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PubMed2003

The presence of water improves reductive openings of benzylidene acetals with trimethylaminoborane and aluminium chloride.

The acidic reagent formed in situ from anhydrous AlCl(3) and H(2)O in 3:1 ratio is much more efficient for the reductive openings of the cyclic benzylidene acetals with Me(3)N x BH(3) in tetrahydrofurane than the AlCl(3) alone. Under proposed conditions, the dioxane-type 4,6-O-bezylidene acetals of hexopyranosides give regioselectively the corresponding 4-hydroxy,6-O-benzyl derivatives in excellent yields. Reductive openings of the dioxolane-type 3,4-O-benzylidene acetals of galactopyranoside are also very efficient and regioselective and give either 3-O-benzyl derivative (from 3,4-O-exo-benzylidene acetal) or 4-O-benzyl derivative (from 3,4-O-endo-benzylidene acetal) depending on the configuration of the acetal carbon atom.

Acetals↗
PubMed1992

[Synthesis and structure of substituted bromo and nitrobenzyl benzylidene imidazolidinediones and thiazolidinediones].

Synthesis and physico-chemical properties of five bromobenzyl-benzylidene-imidazolidinediones and five nitrobenzyl- or benzyl-benzylidene-thiazolidinediones are described. The microbiological activity of bromobenzyl-benzylidene-imidazolidinediones against microorganisms such as Candida albicans, Neurospora crassa and Mycobacterium smegmatis are evaluated.

Anti-Bacterial Agents↗
PubMed1992

[Synthesis and antimicrobial activity of chlorobenzyl benzylidene imidazolidinedione derivatives and substituted thiazolidinediones].

The synthesis of five chlorobenzyl benzylidene imidazolidinediones and four fluorobenzyl benzylidene thiazolidinediones is described. In order to investigate their antimicrobial activity they are evaluated against microorganism such as Candida albicans, Neurospora crassa, Staphylococcus aureus, Mycobacterium smegmatis and Escherichia coli.

Anti-Bacterial Agents↗
PubMedDate not supplied

Induction of DNA fragmentation in human myelogenous leukemic cell lines by sodium 5,6-benzylidene-L-ascorbate and its related compounds.

High-performance liquid chromatography revealed that sodium 5,6-benzylidene-L-ascorbate (SBA), dissolved in distilled water, was gradually decomposed into ascorbic acid and benzaldehyde. Among these three compounds, ascorbic acid showed the most potent cytotoxic activity. The cytotoxic activity of each compound was significantly reduced during degradation in culture medium. Agarose gel electrophoresis and fluorometric determination of DNA revealed that ascorbic acid, as well as SBA, induced DNA fragmentation into nucleosomal oligomers in human myelogenous leukemic cell lines, but not in freshly isolated human peripheral blood cells. The results suggest that antitumor activity of SBA might be at least in part mediated by the action of ascorbic acid, a degradation product of SBA.

Animals↗
PubMed1975

On the stoichiometry between uncouplers of oxidative phosphorylation and respiratory chains. The catalytic action of SF 6847 (3,5-di-tert-butyl-4-hydroxy-benzylidenemalononitrile).

Titration of State 4 rat-liver mitochondria at pH 7.2 with the uncoupler 3,5-di-tert-butyl-4-hydroxybenzylidenemalononitrile (SF 6847) at various concentrations of mitochondria and using various substrates indicates that under optimal conditions less than 0.2 molecule of 3,5-di-tert-butyl-4-hydroxybenzylidenemalononitrile per respiratory chain is sufficient to induce complete uncoupling. This result suggests that there is not a stoichiometric relationship between uncoupler molecules and cytochrome c oxidase, involved in oxidative phosphorylation, or between the former and phosphorylation assemblies. Experiments on the release by 3,5-di-tert-butyl-4-hydroxybenzylidenemalononitrile of azide-inhibited respiration of State 3 mitochondria and titrations with 5-chloro-3-tert-butyl-2'-chloro-4'-nitrosalicylanilide (S13) of State 4 mitochondria at various mitochondrial concentrations confirm this conclusion.

Aniline Compounds↗
PubMed2006

Caspase-dependent and -independent induction of phosphatidylserine externalization during apoptosis in human renal carcinoma Cak(1)-1 and A-498 cells.

Renal cell carcinoma is the most common neoplasm occurring in the kidney and is largely resistant to current chemotherapy. Understanding the mechanisms involved in renal carcinoma cell death may lead to novel and more effective therapies. In Cak(i)-1 renal cancer cells, using phosphatidylserine externalization as a marker of apoptosis, the anti-cancer drugs 5-fluorouracil (5-FU), and its pro-drugs, doxifluridine (Dox) and floxuridine (Flox) proceeds via a caspase-dependent mechanism. In contrast, phosphatidylserine externalization produced by staurosporine in the renal cancer cell lines Cak(i)-1 and A-498 proceeds via a caspase-independent mechanism. That is, the pan caspase inhibitor N-benzyloxycabonyl-Val-Ala-Asp-fluoromethylketone (ZVAD) did not ameliorate annexin V binding, cell shrinkage or changes in nuclear morphology. Subsequent experiments were conducted to determine mediators of phosphatidylserine externalization, using annexin V binding, when caspases were inhibited. Prior treatment of A-498 cells with cathepsin B (CA74 methyl ester), cathespsin D (pepstatin A) or calpain inhibitors (calpeptin, E64d) in the presence or absence of ZVAD did not ameliorate annexin V binding. The endonuclease inhibitor aurintricarboxylic acid (ATA), phospholipase A(2) inhibitor bromoenol lactone (BEL), protein synthesis inhibitor cycloheximide (CH) and chloride channel blockers niflumic acid (NFA) and 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) all had no effect on staurosporine-induced annexin V binding in A-498 cells either in the presence or absence of ZVAD. We also modulated sphingomyelin and the de novo pathways of ceramide synthesis and found no amelioration of staurosporine-induced annexin V binding in A-498 cells either in the presence or absence of ZVAD. These results indicate that 5-FU, Dox and Flox induce externalization of phosphatidylserine during apoptosis in Cak(i)-1 renal cancer cells primarily through a caspase-dependent mechanism and that externalization of phosphatidylserine during apoptosis produced by staurosporine in the renal cancer cell line A-498 is independent of many of the common signaling pathways known to be involved in this process.

Amino Acid Chloromethyl Ketones↗
PubMed2004

Design and photochemical characterization of a biomimetic light-driven Z/E switcher.

Protonated Schiff bases (PSBs) of polyenals constitute a class of light-driven switchers selected by biological evolution that provide model compounds for the development of artificial light-driven molecular devices or motors. In the present paper, our primary target is to show, through combined computational and experimental studies, that it is possible to approach the design of artificial PSBs suitable for such applications. Below, we use the methods of computational photochemistry to design and characterize the prototype biomimetic molecular switchers 4-cyclopenten-2'-enylidene-3,4-dihydro-2H-pyrrolinium and its 5,5'-dimethyl derivative both containing the penta-2,4-dieniminium chromophore. To find support for the predicted behavior, we also report the photochemical reaction path of the synthetically accessible compound 4-benzylidene-3,4-dihydro-2H-pyrrolinium. We show that the preparation and photochemical characterization of this compound (together with three different N-methyl derivatives) provide both support for the predicted photoisomerization mechanism and information on its sensitivity to the molecular environment.

Biomimetic Materials↗
PubMed2003

Apolipoprotein C-I induces apoptosis in human aortic smooth muscle cells via recruiting neutral sphingomyelinase.

OBJECTIVE: Apolipoprotein C-I (apoC-I) influences lipoprotein metabolism, but little is known about its cellular effects in aortic smooth muscle cells (ASMC). METHODS AND RESULTS: In cultured human ASMC, apoC-I and immunoaffinity purified apoC-I-enriched high-density lipoproteins (HDL) markedly induced apoptosis (5- to 25-fold), compared with control cells, apoC-I-poor HDL, and apolipoprotein C-III (apoC-III) as determined by 4', 6-diamidino-2-phenylindole dihydrochloride staining and DNA ladder assay. Preincubation of cells with GW4869, an inhibitor of neutral sphingomyelinase (N-SMase), blocked apoC-I-induced apoptosis, an effect that was bypassed by C-2 ceramide. The activity of N-SMase was increased 2- to 3-fold in ASMC by apoC-I, apoC-I-enriched HDL, and tumor necrosis factor alpha (TNF-alpha) (positive control) after 10 minutes and then decreased over 60 minutes, which is a kinetic pattern not seen with controls, apoC-III, and apoC-I-poor HDL. ApoC-I and apoC-I-enriched HDL stimulated the generation of ceramide, the release of cytochrome c from mitochondria, and activation of caspase-3 greater than that found in controls, apoC-III, and apoC-I-poor HDL. GW4869 inhibited apoC-I-induced production of ceramide and cytochrome c release. CONCLUSIONS: ApoC-I and apoC-I-enriched HDL activate the N-SMase-ceramide signaling pathway, leading to apoptosis in human ASMC, which is an effect that may promote plaque rupture in vivo.

Aniline Compounds↗
PubMedDate not supplied

Role of hydrogen peroxide in cytotoxicity induction by ascorbates and other redox compounds.

Role of hydrogen peroxide (H2O2) in the induction of cytotoxicity by ascorbic acid derivatives was investigated. Ascorbic acid derivatives which produced radicals (sodium 5,6-benzylidene-L-ascorbate (SBA), sodium-L-ascorbate, D-isoascorbic acid) dose-dependently reduced the viable cell number of human squamous carcinoma (HSC-2, HSC-4, NA), human salivary gland tumor (HSG) and human promyelocytic leukemia (HL-60) cell lines. Conversely, L-ascorbic acid-2-phosphate magnesium which did not produce radicals, was inactive. This suggests the possible role of the ascorbate radical in apoptosis induction. The cytotoxic activity of SBA was partially reduced by catalase, and the extent of inhibition by catalase was considerably different, depending upon which target cells were used. On the other hand, the cytotoxic activity of sodium ascorbate, isoascorbic acid, hydrogen peroxide and gallic acid was more effectively inhibited by catalase. These data suggest that mechanisms other than H2O2 might be involved in the induction of cytotoxicity by SBA.

Antineoplastic Agents↗
PubMed2006

Two new homoisoflavonoids from Caesalpinia pulcherrima.

Two new homoisoflavonoids, (E)-7-methoxy-3-(4'-methoxybenzylidene)chroman-4-one (1) and (E)-7-hydroxy-3-(3',4',5'-trimethoxybenzylidene)chroman-4-one (5), along with three known homoisoflavonoids (Z)-7-hydroxy-3-(4'-methoxybenzylidene)chroman-4-one (isobon ducellin) (2), (E)-7-hydroxy-3-(4'-methoxybenzylidene)chroman-4-one (bonducellin) (3) and (E)-7-hydroxy-3-(2',4'-dimethoxybenzylidene)chroman-4-one (4) were isolated from the whole plant of Caesalpinia pulcherrima. The structures of these new compounds were elucidated by electron impact mass spectrometry (EI-MS) and 1D and 2D-NMR spectral studies. Antimicrobial activity of the new compounds was evaluated.

Anti-Infective Agents↗
PubMed1989

Tyrphostins I: synthesis and biological activity of protein tyrosine kinase inhibitors.

A novel class of low molecular weight protein tyrosine kinase inhibitors is described. These compounds constitute a systematic series of molecules with a progressive increase in affinity toward the substrate site of the EGF receptor kinase domain. These competitive inhibitors also effectively block the EGF-dependent autophosphorylation of the receptor. The potent EGF receptor kinase blockers examined were found to competitively inhibit the homologous insulin receptor kinase at 10(2)-10(3) higher inhibitor concentrations in spite of the significant homology between these protein tyrosine kinases. These results demonstrate the ability to synthesize selective tyrosine kinase inhibitors. The most potent EGF receptor kinase inhibitors also inhibit the EGF-dependent proliferation of A431/clone 15 cells with little or no effect on EGF independent cell growth. These results demonstrate the potential use of protein tyrosine kinase inhibitors as selective antiproliferative agents for proliferative diseases caused by the hyperactivity of protein tyrosine kinases. We have suggested the name "tyrphostins" for this class of antiproliferative compounds which act as protein tyrosine kinase blockers.

Benzylidene Compounds↗
PubMed2005

Systematic identification of antiprion drugs by high-throughput screening based on scanning for intensely fluorescent targets.

Conformational changes and aggregation of specific proteins are hallmarks of a number of diseases, like Alzheimer's disease, Parkinson's disease, and prion diseases. In the case of prion diseases, the prion protein (PrP), a neuronal glycoprotein, undergoes a conformational change from the normal, mainly alpha-helical conformation to a disease-associated, mainly beta-sheeted scrapie isoform (PrP(Sc)), which forms amyloid aggregates. This conversion, which is crucial for disease progression, depends on direct PrP(C)/PrP(Sc) interaction. We developed a high-throughput assay based on scanning for intensely fluorescent targets (SIFT) for the identification of drugs which interfere with this interaction at the molecular level. Screening of a library of 10,000 drug-like compounds yielded 256 primary hits, 80 of which were confirmed by dose response curves with half-maximal inhibitory effects ranging from 0.3 to 60 microM. Among these, six compounds displayed an inhibitory effect on PrP(Sc) propagation in scrapie-infected N2a cells. Four of these candidate drugs share an N'-benzylidene-benzohydrazide core structure. Thus, the combination of high-throughput in vitro assay with the established cell culture system provides a rapid and efficient method to identify new antiprion drugs, which corroborates that interaction of PrP(C) and PrP(Sc) is a crucial molecular step in the propagation of prions. Moreover, SIFT-based screening may facilitate the search for drugs against other diseases linked to protein aggregation.

Animals↗
PubMedDate not supplied

A search for new anticonvulsant compounds among 3-aryl-5-benzylidene derivatives of 2-thiohydantoin.

13 New 3-aryl-5-benzylidene-2-thiohydantoins were obtained by condensation of 3-o-tolyl- and 3-m-tołyl-2--thiohydantoin with aromatic aldehydes. The structure of the obtained compounds was confirmed by IR spectra. Derivatives of 2-thiohydantoin 1-13 show weak anticonvulsant activity in pentetrazole test and show no protecting activity against the maximal electric shock.

Animals↗