Percorrer por autor "Vale, Nuno"
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- Anti-Pneumocystis carinii and antiplasmodial activities of primaquine-derived imidazolidin-4-onesPublication . Vale, Nuno; Collins, Margaret S.; Gut, Jiri; Ferraz, Ricardo; Rosenthal, Philip J.; Cushion, Melanie T.; Moreira, Rui; Gomes, PaulaA series of primaquine-derived imidazolidin-4-ones were screened for their in vitro activity against Pneumocystis carinii and Plasmodium falciparum W2 strain. Most compounds were active against P. carinii above 10 lg/mL and displayed slight to marked activity. The imidazolidin-4-ones most active against P. carinii were also those most active antiplasmodial agents, in the lM range. One of the tested imidazolidin-4-ones was slightly more active than the parent primaquine and may represent a lead com pound for the development of novel anti-P. carinii 8-aminoquinolines with increased stability and resistance to metabolic inactivation.
- Anti-pneumoscystis carinni activitiy of primaquine imidazolidin-4-onesPublication . Vale, Nuno; Ferraz, Ricardo; Azevedo, Joana; Araújo, Maria João; Moreira, Rui; Collins, Margaret S.; Cushion, Melanie T.; Gomes, PaulaPneumocystis pneumonia (PCP) is one of the most frequent causes of mortality among HIV-infected patients. Primaquine (PQ) is an antimalarial 8-aminoquinoline effective against PCP when given in combination with clindamycin. This has drawn the attention of Medicinal Chemists towards the anti-PCP activity of 8-aminoquinolines, not only confined to those exhibiting antimalarial activity [1]. It is thought that anti-PCP 8-aminoquinolines exert their anti-PCP activity by acting on the electronic transport and redox system of the P. carinii pathogen [1]. Recently, our research group has been developing imidazolidin-4-one derivatives of PQ (Scheme 1), targeting novel compounds with improved therapeutic action, namely, higher resistance to metabolic inactivation, lower toxicity and equal or higher antimalarial activity than that of the parent drug [2,3]. These imidazolidin-4-ones were seen to block the transmission of rodent malaria, caused by Plasmodium berghei on BalbC mice, to the mosquito vector Anopheles stephensi [3]. The anti-PCP activity of our PQ derivatives is now under study and preliminary in vitro assays [4] show that some of the compounds exhibit slight to moderate activity after a 72 h incubation period against P. carinii. In one case, the IC50 was comparable to that of parent PQ. Both these studies and forthcoming results from ongoing biological assays will be presented and discussed.
- In Silico, In Vitro and In Vivo Toxicological Assessment of BPP-BrachyNH2, A Vasoactive Proline-Rich Oligopeptide from Brachycephalus ephippiumPublication . Arcanjo, Daniel D. R.; Mafud, Ana Carolina; Vasconcelos, Andreanne G.; Silva-Filho, José Couras da; Amaral, Maurício P. M.; Brito, Lucas M.; Bemquerer, Marcelo P.; Kückelhaus, Selma A. S.; Plácido, Alexandra; Delerue-Matos, Cristina; Vale, Nuno; Mascarenhas, Yvonne P.; Carvalho, Fernando Aécio A.; Oliveira, Aldeidia P.; Leite, José Roberto Souza AlmeidaBPP-BrachyNH2 is a proline-rich oligopeptide (PRO) firstly identified in skin secretion of the frog Brachycephalus ephippium, which possess in vitro inhibitory activity of angiotensin-I converting enzyme (ACE) and endothelium-dependent vasorelaxant activity. Considering its potential application in the treatment of cardiovascular diseases, the present work assessed the toxicological profile of the BPP-BrachyNH2. The in silico toxicity prediction was performed from the best model obtained through the optimization of the FASTA query peptide. This prediction study revealed that BPP-BrachyNH2 induced high predicted LD50 values for both humans and rats, and then is well-tolerated in the recommended range. The MTT assay was applied for the in vitro cytotoxic evaluation in murine macrophages. In this assay, a decrease of cell viability was not observed. The in vivo acute toxicological study was performed after the intraperitoneal administration of BPP-BrachyNH2 at doses of 5 and 50 mg/kg. After intraperitoneal administration, no death, alterations in behavioral parameters or weight gain curve was observed, as well as none in the serum biochemical parameters, and gross pathological and histopathological analyses. These observations demonstrates an acceptable safety profile for BPP-BrachyNH2, leading towards further studies focused on investigation of pharmacological and therapeutical applications for this peptide.
- Ocellatin-PT antimicrobial peptides: High-resolution microscopy studies in antileishmania models and interactions with mimetic membrane systemsPublication . Oliveira, Mayara; Gomes-Alves, Ana Georgina; Sousa, Carla; Marani, Mariela Mirta; Plácido, Alexandra; Vale, Nuno; Delerue-Matos, Cristina; Gameiro, Paula; Kuckelhaus, Selma A. S.; Tomás, Ana M.; Leite, José Roberto S. A.; Eaton, PeterAlthough the mechanism of action of antimicrobial peptides (AMPs) is not clear, they can interact electrostatically with the cell membranes of microorganisms. New ocellatin-PT peptides were recently isolated from the skin secretion of Leptodactylus pustulatus. The secondary structure of these AMPs and their effect on Leishmania infantum cells, and on different lipid surface models was characterized in this work. The results showed that all ocellatin-PT peptides have an a-helix structure and five of them (PT3, PT4, PT6 to PT8) have leishmanicidal activity; PT1 and PT2 affected the cellular morphology of the parasites and showed greater affinity for leishmania and bacteria-mimicking lipid membranes than for those of mammals. The results show selectivity of ocellatin-PTs to the membranes of microorganisms and the applicability of biophysical methods to clarify the interaction of AMPs with cell membranes.
- Structure and function of a novel antioxidant peptide from the skin of tropical frogsPublication . Barbosa, Eder Alves; Oliveira, Ana; Plácido, Alexandra; Socodato, Renato; Portugal, Camila C.; Mafud, Ana Carolina; Ombredane, Alicia S.; Moreira, Daniel C.; Vale, Nuno; Bessa, Lucinda J.; Joanitti, Graziella A.; Alves, Cláudia; Gomes, Paula; Delerue-Matos, Cristina; Mascarenhas, Yvonne Primerano; Marani, Mariela M.; Relvas, João B.; Pintado, Manuela; Leite, José Roberto S.A.The amphibian skin plays an important role protecting the organism from external harmful factors such as microorganisms or UV radiation. Based on biorational strategies, many studies have investigated the cutaneous secretion of anurans as a source of bioactive molecules. By a peptidomic approach, a novel antioxidant peptide (AOP) with in vitro free radical scavenging ability was isolated from Physalaemus nattereri. The AOP, named antioxidin-I, has a molecular weight [M+H]+ = 1543.69Da and a TWYFITPYIPDK primary amino acid sequence. The gene encoding the antioxidin-I precursor was expressed in the skin tissue of three other Tropical frog species: Phyllomedusa tarsius, P. distincta and Pithecopus rohdei. cDNA sequencing revealed highly homologous regions (signal peptide and acidic region). Mature antioxidin-I has a novel primary sequence with low similarity compared with previously described amphibian's AOPs. Antioxidin-I adopts a random structure even at high concentrations of hydrophobic solvent, it has poor antimicrobial activity and poor performance in free radical scavenging assays in vitro, with the exception of the ORAC assay. However, antioxidin-I presented a low cytotoxicity and suppressed menadione-induced redox imbalance when tested with fibroblast in culture. In addition, it had the capacity to substantially attenuate the hypoxia-induced production of reactive oxygen species when tested in hypoxia exposed living microglial cells, suggesting a potential neuroprotective role for this peptide.
- Structure-function studies of BPP-BrachyNH 2 and synthetic analogues thereof with Angiotensin I-Converting EnzymePublication . Arcanjo, Daniel D.R.; Vasconcelos, Andreanne G.; Nascimento, Lucas A.; Mafud, Ana Carolina; Plácido, Alexandra; Alves, Michel M.M.; Delerue-Matos, Cristina; Bemquerer, Marcelo P.; Vale, Nuno; Gomes, Paula; Oliveira, Eduardo B.; Lima, Francisco C.A.; Mascarenhas, Yvonne P.; Carvalho, Fernando Aécio A.; Simonsen, Ulf; Ramos, Ricardo M.; Leite, José Roberto S.A.The vasoactive proline-rich oligopeptide termed BPP-BrachyNH2 (H-WPPPKVSP-NH2) induces in vitro inhibitory activity of angiotensin I-converting enzyme (ACE) in rat blood serum. In the present study, the removal of N-terminal tryptophan or C-terminal proline from BPP-BrachyNH2 was investigated in order to predict which structural components are important or required for interaction with ACE. Furthermore, the toxicological profile was assessed by in silico prediction and in vitro MTT assay. Two BPP-BrachyNH2 analogues (des-Trp1-BPP-BrachyNH2 and des-Pro8-BPP-BrachyNH2) were synthesized, and in vitro and in silico ACE inhibitory activity and toxicological profile were assessed. The des-Trp1-BPP-BrachyNH2 and des-Pro8-BPP-BrachyNH2 were respectively 3.2- and 29.5-fold less active than the BPP-BrachyNH2-induced ACE inhibitory activity. Molecular Dynamic and Molecular Mechanics Poisson-Boltzmann Surface Area simulations (MM-PBSA) demonstrated that the ACE/BBP-BrachyNH2 complex showed lower binding and van der Wall energies than the ACE/des-Pro8-BPP-BrachyNH2 complex, therefore having better stability. The removal of the N-terminal tryptophan increased the in silico predicted toxicological effects and cytotoxicity when compared with BPP-BrachyNH2 or des-Pro8-BPP-BrachyNH2. Otherwise, des-Pro8-BPP-BrachyNH2 was 190-fold less cytotoxic than BPP-BrachyNH2. Thus, the removal of C-terminal proline residue was able to markedly decrease both the BPP-BrachyNH2-induced ACE inhibitory and cytotoxic effects assessed by in vitro and in silico approaches. In conclusion, the aminoacid sequence of BPP-BrachyNH2 is essential for its ACE inhibitory activity and associated with an acceptable toxicological profile. The perspective of the interactions of BPP-BrachyNH2 with ACE found in the present study can be used for development of drugs with differential therapeutic profile than current ACE inhibitors.
- Synergistic and antibiofilm properties of ocellatin peptides against multidrug-resistant Pseudomonas aeruginosaPublication . Bessa, Lucinda J; Eaton, Peter; Dematei, Anderson; Plácido, Alexandra; Vale, Nuno; Gomes, Paula; Delerue-Matos, Cristina; Leite, José Roberto Sá; Gameiro, PaulaAim:To test ocellatin peptides (ocellatins-PT2-PT6) for antibacterial and antibiofilm activities and synergy with antibiotics against Pseudomonas aeruginosa. Materials & methods: Normal- and checkerboard-broth microdilution methods were used. Biofilm studies included microtiter plate-based assays and microscopic analysis by confocal laser scanning microscopy and atomic force microscopy. Results: Ocellatins were more active against multidrug-resistant isolates of P. aeruginosa than against susceptible strains. Ocellatin-PT3 showed synergy with ciprofloxacin and ceftazidime against multidrug-resistant isolates and was capable of preventing the proliferation of 48-h mature biofilms at concentrations ranging from 4 to 8× the MIC. Treated biofilms had low viability and were slightly more disaggregated. Conclusion: Ocellatin-PT3 may be promising as a template for the development of novel antimicrobial peptides against P. aeruginosa.