Giseli Capaci Rodrigues

Cloning, Characterization, and Sulfonamide and Thiol Inhibition Studies of an α‑Carbonic Anhydrase from Trypanosoma cruzi, the Causative Agent of Chagas Disease

An α-carbonic anhydrase (CA, EC 4.2.1.1) has been identified, cloned, and characterized from the unicellular protozoan Trypanosoma cruzi, the causative agent of Chagas disease. The enzyme (TcCA) has a very high catalytic activity for the CO2 hydration reaction, being similar kinetically to the human (h) isoform hCA II, although it is devoid of the His64 proton shuttle. A large number of aromatic/heterocyclic sulfonamides and some 5-mercapto-1,3,4-thiadiazoles were investigated as TcCA inhibitors. The aromatic sulfonamides were weak inhibitors (K(I) values of 192 nM to 84 μM), whereas some heterocyclic compounds inhibited the enzyme with K(I) values in the range 61.6-93.6 nM. The thiols were the most potent in vitro inhibitors (K(I) values of 21.1-79.0 nM), and some of them also inhibited the epimastigotes growth of two T. cruzi strains in vivo.

Design, synthesis, and evaluation of hydroxamic acid derivatives as promising agents for the management of Chagas disease.

Today, there are approximately 8 million cases of Chagas disease in the southern cone of South America alone, and about 100 million people are living with the risk of becoming infected. The present pharmacotherapy is sometimes ineffective and has serious side effects. Here, we report a series of 4,5-dihydroisoxazoles incorporating hydroxamate moieties, which act as effective inhibitors of the carbonic anhydrase (CA) from Trypanosoma cruzi (TcCA). One compound (5g) was evaluated in detail and shows promising features as an antitrypanosomal agent. Excellent values for the inhibition of growth for all three developmental forms of the parasite were observed at low concentrations of 5g (IC50 values from 7.0 to <1 μM). The compound has a selectivity index (SI) of 6.7 and no cytotoxicity to macrophage cells. Preliminary in vivo data showed that 5g reduces bloodstream parasites and that all treated mice survived; it was also more effective than the standard drug benznidazole.

Hydroxamic acid derivatives: a promising scaffold for rational compound optimization in Chagas disease.

Abstract This work describes the antitrypanocidal activity of two hydroxamic acid derivatives containing o-ethoxy (HAD1) and p-ethoxy (HAD2) as substituent in the aromatic ring linked to the isoxazoline ring. HAD1 and HAD2 induced a significant reduction in the number of intracellular parasites and consequently showed activity on the multiplication of the parasite. Treatment of cardiomyocytes and macrophages with the compounds revealed no significant loss in cell viability. Ultrastructural alterations after treatment of cardiomyocytes or macrophages infected by Trypanosoma cruzi with the IC50 value of HAD1 revealed alterations to amastigotes, showing initial damage seen as swelling of the kinetoplast. This gave a good indication of the ability of the drug to permeate through the host cell membrane as well as its selectivity to the parasite target. Both compounds HAD1 and 2 were able to reduce the cysteine peptidases and decrease the activity of metallopeptidases

Peptidase Inhibitors as a Possible Therapeutic Strategy for Chagas Disease

Chagas disease, caused by Trypanosoma cruzi, is one of the neglected parasitic tropical diseases affecting thir- teen million people annually. At present, there are only two compounds used in the clinical treatment to this disease and they were introduced in the 1960s and 1970s. Nifurtimox and Benznidazole have limited effectiveness and serious side ef- fects. New strategies and targets for an effective chemotherapy for American trypanosomiasis need to be developed. Within this framework, the peptidases have aroused great interest as a chemotherapeutic target against Chagas disease. This is because some T. cruzi peptidases have been implicated, among other processes, in host-parasite interactions and parasitic survival in their hosts like cruzipain (cysteine peptidase) and prolyl oligopeptidase (serine peptidase). Besides, some of these peptidases are expressed in all life cycle stages of the parasite and it is essential for replication of the intra- cellular forms. The inhibition of these enzymes has shown high anti-T. cruzi activity in vitro and in vivo. In this review, we describe some peptidase inhibitors that have potential in the fight against T. cruzi. Emphasis is given to cruzipain in- hibitors and the inhibition mechanism proposed for some them. Among these inhibitors are peptidyl irreversible (halo- methyl ketone, diazomethane ketones and vinyl sulfones derivatives) and reversible (aryl ureas and oxadiazoles deriva- tives) inhibitors, besides non-peptidyl inhibitors (thiosemicarbazones, triazole, triazine nitriles and vinyl sulfones deriva- tives). Some serine peptidase inhibitors are also described (tic-based peptides, prolylprolylisoxazoles and prolylprolyli- soxazolines). Other peptidases, including the metallo-, aspartic and threonine (proteosome) peptidases are discussed and along with blocking cruzipain are targets for future therapeutic strategies.

Trypanosoma cruzi Peptidases: An Overview

Peptidases are a group of enzymes which have a catalytic function that is to hydrolyze peptide bonds of pro- teins. The enzymes that hydrolyze peptide bonds at the amino- or carboxy- terminus are classified as exopeptidases, and those that cleave peptide bonds inside the polypeptide are endopeptidases. Endopeptidases, such as cysteine-, metalo-, ser- ine- and threonine peptidases as well as some exopeptidases, have been characterized in Trypanosoma cruzi. Understand- ing the pathogenesis of T. cruzi requires the identification of functional properties of those peptidases, as they are implied in virulence, are important for host-parasite interactions and are critical for successful survival in their hosts. Here we examine the main T. cruzi peptidases, focusing on their biological roles, especially concerning the parasite-mammalian host relations.

Therapeutic Potential of Hydroxamic Acids for Microbial Diseases

Hydroxamic acid derivatives have recently been recommended for therapeutic treatment of several diseases, such as hypertension, cancer, as well as inflammations and infectious diseases due to their ability to chelate metals, especially in metalloenzymes. This chapter will focus on the role of metallopeptidases and their homologs in microbial diseases and the potential use of hydroxamates and their derivates for the treatment and control of such diseases. A general overview of the structure, synthesis, and inhibition mechanisms of hydroxamates as well as their potential use, including the advantages and relative problems, for medicinal chemistry will be discussed.

Novel Therapeutic Strategies for Chagas` Disease

Chagas’ disease, also called American trypanosomiasis, is one of the most neglected parasitic diseases in the world. An estimated 10 million people are infected worldwide, mostly in Latin America where Chagas disease is endemic. More than 25 million people are at risk of the disease. It is estimated that in 2008 Chagas disease killed more than 10,000 people. Its infectious agent is the protozoan parasite Trypanosoma cruzi with symptoms progressing from mild swelling to intestinal disease and ultimately heart failure. Currently, 2 antiparasitic drugs are recommended for the treatment of chagasic patients: nifurtimox and benznidazole. However, the effectiveness of both varies according to (i) the phase of the disease (acute and early latent infection), (ii) different parasite isolates, (iii) period of treatment and dosage and (iv) age of patient. Also, their well-known toxicity and limited effect make the search for new drugs imperative. Many trypanocidal compounds have been screened in the past few decades and some promising targets have been reported since the introduction of nifurtimox and benznidazole (1960-1970).