Tuberculosis (TB), caused by Mycobacterium tuberculosis, is the world's number one killer among i... more Tuberculosis (TB), caused by Mycobacterium tuberculosis, is the world's number one killer among infectious diseases. The search for new natural products that can act as drugs against TB has received increased attention during the last years. In this work we describe the isolation and identification of the active antimycobacterial principles of the dichloromethane extract from Lippia lacunosa Mart. & Schauer, Verbenaceae. Compounds were evaluated for their in vitro activity against Mycobacterium tuberculosis (susceptible and rifampicin resistant strain) using a redox bioassay. From the dichloromethane extract of L. lacunosa leaves, seven methoxy-flavones named cirsimaritin (1), eupatilin (2), eupatorin (3), salvigenin (4), 3′-O-methyl-eupatorin (5), 3′,7-dimethoxy-5,6,4′-trihydroxyflavone (6), and 7′-O-methylapigenin (7), and one triterpene, named oleanolic acid (8), were isolated. All compounds were found to display antimycobacterial activity against susceptible strain, with MIC ranging from 25 to 200 µg/mL. None of them was active against rifampicin resistant strain. This is the first report in the antimycobacterial activity of 6-substituted flavones, as well as the first report of the occurrence of these substances in L. lacunosa.
Journal of Venomous Animals and Toxins including Tropical Diseases, 2015
Recebido em 13/7/06; aceito em 10/4/07; publicado na web em 5/10/07 Antimycobacterial and cytotox... more Recebido em 13/7/06; aceito em 10/4/07; publicado na web em 5/10/07 Antimycobacterial and cytotoxicity activity of synthetic and natural compounds. Secondary metabolites from Curvularia eragrostidis and Drechslera dematioidea, Clusia sp. floral resin, alkaloids from Pilocarpus alatus, salicylideneanilines, piperidine amides, the amine 1-cinnamylpiperazine and chiral pyridinium salts were assayed on Mycobacterium tuberculosis H37Rv. N-(salicylidene)-2hydroxyaniline was the most effective compound with a minimal inhibitory concentration (MIC) of 8 µmol/L. Dihydrocurvularin was moderately effective with a MIC of 40 μmol/L. Clusia sp. floral resin and a gallocatechin-epigallocatechin mixture showed MIC of 0.02 g/L and 38 µmol/L, respectively. The cytotoxicity was evaluated for N-(salicylidene)-2-hydroxyaniline, curvularin, dihydrocurvularin and Clusia sp. floral resin, and the selectivity indexes were > 125, 0.47, 0.75 and 5, respectively.
Tuberculosis remains a serious public health problem, with nine million cases being reported annu... more Tuberculosis remains a serious public health problem, with nine million cases being reported annually. Treatment with antibiotics is the most effective mechanism to control this disease, although the increase in cases with resistant strains, co-infection with HIV, and the long duration of treatment has established the need to develop new drugs. Here we show the activity of usnic acid against susceptible and resistant Mycobacterium tuberculosis strains and against nontuberculous mycobacteria. Further, we did not identify any contribution of efflux in innate resistance to usnic acid.
Preparation of 2-oxazoline, a versatile intermediate in synthetic chemistry, from carboxylic acid... more Preparation of 2-oxazoline, a versatile intermediate in synthetic chemistry, from carboxylic acids is a classical and useful method. Since 2-oxazolines can be readily re-converted into carboxylic acids, they can be used as a protecting group for carboxylic acids. 3,6) Among various methods employed to convert derivatives of carboxylic acids to the oxazolines, intramolecular dehydrohalogenation of N-(bhaloethyl)amides to give 2-oxazolines is well established. Although the reaction readily takes place by treatment with either base or silver ion, such reactions have not adapted well to the preparation of 2-oxazolines, presumably because of the cumbersome method used to prepare N-(b-haloethyl)amides. For example, they have been prepared by Ritter reaction of nitriles with halohydrins or haloalkenes, 8) chlorination of N-(b-hydroxyethyl)amides with thionyl chloride, 9) and coupling of 2-haloethylammonium salts with acid chlorides 10,11) or acid anhydrides. We report here a simple and general one-pot method to prepare 2-oxazolines from carboxylic acids; the reaction involves dehydrocondensation of carboxylic acids and 2haloethylammonium salts leading to the formation of N-(bhaloethyl)amides, which then can be readily converted into 2-oxazolines by base treatment.
International journal of antimicrobial agents, 2014
of 4,5-dihydro-1H-pyrazoles against Mycobacterium tuberculosis and nontuberculous mycobacteria (2... more of 4,5-dihydro-1H-pyrazoles against Mycobacterium tuberculosis and nontuberculous mycobacteria (2014), http://dx.
RESUMO: "Estudos antimicrobianos preliminares de plantas da floresta ribeirinha do sul do rio Uru... more RESUMO: "Estudos antimicrobianos preliminares de plantas da floresta ribeirinha do sul do rio Uruguai". As doenças infecciosas ainda são uma das principais causas de morte no mundo, sendo de significativa importância o desenvolvimento de novos compostos antimicrobianos contra diferentes microrganismos. As plantas podem ser uma boa fonte para direcionar a busca destes compostos. Neste estudo, 66 extratos de 25 plantas da floresta ribeirinha do sul do Rio Uruguai foram estudados para a atividade antimicrobiana contra o Staphylococcus aureus, Listeria inocua, Escherichia coli, Pseudomonas aeruginosa, Mycobacterium tuberculosis, Aspergillus niger e Candida albicans. Cinqüenta e três destes extratos apresentaram algum tipo de atividade antimicrobiana. Seis (Eugenia mansoni, Eugenia repanda, Myrcianthes cisplatensis, Paullinia ellegans, Petunia sp e Ruprechtia laxiflora) apresentaram atividade contra o Mycobacterium tuberculosis com CIM de 50 µg/mL.
Tuberculosis is still a major health problem worldwide. Although treatment regimens currently ava... more Tuberculosis is still a major health problem worldwide. Although treatment regimens currently available can cure almost all tuberculosis drug susceptible cases, problems such as the length of treatment, the need for multidrug therapy, the emergence of drug resistance, HIV co-infection and persistent Mycobacterium tuberculosis bacilli, stress the need for new anti-tuberculosis drugs. Strategies to search for new anti-tuberculosis drugs involve: screening libraries of small molecules and natural products or the previous identification of targets crucial to the microorganism and the subsequent design of new molecules. Development of new drugs from known compounds having already shown safety and efficacy is an attractive strategy from the economical, pharmaceutical and clinical point of view. Several derivatives of known molecules and new compounds with different targets have been studied with promising preliminary results. Anti-tuberculosis compounds from natural sources have an enormous potential for the development of new drugs, which have shown not only antimicrobial activity per se but also inhibition of the mechanism of resistance (e.g. efflux pumps) or modulation of the immune response (e.g. macrophage stimulation). If these new drugs are going to have an impact in the treatment of the disease they should ideally be active not only against multiplying microorganisms but also against persistent or dormant bacilli. Due to the complexity of the pathology of M. tuberculosis it is unlikely that a single new drug will be enough. This review will discuss strategies for evaluating drug candidates, new targets, new compounds obtained from synthesis and natural sources, and clinical trials that are currently in progress.
Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis, 2011
The present study was carried out to investigate the presence of polymorphism in the N-acetyltran... more The present study was carried out to investigate the presence of polymorphism in the N-acetyltransferase gene of 41 clinical isolates of Mycobacterium tuberculosis, that were resistant to isoniazid (INH) with no mutations in the hot spots of the genes previously described to be involved in INH resistance (katG, inhA and ahpC). We observed single nucleotide polymorphisms (SNPs) in ten of these, including the G619A SNP in five isolates and an additional four so far un-described mutations in another five isolates. Among the latter SNPs, two were synonymous (C276T, n=1 and C375G, n=3), while two more non-synonymous SNPs were composed of C373A (Leu→Met) and T503G (Met→Arg) were observed in respectively one and two isolates. Molecular modeling and structural analysis based in a constructed full length 3D models of wild type TBNAT (TBNAT_H37Rv) and the isoforms (TBNAT_L125M and TBNAT_M168R) were also performed. The refined models show that, just as observed in human NATs, the carboxyl terminus extends deep within the folded enzyme, into close proximity to the buried catalytic triad. Analysis of tbnat that present non-synonymous mutations indicates that both substitutions are plausible to affect enzyme specificity or acetyl-CoA binding capacity. The results contribute to a better understanding of structure-function relationships of NATs. However, further investigation including INH-sensitive strains as a control group is needed to get better understanding of the possible role of these new mutations on tuberculosis control.
In order to gain a better understanding of the molecular epidemiology of Mycobacterium bovis isol... more In order to gain a better understanding of the molecular epidemiology of Mycobacterium bovis isolates in Cameroon, 75 isolates of M. bovis collected in three provinces of northern Cameroon were studied by spoligotyping. For 65 of these isolates, typing was also carried out by pulsed-field gel electrophoresis (PFGE) with DraI, and 18 of the isolates were also typed by restriction fragment length polymorphism (RFLP) analysis with probe IS6110-RHS. Molecular typing of the isolates by these techniques revealed a high degree of homogeneity, with 10 spoligotypes for 75 isolates, four PFGE profiles for 65 isolates, and three RFLP types for 18 isolates. Some types were present in the three different provinces, while some were confined to one or two areas. These results suggest that geographical mapping of M. bovis strains could be helpful for the control of bovine tuberculosis at the regional level. An interesting feature of all the spoligotypes was the absence of spacer 30, suggesting a common origin for all of the Cameroon isolates tested; an evolutionary scenario for the isolates is discussed. In addition, a comparison of the three techniques showed that for M. bovis strain differentiation in Cameroon and in surrounding countries, spoligotyping would be a more discriminating and practical tool for molecular typing than the other two techniques used in this study.
A case of acquired skin fragility syndrome associated with hepatic disease in a 9-year-old, spaye... more A case of acquired skin fragility syndrome associated with hepatic disease in a 9-year-old, spayed female, domestic shorthair cat is described. The cat was admitted to the veterinary hospital of the University of São Paulo (Brazil) with a 6-week history of vomiting, inappetence and weight loss. Remarkable signs were weakness, lethargy and profound jaundice that had been present for 10 days according to the owner. On completion of the physical examination, when the cat was gently manipulated for blood collection the thoracic limb and interscapular skin tore. Liver enzymes and bilirubin levels were all above the normal range. On histological examination of skin and liver, Masson's trichrome stain showed collagen fibre alteration and major hepatocyte abnormalities. Findings were consistent with feline skin fragility syndrome associated with cholangiohepatitis and hepatic lipidosis.
This paper reports the susceptibility profile to rifabutin (RFB) 1 and six recently synthesized R... more This paper reports the susceptibility profile to rifabutin (RFB) 1 and six recently synthesized RFB analogs 3e8, of either rifampicin (RFP) susceptible Mycobacterium tuberculosis and resistant clinical isolates from two sources: Mexico and Brazil. Taking into account that about 95% of M. tuberculosis strains resistant to RFP present mutations in the rpoB gene, with some of these mutations being determinant also to RFB resistance, the RFB analogs were screened for activity against a set of known RFP susceptible and resistant strains. N 0 -Acetyl-RFB 5 and N 0 -(undec-10 00 -enoyl)-RFB 8 showed the best results, in particular with mutations in the codon 516, 522 and 531 of the rpoB gene, and were therefore selected for in vivo assessment of their efficacy. Studies conducted with tuberculous Balb/C mice previously infected with Ser531Leu mutated clinical isolate, evidenced both 5 and 8 as promoters of a significant decrease on tubercle bacilli burden in lungs associated with lower tissue damage, thus confirming them as good leads for drug discovery. The SAR of the acylated compounds 5 and 8 envisaging the identification of pharmacophore features, highlights the importance of profiling more clearly the chemistry within the molecular aspects for elucidation of the mode of action of RFB and analogs, in relation to mutations in Multidrug-Resistant (MDR) strains.
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2007
concentrations of 10 and 100 μg/L arsenic induced significant augment in protein oxidation, this ... more concentrations of 10 and 100 μg/L arsenic induced significant augment in protein oxidation, this last result is in line with the lack of antioxidant response. The amnesic effect and the oxidative stress induced by As suggest that the concentration of this metalloid considered safe by Brazilian legislation needs reevaluation. Supported by CAPES (MRC, LAG), CNPq (DA, JMM, DMB) and FAPERGS (JMM).
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 2008
Three crude extracts of Aplysina caissara, a marine sponge endemic to Brazil, were tested against... more Three crude extracts of Aplysina caissara, a marine sponge endemic to Brazil, were tested against a hepatoma cell line and Mycobacterium tuberculosis. The results demonstrate that all extracts are toxic and capable of inhibiting cellular growth. Additionally, the extracts produced morphological aberrations and inhibited cell attachment to culture substrates. These effects were dose/time dependent. Our results also suggest that reactive oxygen species (ROS) production is not involved in the cytotoxic processes levied by the extracts employed in this study and that active metabolites are likely to be present in the polar fractions of the crude extracts. Finally, our results indicate that all three extracts exhibit a moderate anti-tuberculosis capacity, and that the removal of an extract's lipid fraction appears to diminish this activity.
Tuberculosis remains as a serious infection disease of worldwide distribution, with high morbidit... more Tuberculosis remains as a serious infection disease of worldwide distribution, with high morbidity and mortality, mainly in low socio-economic condition countries. The state of emergency of tuberculosis caused by the resistant and multidrug-resistant (MDR) strains, became the main threat to the tuberculosis treatment and control programs. A fast detection method for the resistant strains will allow the implementation of an adequate treatment and contribute for controlling the dissemination of these resistant strains. This study evaluated the performance of the nitrate reductase assay in solid (NRA-LJ) and liquid (NRA-7H9) media, to determine the susceptibility to first line anti-tuberculosis drugs: isoniazid (INH), rifampicin (RMP), ethambutol (EMB) and streptomycin (SMR). Both methods NRA-LJ and NRA-7H9 were evaluated among 18 strains with a known susceptibility profile. The resazurin microtiter assay (REMA) was performed as a reference method. One hundred percent of accordance was observed between NRA-7H9 and REMA for the four tested drugs. When the NRA-LJ method was compared to REMA, the sensitivity and the specificity to INH, RMP, EMB and SMR were 100%, 100 %, 85.7%, 76.9% and 80%, 100%, 75% and 80%, respectively. From the 57 clinical isolates of M. tuberculosis evaluated by NRA-7H9 and REMA, 56 (98.2%) were sensitive to all antibiotics tested (INH, RMP, EMB and SMR) by the NRA-7H9 method, while three of these strains were resistant to INH by REMA. One strain showed resistance to INH and RMP for both methods, and MIC of 1.0 μg/ml to INH for both methods, while MIC of 1.0 and 2.0 μg/ml to RMP for REMA and NRA-7H9, respectively. The three assays showed a high level of agreement for rapid detection of rifampicin and isoniazid resistance. Regarding rapidness, the detection of color change in the NRA method is within instants as compared to the overnight incubation required for the REMA test. NRA might represent an inexpensive and alternative assay for rapid detection of resistance in low-income countries.
Revista Brasileira de Ciências Farmacêuticas, 2008
Thirty-six plant extracts from the brazilian Atlantic Forest were tested for their antimycobacter... more Thirty-six plant extracts from the brazilian Atlantic Forest were tested for their antimycobacterial activity against Mycobacterium tuberculosis H 37 Rv and M. kansasii, using the method REMA in seriate concentrations of 100 to 0.20 µg/mL. Among the thirty six extracts tested, five were active against M. tuberculosis, and three of these extracts also showed activity against M. kansasii. Cytotoxicity test with VERO cells was performed with the five extracts active against M. tuberculosis. Only the extract of Peschiera affinis was identified as non-toxic in the concentration of 100µg/mL.
A series of amino-5-[(substituted) phenyl]-3-(4-hydroxy-3-methylphenyl)-4,5-dihydro-1H-1-pyrazoly... more A series of amino-5-[(substituted) phenyl]-3-(4-hydroxy-3-methylphenyl)-4,5-dihydro-1H-1-pyrazolylmethanethione were synthesized by the reaction between thiosemicarbazide and chalcones and were tested for their antimycobacterial activity in vitro against Mycobacterium tuberculosis H 37 R v and INH resistant Mycobacterium tuberculosis using bactec method. Among the synthesized compounds, compound (4b), amino-5-(4-chlorophenyl)-3-(4-hydroxy-3-methylphenyl)-4,5-dihydro-1H-1-pyrazolylmethanethione was found to be the most active agent against Mycobacterium tuberculosis H37 Rv (MTB) and INH resistant Mycobacterium tuberculosis (INHR-MTB) with minimum inhibitory concentration of 0.43 µM . When compared to INH-compound (4b) was found to be 1.62 fold and 26.41 fold more active against MTB and INHR-MTB, respectively.
Clinical utility of rifabutin 1 (RBT), a potent antibiotic used in multidrug regimens for tubercu... more Clinical utility of rifabutin 1 (RBT), a potent antibiotic used in multidrug regimens for tuberculosis (TB) as well as for infections caused by Mycobacterium avium complex (MAC), has been hampered due to dose-limiting toxicity. RBT analogs 2-11 were synthesized and evaluated against M. avium 1581 and Mycobacterium tuberculosis susceptible and resistant strains in vitro. A selection of candidates were also assayed against non-replicating persistent (NRP) M. tuberculosis. Subsequent in vivo studies with the best preclinical candidate drugs 5 and 8, in a model of progressive pulmonary tuberculosis of Balb/C mice infected either with H(37)Rv drug-sensible strain or with multidrug resistant (MDR) clinical isolates, resistant to all primary antibiotics including rifampicin, were performed. The results disclosed here suggest that 5 and 8 have potential for clinical application.
Highly active antiretroviral therapy has brought about a substantial improvement in the prognosis... more Highly active antiretroviral therapy has brought about a substantial improvement in the prognosis of HIV/AIDS. In this context, therapy-related body changes (lipodystrophy) gain in importance, in light of the psychological distress they cause and of their association with adherence to treatment. This study analyses patients' self-perception of central fat gain (CFG) and peripheral fat loss (PFL). A total of 457 patients were interviewed in a university outpatient facility for the treatment of adults and adolescents with HIV/AIDS in the city of São Paulo, Brazil, between September and December 2001. Two-thirds of subjects (64.3%) perceived body changes. The self-perception of CFG and PFL was associated with greater schooling. The self-perception of CFG was more frequent among women and in patients who used protease inhibitors for longer periods. The self-perception of PFL was more frequent among older patients, patients who used stavudine for longer periods, and patients who reported a lack of adherence to antiretroviral agents. The quality of affective/social relationships with friends and family was inversely associated with the self-perception of PFL. The evaluation of self-perceived body changes and their determinants in individuals living with HIV/AIDS may help improve provided care. Listening to what patients have to say concerning antiretroviral therapy-related body changes and how they perceive them, as well as including the patient in therapeutic decisions in this regard will contribute towards greater adherence to proposed interventions and towards an improvement in the quality of life.
The increase in both opportunistic mycoses and antimicrobial resistance of pathogenic microorgani... more The increase in both opportunistic mycoses and antimicrobial resistance of pathogenic microorganisms has determined the need to develop new chemotherapies agents. Amazon Forest Plants has been used as natural drug by local people in the treatment of various tropical diseases. The objective of the study is to evaluate the antifungal activity of twenty-eight species of plants extracts belonging to twenty botanical families from the Amazon forest. The minimum inhibitory concentration of the one hundred fourteen crude extracts of dichloromethane, methanol and water were evaluated against three Candida species: Candida albicans, Candida glabrata and Candida parapsilosis. Seventy-four extracts showed activity, with minimum inhibitory concentration between 0.06 and 1mg/mL, against the three species evaluated. The results observed in this study, mainly about the families Arecaceae, Apocynaceae, Salicaceae and Urticaceae, showed that these extracts are promising for the development of new drugs that can be used in the treatment against opportunistic fungal infections.
Tuberculosis (TB), caused by Mycobacterium tuberculosis, is the world's number one killer among i... more Tuberculosis (TB), caused by Mycobacterium tuberculosis, is the world's number one killer among infectious diseases. The search for new natural products that can act as drugs against TB has received increased attention during the last years. In this work we describe the isolation and identification of the active antimycobacterial principles of the dichloromethane extract from Lippia lacunosa Mart. & Schauer, Verbenaceae. Compounds were evaluated for their in vitro activity against Mycobacterium tuberculosis (susceptible and rifampicin resistant strain) using a redox bioassay. From the dichloromethane extract of L. lacunosa leaves, seven methoxy-flavones named cirsimaritin (1), eupatilin (2), eupatorin (3), salvigenin (4), 3′-O-methyl-eupatorin (5), 3′,7-dimethoxy-5,6,4′-trihydroxyflavone (6), and 7′-O-methylapigenin (7), and one triterpene, named oleanolic acid (8), were isolated. All compounds were found to display antimycobacterial activity against susceptible strain, with MIC ranging from 25 to 200 µg/mL. None of them was active against rifampicin resistant strain. This is the first report in the antimycobacterial activity of 6-substituted flavones, as well as the first report of the occurrence of these substances in L. lacunosa.
Journal of Venomous Animals and Toxins including Tropical Diseases, 2015
Recebido em 13/7/06; aceito em 10/4/07; publicado na web em 5/10/07 Antimycobacterial and cytotox... more Recebido em 13/7/06; aceito em 10/4/07; publicado na web em 5/10/07 Antimycobacterial and cytotoxicity activity of synthetic and natural compounds. Secondary metabolites from Curvularia eragrostidis and Drechslera dematioidea, Clusia sp. floral resin, alkaloids from Pilocarpus alatus, salicylideneanilines, piperidine amides, the amine 1-cinnamylpiperazine and chiral pyridinium salts were assayed on Mycobacterium tuberculosis H37Rv. N-(salicylidene)-2hydroxyaniline was the most effective compound with a minimal inhibitory concentration (MIC) of 8 µmol/L. Dihydrocurvularin was moderately effective with a MIC of 40 μmol/L. Clusia sp. floral resin and a gallocatechin-epigallocatechin mixture showed MIC of 0.02 g/L and 38 µmol/L, respectively. The cytotoxicity was evaluated for N-(salicylidene)-2-hydroxyaniline, curvularin, dihydrocurvularin and Clusia sp. floral resin, and the selectivity indexes were > 125, 0.47, 0.75 and 5, respectively.
Tuberculosis remains a serious public health problem, with nine million cases being reported annu... more Tuberculosis remains a serious public health problem, with nine million cases being reported annually. Treatment with antibiotics is the most effective mechanism to control this disease, although the increase in cases with resistant strains, co-infection with HIV, and the long duration of treatment has established the need to develop new drugs. Here we show the activity of usnic acid against susceptible and resistant Mycobacterium tuberculosis strains and against nontuberculous mycobacteria. Further, we did not identify any contribution of efflux in innate resistance to usnic acid.
Preparation of 2-oxazoline, a versatile intermediate in synthetic chemistry, from carboxylic acid... more Preparation of 2-oxazoline, a versatile intermediate in synthetic chemistry, from carboxylic acids is a classical and useful method. Since 2-oxazolines can be readily re-converted into carboxylic acids, they can be used as a protecting group for carboxylic acids. 3,6) Among various methods employed to convert derivatives of carboxylic acids to the oxazolines, intramolecular dehydrohalogenation of N-(bhaloethyl)amides to give 2-oxazolines is well established. Although the reaction readily takes place by treatment with either base or silver ion, such reactions have not adapted well to the preparation of 2-oxazolines, presumably because of the cumbersome method used to prepare N-(b-haloethyl)amides. For example, they have been prepared by Ritter reaction of nitriles with halohydrins or haloalkenes, 8) chlorination of N-(b-hydroxyethyl)amides with thionyl chloride, 9) and coupling of 2-haloethylammonium salts with acid chlorides 10,11) or acid anhydrides. We report here a simple and general one-pot method to prepare 2-oxazolines from carboxylic acids; the reaction involves dehydrocondensation of carboxylic acids and 2haloethylammonium salts leading to the formation of N-(bhaloethyl)amides, which then can be readily converted into 2-oxazolines by base treatment.
International journal of antimicrobial agents, 2014
of 4,5-dihydro-1H-pyrazoles against Mycobacterium tuberculosis and nontuberculous mycobacteria (2... more of 4,5-dihydro-1H-pyrazoles against Mycobacterium tuberculosis and nontuberculous mycobacteria (2014), http://dx.
RESUMO: "Estudos antimicrobianos preliminares de plantas da floresta ribeirinha do sul do rio Uru... more RESUMO: "Estudos antimicrobianos preliminares de plantas da floresta ribeirinha do sul do rio Uruguai". As doenças infecciosas ainda são uma das principais causas de morte no mundo, sendo de significativa importância o desenvolvimento de novos compostos antimicrobianos contra diferentes microrganismos. As plantas podem ser uma boa fonte para direcionar a busca destes compostos. Neste estudo, 66 extratos de 25 plantas da floresta ribeirinha do sul do Rio Uruguai foram estudados para a atividade antimicrobiana contra o Staphylococcus aureus, Listeria inocua, Escherichia coli, Pseudomonas aeruginosa, Mycobacterium tuberculosis, Aspergillus niger e Candida albicans. Cinqüenta e três destes extratos apresentaram algum tipo de atividade antimicrobiana. Seis (Eugenia mansoni, Eugenia repanda, Myrcianthes cisplatensis, Paullinia ellegans, Petunia sp e Ruprechtia laxiflora) apresentaram atividade contra o Mycobacterium tuberculosis com CIM de 50 µg/mL.
Tuberculosis is still a major health problem worldwide. Although treatment regimens currently ava... more Tuberculosis is still a major health problem worldwide. Although treatment regimens currently available can cure almost all tuberculosis drug susceptible cases, problems such as the length of treatment, the need for multidrug therapy, the emergence of drug resistance, HIV co-infection and persistent Mycobacterium tuberculosis bacilli, stress the need for new anti-tuberculosis drugs. Strategies to search for new anti-tuberculosis drugs involve: screening libraries of small molecules and natural products or the previous identification of targets crucial to the microorganism and the subsequent design of new molecules. Development of new drugs from known compounds having already shown safety and efficacy is an attractive strategy from the economical, pharmaceutical and clinical point of view. Several derivatives of known molecules and new compounds with different targets have been studied with promising preliminary results. Anti-tuberculosis compounds from natural sources have an enormous potential for the development of new drugs, which have shown not only antimicrobial activity per se but also inhibition of the mechanism of resistance (e.g. efflux pumps) or modulation of the immune response (e.g. macrophage stimulation). If these new drugs are going to have an impact in the treatment of the disease they should ideally be active not only against multiplying microorganisms but also against persistent or dormant bacilli. Due to the complexity of the pathology of M. tuberculosis it is unlikely that a single new drug will be enough. This review will discuss strategies for evaluating drug candidates, new targets, new compounds obtained from synthesis and natural sources, and clinical trials that are currently in progress.
Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis, 2011
The present study was carried out to investigate the presence of polymorphism in the N-acetyltran... more The present study was carried out to investigate the presence of polymorphism in the N-acetyltransferase gene of 41 clinical isolates of Mycobacterium tuberculosis, that were resistant to isoniazid (INH) with no mutations in the hot spots of the genes previously described to be involved in INH resistance (katG, inhA and ahpC). We observed single nucleotide polymorphisms (SNPs) in ten of these, including the G619A SNP in five isolates and an additional four so far un-described mutations in another five isolates. Among the latter SNPs, two were synonymous (C276T, n=1 and C375G, n=3), while two more non-synonymous SNPs were composed of C373A (Leu→Met) and T503G (Met→Arg) were observed in respectively one and two isolates. Molecular modeling and structural analysis based in a constructed full length 3D models of wild type TBNAT (TBNAT_H37Rv) and the isoforms (TBNAT_L125M and TBNAT_M168R) were also performed. The refined models show that, just as observed in human NATs, the carboxyl terminus extends deep within the folded enzyme, into close proximity to the buried catalytic triad. Analysis of tbnat that present non-synonymous mutations indicates that both substitutions are plausible to affect enzyme specificity or acetyl-CoA binding capacity. The results contribute to a better understanding of structure-function relationships of NATs. However, further investigation including INH-sensitive strains as a control group is needed to get better understanding of the possible role of these new mutations on tuberculosis control.
In order to gain a better understanding of the molecular epidemiology of Mycobacterium bovis isol... more In order to gain a better understanding of the molecular epidemiology of Mycobacterium bovis isolates in Cameroon, 75 isolates of M. bovis collected in three provinces of northern Cameroon were studied by spoligotyping. For 65 of these isolates, typing was also carried out by pulsed-field gel electrophoresis (PFGE) with DraI, and 18 of the isolates were also typed by restriction fragment length polymorphism (RFLP) analysis with probe IS6110-RHS. Molecular typing of the isolates by these techniques revealed a high degree of homogeneity, with 10 spoligotypes for 75 isolates, four PFGE profiles for 65 isolates, and three RFLP types for 18 isolates. Some types were present in the three different provinces, while some were confined to one or two areas. These results suggest that geographical mapping of M. bovis strains could be helpful for the control of bovine tuberculosis at the regional level. An interesting feature of all the spoligotypes was the absence of spacer 30, suggesting a common origin for all of the Cameroon isolates tested; an evolutionary scenario for the isolates is discussed. In addition, a comparison of the three techniques showed that for M. bovis strain differentiation in Cameroon and in surrounding countries, spoligotyping would be a more discriminating and practical tool for molecular typing than the other two techniques used in this study.
A case of acquired skin fragility syndrome associated with hepatic disease in a 9-year-old, spaye... more A case of acquired skin fragility syndrome associated with hepatic disease in a 9-year-old, spayed female, domestic shorthair cat is described. The cat was admitted to the veterinary hospital of the University of São Paulo (Brazil) with a 6-week history of vomiting, inappetence and weight loss. Remarkable signs were weakness, lethargy and profound jaundice that had been present for 10 days according to the owner. On completion of the physical examination, when the cat was gently manipulated for blood collection the thoracic limb and interscapular skin tore. Liver enzymes and bilirubin levels were all above the normal range. On histological examination of skin and liver, Masson's trichrome stain showed collagen fibre alteration and major hepatocyte abnormalities. Findings were consistent with feline skin fragility syndrome associated with cholangiohepatitis and hepatic lipidosis.
This paper reports the susceptibility profile to rifabutin (RFB) 1 and six recently synthesized R... more This paper reports the susceptibility profile to rifabutin (RFB) 1 and six recently synthesized RFB analogs 3e8, of either rifampicin (RFP) susceptible Mycobacterium tuberculosis and resistant clinical isolates from two sources: Mexico and Brazil. Taking into account that about 95% of M. tuberculosis strains resistant to RFP present mutations in the rpoB gene, with some of these mutations being determinant also to RFB resistance, the RFB analogs were screened for activity against a set of known RFP susceptible and resistant strains. N 0 -Acetyl-RFB 5 and N 0 -(undec-10 00 -enoyl)-RFB 8 showed the best results, in particular with mutations in the codon 516, 522 and 531 of the rpoB gene, and were therefore selected for in vivo assessment of their efficacy. Studies conducted with tuberculous Balb/C mice previously infected with Ser531Leu mutated clinical isolate, evidenced both 5 and 8 as promoters of a significant decrease on tubercle bacilli burden in lungs associated with lower tissue damage, thus confirming them as good leads for drug discovery. The SAR of the acylated compounds 5 and 8 envisaging the identification of pharmacophore features, highlights the importance of profiling more clearly the chemistry within the molecular aspects for elucidation of the mode of action of RFB and analogs, in relation to mutations in Multidrug-Resistant (MDR) strains.
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2007
concentrations of 10 and 100 μg/L arsenic induced significant augment in protein oxidation, this ... more concentrations of 10 and 100 μg/L arsenic induced significant augment in protein oxidation, this last result is in line with the lack of antioxidant response. The amnesic effect and the oxidative stress induced by As suggest that the concentration of this metalloid considered safe by Brazilian legislation needs reevaluation. Supported by CAPES (MRC, LAG), CNPq (DA, JMM, DMB) and FAPERGS (JMM).
Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 2008
Three crude extracts of Aplysina caissara, a marine sponge endemic to Brazil, were tested against... more Three crude extracts of Aplysina caissara, a marine sponge endemic to Brazil, were tested against a hepatoma cell line and Mycobacterium tuberculosis. The results demonstrate that all extracts are toxic and capable of inhibiting cellular growth. Additionally, the extracts produced morphological aberrations and inhibited cell attachment to culture substrates. These effects were dose/time dependent. Our results also suggest that reactive oxygen species (ROS) production is not involved in the cytotoxic processes levied by the extracts employed in this study and that active metabolites are likely to be present in the polar fractions of the crude extracts. Finally, our results indicate that all three extracts exhibit a moderate anti-tuberculosis capacity, and that the removal of an extract's lipid fraction appears to diminish this activity.
Tuberculosis remains as a serious infection disease of worldwide distribution, with high morbidit... more Tuberculosis remains as a serious infection disease of worldwide distribution, with high morbidity and mortality, mainly in low socio-economic condition countries. The state of emergency of tuberculosis caused by the resistant and multidrug-resistant (MDR) strains, became the main threat to the tuberculosis treatment and control programs. A fast detection method for the resistant strains will allow the implementation of an adequate treatment and contribute for controlling the dissemination of these resistant strains. This study evaluated the performance of the nitrate reductase assay in solid (NRA-LJ) and liquid (NRA-7H9) media, to determine the susceptibility to first line anti-tuberculosis drugs: isoniazid (INH), rifampicin (RMP), ethambutol (EMB) and streptomycin (SMR). Both methods NRA-LJ and NRA-7H9 were evaluated among 18 strains with a known susceptibility profile. The resazurin microtiter assay (REMA) was performed as a reference method. One hundred percent of accordance was observed between NRA-7H9 and REMA for the four tested drugs. When the NRA-LJ method was compared to REMA, the sensitivity and the specificity to INH, RMP, EMB and SMR were 100%, 100 %, 85.7%, 76.9% and 80%, 100%, 75% and 80%, respectively. From the 57 clinical isolates of M. tuberculosis evaluated by NRA-7H9 and REMA, 56 (98.2%) were sensitive to all antibiotics tested (INH, RMP, EMB and SMR) by the NRA-7H9 method, while three of these strains were resistant to INH by REMA. One strain showed resistance to INH and RMP for both methods, and MIC of 1.0 μg/ml to INH for both methods, while MIC of 1.0 and 2.0 μg/ml to RMP for REMA and NRA-7H9, respectively. The three assays showed a high level of agreement for rapid detection of rifampicin and isoniazid resistance. Regarding rapidness, the detection of color change in the NRA method is within instants as compared to the overnight incubation required for the REMA test. NRA might represent an inexpensive and alternative assay for rapid detection of resistance in low-income countries.
Revista Brasileira de Ciências Farmacêuticas, 2008
Thirty-six plant extracts from the brazilian Atlantic Forest were tested for their antimycobacter... more Thirty-six plant extracts from the brazilian Atlantic Forest were tested for their antimycobacterial activity against Mycobacterium tuberculosis H 37 Rv and M. kansasii, using the method REMA in seriate concentrations of 100 to 0.20 µg/mL. Among the thirty six extracts tested, five were active against M. tuberculosis, and three of these extracts also showed activity against M. kansasii. Cytotoxicity test with VERO cells was performed with the five extracts active against M. tuberculosis. Only the extract of Peschiera affinis was identified as non-toxic in the concentration of 100µg/mL.
A series of amino-5-[(substituted) phenyl]-3-(4-hydroxy-3-methylphenyl)-4,5-dihydro-1H-1-pyrazoly... more A series of amino-5-[(substituted) phenyl]-3-(4-hydroxy-3-methylphenyl)-4,5-dihydro-1H-1-pyrazolylmethanethione were synthesized by the reaction between thiosemicarbazide and chalcones and were tested for their antimycobacterial activity in vitro against Mycobacterium tuberculosis H 37 R v and INH resistant Mycobacterium tuberculosis using bactec method. Among the synthesized compounds, compound (4b), amino-5-(4-chlorophenyl)-3-(4-hydroxy-3-methylphenyl)-4,5-dihydro-1H-1-pyrazolylmethanethione was found to be the most active agent against Mycobacterium tuberculosis H37 Rv (MTB) and INH resistant Mycobacterium tuberculosis (INHR-MTB) with minimum inhibitory concentration of 0.43 µM . When compared to INH-compound (4b) was found to be 1.62 fold and 26.41 fold more active against MTB and INHR-MTB, respectively.
Clinical utility of rifabutin 1 (RBT), a potent antibiotic used in multidrug regimens for tubercu... more Clinical utility of rifabutin 1 (RBT), a potent antibiotic used in multidrug regimens for tuberculosis (TB) as well as for infections caused by Mycobacterium avium complex (MAC), has been hampered due to dose-limiting toxicity. RBT analogs 2-11 were synthesized and evaluated against M. avium 1581 and Mycobacterium tuberculosis susceptible and resistant strains in vitro. A selection of candidates were also assayed against non-replicating persistent (NRP) M. tuberculosis. Subsequent in vivo studies with the best preclinical candidate drugs 5 and 8, in a model of progressive pulmonary tuberculosis of Balb/C mice infected either with H(37)Rv drug-sensible strain or with multidrug resistant (MDR) clinical isolates, resistant to all primary antibiotics including rifampicin, were performed. The results disclosed here suggest that 5 and 8 have potential for clinical application.
Highly active antiretroviral therapy has brought about a substantial improvement in the prognosis... more Highly active antiretroviral therapy has brought about a substantial improvement in the prognosis of HIV/AIDS. In this context, therapy-related body changes (lipodystrophy) gain in importance, in light of the psychological distress they cause and of their association with adherence to treatment. This study analyses patients' self-perception of central fat gain (CFG) and peripheral fat loss (PFL). A total of 457 patients were interviewed in a university outpatient facility for the treatment of adults and adolescents with HIV/AIDS in the city of São Paulo, Brazil, between September and December 2001. Two-thirds of subjects (64.3%) perceived body changes. The self-perception of CFG and PFL was associated with greater schooling. The self-perception of CFG was more frequent among women and in patients who used protease inhibitors for longer periods. The self-perception of PFL was more frequent among older patients, patients who used stavudine for longer periods, and patients who reported a lack of adherence to antiretroviral agents. The quality of affective/social relationships with friends and family was inversely associated with the self-perception of PFL. The evaluation of self-perceived body changes and their determinants in individuals living with HIV/AIDS may help improve provided care. Listening to what patients have to say concerning antiretroviral therapy-related body changes and how they perceive them, as well as including the patient in therapeutic decisions in this regard will contribute towards greater adherence to proposed interventions and towards an improvement in the quality of life.
The increase in both opportunistic mycoses and antimicrobial resistance of pathogenic microorgani... more The increase in both opportunistic mycoses and antimicrobial resistance of pathogenic microorganisms has determined the need to develop new chemotherapies agents. Amazon Forest Plants has been used as natural drug by local people in the treatment of various tropical diseases. The objective of the study is to evaluate the antifungal activity of twenty-eight species of plants extracts belonging to twenty botanical families from the Amazon forest. The minimum inhibitory concentration of the one hundred fourteen crude extracts of dichloromethane, methanol and water were evaluated against three Candida species: Candida albicans, Candida glabrata and Candida parapsilosis. Seventy-four extracts showed activity, with minimum inhibitory concentration between 0.06 and 1mg/mL, against the three species evaluated. The results observed in this study, mainly about the families Arecaceae, Apocynaceae, Salicaceae and Urticaceae, showed that these extracts are promising for the development of new drugs that can be used in the treatment against opportunistic fungal infections.
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Papers by Daniela Ramos