Ana M. Bruno

New potent imidazoisoquinolinone derivatives as anti-Trypanosoma cruzi agents: biological evaluation and structure-activity relationships.

A series of novel benzoimidazo and N-aryl-5-oxo-imidazo[1,2-b]isoquinoline-10-carbothioamides was developed. All the compounds were evaluated for their in vitro action against the epimastigote form of Trypanosoma cruzi. Four of them showed higher activity than Nifurtimox. Their unspecific cytotoxicity was evaluated using HeLa and L6 cells, being non-toxic at concentrations at least 15 and 200 times higher than that of T. cruzi IC(50.) To gain insight into the mechanism of action, their DNA binding properties and reactivity with glutathione were studied, and QSAR study was performed.

Study of benzo[a]phenazine 7,12-dioxide as selective hypoxic cytotoxin-scaffold. Identification of aerobic-antitumoral activity through DNA fragmentation

Phenazine 5,10-dioxides are prodrugs for antitumor therapy that undergo hypoxic-selective bioreduction to form cytotoxic species. Here we investigate the expanded system benzo[a]phenazine 7,12-dioxides as selective hypoxic cytotoxin-scaffold. The clonogenic survival of V79 cells on aerobic and anaerobic conditions, conduct us to study antiproliferative activity on Caco-2 tumoral cells in normoxia. Electrochemical, DNA-interaction and DNA-damage studies were performed to establish the mode of action. The results demonstrated the potential biological properties of the studied scaffold being derivatives 6-10 structural hits for further chemical-modifications to become into therapeutics for solid tumors. Compounds 6 and 8 with cytotoxicity against V79 cells in both conditions (aerobia and anaerobia) were also cytotoxic against Caco-2 tumoral cells in aerobiosis.

Diarylsemicarbazones: synthesis, antineoplastic activity and topoisomerase I inhibition assay

A series of diarylsemicarbazones was synthesized and tested against human neoplastic cell lines. The more active members have a l-naphthyl ring at the carbamidic nitrogen, and chloro, dimethylamino or nitro group substituents at the benzylidene moiety. None of these showed affinity to DNA. One of the more active compounds was tested as a topoisomerase I inhibitor and showed a potent effect. SAR studies demonstrated linear correlation between lypophilicity and activity on the most sensitive lines and a definite conformational shape for antineoplastic action.

Synthesis and biological evaluation of 1,2,5-oxadiazole N-oxide derivatives as potential hypoxic cytotoxins and DNA-binders.

Several new 1,2,5‐oxadiazole N‐oxide derivatives were synthesized to be tested both as potential selective hypoxic cell cytotoxins and as DNA‐binding agents. The compounds prepared included bis(1,2,5‐oxadiazole N‐oxide) derivatives and oxadiazole rings linked to naphthyl residues. The compounds were tested for their cytotoxicity in oxia and hypoxia and they proved to be non‐selective and less active than the parent compounds 3‐formyl‐4‐phenyl‐1,2,5‐oxadiazole N2‐oxide (3) and 3‐chloromethyl‐4‐phenyl‐1,2,5‐oxadiazole N2‐oxide (4). The DNA‐affinity assays showed that the compounds tested have poor affinity for this biomolecule.

Design, synthesis, and antitumor activity of new bis-aminomethylnaphthalenes.

A new series of bis-aminomethylnaphthalenes were synthesized in satisfactory overall yield, through a simple synthetic strategy using reductive amination. The DNA binding properties of these compounds have been examined and compared to those of reference drugs using an UV spectroscopy method. The compounds were evaluated for their in vitro anticancer activity and some of them were studied in vivo. Compound 15 exhibited remarkable antitumor activity and represents a novel template for anticancer chemotherapy and can serve as a new lead compound.

Phenazine 5,10-Dioxide Derivatives as Hypoxic Selective Cytotoxins: Part II. Structure-Activity Relationship Studies

The synthesis and evaluation as hypoxic selective cytotoxins of new derivatives of 2-amino or 2-hydroxyphenazine 5,10-dioxide are described. The compounds were developed as structural analogs of other bioreductive compounds and its in vitro cytotoxicities on V79 cells under hypoxic and aerobic conditions were determined. To gain insight into its mechanism of action electrochemical behavior, interaction with DNA experiments and QSAR studies were performed.

EVALUATION OF ANTIPARASITIC, ANTITUBERCULOSIS AND ANTIANGIOGENIC ACTIVITIES OF 3-AMINOQUINOLIN-2-ONE DERIVATIVES

Parasitic infections such as leishmaniasis, trypanosomiasis and malaria have significant impacts in third world countries and are the major reasons of mortality. In order to search a new class of antiprotozoal agent, a series of ten quinolin-2-one derivatives was tested in vitro against the parasites causative of malaria, leishmaniasis, sleeping sickness and Chagas´ disease. In general, these compounds exhibited moderate activity against Plasmodium falciparum and showed no activity against Leishmania donovani, Trypanosoma cruzi and Trypanosoma brucei. Facing to establish a possible mechanism of antimalarial activity their binding to hemin was assayed. Furthermore, the need of developing new therapeutic strategies for the effective control of tuberculosis prompted us to assay twelve of these compounds against Mycobacterium tuberculosis but they did not demonstrate inhibitory activity. In addition, three terms resulted also structurally related to linomide, a recognized drug against angiogenesis, an interesting target for designing new antineoplastic agents. So these compounds were selected at the National Cancer Institute for angiogenesis testing and they exhibited similar activity to those recently reported for linomide and its analogues

Thalidomide analogues: Tumor necrosis factor-alpha inhibitors and their evaluation as anti-inflammatory agents.

A series of related thalidomide derivatives (2-9) were synthesized by microwave irradiation and evaluated for anti-inflammatory activity. Such activity was assessed in vivo and ex vivo. Compounds 2, 8 and 9 showed the highest levels of inhibition of TNF-α production. On rat paw edema and hyperalgesia assays, compound 9, (1,4-phthalazinedione) demonstrated the highest in vivo anti-inflammatory activity. Thus, compound 9 can be considered as a promising compound to be subjected to further modification to obtain new agents for the treatment of inflammatory diseases.

Trypanocidal Activity of Thioamide-Substituted Imidazoquinolinone: Electrochemical Properties and Biological Effects

Three thioamide-substituted imidazoquinolinone, which possess a heterocyclic center similar to tryptanthrin and are named C1, C2, and C3, were studied regarding (a) their in vitro anti-Trypanosoma cruzi activity, (b) their cytotoxicity and electrochemical behaviour, and (c) their effect on cell viability, redox state, and mitochondrial function. The assayed compounds showed a significant activity against the proliferative forms, but only C1 showed activity on the trypomastigote form (for C1, IC50  epi = 1.49 μM; IC50  amas = 1.74 μM; and IC50  try = 34.89 μM). The presence of an antioxidant compound such as ascorbic acid or dithiotreitol induced a threefold increase in the antiparasitic activity, whereas glutathione had a dual effect depending on its concentration. Our results indicate that these compounds, which exhibited low toxicity to the host cells, can be reduced inside the parasite by means of the pool of low molecular weight thiols, causing oxidative stress and parasite death by apoptosis. The antiparasitic activity of the compounds studied could be explained by a loss of the capacity of the antioxidant defense system of the parasite to keep its intracellular redox state. C1 could be considered a good candidate for in vivo evaluation.

Synthesis, 2D-QSAR studies and Biological Evaluation of Quinazoline Derivatives as potent Anti-Trypanosoma cruzi Agents

BACKGROUND Chagas disease affects about 7 million people worldwide. Only two drugs are currently available for the treatment for this parasite disease, namely, benznidazol (Bzn) and nifurtimox (Nfx). Both drugs have limited curative power in the chronic phase of the disease. Therefore, continuous research is an urgent need so as to discover novel therapeutic alternatives. OBJECTIVE The development of safer and more efficient therapeutic anti-T. cruzi drugs continues to be a major goal in trypanocidal chemotherapy. METHOD Synthesis, 2D-QSAR and drug-like physicochemical properties of a set of quinazolinone and quinazoline derivatives were studied as trypanocidal agents. All compounds were screened in vitro against Trypanosoma cruzi (Tulahuen strain, Tul 2 stock) epimastigotes and bloodstream trypomastigotes. RESULTS Out of 34 compounds synthesized and tested, six compounds (5a, 5b, 9b, 9h, 13f and 13p) displayed significant activity against both epimastigotes and tripomastigotes, without exerting toxicity on Vero cells. CONCLUSION The antiprotozoal activity of these quinazolinone and quinazoline derivatives represents an interesting starting point for a medicinal chemistry program aiming at the development of novel chemotherapies for Chagas disease.