Ján Mojžiš

Spirocyclization strategy toward indole phytoalexins. The first synthesis of (′)-1-methoxyspirobrassinin, (′)-1-methoxyspirobrassinol, and (′)-1-methoxyspirobrassinol methyl ether

Abstract The first syntheses of cruciferous indole phytoalexins (±)-1-methoxyspirobrassinin, (±)-1-methoxyspirobrassinol, (±)-1-methoxyspirobrassinol methyl ether as well as a new syntheses of phytoalexins (±)-spirobrassinin and cyclobrassinin were achieved by dioxane dibromide (DDB)-mediated spirocyclization of brassinin and its 1-substituted derivatives.

2-(Substituted phenyl)amino analogs of 1-methoxyspirobrassinol methyl ether: Synthesis and anticancer activity

New analogs of indole phytoalexin 1-methoxyspirobrassinol methyl ether have been designed by replacement of its 2-methoxy group with 2-(substituted phenyl)amino group. Synthesized by spirocyclization methodology, trans- and cis-diastereoisomers of target compounds were isolated and evaluated as potential anticancer and antimicrobial agents. Their molecular geometries were refined by ab initio minimizations. Pharmacophore modeling and QSAR studies were performed in order to correlate their molecular structure and biological activity.

Hsp90 inhibitor as a sensitizer of cancer cells to different therapies (Review)

Hsp90 is a molecular chaperone that maintains the structural and functional integrity of various client proteins involved in signaling and many other functions of cancer cells. The natural inhibitors, ansamycins influence the Hsp90 chaperone function by preventing its binding to client proteins and resulting in their proteasomal degradation. N- and C-terminal inhibitors of Hsp90 and their analogues are widely tested as potential anticancer agents in vitro, in vivo as well as in clinical trials. It seems that Hsp90 competitive inhibitors target different tumor types at nanomolar concentrations and might have therapeutic benefit. On the contrary, some Hsp90 inhibitors increased toxicity and resistance of cancer cells induced by heat shock response, and through the interaction of survival signals, that occured as side effects of treatments, could be very effectively limited via combination of therapies. The aim of our review was to collect the data from experimental and clinical trials where Hsp90 inhibitor was combined with other therapies in order to prevent resistance as well as to potentiate the cytotoxic and/or antiproliferative effects.

Anticancer Properties of 2-Piperidyl Analogues of the Natural Indole Phytoalexin 1-Methoxyspirobrassinol

Background: Several indole phytoalexins exhibit antiproliferative and/or cancer chemopreventive properties in vitro. However, the potency and selectivity of their anticancer effects were reported to be relatively weak. In order to improve the anticancer activity of the natural phytoalexin 1-methoxyspirobrassinol, its new 2-amino analogues were synthesized and evaluated. Methods:Cis-1-Boc-, trans-1-Boc-, cis-1-methoxy- and trans-1-methoxy-2-deoxy-2-(1-piperidyl)spirobrassinols (compounds 4–7) were synthesized by spirocyclization reaction and their potency evaluated by SRB assay on the NCI60 panel of human cancer cells. The COMPARE program was employed to analyze patterns of activity of compounds 4–7 against the NCI60 panel for prediction of their probable targets and mode of action. Cellular glutathione, a predicted target, was quantified by DTNB assay. Results: Compounds 4–7 exhibit growth inhibitory effects across the NCI60 panel and, consistent with COMPARE prediction, a glutathione-depleting effect on MCF-7 cells. Conclusion: Considering their remarkable glutathione-depleting effects, compounds 4–7 could be developed as radio- and/or chemosensitizing agents for combination cancer chemotherapy.

The synthesis and anticancer activity of analogs of the indole phytoalexins brassinin, 1-methoxyspirobrassinol methyl ether and cyclobrassinin.

An effective synthesis of analogs of the indole phytoalexin cyclobrassinin with NR1R2 group instead of SCH3 was developed starting from indole-3-carboxaldehyde. The target compounds were prepared by spirocyclization of 1-Boc-thioureas with the formation of isolable spiroindoline intermediates, followed by the trifluoroacetic acid-induced cascade reaction consisting of methanol elimination, deprotection and rearrangement of the iminium ion. The structures of novel products were elucided by the (1)H and (13)C NMR spectroscopy, including HMBC, HSQC, COSY, NOESY and DEPT measurements. Several newly synthesized compounds demonstrated significant antiproliferative/cytotoxic activity against human leukemia and solid tumor cell lines, as well as remarkable selectivity of these effects against cancer cells relative to the non-malignant HUVEC cells.

CdS/ZnS nanocomposites: from mechanochemical synthesis to cytotoxicity issues.

CdS/ZnS nanocomposites have been prepared by a two-step solid-state mechanochemical synthesis. CdS has been prepared from cadmium acetate and sodium sulfide precursors in the first step. The obtained cubic CdS (hawleyite, JCPDS 00-010-0454) was then mixed in the second step with the cubic ZnS (sphalerite, JCPDS 00-005-0566) synthesized mechanochemically from the analogous precursors. The crystallite sizes of the new type CdS/ZnS nanocomposite, calculated based on the XRD data, were 3-4 nm for both phases. The synthesized nanoparticles have been further characterized by high-resolution transmission electron microscopy (HRTEM) and micro-photoluminescence (μPL) spectroscopy. The PL emission peaks in the PL spectra are attributed to the recombination of holes/electrons in the nanocomposites occurring in depth associated with Cd, Zn vacancies and S interstitials. Their photocatalytic activity was also measured. In the photocatalytic activity tests to decolorize Methyl Orange dye aqueous solution, the process is faster and its effectivity is higher when using CdS/ZnS nanocomposite, compared to single phase CdS. Very low cytotoxic activity (high viability) of the cancer cell lines (selected as models of living cells) has been evidenced for CdS/ZnS in comparison with CdS alone. This fact is in a close relationship with Cd(II) ions dissolution tested in a physiological solution. The concentration of cadmium dissolved from CdS/ZnS nanocomposites with variable Cd:Zn ratio was 2.5-5.0 μg.mL(-1), whereas the concentration for pure CdS was much higher - 53 μg.ml(-1). The presence of ZnS in the nanocrystalline composite strongly reduced the release of cadmium into the physiological solution, which simulated the environment in the human body. The obtained CdS/ZnS quantum dots can serve as labeling media and co-agents in future anti-cancer drugs, because of their potential in theranostic applications.

Hypocrellin and hypericin-induced phototoxicity of HL-60 cells: apoptosis or necrosis?

Hypericin and hypocrellin are potential antiviral and antineoplastic agents with multiple modes of light-induced biological activity connected with a production of singlet oxygen and/or excited-state proton transfer and consequent pH drop formation in the drugs environment. In present work light-induced cytotoxicity of hypericin and hypocrellin and mechansim of cell death (apoptosis or necrosis) on human leukemic cell line HL-60 was studied. As a mean for apoptosis detection we used poly (ADP-ribose) polymerase (PARP) as a sensitive marker of early stages of apoptosis. Our results show that exposition of HL-60 cells to hypericin (1 x 10(-5) mol x l(-1)) for 4 hours has no effect on PARP cleavage. However, after 24 and 48 hours of illumination there is evident that hypericin in this concentration cleaved PARP (116 kDa) into two fragments (85 and 25 kDa). Contrary to hypericin, hypocrellin in concentration 1 x 10(-5) mol x l(-1) after 4 hours of illumination cleaved PARP into two fragments typical for apoptosis. In lower concentration (1 x 10(-6) mol x l(-1)) hypocrellin possess also significant cytotoxic activity. Because we detected no fragmentation of PARP in all observed time periods we suggest that cytotoxic effect of hypocrellin in this concentration is due to induction of necrosis. Our results support the hypotesis that the hypericin and hypocrellin has similar mechanism of action and illumination increases cytotoxic effect of both agents.

Polymorphisms of the XRCC1 and XPD Genes and Breast Cancer Risk: A Case-Control Study

The purpose of this case control study was to evaluate the role of X-ray repair cross-complementing group 1 (XRCC1) and xeroderma pigmentosum group D (XPD) genotypes as genetic indicators of susceptibility to breast cancer (BC). We analysed DNA samples from 114 breast cancer patients and 113 control subjects using polymerase chain reaction–restriction fragment length polymorphism. For the single nucleotide polymorphisms in XRCC1 exon 10 (Arg399Gln, G/A) and XPD exon 23 (Lys751Gln, A/C), no remarkable differences for genotype distribution and allele frequencies were observed between BC group and control group in the study. The genotype frequency for homozygote A/A in XPD exon 6 (Arg156Arg, C/A) were significantly different between BC and control groups (P < 0.0001, odds ratio = 2.14; 95% confidence interval 1.44–3.17). The data indicate a possible role for XPD (Arg156Arg, C/A) polymorphisms in BC susceptibility.

Synthesis, self-aggregation and biological properties of alkylphosphocholine and alkylphosphohomocholine derivatives of cetyltrimethylammonium bromide, cetylpyridinium bromide, benzalkonium bromide (C16) and benzethonium chloride

A series of alkylphosphocholine and alkylphosphohomocholine derivatives of cetyltrimethylammonium bromide, cetylpyridinium bromide, benzalkonium bromide (C16) and benzethonium chloride have been synthesized. Their physicochemical properties were also investigated. The critical micelle concentration (cmc), the surface tension value at the cmc (γcmc), and the surface area at the surface saturation per head group (Acmc) were determined by means of surface tension measurements. The prepared compounds exhibit significant cytotoxic, antifungal and antiprotozoal activities. Alkylphosphocholines and alkylphosphohomocholines possess higher antifungal activity against Candida albicans in comparison with quaternary ammonium compounds in general. However, quaternary ammonium compounds exhibit significantly higher activity against human tumor cells and pathogenic free-living amoebae Acanthamoeba lugdunensis and Acanthamoeba quina compared to alkylphosphocholines. The relationship between structure, physicochemical properties and biological activity of the tested compounds is discussed.

Young Barley Indicates Antitumor Effects in Experimental Breast Cancer In Vivo and In Vitro.

ABSTRACT The effect of dietary administered young barley containing a mixture of phytochemicals to female rats for the prevention of N-methyl-N-nitrosourea-induced mammary carcinogenesis was evaluated. After carcinogen administration (14 wk), mammary tumors were removed and prepared for histopathological and immunohistochemical analysis. Moreover, in vitro evaluation of possible mechanisms in MCF-7 breast cancer cell line was performed. Barley (0.3%) demonstrated mild antitumor effect in mammary carcinogenesis, yet 3% barley did not further improve this effect. Immunohistochemical analysis of rat tumor cells in treated groups showed significant increase in caspase-3 expression and significant reduction in Ki67 expression. In addition, 3% barley significantly decreased dityrosine levels versus control. Barley in higher dose significantly decreased serum low-density lipoprotein-cholesterol in rats. In vitro studies showed that barley significantly decreased survival of MCF-7 cells in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and significantly decreased 5-bromo-20-deoxyuridine incorporation versus control. Barley prevented cell cycle progression and extended incubation with barley showed significant increase in the percentage of annexin V/propidium iodide-positive MCF-7 cells. Our results propose an antitumor effect for the mixture of phytochemicals present in young barley in a breast cancer model.