Synthesis of New Chiral ß-Carbonyl Selenides with Antioxidant and Anticancer Activity Evaluation-Part I.

A series of unsymmetrical phenyl ß-carbonyl selenides with o-amido function substituted on the nitrogen atom with chiral alkyl groups was obtained. The compounds form a series of enantiomeric and diastereomeric pairs and present the first examples of this type of chiral Se derivatives. All obtained selenides were further evaluated as antioxidants and anticancer agents to define the influence of the particular stereochemistry of the attached functional groups on the bioactivity of the molecules. The highest H2O2 reduction potential was observed for N-(cis-2-hydroxy-1-indanyl)-2-((2-oxopropyl)selanyl)benzamide, and the best radical scavenging properties for N-(-1-hydroxy-2-butanyl)-2-((2-oxopropyl)selanyl)benzamide. Also, both enantiomers of the N-(1-hydroxy-2-butanyl) selenide expressed the highest cytotoxic potential towards human promyelocytic leukemia HL-60 cell line with similar IC50 values 14.4 ± 0.5 and 16.2 ± 1.1 µM, respectively. On the other hand, breast cancer cell line MCF-7 was most sensitive to N-((R)-(-)-1-hydroxy-2-butanyl)- 2-((2-oxopropyl)selanyl)benzamide (IC50 of 35.7 ± 0.6 µM). The structure-activity dependence of the obtained Se derivatives was discussed, and the most potent compounds were selected.

The Influence of Long Carbon Chains on the Antioxidant and Anticancer Properties of N-Substituted Benzisoselenazolones and Corresponding Diselenides.

Organoselenium compounds are well-known for their numerous biocapacities, which result from the uniqueness of the selenium atom and the possibility of constructing heterorganic molecules that can mimic the activity of selenoenzymes, crucial for a multitude of important physiological processes. In this paper, we have synthesized a series of N-substituted benzisoselenazolones and corresponding diphenyl diselenides possessing lipophilic long carbon chains, solely or with additional polar insets: phenyl linkers and ester groups. Evaluation of their antioxidant and cytotoxic activity revealed an increased H2O2-reduction potential of diphenyl diselenides bearing N-octyl, ethyl N-(12-dodecanoate)- and N-(8-octanoate) groups, elevated radical scavenging activity of 2,2'-diselenobis(N-dodecylbenzamide) and a promising cytotoxic potential of N-(4-dodecyl)phenylbenzisoselenazol-3(2H)-one.

New Uracil Analog with Exocyclic Methylidene Group Can Reverse Resistance to Taxol in MCF-7 Cancer Cells.

Introduction: Taxol (Tx), a microtubule-stabilizing drug, has been widely used as a chemotherapeutic in several types of cancer. However, the development of resistance limited its application. One of the strategies used to prevent the emergence of drug resistance is combination treatment, involving at least two drugs. The aim of the current study was to assess if a new uracil analog, 3-p-bromophenyl-1-ethyl-5-methylidenedihydrouracil (U-359) can prevent the development of Tx resistance in breast cancer cells. Methods: The cytotoxicity of the new drug was tested in MCF-7 (hormone receptor (ER, PR) positive cell-line) and MCF-10A cell lines using MTT method. For the detection of apoptosis and necrosis, the Wright and Giemsa staining was used. Gene expression was measured by real-time PCR, and changes in the protein levels were evaluated by ELISA and bioluminescent method. Results: We investigated the effect of Tx and U-359 on cancer MCF-7 and normal MCF-10A cells alone and in combination. Tx co-administered with U-359 inhibited proliferation of MCF-7 cells to 7% while the level of ATPase drastically decreased to 14%, compared with effects produced by Tx alone. The apoptosis process was induced through the mitochondrial pathway. These effects were not seen in MCF-10A cells, showing the wide safety margin. The obtained results have shown that U-359 produced a synergistic effect with Tx probably by reducing Tx resistance in MCF-7 cells. To elucidate the possible mechanism of resistance, expression of tubulin III (TUBIII), responsible for microtubule stabilization and tau and Nlp proteins, responsible for microtubule dynamics, was assessed. Conclusion: Combination of Tx with U-359 reduced overexpression of TUBIII and Nlp. Thus, U-359 may stand for a potential reversal agent for the treatment of MDR in cancer cells.

Attachment of Chiral Functional Groups to Modify the Activity of New GPx Mimetics.

A series of new chiral benzisoselenazol-3(2H)-ones and their corresponding diselenides bearing an o-amido function substituted on the nitrogen atom with various aliphatic and aromatic moieties were synthesized. All derivatives representing pairs of enantiomers or diastereoisomers were obtained to thoroughly evaluate the three-dimensional structure-activity correlation. First, bensisoselenazol-3(2H)-ones were synthesized by reacting 2-(chloroseleno)benzoyl chloride with an appropriate enantiomerically pure amine. Then, the Se-N bond was cleaved by a reduction-oxidation procedure using sodium borohydride and then air oxidation to obtain the corresponding diselenides. All derivatives were tested as antioxidants and anticancer agents. In general, the diselenides were more reactive peroxide scavengers, with the highest activity observed for 2,2'-diselenobis[N-(1S,2S)-(-)-trans-2-hydroksy-1-indanylbezamide]. The most cytotoxic derivative towards human promyelocytic leukemia HL-60 and breast cancer MCF-7 cell lines was N-[(1S,2R)-(-)-cis-2-hydroksy-1-indanyl]-1,2-benzizoselenazol-3(2H)-one. The structure-activity relationship of the obtained organoselenium derivatives was discussed.

A New Hybrid δ-Lactone Induces Apoptosis and Potentiates Anticancer Activity of Taxol in HL-60 Human Leukemia Cells.

In the search for new drug candidates, researchers turn to natural substances isolated from plants which may be either used directly or may serve as a source for chemical modifications. An interesting strategy in the design of novel anticancer agents is based on the conjugation of two or more biologically active structural motifs into one hybrid compound. In this study, we investigated the anticancer potential of 4-benzyl-5,7-dimethoxy-4-methyl-3-methylidene-3,4-dihydro-2H-chroman-2-one (DL-247), a new hybrid molecule combining a chroman-2-one skeleton with an exo-methylidene bond conjugated with a carbonyl group, in human myeloid leukemia HL-60 cell line. The cytotoxicity of the new compound was tested using MTT assay. The effect of DL-247 on cell proliferation and apoptosis induction were studied by flow cytometry, fluorometric assay and ELISA analysis. DL-247 displayed high cytotoxic activity (IC50 = 1.15 µM, after 24 h incubation), significantly inhibited cell proliferation and induced apoptosis by both, the intrinsic and extrinsic pathways. A combination of DL-247 with taxol exhibited a strong synergistic effect on DNA damage generation, apoptosis induction and inhibition of cell growth.

New uracil analog U-332 is an inhibitor of NF-κB in 5-fluorouracil-resistant human leukemia HL-60 cell line.

BACKGROUND: 5-Fluorouracil (5-FU) is an antimetabolite that interferes with DNA synthesis and has been widely used as a chemotherapeutic drug in various types of cancers. However, the development of drug resistance greatly limits its application. Overexpression of ATP-binding cassette (ABC) transporters in many types of cancer is responsible for the reduction of the cellular uptake of various anticancer drugs causing multidrug resistance (MDR), the major obstacle in cancer chemotherapy. Recently, we have obtained a novel synthetic 5-FU analog, U-332 [(R)-3-(4-bromophenyl)-1-ethyl-5-methylidene-6-phenyldihydrouracil], combining a uracil skeleton with an exo-cyclic methylidene group. U-332 was highly cytotoxic for HL-60 cells and showed similar cytotoxicity in the 5-FU resistant subclone (HL-60/5FU), in which this analog almost completely abolished expression of the ATP-binding cassette (ABC) transporter, multidrug resistance associate protein 1 (ABCC1). The expression of ABC transporters is usually correlated with NF-κB activation. The aim of this study was to determine the level of NF-κB subunits in the resistant HL-60/5-FU cells and to evaluate the potential of U-332 to inhibit activation of NF-κB family members in this cell line. METHODS: Anti-proliferative activity of compound U-332 was assessed by the MTT assay. In order to disclose the mechanism of U-332 cytotoxicity, quantitative real-time PCR analysis of the NF-κB family genes, c-Rel, RelA, RelB, NF-κB1, and NF-κB2, was investigated. The ability of U-332 to reduce the activity of NF-κB members was studied by ELISA test. RESULTS: In this report it was demonstrated, using RT-PCR and ELISA assay, that members of the NF-κB family c-Rel, RelA, RelB, NF-κB1, and NF-κB2 were all overexpressed in the 5-FU-resistant HL-60/5FU cells and that U-332 potently reduced the activity of c-Rel, RelA and NF-κB1 subunits in this cell line. CONCLUSIONS: This finding indicates that c-Rel, RelA and NF-κB1 subunits are responsible for the resistance of HL-60/5FU cells to 5-FU and that U-332 is able to reverse this resistance. U-332 can be viewed as an important lead compound in the search for novel drug candidates that would not cause multidrug resistance in cancer cells.

Molecular mechanisms of apoptosis induced by a novel synthetic quinolinone derivative in HL-60 human leukemia cells.

The mortality rates for acute myeloid leukemia are very high, necessitating the search for novel chemotherapeutic candidates. Herein, we investigated the anticancer potential of a new synthetic compound, 2-ethyl-3-methyliden-1-tosyl-2,3-dihydroquinolin-4-(1H)-one (AJ-374) against myeloid leukemia HL-60 cell line. This analog was selected from the small library of synthetic dihydroquinolinones on the basis of its strong antiproliferative activity against HL-60 cells and 30-fold lower cytotoxicity towards healthy HUVEC cells. AJ-374 promoted the arrest of the cells in the subG0/G1 phase of the cell cycle in the first 24 h. Treatment of HL-60 cells with AJ-374 caused an increase in annexin-V positive cells, activation of caspase-8, -9 and -3, dissipation of the mitochondrial membrane potential and enhancement of FAS protein level. Apoptosis induction triggered by this quinolinone was blocked by the pre-treatment of the cells with caspase-8, -9 and -3 inhibitors. The obtained results indicated that AJ-374-induced apoptosis was executed by both, the extrinsic and intrinsic pathways. The cytotoxic activity of AJ-374 was also associated with down-regulation of the mitogen-activated protein kinase (MAPK) pathway and was independent of reactive oxygen species generation. Taken together, these results suggest that AJ-374 exerts a potent anticancer effect on leukemia cells, with a wide safety margin, which makes this analog an attractive drug candidate for further testing.

Seleninic Acid Potassium Salts as Water-Soluble Biocatalysts with Enhanced Bioavailability.

Organoselenium compounds are well-known glutathione peroxidase (GPx) mimetics that possess antioxidants/prooxidant properties and are able to modulate the concentration of reactive oxygen species (ROS), preventing oxidative stress in normal cells or inducing ROS formation in cancer cells leading to apoptosis. The purpose of this study was the synthesis of potent GPx mimics with antioxidant and anticancer activity along with improved bioavailability, as a result of good solubility in protic solvents. As a result of our research, glutathione peroxidase (GPx) mimetics in the form of water-soluble benzeneseleninic acid salts were obtained. The procedure was based on the synthesis of 2-(N-alkylcarboxyamido)benzeneselenenic acids, through the oxidation of benzisoselenazol-3(2H)-ones or analogous arenediselenides with an amido group, which were further converted to corresponding potassium salts by the treatment with potassium tert-butanolate. All derivatives were tested as potential antioxidants and anticancer agents. The areneseleninic acid salts were significantly better peroxide scavengers than analogous acids and the well-known organoselenium antioxidant ebselen. The highest activity was observed for the 2-(N-ethylcarboxyamido)benzeneselenenic acid potassium salt. The strongest cytotoxic effect against breast cancer (MCF-7) and human promyelocytic leukemia (HL-60) cell lines was found for 2-(N-cyclohexylcarboxyamido)benzeneselenenic acid potassium salt and the 2-(N-ethylcarboxyamido)benzeneselenenic acid, respectively. The structure-activity correlations, including the differences in reactivity of benzeneseleninic acids and corresponding salts were evaluated.

New Uracil Analogs with Exocyclic Methylidene Group as Potential Anticancer Agents.

BACKGROUND: Hybrid molecules combining uracil skeleton with methylidene exo-cyclic group were designed in the search for novel anticancer drug candidates. OBJECTIVE: Two series of racemic 5-methylidenedihydrouracils, either 1,3-disubstituted or 1,3,6-trisubstituted were synthesized and tested for their possible cytotoxic activity against two cancer cell lines (HL-60 and MCF-7) and two healthy cell lines (HUVEC and MCF-10A). The most cytotoxic analogs were re-synthesized as pure enantiomers. The analog designated as U-332 [(R)-3-(4-bromophenyl)-1-ethyl-5-methylidene-6-phenyldihydrouracil], which had a very low IC50 value in HL-60 cell line (0.77µM) and was the most selective towards cancer cells was chosen for further experiments on HL-60 cell line, in order to determine the possible mechanism involved in its antineoplastic action. METHODS: Cytotoxic activities of compound was assessed by the MTT assay. In order to explore the mechanism of U-332 activity, we performed quantitative real-time PCR analysis of p53 and p21 genes. Apoptosis, cell proliferation and DNA damage in HL-60 cells were determined using the flow cytometry. The ability of U-332 to determine GADD45ɑ protein level in HL-60 cells incubated with U-332 was analyzed by ELISA test. RESULTS: U-332 was shown to generate excessive DNA damage (70% of the cell population), leading to p53 activation, resulting in p21 down-regulation and a significant increase of GADD45α protein, responsible for the cell cycle arrest in G2/M phase. CONCLUSION: U-332 can be used as a potential lead compound in the further development of novel uracil analogs as anticancer agents.

New uracil analogs as downregulators of ABC transporters in 5-fluorouracil-resistant human leukemia HL-60 cell line.

Overexpression of ATP-binding cassette (ABC) transporters causing multidrug resistance (MDR) in cancer cells is one of the major obstacles in cancer chemotherapy. The 5-FU resistant subclone (HL-60/5FU) of the human HL-60 promyelocytic leukemia cell line was selected by the conventional method of continuous exposure of the cells to the drug up to 0.08 mmol/L concentration. HL-60/5FU cells exhibited six-fold enhanced resistance to 5-FU than HL-60 cells. RT-PCR and ELISA assay showed significant overexpression of MDR-related ABC transporters, ABCB1, ABCG2 but especially ABCC1 in the HL-60/5FU as compared with the parental cell line. Three novel synthetic 5-methylidenedihydrouracil analogs, U-236, U-332 and U-359, selected as highly cytotoxic for HL-60 cells in MTT test, showed similar cytotoxicity in the resistant cell line. When co-incubated with 5-FU, these analogs were found to down-regulate the expression of all three transporters. However, the most pronounced effect was caused by U-332 which almost completely abolished ABCC1 expression in the resistant HL-60/5FU cells. Additionally, U-332 inhibited the activity of ATPase, an enzyme which catalyzes hydrolysis of ATP, providing energy to efflux drugs from the cells through the cellular membranes. Taken together, the obtained data suggest that acquired 5-FU resistance in HL-60/5FU cells results from overexpression of ABCC1 and that targeting ABCC1 expression could be a potential approach to re-sensitize resistant leukemia cells to 5-FU. The synthetic uracil analog U-332, which can potently down-regulate ABC transporter expression and therefore disturb drug efflux, can be considered an efficient ABCC1 regulator in cancer cells.

Bioselectivity Induced by Chirality of New Terpenyl Organoselenium Compounds.

A series of new chiral benzisoselenazol-3(2H)-ones substituted on the nitrogen atom with three monoterpene moieties-p-menthane, pinane and carane-was synthesized. The compounds were obtained by the reaction of 2-(chloroseleno)benzoyl chloride with an appropriate terpene amine, first synthesized by a multistep methodology starting from the corresponding alcohol (p-menthane system) or alkene (pinene and carene systems). Compounds were tested as antioxidants and anticancer agents. The N-isopinocampheyl-1,2-benzisoselenazol-3(2H)-one was the best peroxide scavenger and antiproliferative agent on the human promyelocytic leukemia cell line HL-60. The N-menthyl-1,2-benzisoselenazol-3(2H)-one revealed the highest anticancer potential towards breast cancer line MCF-7. The influence of structure and chirality on the bio-activity of the obtained organoselenium compounds was thoroughly evaluated.