c were somewhat more cytotoxic and active against herpes simplex virus type 1. Compounds 3d-i with other substituents in the 2-position were inactive against both viruses and non-cytotoxic. In contrast, compounds with amine substituents in the 2-position (5, 6, 10) were active against HCMV albeit less so than TCRB. These results establish that 2-deoxy-D-ribosyl benzimidazoles are less active against the DNA virus HCMV than are the corresponding D-ribosides.     

Increased mutagenicity of some nitroimidazoles by non-mutagenic nitrotoluene on Klebsiella pneumoniae (fluctuation test).

In the fluctuation test the mutation frequency of Klebsiella pneumoniae by the 5-nitroimidazoles panidazole and dimetridazole was increased by adding the non-mutagenic substances 4-nitrotoluene or toluene-4-sulfonamide. This effect was not found with 1-methyl-5-nitroimidazole, metronidazole, ronidazole, nimorazole and 1-methyl-2-hydroxymethyl-5-nitroimidazole. It is suggested that the molecules of panidazole or dimetridazole form some association, which is destroyed by 4-nitrotoluene or toluene-4-sulfonamide, thus increasing the concentration of mutagenic particles.     

Design, synthesis, and structure-activity relationships of a series of 2-Ar-8-methyl-5-alkylaminoquinolines as novel CRF(1) receptor antagonists

We designed and synthesized a series of 2-Ar-8-methyl-5-alkylaminolquinolines as potent corticotropin-releasing factor 1 (CRF(1)) receptor antagonists. The structure-activity relationships of substituents at each position (R(3), R(5), R(5'), and R(8)) was investigated. By derivatization, three compounds (6, 14b, and 14c) were identified as orally active CRF(1) receptor antagonists.     

Chromosomal Breakage in the B. fragilis Group Induced by Metronidazole Treatment

Metronidazole is used in clinical practice for the treatment of protozoan and anaerobic infections. Under anaerobic conditions, 5-nitroimidazoles are reduced to cytotoxic nitroradicals which have been shown to act by non-specific binding to, and inactivation of the organism's DNA and enzymes. Among anaerobes, the Bacteroides fragilis group is the most relevant both in terms of frequency of isolation and antimicrobial resistance. In the present study we investigated the mechanism of action of metronidazole in the B. fragilis group. We evaluated chromosomal DNA integrity in susceptible and resistant strains during a period of 5 h after metronidazole exposure and we quantified the drug remaining in the medium after microbial growth. Metronidazole was not reduced in resistant cells which remained metabolically active and with their entire genetic material throughout the experiment. On the other hand, susceptible cells presented chromosomal breakage, a rapid consumption of dissolved metronidazole and a mortality of 90% of the bacterial population during the first 30 minutes of exposure. This interaction between metronidazole and DNA molecules that suggests strands breakage has been previously demonstrated in cell-free extract and in Escherichia coli cells. Our results show this phenomenon also occurring inBacteroides group what was not previously observed in the literature.     

Development of Satranidazole Mucoadhesive Gel for the Treatment of Periodontitis

The aim of the paper was to develop satranidazole-containing mucoadhesive gel for the treatment of periodontitis. Different mucoadhesive gels were prepared, using various gelling agents like sodium carboxymethylcellulose (SCMC), poloxamer 407, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, and the mucoadhesive polymer carbopol 934P. The selected formulations (based on the mucoadhesive force) were studied for different mechanical properties, such as mucoadhesive strength, hardness, compressibility, adhesiveness, and cohesiveness through Texture Profile Analyzer. In vitro satranidazole release from the prepared formulations was also determined and compared with marketed preparation of metronidazole (Metrogyl® gel). The formulation SC30 (containing SCMC 3% w/v) showed maximum mucoadhesive strength (167.72 ± 3.76 g) and adhesiveness (−46.23 ± 0.34 N mm), with low hardness (9.81 ± 0.04 N) and compressibility (40.05 ± 0.48 N mm) and moderate cohesiveness (0.87 ± 0.01). SC30 formulation exhibited long-term release. Thus, SC30 gel was evaluated for its clinical effectiveness along with marketed metronidazole gel. At the end of the study (42 days of clinical studies), both formulations were found to significantly reduce the probing depth, plaque index, gingival index, calculus criteria, and bleeding index. However, the SC30 gel was more effective in reducing the above parameters than marketed metronidazole gel. This study confirmed the acceptability and effectiveness of satranidazole gel for treatment of periodontitis.Key words: mucoadhesive gel, periodontitis, satranidazole, texture profile analysis     

Electron-Affinic Sensitization VII. A Correlation between Structures, One-Electron Reduction Potentials, and Efficiencies of Nitroimidazoles as Hypoxic Cell Radiosensitizers

Radiosensitization efficiencies for seven different 2-nitroimidazoles including Ro-07-0582 and its urinary metabolite, Ro-05-9963, and two 5-nitroimidazoles including metronidazole, have been determined in hypoxic Chinese Hamster cells, line V79-379A, X-irradiated in vitro. All the compounds were active hypoxic cell sensitizers with the enhancement ratios increasing with drug concentration. The 2-nitroimidazoles were all more efficient than the 5-nitroimidazoles. Overall, the efficiencies, defined as the concentration required to give a particular enhancement ratio, varied by a factor of about 200. Electron-affinities of the sensitizers were determined by pulse radiolysis as the one-electron reduction potentials and these correlate well with the sensitization efficiencies of the compounds. The correlation extends beyond the nitroimidazole series as is shown by data for p-nitroacetophenone, nifuroxime (a nitrofuran) and oxygen itself. The nitroimidazoles varied by a factor of 70 in their octanol/water partition coefficients, but the effect of this parameter on sensitizing efficiency is small compared with the influence of electron affinity.     

Synthesis, antioxidant and toxicological study of novel pyrimido quinoline derivatives from 4-hydroxy-3-acyl quinolin-2-one

A series of novel pyrimido and other fused quinoline derivatives like 4-methyl pyrimido [5,4-c]quinoline-2,5(1H,6H)-dione (4a), 4-methyl-2-thioxo-1,2-dihydropyrimido [5,4-c]quinoline-5(6H)-one (4b), 2-amino-4-methyl-1,2-dihydropyrimido [5,4-c]quinolin-5(6H)-one (4c), 3-methylisoxazolo [4,5-c]quinolin-4(5H)-one (4d), 3-methyl-1H-pyrazolo [4,3-c]quinoline-4(5H)-one (5e), 5-methyl-1H-[1,2,4] triazepino [6,5-c]quinoline-2,6(3H,7H)-dione (5f), 5-methyl-2-thioxo-2,3-dihydro-1H-[1,2,4]triazepino [6,5-c]quinolin-6(7H)-one (5 g) were synthesized regioselectively from 4-hydroxy-3-acyl quinolin-2-one 3. They were screened for their in vitro antioxidant activities against radical scavenging capacity using DPPH(), Trolox equivalent antioxidant capacity (TEAC), total antioxidant activity by FRAP, superoxide radical (O(2)(°-)) scavenging activity, metal chelating activity and nitric oxide scavenging activity. Among the compounds screened, 4c and 5 g exhibited significant antioxidant activities.     

Synthesis of 6-arylvinyl analogues of the HIV drugs SJ-3366 and Emivirine

This paper reports the synthesis and the antiviral activities of a series of 6-arylvinyl substituted analogues of SJ-3366, a highly potent agent against HIV. The objective was to investigate whether substitution of the 6-arylketone with a 6-arylvinyl group could lead to an improved antiviral activity against HIV-1. The most active compounds 1-ethoxymethyl, 1-(2-propynyloxymethyl), and 1-(2-methyl-3-phenylallyloxymethyl) substituted 6-[1-(3,5-dimethylphenyl)vinyl]-5-ethyl-1H-pyrimidine-2,4-dione (5b, 16, and 18) showed activities against HIV-1 wild type in the range of Efavirenz, and moderate activities against Y181C and Y181C+K103N mutant strains were also observed.     

Synthesis, structure, and bioactivity of N'-substituted benzylidene-3,4,5-trimethoxybenzohydrazide and 3-acetyl-2-substituted phenyl-5-(3,4,5-trimethoxyphenyl)-2,3-dihydro-1,3,4-oxadiazole derivatives

Some 3-acetyl-2-substituted phenyl-5-(3,4,5-trimethoxyphenyl)-2,3-dihydro-1,3,4-oxadiazole derivatives were synthesized by cyclization reaction of N'-substituted benzylidene-3,4,5-trimethoxybenzohydrazide in acetic anhydride. Their structures were verified by elemental analysis, IR, (1)H NMR, and (13)C NMR. Compound 3i was provided with X-ray crystallographic data. The compounds were evaluated for their antiproliferative activities against some cancer cells in vitro by MTT method. Among them, 2a, 2b, 2c, 2f, 3l, and 3m were highly effective against PC3 cells and 2a, 2c, and 2f showed moderate activities against Bcap37 and BGC823 cells. The IC(50) values of high active compounds 2a, 2b, 2c, 2f, 3l, and 3m against PC3 cells were 0.2, 1.8, 0.2, 1.2, 1.7, and 0.3muM, respectively.     

Validation of a method for the detection and confirmation of nitroimidazoles and corresponding hydroxy metabolites in turkey and swine muscle by means of gas chromatography–negative ion chemical ionization mass spectrometry

The results of a validation study of a GC–NCI–MS method for the quantitative determination of 5-nitroimidazoles {1,2-Dimethyl-5-nitroimidazole (dimetridazole, DMZ), 1-methyl-2-[(carbamoyloxy)methyl]-5-nitroimidazole (ronidazole, RNZ), 1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole (metronidazole, MNZ) and 2-isopropyl-1-methyl-5-nitroimidazole (ipronidazole, IPZ)} including the hydroxy metabolites of these agents {2-hydroxymethyl-1-methyl-5-nitroimidazole (HMMNI), 1-(2-hydroxyethyl)-2-hydroxymethyl-5-nitroimidazole (MNZOH), and 1-methyl-2-(2′-hydroxyisopropyl)-5-nitroimidazole (IPZOH)} in turkey and swine muscle are presented. The validation was carried out according to the requirements of the draft for the revision of Commission Decision 93/256/EC, which is expected to be adopted by the European Commission in due course. The determination of the method’s performance parameters revealed decision limits (CC_α) between 0.65 and 2.8 μg/kg for DMZ, RNZ/HMMNI, MNZ and MNZOH. Confirmatory analyses according to the requirements of the forthcoming EC decision are possible for all analytes except for IPZ and IPZOH where already the decision limits (CC_α) were higher (5.2 μg/kg) than for the above-mentioned nitroimidazoles. The within-laboratory reproducibility and the mean recovery were in an acceptable range for all analytes.     

Absence of genotoxic effects of metronidazole and two of its urinary metabolites on human lymphocytes in vitro.

The antiprotozoan agent metronidazole (1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole) and two of its major human urinary excretion products, 2-methyl-5-nitromidazole-1-yl acetic acid and 1-(2-hydroxyethyl)-2-hydroxymethyl-5-nitroimidazole were tested for genotoxic activity in human lymphocytes in vitro by analysis of chromosome aberrations, sister-chromatid exchanges and DNA-repair synthesis. The positive control compounds methyl methanesulphonate (MMS) and nitrogen mustard (HN2) showed significant genotoxic activity in these tests. No such activity of metronidazole and its two metabolites was detected in concentrations up to 1000 microgram/ml (5.8 X 10(-3) M). Nor did these 3 compounds influence DNA-repair synthesis induced by MMS and HN2. These results suggest that metronidazole, 2-methyl-5-nitroimidazole-1-yl acetic acid and 1-(2-hydroxyethyl)-2-hydroxymethyl-5-nitroimidazole have no direct genotoxic effect on human lymphocytes in vitro.     

Compounds containing 2-substituted imidazole ring for treatment against human African trypanosomiasis

A series of compounds containing 2-substituted imidazoles has been synthesized from imidazole and tested for its biological activity against human African trypanosomiasis (HAT). The 2-substituted 5-nitroimidazoles such as fexinidazole (7a) and 1-[4-(1-methyl-5-nitro-1H-imidazol-2-ylmethoxy)-pyridin-2-yl-piperazine (9e) exhibited potent activity against T. brucei in vitro with low cytotoxicity and good solubility. The presence of the NO₂ group at the 5-position of the imidazole ring in 2-substituted imidazoles is the crucial factor to inhibit T. brucei.     

Synthesis and antimicrobial activity of new 3-(1-R-3(5)-methyl-4-nitroso-1H-5(3)-pyrazolyl)-5-methylisoxazoles

A number of new 3-(1-R-3(5)-methyl-4-nitroso-1H-5(3)-pyrazolyl)-5-methylisoxazoles 6a–g (7b–f) were synthesized and tested for antibacterial and antifungal activity. Some of these compounds displayed antifungal activity at non-cytotoxic concentrations. Derivative 6c was 9 times more potent in vitro than miconazole and 20 times more selective against C. neoformans. 6c was also 8- and 125-fold more potent than amphotericin B and fluconazole, respectively. None of the compounds was active against bacteria. Preliminary structure–activity relationship (SAR) studies showed that the NO group at position 4 of the pyrazole ring is essential for the activity. Lipophilicity of the pyrazole moiety, N-alkyl chain length and planarity of the two heterocyclic rings appear to play a decisive role in modulating cytotoxicity and antifungal activity.     

Electron-capture gas chromatographic assays of 5-nitroimidazole class of antimicrobials in blood

Sensitive and selective electron-capture gas chromatographic methods for the determination of N-1-substituted 5-nitroimidazole class of antiprotozoals from blood are described. Metronidazole, secnidazole and ornidazole having a hydroxyl function in the N-1 substitution, were converted to their respective trimethylsilyl derivatives before chromatography on an OV-11 column. Tinidazole and satranidazole, devoid of the hydroxy group but containing a sulphur atom in the molecule, were chromatographed as such on the same stationary phase. Blood levels as low as 50 ng/ml for all the 5-nitroimidazoles have been measured with good precision. The methods can be readily utilized for pharmacokinetic studies.     

Natural daucane sesquiterpenes with antiproliferative and proapoptotic activity against human tumor cells

Plants of the genera Ferula and Ferulago are known for their complex content in bioactive secondary metabolites such as coumarins, phenylpropanoids, and sesquiterpenes. We used the ground parts of Ferula communis subsp. communis, Ferula glauca subsp. glauca and Ferulago campestris as natural sources for the isolation of four coumarins (CU-1 to CU-4), two phenylpropanoids (PE-1 and PE-2), one polyacetylene (PA-1) and 16 daucane esters (DE-1 to DE-16). The cytotoxic activity of the isolated compounds was evaluated against a panel of seven human tumor cell lines. Fourteen of the daucane derivatives showed antiproliferative activity at least against one of the human tumor cell lines tested, four compounds (DE-5, DE-8, DE-11, and DE-16) were active against all the tested cell lines. Among them DE-11 was the most cytotoxic compound against HeLa (4.4 ± 0.7 μM), A549 (2.8 ± 1.4 μM), HL-60 (2.6 ± 0.4 μM), K562 (26.5 ± 6.0 μM) RS 4;11 (1.7 ± 0.3 μM) and SEM (2.4 ± 0.1 μM) cell lines, while DE-8 was the most active against Jurkat (3.3 ± 0.8 μM). Preliminary structure-activity relationship suggests that the most active compounds in the daucane series present the trans fusion of the penta- and hepta-atomic cycles, and lipophylic ester groups linked to position 6. Isomeric derivatives such as DE-8 and DE-9 or DE-3, DE-4, and DE-5 exhibited significant differences in their IC(50) supporting that the β orientation for the ester group in the position 2 enhances the cytotoxic activity. Furthermore, the pro-apoptotic effect of the most active compounds evaluated in Jurkat cell line showed that these compounds are able to induce apoptosis in a time and concentration-dependent manner. Our findings suggest the potential role of daucane derivatives as models for the development of proapoptotic compounds.     

In vitro activity of oritavancin (LY333328), vancomycin, clindamycin, and metronidazole against Clostridium perfringens, Propionibacterium acnes, and anaerobic Gram-positive cocci

Using an agar dilution method, we determined the in vitro activity of oritavancin, vancomycin, clindamycin and metronidazole against 114 unique clinical isolates of Gram-positive anaerobes. MIC(90)s (microg/mL) for oritavancin were as follows: Clostridium perfringens 1.0, Propionibacterium acnes 0.25, Peptostreptococcus anaerobius 0.25, Peptoniphilus asaccharolyticus 0.5, Finegoldia magna 0.25, Micromonas. micros 0.25, and Anaerococcus prevotii 0.25. On a weight basis, oritavancin is slightly more active than vancomycin against the strains tested. The oritavancin MICs are comparable to those previously reported against staphylococci and enterococci. Oritavancin shows excellent potential for treatment of infections containing Gram-positive anaerobes such as these.     

Development of an obligate anaerobe specific biocide

Summary Anaerobic bacteria, such as sulfate-reducing bacteria and clostridia, are capable of generating H₂S and organic acids which corrode metallurgy resulting in millions of dollars of damage to industry annually. The bacteria are obligate anaerobes which grow typically on equipment surfaces under deposits such as biofilms. A successful method of penetrating biofilm and killing the anaerobic bacteria specifically has not been previously presented. We have investigated whether a blend of 1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole (metronidazole) and a biodispersant would killDesulfovibrio, Desulfotomaculum, andClostridium species grown in the laboratory and in field applications. We found the blend significantly reduced the anaerobes in laboratory cultures. However, in a bioreactor designed to induced a high level of biofilm production and enhance underdeposit growth of anaerobic bacteria, a 40–58% increase in the antibiotic-biodispersant blend concentration was required. The metronidazole blend killed obligate anaerobic bacteria specifically but was non-toxic to aerobic bacteria and fungi. These results were confirmed in cooling tower field trial studies.     

Three isoflavanones with cannabinoid-like moieties from Desmodium canum

Three further derivatives of 5,7,2',4'-tetrahydroxy-6-methyl isoflavanone have been isolated from the root extract of Desmodium canum and assigned the structures 2,3-dihydro-5,7-dihydroxy-6-methyl-3-(1a,2,3,3a,8b,8c-hexahydro-6-hydroxy-1,1,3a-trimethyl-1H-4-oxabenzo[f]cyclobut[c,d]inden-7-yl)-4H-1-benzopyran-4-one (1) 2,3-dihydro-5,7-dihydroxy-6-methyl-3-(6a,7,8,10a-tetrahydro-3-hydroxy-6,6,9-trimethyl-6H-dibenzo[b,d]pyran-2-yl)-4H-1-benzopyran-4-one (2) 2,3-dihydro-5,7-dihydroxy-6-methyl-3-(3-hydroxy-6,6,9-trimethyl-6H-dibenzo[b,d]pyran-2-yl) 4H-1-benzopyran-4-one (3). The three compounds and the previously isolated chromene 4 all derive from the geranylated precursor 5 by a series of cannabinoid-like oxidative rearrangements.     

Metronidazole acid acyl sulfonamide: a novel class of anticancer agents and potential EGFR tyrosine kinase inhibitors

A series of novel metronidazole derivatives were recently reported as potent anticancer agents targeting EGFR and HER-2 by our group [Qian, Y.; Zhang, H. J.; Zhang, H.; Xu, C.; Zhao, J.; Zhu, H. L. Bioorg. Med. Chem.2010, 18, 4991]. Based on the previous results, we designed and synthesized a new series of metronidazole acid acyl sulfonamide derivatives and a new series of phenylacetyl benzenesulfonamide derivatives and their anticancer activities were evaluated as potential EGFR and HER-2 kinase inhibitors. Among all the compounds, compound 12 displayed the most potent inhibitory activity EGFR and HER-2 (IC(50)=0.39 μM for EGFR and IC(50)=1.53 μM for HER-2) and it also showed the most potent growth inhibitory activity against A549 and B16-F10 cancer cell line in vitro, with an IC(50) value of 1.26 μg/mL for A549 and 0.35 μg/mL for B16-F10. Docking simulation was further performed to position compound 12 into the EGFR active site to determine the probable binding model.