Chemical Composition and Biological Activity of Centaurea baseri: New Species from Turkey.

The genus Centaurea L. is one of the largest and important genera of Asteraceae family. Centaurea species have been widely used as herbal remedies in folk medicine for their antidandruff, antidiarrheic, antirheumatic, anti-inflammatory, choleretic, diuretic, digestive, stomachic, astringent, antipyretic, cytotoxic, and antibacterial properties. Centaurea baseri Kose & Alan is a recently described local endemic species in Turkey and this is the first study on the chemical composition and bioactivity of its hydrodistilled essential oil and the crude extract. According to chromatospectral analysis, hexadecanoic acid (42.3%), nonacosane (8.2%), and heptacosane (8.0%) were the main compounds of the essential oil, while 16 compounds were determined in the MeOH extract using LC/MS. Furthermore, antimicrobial, antioxidant, and cytotoxic effects of the essential oil and the extract were evaluated in comparison with the standard agents. The extract showed strong antifungal effect against Candida utilis at the concentration of 60 µg/ml (MIC) where the EO showed growth inhibition at the concentration of 47.00 µg/ml (MIC) against pathogen Bacillus cereus. Both the essential oil and the extract did not show any selective antioxidant properties. The extract showed remarkably selective cytotoxic properties against MCF-7, PANC-1, A549, and C6 glioma cells.

Towards novel anti-tumor strategies for hepatic cancer: ɛ-viniferin in combination with vincristine displays pharmacodynamic synergy at lower doses in HepG2 cells.

Hepatocellular carcinoma is the fifth most common cancer and the third leading cause of cancer-related deaths worldwide. The efficacy of novel combination treatments are increasingly evaluated with use of integrative biology research and development (R&D) strategies and methodological triangulation. We investigated the anti-tumor effect of ɛ-viniferin alone, and the putative synergy of ɛ-viniferin with vincristine on the growth of HepG2 cells in vitro. Growth inhibition and apoptosis induction were determined by MTT assay and annexin V/propidium iodide (PI), respectively. Morphological changes and DNA fragmentation were investigated under electron microscopy and by agarose gel electrophoresis, respectively. The results collectively showed that treating cells with ɛ-viniferin and vincristine significantly inhibited cell viability at lower doses as compared to each agent applied alone. IC(50) values for ɛ-viniferin and vincristine were determined as 98.3 and 52.5 µM at 24 h, respectively. IC(50) value of ɛ-viniferin in combination with vincristine was 15.8+11.25 µM (mean/SD) at 24 h. The viability of cells treated with 17.9 µM vincristine alone for 24 h was 79.62%; it reduced to 26.53% when 25 µM ɛ-viniferin was added in combination with vincristine (p<0.05). We found that combination of drugs promoted the sensitivity of cells against to vincristine treatment. The effect of combined use was in support of a synergistic pharmacodynamic effect. Moreover, low doses of the combination regimen induced phosphatidyl re-localization, morphological changes, and DNA fragmentation, and therefore caused apoptotic death. This study thus suggests that low concentrations of ɛ-viniferin and vincristine can enhance the anti-tumor effects efficiently by inducing HepG2 cell apoptosis. Further studies in other model systems are warranted with a view to potential future applications in the clinic of such combination regimens and their putative mechanism of action in the observed synergy reported here.

Synthesis, anticandidal activity and cytotoxicity of some tetrazole derivatives.

In this study, 14 different 2-[(1-methyl-1H-tetrazole-5-yl)thio]-1-(phenyl)ethanone derivatives (1-14) were synthesized. The structures of the obtained compounds were elucidated using IR, (1)H-NMR, (13)C-NMR and FAB(+)-MS spectral data and elemental analyses results. The compounds were screened for their anticandidal activity using the microbroth dilution method and for their cytotoxic effects using the MTT assay against NIH/3T3 cells. Some of the compounds were found to be potent anticandidal agents with weak cytotoxicities.

Synthesis and anti-Candida activity of novel 2-hydrazino-1,3-thiazole derivatives.

Eighteen new hydrazino-1,3-thiazole derivatives were evaluated against 8 strains of multi-resistant Candida spp. Introduction of an indolyl moiety linked to the hydrazone function enhanced the in vitro anti-Candida activity, with an activity spectrum towards Candida albicans strains. Introduction of a (S)-2-aminoethyl chain on the thiazole nucleus largely enhanced the in vitro antifungal activity, with a selectivity oriented towards non-C. albicans species.

Synthesis and in vitro biological activity of new 4,6-disubstituted 3(2H)-pyridazinone-acetohydrazide derivatives.

New 3(2H)-pyridazinone derivatives containing a N'-benzyliden-acetohydrazide moiety at position 2 were synthesized. The structures of these newly synthesized compounds were confirmed by IR, 1H NMR, and MS data. These compounds were tested for their antibacterial, antifungal, antimycobacterial, and cytotoxic activities. The compounds 2-[4-(4-chlorophenyl)-6-(morpholin-4-yl)-3-oxo-(2H)-pyridazin-2-yl]-N'-(4-tert-butylbenzyliden)acetohydrazide and 2-[4-(4-chlorophenyl)-6-(morpholin-4-yl)-3-oxo-(2H)-pyridazin-2-yl]-N'-(4-chlorobenzyliden) acetohydrazide exhibited activity against both Gram-positive and Gram-negative bacteria. Most of the compounds were active against E. coli ATCC 35218. The preliminary results of this study revealed that some target compounds exhibited promising antimicrobial activities.

Synthesis, antimicrobial activity and cytotoxicity of novel oxadiazole derivatives.

In the present study, 5-substituted-1,3,4-oxadiazolin-2-thiones (1a-b) were synthesized via the ring closure reactions of appropriate acid hydrazides with carbon disulphide. N-(Benzothiazol-2-yl)-2-[[5-substituted-1,3,4-oxadiazol-2-yl]sulfanyl]acetamide derivatives (3a-j) were obtained by the nucleophilic substitution reactions of 5-substituted-1,3,4-oxadiazolin-2-thiones (1a-b) with N-(benzothiazol-2-yl)-2-chloroacetamides. The chemical structures of the compounds were elucidated by IR, (1)H NMR, (13)C NMR and FAB(+)-MS spectral data and elemental analyses. The synthesized compounds were screened for their antimicrobial activities against Micrococcus luteus, Bacillus subtilis, Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, Listeria monocytogenes and Candida albicans. All compounds except compound 3h exhibited the highest antibacterial activity against P. aeruginosa. Among all compounds (3a-j), the compounds bearing 4-methoxyphenoxymethyl moiety on oxadiazole ring (3a-e) exhibited the highest inhibitory activity against C. albicans. Although compound 3j did not possess 4-methoxyphenoxymethyl moiety on oxadiazole ring, this derivative also exhibited the same level of anti-candidal activity. The compounds were also investigated for their cytotoxic effects using MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Compound 3a exhibited the highest cytotoxic activity, whereas compound 3g possessed the lowest cytotoxic activity against NIH/3T3 cells.

Synthesis and anticholinesterase activity and cytotoxicity of novel amide derivatives.

In the present study, some amide derivatives were synthesized and their potential anticholinesterase properties were investigated. N-(Benzothiazol-2-yl)-2-[(5-amino/methyl-1,3,4-thiadiazol-2-yl)thio]acetamide derivatives were obtained by nucleophilic substitution of 2-chloro-N-(benzothiazole-2-yl)acetamide derivatives with appropriate 1,3,4-thiadiazole-2-thioles. The chemical structures of the compounds were elucidated by (1) H-NMR, (13) C-NMR and FAB(+) -MS spectral data and elemental analyses. Each amide derivative was evaluated for its ability to inhibit AChE and BuChE using a modification of Ellman's spectrophotometric method. The compounds were also investigated for their cytotoxic properties using MTT assay. 2-(5-Amino-1,3,4-thiadiazol-2-yl)thio-N-(benzothiazol-2-yl)acetamide derivatives have anticholinesterase activity, whereas 2-(5-methyl-1,3,4-thiadiazol-2-yl)thio-N-(benzothiazol-2-yl)acetamide derivatives have no inhibitory effect on enzyme activity. Among these compounds, it is clear that compound IIh is the most potent derivative.

Anticancer activity of some bisbenzimidazoles.

The discovery of DNA topoisomerases has added a new dimension to the study of anticancer drugs. Bisbenzimidazole derivatives are important compounds known as DNA topoisomerase I inhibitors. In the present study, some symmetrical bisbenzimidazole derivatives were synthesized and investigated for their anticancer activity. Anticancer activity screening was applied on HT-29 (colon carcinoma) and MCF-7 (breast carcinoma) cell lines by investigation of cytotoxicity, analysis of DNA synthesis, and DNA fragmentation assays. One of the seven compounds tested showed significant cytotoxicity in both cell lines and caused DNA degradation in the HT-29 cell line.

Synthesis and anticandidal activity of new triazolothiadiazine derivatives.

New triazolothiadiazine derivatives were synthesized via the ring closure reaction of 4-amino-5-substituted-2,4-dihydro-3H-1,2,4-triazol-3-thiones with phenacyl bromides. The compounds were tested in vitro against various Candida species and compared with ketoconazole. Among these compounds, the compound bearing cyclohexyl moiety and p-chlorophenyl substituent on triazolothiadiazine ring (2i) was found to be the most potent derivative against Candida albicans (ATCC 90028). It is clear that there is a positive correlation between anticandidal activity and two functional moieties, namely cycloaliphatic group and p-chlorophenyl substituent on triazolothiadiazine ring. The compounds were also investigated for their cytotoxic effects using MTT assay. Compound 2a exhibited the highest cytotoxic activity, whereas compound 2f possessed the lowest cytotoxic activity against NIH/3T3 cells.

Synthesis of 2-substituted-N-[4-(1-methyl-4,5-diphenyl-1H-imidazole-2-yl)phenyl]acetamide derivatives and evaluation of their anticancer activity.

In the present study 18 novel imidazole-(benz)azole and imidazole-piperazine derivatives were synthesized in order to investigate their probable anticancer activity. The structures of the compounds were confirmed by IR, (1)H NMR and EI-MS spectral data. Cytotoxicity (MTT), analysis of DNA synthesis and detection of apoptotic DNA assays were applied to determine anticancer activity of the compounds against colon (HT-29) and breast (MCF-7) carcinoma cell lines. Most of the compounds, showed greater activity against HT-29 cells than MCF-7 cells. Some of them indicated considerable cytotoxicity against both of the carcinogenic cell lines. However, their inhibitory activity on DNA synthesis was relatively poor. Anticancer activity screening results revealed that 11, 12 and 13 were the most active compounds in the series. They exhibited significant cytotoxicity against both of the carcinogenic cell lines and caused DNA fragmentation of the HT-29 cells.

Synthesis and antituberculosis activity of new thiazolylhydrazone derivatives.

The increasing clinical importance of drug-resistant mycobacterial pathogens has lent additional urgency to microbiological research and new antimycobacterial compound development. For this purpose, new thiazolylhydrazone derivatives were synthesized and evaluated for antituberculosis activity. The reaction of thiosemicarbazide with acetophenone derivatives gave 1-(1-arylethylidene)thiosemicarbazide (1). The N-(1-arylethylidene)-N'-[4-(indan-5-yl)thiazol-2-yl]hydrazone (3) derivatives were synthesized by reacting 1-(1-arylethylidene)thiosemicarbazide with 1-(5-indanyl)-2-bromoethanone (2). The chemical structure of the compounds was elucidated by elemental analyses, IR, (1)H NMR, MS-FAB(+) spectral data. Antituberculosis activities of the synthesized compounds were determined by broth microdilution assay, the Microplate Alamar Blue Assay, in BACTEC12B medium and the results were screened in vitro, using BACTEC 460 Radiometric System against Mycobacterium tuberculosis H(37)Rv (ATCC 27294) at 6.25 microg/ml and some of the tested compounds showed important inhibition ranging from 92% to 96%. The compounds were also investigated for their cytotoxic properties on normal mouse fibroblast (NIH/3T3) cell line and the results obtained here showed that all the compounds used have no significant cytotoxicity at the concentrations under 50 microg/ml.