Marina Galdino da Rocha Pitta

Synthesis and cytotoxic activity of new acridine-thiazolidine derivatives

Although their exact role in controlling tumour growth and apoptosis in humans remains undefined, acridine and thiazolidine compounds have been shown to act as tumour suppressors in most cancers. Based on this finding, a series of novel hybrid 5-acridin-9-ylmethylene-3-benzyl-thiazolidine-2,4-diones were synthesised via N-alkylation and Michael reaction. The cell viability was analysed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and DNA interaction assays were performed using electrochemical techniques.

Inhibition of DNA topoisomerase I activity and induction of apoptosis by thiazacridine derivatives.

Thiazacridine derivatives (ATZD) are a novel class of cytotoxic agents that combine an acridine and thiazolidine nucleus. In this study, the cytotoxic action of four ATZD were tested in human colon carcinoma HCT-8 cells: (5Z)-5-acridin-9-ylmethylene-3-(4-methylbenzyl)-thiazolidine-2,4-dione - AC-4; (5ZE)-5-acridin-9-ylmethylene-3-(4-bromo-benzyl)-thiazolidine-2,4-dione - AC-7; (5Z)-5-(acridin-9-ylmethylene)-3-(4-chloro-benzyl)-1,3-thiazolidine-2,4-dione - AC-10; and (5ZE)-5-(acridin-9-ylmethylene)-3-(4-fluoro-benzyl)-1,3-thiazolidine-2,4-dione - AC-23. All of the ATZD tested reduced the proliferation of HCT-8 cells in a concentration- and time-dependent manner. There were significant increases in internucleosomal DNA fragmentation without affecting membrane integrity. For morphological analyses, hematoxylin-eosin and acridine orange/ethidium bromide were used to stain HCT-8 cells treated with ATZD, which presented the typical hallmarks of apoptosis. ATZD also induced mitochondrial depolarisation and phosphatidylserine exposure and increased the activation of caspases 3/7 in HCT-8 cells, suggesting that this apoptotic cell death was caspase-dependent. In an assay using Saccharomyces cerevisiae mutants with defects in DNA topoisomerases 1 and 3, the ATZD showed enhanced activity, suggesting an interaction between ATZD and DNA topoisomerase enzyme activity. In addition, ATZD inhibited DNA topoisomerase I action in a cell-free system. Interestingly, these ATZD did not cause genotoxicity or inhibit the telomerase activity in human lymphocyte cultures at the experimental levels tested. In conclusion, the ATZD inhibited the DNA topoisomerase I activity and induced tumour cell death through apoptotic pathways.

Development of Novel Therapeutic Drugs in Humans from Plant Antimicrobial Peptides

All living organisms, ranging from microorganisms to plants and mammals, have evolved mechanisms to actively defend themselves against pathogen attack. A wide range of biological activities have been attributed to plant antimicrobial peptides (AMPs) including growth inhibitory effects on a broad range of fungi, Gram-positive and Gram-negative bacteria, viruses, neoplasic cells and parasitic protozoa. Classes of AMPs, their mechanisms of action, biological activity, and cytotoxicity towards host cells are discussed. A particular focus regards AMP candidates with potential for use in defense against biological warfare agents. This field is young, but provides additional stimulus to consideration of these molecules as a new class of therapeutic agents and promises to revolutionize treatment of many infectious diseases.

Synthesis, DNA binding and topoisomerase I inhibition activity of thiazacridine and imidazacridine derivatives.

Thiazacridine and imidazacridine derivatives have shown promising results as tumors suppressors in some cancer cell lines. For a better understanding of the mechanism of action of these compounds, binding studies of 5-acridin-9-ylmethylidene-3-amino-2-thioxo-thiazolidin-4-one, 5-acridin-9-ylmethylidene-2-thioxo-thiazolidin-4-one, 5-acridin-9-ylmethylidene-2-thioxo-imidazolidin-4-one and 3-acridin-9-ylmethyl-thiazolidin-2,4-dione with calf thymus DNA (ctDNA) by electronic absorption and fluorescence spectroscopy and circular dichroism spectroscopy were performed. The binding constants ranged from 1.46 × 104 to 6.01 × 104 M−1. UV-Vis, fluorescence and circular dichroism measurements indicated that the compounds interact effectively with ctDNA, both by intercalation or external binding. They demonstrated inhibitory activities to human topoisomerase I, except for 5-acridin-9-ylmethylidene-2-thioxo-1,3-thiazolidin-4-one. These results provide insight into the DNA binding mechanism of imidazacridines and thiazacridines.

The Evolution of Drugs on Schistosoma Treatment: Looking to the Past to Improve the Future

Schistosomiasis is a devastating worldwide widespread tropical disease that currently affects more than 230 million people, making it an issue of great socioeconomic and public health importance. Unfortunatelly there is a single drug for the treatment of all forms of schistosomiasis, praziquantel, which was introduced in therapy in 1980. The article goes by antimony compounds, emetine, hydantoin, nitrofurans, lucanthone, hycanthone, oxamniquine derivatives and organophosphates until it finally gets to praziquantel derivatives. The intent of this review is to provide a panorama of drugs that were and are being used in human chemotherapy looking to the past to improve rational design drugs in the future. Not only clinical used compounds will be shown but also synthesized and tested compounds in vitro and in vivo in animal models which havent yet to be used in humans. Prospects for drug discovery and vaccines to be used in the treatment and prevention of schistosomiasis, clinical trials, concerns about the resistance/decreased effectiveness of the treatment, and patent database will also be discussed. At the end of the review the reader will notice that much has been done but much still needs to be done yet.

Synthesis and in vitro anticancer activity of novel thiazacridine derivatives

Acridine derivatives represent a well-known class of anticancer agents that generally interfere with DNA synthesis and inhibit topoisomerase II. A series of eight new 3-acridin-9-ylmethyl-thiazolidine-2,4-dione and 3-acridin-9-ylmethyl-5-arylidene-thiazolidine-2,4-dione derivatives were synthesized. All the compounds were evaluated for their cell antiproliferation activity with the 3-(4,5-dimethyl-2-thiozolyl)-2,5-diphenyl-2H-tetrazolium bromide, MTT assay. The antiproliferative effects of the synthesized compounds were tested against several tumoral cell lines, namely SF-295 (central nervous system), HCT-8 (colon carcinoma), and MDA-MB-435 (melanoma) cells using doxorubicin as a positive control. Among the synthesized compounds, 3-acridin-9-ylmethyl-5-acridin-9-ylmethylene-thiazolidine-2,4-dione, 3-acridin-9-ylmethyl-5-(4-methoxy-benzylidene)-thiazolidine-2,4-dione, and 3-acridin-9-ylmethyl-5-(4-bromo-benzylidene)-thiazolidine-2,4-dione exhibited the most potent anticancer activity against the HCT-8 and MDA-MB-435 cell lines. After a detailed analysis of the structure of the thiazacridine molecules, we revealed the main possible interactions using the compound 3-acridin-9-ylmethyl-5-acridin-9-ylmethylene-thiazolidine-2,4-dione as an example. The benefits of these compounds, regardless of the pharmacological target are the presence of two aromatic rings (pi systems), significant planarity (intercalating ability) and the presence of three hydrogen-bond acceptors, two of which are stronger (oxygen atoms) than the other (sulfur atom).

Synthesis of a Novel Thiazolidinedione and Evaluation of Its Modulatory Effect on IFN-γ, IL-6, IL-17A, and IL-22 Production in PBMCs from Rheumatoid Arthritis Patients

Rheumatoid arthritis (RA) is an autoimmune disease frequently characterized by chronic synovitis of multiple joints. The pathogenesis of RA is complex and involves many proinflammatory cytokines as Th17 related ones. PPARγ is a nuclear receptor activator that represses proinflammatory gene expression. Thus, this work aimed to synthetize a new thiazolidinedione (TZD) analogue based on a well-known anti-inflammatory and PPARγ agonist activity of this ring and evaluate its anti-inflammatory activity. After chemical structure confirmation, the compound named 5-(5-bromo-2-methoxy-benzylidene)-3-(2-nitro-benzyl)-thiazolidine-2,4-dione TM17 was submitted to cytokine releasing inhibition and PPARγ genetic modulation assays. The new compound showed no toxicity on human and murine cells, decreasing IL-6 secretion by murine splenocytes and reducing IL-17A, IL-22, and IFN-γ expression in peripheral blood mononuclear cells from patients with RA. TM17 was more efficient in modulating the mRNA expression of PPARγ than its well-used TZD agonist rosiglitazone. Surprisingly, TM17 was efficient on IL-17A and IFN-γ reduction, like the positive control methylprednisolone, and presented a better effect on IL-22 levels. In conclusion, PBMCs obtained from RA patients under TM17 treatment present a significant reduction in IL-17A, IL-22, and IFN-γ levels, but not IL-6 when compared with nontreated cells, as well as increase PPARγ mRNA expression in absence of stimulus addressing it as a promising molecule in RA treatment.

GQ-16, a TZD-Derived Partial PPARγ Agonist, Induces the Expression of Thermogenesis-Related Genes in Brown Fat and Visceral White Fat and Decreases Visceral Adiposity in Obese and Hyperglycemic Mice

Background Beige adipocytes comprise a unique thermogenic cell type in the white adipose tissue (WAT) of rodents and humans, and play a critical role in energy homeostasis. In this scenario, recruitment of beige cells has been an important focus of interest for the development of novel therapeutic strategies to treat obesity. PPARγ activation by full agonists (thiazolidinediones, TZDs) drives the appearance of beige cells, a process so-called browning of WAT. However, this does not translate into increased energy expenditure, and TZDs are associated with weight gain. Partial PPARγ agonists, on the other hand, do not induce weight gain, but have not been shown to drive WAT browning. The present study was designed to investigate the effects of GQ-16 on BAT and on browning of WAT in obese mice. Methods Male Swiss mice with obesity and hyperglycemia induced by high fat diet were treated with vehicle, rosiglitazone (4 mg/kg/d) or the TZD-derived partial PPARγ agonist GQ-16 (40 mg/kg/d) for 14 days. Fasting blood glucose, aspartate aminotransferase, alanine aminotransferase and lipid profile were measured. WAT and brown adipose tissue (BAT) depots were excised for determination of adiposity, relative expression of Ucp-1, Cidea, Prdm16, Cd40 and Tmem26 by RT-qPCR, histological analysis, and UCP-1 protein expression analysis by immunohistochemistry. Liver samples were also removed for histological analysis and determination of hepatic triglyceride content. Results GQ-16 treatment reduced high fat diet-induced weight gain in mice despite increasing energy intake. This was accompanied by reduced epididymal fat mass, reduced liver triglyceride content, morphological signs of increased BAT activity, increased expression of thermogenesis-related genes in interscapular BAT and epididymal WAT, and increased UCP-1 protein expression in interscapular BAT and in epididymal and inguinal WAT. Conclusion This study suggests for the first time that a partial PPARγ agonist may increase BAT activity and induce the expression of thermogenesis-related genes in visceral WAT. General Significance These findings suggest that PPARγ activity might be modulated by partial agonists to induce WAT browning and treat obesity.

New PPARγ partial agonist improves obesity-induced metabolic alterations and atherosclerosis in LDLr(-/-) mice.

Peroxisome proliferator-activated receptor gamma (PPARγ) regulates multiple pathways involved in the pathogenesis of obesity and atherosclerosis. Here, we evaluated the therapeutic potential of GQ-177, a new thiazolidinedione, on diet-induced obesity and atherosclerosis. The intermolecular interaction between PPARγ and GQ-177 was examined by virtual docking and PPAR activation was determined by reporter gene assay identifying GQ-177 as a partial and selective PPARγ agonist. For the evaluation of biological activity of GQ-177, low-density lipoprotein receptor-deficient (LDLr(-/-)) C57/BL6 mice were fed either a high fat diabetogenic diet (diet-induced obesity), or a high fat atherogenic diet, and treated with vehicle, GQ-177 (20mg/kg/day), pioglitazone (20mg/kg/day, diet-induced obesity model) or rosiglitazone (15mg/kg/day, atherosclerosis model) for 28 days. In diet-induced obesity mice, GQ-177 improved insulin sensitivity and lipid profile, increased plasma adiponectin and GLUT4 mRNA in adipose tissue, without affecting body weight, food consumption, fat accumulation and bone density. Moreover, GQ-177 enhanced hepatic mRNA levels of proteins involved in lipid metabolism. In the atherosclerosis mice, GQ-177 inhibited atherosclerotic lesion progression, increased plasma HDL and mRNA levels of PPARγ and ATP-binding cassette A1 in atherosclerotic lesions. GQ-177 acts as a partial PPARγ agonist that improves obesity-associated insulin resistance and dyslipidemia with atheroprotective effects in LDLr(-/-) mice.

Reduction of carrageenan-induced acute pulmonary inflammation in mice by novel thiazolidinedione derivative LPSF/RA-4.

A number of studies have demonstrated the biological activities of peroxisome proliferator-activated receptors. However, few studies have addressed the effects of the agonists of these receptors on lung diseases. The aim of the present study was to evaluate the anti-inflammatory action of a novel synthetic thiazolidine derivative (5Z)-3-benzyl-5-(1H-indol-3-ylmethylene)-thiazolidine-2,4-dione (LPSF/RA-4) on acute lung inflammation (pleurisy) induced by carrageenan. Forty mice were randomly allocated to the following groups: (I) saline control group (sham); (II) carrageenan (CAR) group; (III) CAR+LPSF/RA-4 group treated with LPSF/RA-4 (60 μmol/kg); and (IV) INDO group treated with indometacin (5mg/kg). Total cell counts and the measure of nitric oxide (NO) were performed in pleural exudates. Lung fragments were processed for light microscopy, transmission electron microscopy, immunohistochemistry and Western blotting. The influx of leucocytes and NO levels were significantly reduced following treatment with LPSF/RA-4 and INDO. Histopathological and ultrastructural analyses of the CAR group revealed evident tissue alterations, such as oedema, infiltrates of inflammatory cells and emphysema. These alterations were significantly reduced in the groups treated with LPSF/RA-4 or INDO. Immunohistochemistry revealed an increase in inflammatory markers (COX-2, iNOS, TNF-α and IL-1β) in the lung tissue of the CAR group, whereas the groups treated with LPSF/RA-4 and INDO exhibited significant reductions in such immunomarkers. Western blot analysis revealed an increased expression of COX-2 and IL-1 in the CAR group, which was reduced by treatment with LPSF/RA-4. The present findings demonstrate the potent anti-inflammatory action of the novel derivative thiazolidinedione LPSF/RA-4 in acute lung injury induced by carrageenan.