Percorrer por autor "Ferraz, Ricardo"
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- 11 - Collagen-like materials for tissue regeneration and repairPublication . Teixeira, Cátia; Ferraz, Ricardo; Prudêncio, Cristina; Gomes, PaulaPeptides can be designed to recreate the higher-order assembly (triple helix) and biological function of natural collagens. Collagen triple-helical domain contains Gly-Xaa-Yaa triplets where Xaa and Yaa are frequently proline and hydroxyproline, respectively. Glycine must be in every third position forming a hydrogen bond to an adjacent proline to stabilize collagen structure. Hydroxyproline residues are important in the thermal stability of the collagen triple-helix conformation. Although it is difficult to produce a stable triple helix, collagen-like peptides can be used to produce scaffolds that mimic natural tissue networks for biomedical engineering, without the liabilities of nonhuman natural collagens such us immunogenicity and pathogen transmission. This chapter describes the major approaches towards synthesis of collagen-like peptides, essentially aimed at production of artificial biocompatible and biofunctional frameworks for regenerative medicine.
- 4,9-Diaminoacridines and 4-Aminoacridines as Dual-Stage Antiplasmodial HitsPublication . Fonte, Mélanie; Tassi, Natália; Fontinha, Diana; Bóuzon-Arnáiz, Inês; Ferraz, Ricardo; Araújo, Maria J.; Fèrnandez-Busquets, Xavier; Prudêncio, Miguel; Gomes, Paula; Teixeira, CátiaMulti‐stage drugs have been prioritized in antimalarial drug discovery, as targeting more than one process in the Plasmodium life cycle is likely to increase efficiency, while decreasing the chances of emergence of resistance by the parasite. Herein, we disclose two novel acridine‐based families of compounds that combine the structural features of primaquine and chloroquine. Compounds prepared and studied thus far retained the in vitro activity displayed by the parent drugs against the erythrocytic stages of chloroquine‐sensitive and ‐resistant Plasmodium falciparum strains, and against the hepatic stages of Plasmodium berghei, hence acting as dual‐stage antiplasmodial hits.
- 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.
- Antibacterial activity of Ionic Liquids based on ampicillin against resistant bacteriaPublication . Ferraz, Ricardo; Teixeira, Vânia; Rodrigues, Débora; Prudêncio, Cristina; Fernandes, Rúben; Noronha, João Paulo; Petrovski, Zeljko; Branco, LuísAntibacterial activity of novel Active Pharmaceutical Ingredient Ionic Liquids (API-ILs) based on ampicillin anion [Amp] have been evaluated. They showed growth inhibition and bactericidal properties on some sensitive bacteria and especially some Gram-negative resistant bacteria when compared to the [Na][Amp] and the initial bromide and chloride salts. For these studies were analysed the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBIC) against sensitive Gram-negative bacteria Escherichia coli ATCC 25922 and Klebsiella pneumonia (clinically isolated), as well as sensitive Gram positive S. Aureus ATCC 25923, Staphylococcus epidermidis and Enterococcus faecalis and completed using clinically isolated resistent strains: E. coli TEM CTX M9, E. coli CTX M2 and E. coli AmpC Mox. From the obtained MIC values of studied APIs-ILs and standard [Na][Amp] were derived RDIC values (relative decrease of inhibitory concentration). High RDIC values of [C16Pyr][Amp] especially against two resistant Gram-negative strains E. coli TEM CTX M9 (RDIC>1000) and E. coli CTX M2 (RDIC>100) point clearly to a potential promising role of APIs-ILs as antimicrobial drugs especially against resistant bacterial strains.
- Antibacterial activity of ionic liquids based on betalactamantibiotics against resistant bacteriaPublication . Dias, Vitorino; Santos, Miguel; Prudêncio, Cristina; Noronha, João P.; Grilo, Inês R.; Sobral, Rita G.; Dias, Ana Rita; Branco, Luís C.; Ferraz, RicardoThe cases of antibiotic resistance are increasing and becoming more and more common, giving rise to a new problem for public health. Therefore, the discovery of new antibiotics is important and necessary.
- Antifungal activity of Imidazolidin-4-ones of the antimalarial primaquinePublication . Ferraz, Ricardo; Fernandes, Rúben; Vieira, Mónica; Barros, Piedade; Gomes, Paula; Prudêncio, CristinaThe 5-Isopropyl-3-[4-(6-methoxy-quinolin-8-ylamino)-pentyl]-2,2-dimethyl-imidazolidin-4-one (ValPQacet) was sinthesized through acylation of the anti-malarial primaquine with α-valine and subsequent reaction of the resulting -aminoamide with propanone (Sheme 1).Imidazolidin-4-ones of the anti malarial primaquine are being sinthesized to develop new variants in order to improve more effective treatments against malaria . Recently it has been observed that primaquine derivates could have effect in a new kind of yeast . To study the fungicidal activity against Candida albicans, Candida tropicalis, Issatchenkia orientalis, Sacharomyces cerevisae, the ValPQacet was put in the form of the hydrochloride salt. The minimal inhibitory concentration (MIC) could be determined for all yeast in the concentration range assayed. Also was determined MIC’s of primaquine hydrochloride salt for all yeast, and this shows that the parent drug is less active than our compound. Further studies are being performed to determine viability and cellular injury with this drugs.
- Antimicrobial activity of pyrazine and quinoxaline N,N’-dioxide heterocyclic compoundsPublication . Vieira, Mónica; Ferraz, Ricardo; Fernandes, Rúben; Noronha, João Paulo; Silva, M.; Prudêncio, CristinaThe nitrogen heterocyclic organic compounds 1,4 dioxide pyrazine and quinoxaline derivatives have been widely studied due to their potential use as synthetic drugs. The thermochemical study of three N,N´-dioxides: 2,3,5-trimethylpyrazine-1,4-dioxide, tetramethylpyrazine-1,4-dioxide and 6-chloro-2,3-dimethilquinoxaline 1,4-dioxide has been recently developed in order to establish relationships among the energetical, structural and reactivity properties [4,5]. Several studies have reported their pharmacological activity, particularly as antimicrobial agents [1,2,3]. It has also been established a relation between energetical and structural properties and biological activity, once these compounds present N – oxide bonds, increasing their oxidative capacity. The present work reports the study of antimicrobial activity for those compounds against the bacteria Geobacillus stearothermophylus, Staphylococcus aureus, Streptococcus agalactiae, Escherichia coli and also against the yeasts Saccharomyces cerevisiae PYCC 4072, Candida albicans PYCC3436T, Candida tropicalis PYCC, Issatchenka Orientalis PYCC. The determination of the minimal inhibitory concentration (MIC), points to an antimicrobial activity and the preliminary results indicate that these compounds may be potential candidates as antimicrobial drugs with clinical, agriculture or food industries applications.
- Antimicrobial peptides as potential alternatives to prevent food spoilagePublication . Povkhanych, Maksym; Amorim, Maria Teresa; Ferraz, Ricardo; Prudêncio, Cristina; Gomes, Paula; Teixeira, CátiaIn 2015 it was estimated that on average the world consumption of antibiotics was 45 mg·kg−1 for cattle, 148 mg·kg−1 for chicken and 172 mg·kg−1 for pigs. Various studies suggested that low dosage exposure of antibiotics to livestock creates ideal conditions for the development of resistances and their spread between animals.1 Consequently, there is an increasingly robust global campaign to ban the use of synthetic antibiotics from agriculture, livestock management and the agro-food industry (AFI). Therefore, increasing the shelf life (commercial validity) of food products, and the use of sustainable production and consumption processes are some of the current challenges faced by the AFI. Furthermore, the current increase in consumer demand for natural 'organic' foods has forced companies and researchers to explore different ways to improve their market penetration by offering products with improvements in freshness, quality and food safety.2 This has made the AFI to suffer rapid changes in the last few years, including the use of antimicrobial peptides (AMP) as a mean of prevention of food spoilage.
- Antimicrobial properties of PLA scaffolds functionalized via LbL method with Manuka and multifloral honeyPublication . Alves, Inês; Ferraz, Ricardo; Prudêncio, Cristina; Rufo, João; Prudêncio, Cristina; Cavaleiro Rufo, JoãoTissue engineering and chronic wound management face obstacles due to the global rise of resistances. Natural bioactive agents, such as Manuka honey, offer a unique therapeutic profile by combining antimicrobial activity with the ability to modulate the biochemical wound environment and promote cellular regeneration. However, the seamless integration of these biological compounds into synthetic matrices, such as polylactic acid (PLA), remains a challenge. This study aims to develop PLA scaffolds functionalised with honey using the Layer-by-Layer (LbL) technique and evaluate their inhibitory capacity against microbial growth. Two honey types are com-pared, MGO 263+/UMF10+ Manuka honey and a Portuguese multifloral honey. Concentrations of 15%, 20%, 25%, 30% and 35% will be tested by diluting the honey in 3M sodium acetate buffer and adjusting pH to 5.5. The method has currently been successfully optimized for the 15% concentration. The LbL process consist-ed of three immersion cycles, alternating with coating in the honey solutions, washing in acetate buffer and short periods of drying. As a negative control, PLA scaffolds were subjected only to the washing steps. Biological activity was assessed against Escherichia coliand Staphylococcus aureus. In the disc diffusion test, the plates were inoculated uniformly and the scaffolds arranged in quadrants, including positive controls of ciprofloxacin for E. coli andpenicillin G for S. aureus. After incubation, inhibition was quantified by two per-pendicular measurements of the halo. Quantification of Colony-Forming Units (CFU) was performed after recovery of the microorganisms from the scaffolds by vortexing and centrifugation in saline solution. The study is currently in the optimization phase. Sterilization has been successfully achieved by im-mersing the scaffolds in 70% ethanol for 2 hours with gentle stirring, followed by vacuum drying in a Petry dish for 24 hours. Microscopic observation of the scaf-folds showed a clear coating layer in functionalized samples. This research seeks to validate LbL functionalisation as a simple strategy for developing bioactive scaffolds. The present work establishes a foundation for subsequent phases involving various honey concentrations, with the goal of demonstrating a synergistic effect between the PLA scaffold and nat-ural antimicrobial agents.