Synthesis of chalcone-amidobenzothiazole conjugates as antimitotic and apoptotic inducing agents

A series of chalcone-amidobenzothiazole conjugates (9a-k and 10a,b) have been synthesized and evaluated for their anticancer activity. All these compounds exhibited potent activity and the IC(50) of two potential compounds (9a and 9f) against different cancer cell lines are in the range of 0.85-3.3 μM. Flow cytometric analysis revealed that these compounds induced cell cycle arrest at G2/M phase in A549 cell line leading to caspase-3 dependent apoptotic cell death. The tubulin polymerization assay (IC(50) of 9a is 3.5 μM and 9f is 5.2 μM) and immuofluorescence analysis showed that these compounds effectively inhibit microtubule assembly at both molecular and cellular levels in A549 cells. Further, Annexin staining also suggested that these compounds induced cell death by apoptosis. Moreover, docking experiments have shown that they interact and bind efficiently with tubulin protein. Overall, the current study demonstrates that the synthesis of chalcone-amidobenzothiazole conjugates as promising anticancer agents with potent G2/M arrest and apoptotic-inducing activities via targeting tubulin.     

Treatment with annexin V increases immunogenicity of apoptotic human T-cells in Balb/c mice

Exposure of phosphatidylserine on the outer leaflet of the cytoplasmic membrane is an early event during apoptotic cell death and serves as a recognition signal for phagocytes. Usually the clearance of apoptotic cells does not initiate inflammation or immune response. We investigated the immune response in Balb/c mice towards apoptotic human T-cells. Animals injected with apoptotic cells showed significantly reduced humoral immune responses, especially Th1-dependent IgG2a titres, compared to controls immunised with viable cells. However, treatment of apoptotic cells with annexin V (AxV) significantly increased the humoral immune response. AxV binds with high affinity to anionic phospholipids and as a result interferes with the phosphatidylserine recognition by phagocytes. Our results indicate that AxV treatment may be used to increase the efficiency of apoptotic cell-based vaccines, e.g. some tumour vaccines.     

Antitubulin agents can initiate different apoptotic pathways

The effect of antitubulin agents (Taxol, Vincristine, and Nocodazole) on MCF-7 human breast carcinoma cells was studied. The purpose of the study was to determine the type of death of these cells and the role of p53 protein in this process. The data obtained show that the antitubulin agents can activate not only both subtypes of the mitotic catastrophe (death during mitosis and postmitotic death of polyploid cells) but also death of mononuclear cells. It is assumed that disturbance of the organization of the microtubule system activates the G1 checkpoint in the cell cycle. Apoptosis is activated in a p53-independent manner in K-mitotic cells and after complete microtubule disassembly in interphase cells.     

Antimicrotubule agents can activate different apoptotic pathways

The effect of agents (taxol, vincristine, and nocodazole) disturbing the microtubule network in MCF-7 human breast carcinoma cells has been examined. The aim of the study was to determine the subtypes of mitotic catastrophe and the dependence of cell death on the status of protein p53. Antimicrotubule agents can not only induce mitotic catastrophe, that is, cell death during mitosis and the death of micronucleated cells, but also activate apoptosis in interphase cells. We assume that the G1 checkpoint activation in this case occurs as a result of microtubule disruption. Apoptosis can be activated in a p53-independent manner in K-mitotic cells and after the complete disruption of the microtubule network.     

Guanosine Derivatives as Immunostimulants. Discovery of Loxoribine

Abstract

7-Allyl-8-oxoguanosine (loxoribine, 5) was selected from a series of guanosine derivatives for further evaluation as an immunostimulant. Numerous related analogs were also synthesized and evaluated: 2′,3′-ketals of 5 are particularly interesting because they are active, apparently without being cleaved to the free nucleoside.     

Inhibition of Listeria monocytogenes by fatty acids and monoglycerides.

Fatty acids and monoglycerides were evaluated in brain heart infusion broth and in milk for antimicrobial activity against the Scott A strain of Listeria monocytogenes. C12:0, C18:3, and glyceryl monolaurate (monolaurin) had the strongest activity in brain heart infusion broth and were bactericidal at 10 to 20 micrograms/ml, whereas potassium (K)-conjugated linoleic acids and C18:2 were bactericidal at 50 to 200 micrograms/ml. C14:0, C16:0, C18:0, C18:1, glyceryl monomyristate, and glyceryl monopalmitate were not inhibitory at 200 micrograms/ml. The bactericidal activity in brain heart infusion broth was higher at pH 5 than at pH 6. In whole milk and skim milk, K-conjugated linoleic acid was bacteriostatic and prolonged the lag phase especially at 4 degrees C. Monolaurin inactivated L. monocytogenes in skim milk at 4 degrees C, but was less inhibitory at 23 degrees C. Monolaurin did not inhibit L. monocytogenes in whole milk because of the higher fat content. Other fatty acids tested were not effective in whole or skim milk. Our results suggest that K-conjugated linoleic acids or monolaurin could be used as an inhibitory agent against L. monocytogenes in dairy foods.     

Antisense oligonucleotides as antiviral agents.

Antisense oligonucleotides are an attractive potential alternative to conventional drugs as antiviral agents. A major advantage is the relatively simple rational design of oligonucleotides which should bind only to specific nucleic acid sequences, compared with conventional drugs which are frequently targeted against sites of unknown structure in proteins. Progress to date provides hope for the development of a new class of antiviral chemotherapeutics based on antisense oligonucleotides.     

Antisense oligonucleotides as therapeutic agents.

Antisense oligonucleotides can block the expression of specific target genes involved in the development of human diseases. Therapeutic applications of antisense techniques are currently under investigation in many different fields. The use of antisense molecules to modify gene expression is variable in its efficacy and reliability, raising objections about their use as therapeutic agents. However, preliminary results of several clinical studies demonstrated the safety and to some extent the efficacy of antisense oligodeoxynucleotides (ODNs) in patients with malignant diseases. Clinical response was observed in some patients suffering from ovarian cancer who were treated with antisense targeted against the gene encoding for the protein kinase C-alpha. Some hematological diseases treated with antisense oligos targeted against the bcr/abl and the bcl2 mRNAs have shown promising clinical response. Antisense therapy has been useful in the treatment of cardiovascular disorders such as restenosis after angioplasty, vascular bypass graft occlusion, and transplant coronary vasculopathy. Antisense oligonucleotides also have shown promise as antiviral agents. Several investigators are performing trials with oligonucleotides targeted against the human immunodeficiency virus-1 (HIV-1) and hepatitis viruses. Phosphorothioate ODNs now have reached phase I and II in clinical trials for the treatment of cancer and viral infections, so far demonstrating an acceptable safety and pharmacokinetic profile for continuing their development. The new drug Vitravene, based on a phosphorothioate oligonucleotide designed to inhibit the human cytomegalovirus (CMV), promises that some substantial successes can be reached with the antisense technique.     

Novel coumarin-6-sulfonamides as apoptotic anti-proliferative agents: synthesis,in vitro biological evaluation,and QSAR studies

Herein, we report the synthesis of different novel sets of coumarin-6-sulfonamide derivatives bearing different functionalities (4a, b, 8a–d, 11a–d, 13a, b, and 15a–c), and in vitro evaluation of their growth inhibitory activity towards the proliferation of three cancer cell lines; HepG2 (hepatocellular carcinoma), MCF-7 (breast cancer), and Caco-2 (colon cancer). HepG2 cells were the most sensitive cells to the influence of the target coumarins. Compounds 13a and 15a emerged as the most active members against HepG2 cells (IC₅₀?=?3.48?±?0.28 and 5.03?±?0.39?µM, respectively). Compounds 13a and 15a were able to induce apoptosis in HepG2 cells, as assured by the upregulation of the Bax and downregulation of the Bcl-2, besides boosting caspase-3 levels. Besides, compound 13a induced a significant increase in the percentage of cells at Pre-G1 by 6.4-folds, with concurrent significant arrest in the G2-M phase by 5.4-folds compared to control. Also, 13a displayed significant increase in the percentage of annexin V-FITC positive apoptotic cells from 1.75–13.76%. Moreover, QSAR models were established to explore the structural requirements controlling the anti-proliferative activities.     

Resistance of the suppressor function of T-cells to agents possessing an antiproliferative action]

Administration of cyclophosphamide in a dose of 50 to 400 mg/kg to mice immunized with sheep red blood cells failed to decrease significantly the capacity of the splenic cells of these mice to suppress the primary immune response in transplantation to intact syngeneic recipients. Irradiation of the donors of immune splenic cells (ISC) in a dose of 900 r or treatment of ISC in vitro with mitomycin C failed to influence their suppressor activity. Supernatant obtained after the ultracentrifugation of ISC treated with ultrasound inhibited the primary immune response of intact mice. A conclusion was drawn that the suppressor effect of ISC was caused by the factor produced by T-cells. Active proliferation of these cells was not necessary for the realization of its action.     

Selenazolidines as novel organoselenium delivery agents.

Two new classes of selenazolidine-4(R)-carboxylic acids (2-oxo and 2-methyl-SCAs) were synthesized and characterized. Both were designed as latent forms of selenocysteine, intended to provide a chemically superior delivery form for selenium. The prodrugs may be clinically useful when selenium supplementation at supranutritional levels is indicated, such as in cancer chemoprevention.     

Oligonucleotide-peptide conjugates as potential antisense agents.

Oligonucleotide-peptide conjugates have several applications, including their potential use as improved antisense agents for interfering with the RNA function within cells. In order to provide robust and generally applicable conjugation chemistry, we developed a novel approach of fragment coupling of pre-synthesized peptides to the 2'-position of a selected nucleotide within an otherwise protected oligonucleotide chain attached to a solid support.     

Peptide nucleic acids as therapeutic agents.

Peptide nucleic acids (PNAs) have been around for more than seven years and it was hoped, at their introduction, that they would quickly enter the fields of antisense and antigene technology and drug development. Despite their extremely favorable hybridization and stability properties, as well as the encouraging antisense and antigene activity of PNA in cell-free systems, progress has been slow and experiments on cells in culture and in animals have been lacking. Judging from the very promising results published within the past year, however, there is every reason to believe that both PNA antisense and, possibly, PNA antigene research will strongly pick up momentum again. Specifically, it has been demonstrated that certain peptide-PNA conjugates are taken up very efficiently by, at least some, eukaryotic cells and that antisense down regulation of target genes in nerve cells in culture is attainable using such PNA conjugates. Perhaps even more exciting is that antisense-compatible effects have been reported using PNAs injected into the brain of rats. Finally, it has been shown that the bacterium Escherichia coli is susceptible to antisense gene regulation using PNA.     

Gangliosides as apoptotic signals in ER stress response

Renewed attention has been given lately to gangliosides and to their function as intracellular messengers of the adaptive responses to stress. Gangliosides are vital components of cell membranes; therefore, deleterious consequences can result from changes in their chemical composition and concentration, that is, membrane dynamics and structure can be altered as can the behavior of other membrane proteins. The importance of gangliosides in human health is evident in neurodegenerative diseases associated with defects in their degradation. As key modulators of intracellular calcium flux, gangliosides are involved in cellular processes downstream of calcium signaling. In this review, we focus on the effect of ganglioside accumulation on the endoplasmic reticulum calcium homeostasis and on the integrity of the mitochondrial membranes. We discuss how these events elicit an apoptotic program that ultimately leads to cell death. Owing to interorganelle crosstalk, these events are not necessarily self-contained, and gangliosides may serve as the common factor.