Samuel Silva PitaUniversidade Federal da Bahia · Faculty of Pharmacy
Samuel Silva Pita
Professor
About
36
Publications
6,500
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
250
Citations
Citations since 2017
Introduction
MSc in Chemistry from the Federal University of Rio de Janeiro (2006) and post-doctorate at the Institute of Biophysics Carlos Chagas Filho at Universidade Federal do Rio de Janeiro (2011). He is Professor of Pharmaceutical Chemistry, Faculty of Pharmacy at the Federal University of Bahia and has experience in Pharmacy, with emphasis on Medicinal Chemistry (QSAR, Docking, Computer Simulation, Generalized Simulated Annealing) and drugs development against Chagas disease, Malaria and HIV.
Additional affiliations
September 2011 - present
August 2011 - present
March 2007 - March 2011
Publications
Publications (36)
Dental caries is a global public health problem, being the most common non-communicable disease. Streptococcus mutans, the causative agent of human cariogenic dental biofilms, produce glycosyltransferases (Gtfs) whose gene expression is modulated by the VicRK system, which makes them a promising target for dental biofilm inhibitor developments. Bio...
Aedes aegypti mosquitoes transmit several human pathogens that cause millions of deaths worldwide, mainly in Latin America. The indiscriminate use of insecticides has resulted in the development of species resistance to some such compounds. Piperidine, a natural alkaloid isolated from Piper nigrum, has been used as a hit compound due to its larvici...
Studies showed that JM-20, a benzodiazepine-dihydropyridine hybrid molecule, protects against rotenone and 6-hydroxydopamine neurotoxicity. However, its protective effects against cytotoxicity induced by endogenous neurotoxins involved in Parkinson’s disease (PD) pathogenesis have never been investigated. In this study, we evaluated the ability of...
The past two decades have been marked by a global spread of bacterial resistance to β-lactam drugs and carbapenems derivatives are the ultimate treatment against multidrug-resistant bacteria. β-lactamase expression is related to resistance which demands the development of bacterial resistance blockers. Drug inhibitor combinations of serine-β-lactam...
Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has received global attention due to the serious threat it poses to public health. Since the outbreak in December 2019, millions of people have been affected and its rapid global spread has led to an upsurge in the search for treatment. To d...
Tetragonisca angustula honey was fractioned in a SiO2 column to furnish three fractions (A-C) in which four hydroxycinnamic acid-Spermidine amides (HCAAs), known as N', N", N'" - tris-p-coumaroyl spermidine, N', N" - dicaffeoyl, N'" - coumaroyl spermidine, N', N", N'" - tris-caffeoyl spermidine and N', N" - dicaffeoyl and N'" - feruloyl spermidine...
Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), receives global attention due to the serious threat that affect public health. Since December 2019, its incidence affecting millions of patients and its rapid dissemination on a worldwide scale have led the searching for its treatment. To di...
Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), receives global attention due to the serious threat that affect public health. Since December 2019, its incidence affecting millions of patients and its rapid dissemination on a worldwide scale have led the searching for its treatment. To di...
Hundreds of millions of people worldwide are affected by Chagas’ disease caused by Trypanosoma cruzi . Since the current treatment lack efficacy, specificity, and suffers from several side-effects, novel therapeutics are mandatory. Natural products from endophytic fungi have been useful sources of lead compounds. In this study, three lactones isola...
Sickle cell disease (SCD) is a disease resulting from mutation in the globin portion of hemoglobin caused by the replacement of adenine for thymine in the codon of the β globin gene. In Brazil, SCD affects about 0.3% of the black and Caucasian population. Until now, there is no specific treatment and the available drugs have several serious adverse...
As leishmanioses são um grupo de doenças negligenciadas causadas por protozoários intracelulares do gênero Leishmania. Suas principais formas clínicas são a tegumentar (LT) e a visceral (LV). Atualmente a terapêutica contra a leishmaniose baseia-se na utilização de cinco fármacos: os antimoniais pentavalentes, a anfotericina B e a sua formulação li...
Leishmaniasis are group of neglected diseases with worldwide distribution that affect about 12 million people. The current treatment is limited and may cause severe adverse effects, and thus, the search for new drugs more effective and less toxic is relevant. We have previously investigated the immunomodulatory effects of LASSBio-1386, an N -acylhy...
Rhipicephalus microplus is responsible for high economic losses in livestock and its control has become difficult due to the establishment of tick populations resistant to commercial acaricides. This study aimed to evaluate the in vitro larvicidal effect of the alkaloids berberine and piperine, and also to investigate their inhibitory mechanisms ag...
The present work describes the acetylcholinesterase inhibitory activity of Ocotea pomaderroides extracts besides the chemical composition of chromatographic fractions. The hexane, dichloromethane and ethyl acetate extract soluble fractions showed high Electrophorus electricus acetylcholinesterase (EelAChE) inhibition (92.18, 71.86 and 74.25%, respe...
The visceral form of Leishmaniasis, also known as kala-azar, caused by Leishmania chagasi is the main etiological agent of this form in Brazil responsible for 30,000 annual deaths. Despite its epidemiological impact, treatment of the disease is limited by resistance, species-dependent efficacy and serious adverse effects. The application of computa...
We investigated the in vitro acaricide activity of the methanolic extract (ME) and alkaloid-rich fraction (AF) of Prosopis juliflora on Rhipicephalus microplus and correlated this effect with acetylcholinesterase (AChE) inhibition. The acaricide activity was evaluated using adult and larval immersion tests. Also, we studied the possible interaction...
The filamentous fungus Trametes versicolor is a rich source of laccase (Tvlac). Laccases catalyze reactions that convert substituted phenol substrates into diverse derivatives through aromatic oxidation. We investigated methyl p-coumarate, methyl ferulate, and methyl caffeate biotransformation by Trametes versicolor ATCC 200801. Despite sub-strate...
Background
Leishmania infantum causes the most lethal form of Leishmaniasis: Visceral leishmaniasis. Current therapy for this disease is related with both the development of drug-resistant species and toxicity. Trypanothione Reductase (LiTR), a validated target for drug discovery process, is involved with parasite’s thiol‐redox metabolism.
Objecti...
Trypanosoma cruzi Trypanothione Reductase (TcTR) is one of the therapeutic targets studied in the development of new drugs against Chagas’ disease. Due to its biodiversity, Brazil has several compounds of natural origin that were not yet properly explored in drug discovery. Therefore, we employed the Virtual Screening against TcTR aiming to discove...
Abstract: Introduction: American trypanosomiasis, also known as Chagas disease, is caused by the protozoan Trypanosoma cruzi (T. cruzi) and affects approximately 10 to 12 million, primarily in Latin America. Since its discovery in 1909, there is no effective treatment for its chronic phase, with benzonidazole being the only anti-trypanosoma drug us...
Introduction:
Schistosoma mansoni is responsible for virtually all reported cases of schistosomiasis in Latin America and the emergence of praziquantel- and oxaminiquine-resistant strains makes it urgent to develop new schistosomicide agents. Dihydrofolate reductases (DHFR) from bacteria and protozoan parasites are considered validated macromolecu...
The combination of two low-cost classical procedures based on titrimetric techniques is presented for the determination of pyridoxine hydrochloride in pharmaceuticals samples. Initially some experiments were carried out aiming to determine both pKa1 and pKa2 values, being those compared to values of literature and theoretical procedures. Commercial...
The tick cattle Rhipicephalus microplus is responsible for losses in cattle raising of R$ 6 billion annually and it is still the vector of several ectopara- sitic diseases. Acetylcholinesterase from R. microplus (RmAChE) is presented as a target for the search for new acaricides with less re-sistance and more po- tency than the anticholinesterasics...
Virtual screening methodologies have been used to help drug researchers to discover new medicine. The goal of these methodologies is to work on the docking phase verifying which molecules interact with a specific protein. Typically, the number of molecules could be very large and, because of this, a great computational power is required to compare...
Despite the fact that Leishmania ssp are pteridine auxotrophs, Dihydrofolate Reductase-Thymidylate Synthase (DHFR-TS) inhibitors are ineffective against Leishmania major. On the other hand Pteridine Reductase 1 (PTR1) inhibitors proved to be lethal to the parasite. Aiming at identifying hits that lie outside the chemical space of known PTR1 inhibit...
Neglected Tropical Diseases (NTDs) affect primarily the most vulnerable populations in developing countries and are the major causes of bacterial, parasitic and viral infections. According to the World Health Organization (WHO), Chagas disease, caused by Trypanosoma cruzi, affects 21 countries in Latin America and it is a public health problem. The...
The treatment of Chagas disease in its chronic form is inefficient and thus new therapeutic approaches have been studied. Among these, the Trypanothione Reductase (TR) is presented as a selective and specific target for chemotherapy of this disease. We studied, by molecular dynamics (MD) using the program GROMACS, the behavior of a series of six co...
The drugs against tropical neglected diseases, especially Chagas' Disease, were launched more than 30 years ago, and the development of resistance requires the discovery of new and more effective chemotherapeutic agents. Trypanosoma cruzi has a redox enzyme called trypanothione reductase which was successfully inhibited for peptide derivatives (McK...
Receptor-dependent four-dimensional quantitative structure-activity relationship (RD-4D-QSAR) studies were applied on a series of 21 peptides reversible inhibitors of Trypanosoma cruzi trypanothione reductase (TR) (Amino Acids, 20, 2001, 145). The RD-4D-QSAR (J Chem Inform Comp Sci, 43, 2003, 1591) approach can evaluate multiple conformations from...
The work of Carlos Chagas culminated with the description of the disease that bears his name. His discovery reaches over a century. Since the first reports of this disease, many therapeutic approaches have been developed intending treatment of the disease. However, to date, none therapy has proven to be enough to cure the acute and chronic disease'...
One of the most interesting aspects of Trypanosoma cruzi is its adaptation to obtain sialic acid from its host, fulfilling this need exclusively through the reaction catalyzed by enzymatically active trans-sialidase (aTS), thought to play an important role in the pathogenesis of Chagas' disease. Herein, we report that 2-difluoromethyl-4-nitrophenyl...
The combination of two low-cost classical procedures based on titrimetric techniques is presented for the determination of pyridoxine hydrochloride in pharmaceuticals samples. Initially some experiments were carried out aiming to determine both pKal and pKa2 values, being those compared to values of literature and theoretical procedures. Commercial...
Chagas' disease (CD) has been responsible for many deaths and disabilities mainly in South America. Currently, 40 million people are at risk of acquiring this disease and, existing therapies are still unsatisfactory, presenting harsh side effects. Therefore, the development of new chemical entities to reverse this state is critical. A series of pep...
Molecular dynamics (MD) simulations of a well known hydrophobic structure, the heme (ferroprotoporphyrin IX) and its precursor in the heme synthesis, protoporphyrin IX (PPIX) are presented. The objective of the present study is to determine the stability of both structures in an aqueous medium, as well as the structure-solvent relation, hydration s...
Since the middle 70s, the main molecular docking problem consists in limitations to treat adequately the degrees of freedom of protein (or a receptor) due to the energy landscape roughness and the high computational cost. Until recently, only few algorithms considering flexible simultaneously both ligand and receptor at low computational cost were...
Questions
Questions (2)
I'm trying to analyze after a Molecular Dynamics Simulation (MDS) the protein pockets. I'm looking for scripts, servers or subroutines that allows us to measure and to assign the pockets into a protein during MDS at its trajectory (mainly GROMACS XTC file). I know the CASTp, METAPOCKET and FTDyn tools but any of these allow me to analyze the XTC file completely, only (one) PDB structures (CASTp or METAPOCKET) or waiting for MD data to be generated by FTDyn.
I'll try the atomic charges for a database of 10.000 compounds in a mol2 (or sdf) format and I wonder to know if there is some program or some computational routine (script, flow chart) to do this calculation automatically.
Projects
Projects (5)
This is an umbrella entry for some collaborations and research involving hybrid architectures (multiple GPUs) for different areas.
