Browsing by Author "Sarmento, B."
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- A biofertilizer with diazotrophic bacteria and a filamentous fungus increases Pinus pinaster tolerance to the pinewood nematode (Bursaphelenchus xylophilus)Publication . Silva, M. Nunes da; Pintado, M. E.; Sarmento, B.; Stamford, N. P.; Vasconcelos, M. W.The pine wilt disease (PWD), caused by the pine wood nematode (PWN) Bursaphelenchus xylophilus, is a devastating illness that mainly affects P. pinaster trees, and that poses great environmental and economic challenges. Current disease management involves the cut down of infected trees, tree fumigation, use of nematicides, or the control of the insect vector; however, these methodologies are expensive, labour-intensive and have limited success. The aim of this work was to evaluate the effect of a biofertilizer enriched with diazotrophic bacteria and a chitosan-producing fungus, Cunninghamella elegans, in inducing P. pinaster and P. pinea resistance against the PWN. In non-inoculated (control) P. pinaster plants, PWN population significantly increased (ca. 2.3-fold) throughout the experimental period, whereas in plants treated with 7.5 and 15% of biofertilizer nematode numbers were up to 36.3-fold lower than in control plants. In P. pinea, nematode numbers decreased with time for all biofertilizer concentrations tested, and P. pinea had up to 27.3-fold lower nematode counts than P. pinaster. In addition, the biofertilizer prevented the decrease of photosynthetic pigments and the reduction of water content in infected P. pinaster plants. In P. pinea the biosynthesis of phenolics increased in PWN-inoculated plants, especially in the presence of the biofertilizer. The addition of this biofertilizer to soils forested by P. pinaster may improve plant defence and could be a potentially simple and inexpensive strategy for the control of the PWD.
- Biological activities of chitin, chitosan and respective oligomersPublication . Tavaria, F. K.; Fernandes, J. C.; Santos-Silva, A.; Silva, S. Baptista da; Sarmento, B.; Pintado, M. E.Chitin and chitosan have been receiving great attention as a novel functional material for their excellent biological properties such as biodegradation, immunological, antioxidant and antibacterial activities. However, the use has been scarcely developed due to its high molecular weight, which causes poor water solubility and high viscosity of the solutions. Compared with ordinary chitosan, chitosan oligomers have much improved water-solubility and some special biological functions due to the high absorption rate at intestinal level, thus permitting its entrance in blood circulation and distribution all over the body. The potential application of chitin and chitosan, and respective oligomers, is multidimensional and it has been found in food and nutrition, biotechnology, material science, drug delivery, agriculture and environmental protection, and recently gene therapy too. In the realm of this chapter we will focus on some biological activities attributed to those molecules, such as, antimicrobial and antifungal activities, wound healing, antioxidant, anti-inflammatory, anti-carcinogenic and anti-coagulant.
- Development and characterization of natural antioxidant-containing chitosan nanoparticlesPublication . Silva, S. Baptista da; Oliveira, A.; Ferreira, D.; Pintado, M.; Sarmento, B.The use of nanotechnology in medical sciences is an innovation that promises a new age of health. Among the different approaches explored so far, chitosan exhibits favourable and unique biological properties, such as biocompatibility, biodegradability, nonantigenic, non-toxicity and mucoadhesiveness. Natural extracts rich in antioxidant molecules have been incorporated in chitosan films, or macro/microparticles, becoming more effective as improving the antioxidant protection [da Silva 2010]. In the present study, chitosan nanoparticles with extracts of sage and savoury and rosmarinic acid were prepared and characterized in order to ensure their best size, efficient encapsulation and to test the retention of the active compounds and evaluate their controlled release performance. This work proposes for the first time in literature, a simultaneous HPLC method for the determination and quantification of phenolic and flavonoid compounds, namely quercetin and rosmarinic acid encapsulated into chitosan nanoparticles. The method can be used to determine the loading capacity and association efficiency as well as its in vitro release.
- Encapsulation of natural compounds in the prevention and treatment of Diabetic RetinopathyPublication . Silva, S. Baptista da; Pintado, M.; Ferreira, D.; Sarmento, B.Introduction Diabetic retinopathy is a disease resulting from diabetic chronic hyperglycemia characterized by microvascular complications in the retina, where neuronal elements responsible for vision are located. Oxidative stress has been widely regarded as the main etiological factor for the emergence of ocular disease. Antioxidant therapy has been related with inhibition of diabetes-induced abnormalities of retinal metabolism. However ocular treatment effectiveness is purely low, considering the several routes of administration. The improvement of ocular bioavailability is the ultimate era of Science. This review data encompasses new nanosystems with therapeutic potential improvements and involving routes of administration local and with a better performance facing biological barriers. Nanoparticles are described to offer real benefits to the stability, drug delivery and therapy of the patient and the most advanced treatment modalities for ocular conditions.
- Encapsulation of rosmarinic acid into chitosan nanoparticlesPublication . Silva, S. B.; Amorim, M.; Oliveira, A.; Ramos, O.; Pintado, M.; Ferreira, D.; Sarmento, B.Introduction: The use of nanotechnology in medical sciences is a innovation that promises a new age of health. Among the different approaches explored so far, chitosan exhibits favourable and unique biological properties, such as biocompatibility, biodegradability, non-antigenic, non-toxicity and mucoadhesiveness . On the other hand, natural extracts have been incorporated in chitosan films, or macro/microparticles, becoming more effective as antimicrobial or improving the antioxidant protection. The combination of antioxidants and nanoparticles is seen as the key to success in the topical administration of therapeutic antioxidants . Phenolic compound like rosmarinic acid are potent natural antioxidant with a multitude of biological activities like anti-inflammatory, antimutagen, antibacterial and antiviral as well as high potential radical scavenging activity.
- Natural antioxidant extracts produced from five microalgae species by enzymatic hydrolysis for application in anti-aging cosmeticsPublication . Cunha, S. A.; Costa-Pinto, A. R.; Sarmento, B.; Pintado, M. E.Skin aging represents a huge concern in almost all cultures in the world. The excessive production of reactive oxygen species (ROS) combined with a normal intrinsic reduced antioxidant activity are factors that deeply contribute to the aging process (1). Thus, it is important to develop strategies to decrease ROS production in the skin or reduce the damage caused by them. The valorisation of natural cosmetic ingredients and formulations in cosmetic industry has been increasing over the past few years. Microalgae, abundant and easy to produce, are described to be an interesting source of bioactive peptides with antioxidant properties (2). Therefore, this work aims to produce water soluble extracts from five different microalgae species with focus on their antioxidant activity to meet the increasing demand for natural cosmetic ingredients. METHODS: Extracts were prepared by enzymatic hydrolysis from the microalgae Chlorella vulgaris, Nannochloropsis oceanica, Tetraselmis sp., Senedesmus obliquus and Phaeodactylum tricornutum. First, microalgae were submitted to an incubation with cellulase - to weaken the cellular wall, followed by an incubation with a subtilisin protease to break proteins into smaller peptides. Prior to enzymatic hydrolysis, Chlorella vulgaris was first submitted to an acid hydrolysis with a weak acid. The protein content was determined by Kjeldahl method and the antioxidant activity was determined by ORAC and ABTS assays. RESULTS: The extraction strategy resulted in high levels of hydrolysis with a yield of 44%, 30%, 16%, 52% and 36% of soluble protein for the microalgae Chlorella, Nannochloropsis, Tetraselmis, Senedesmus and Phaeodactylum, respectively. The results obtained for the ORAC were 400, 350, 150, 530 and 350 µM TE/g of extract, and the ABTS activity was 80, 57, 63, 80 and 82 µM TE/g of extract for Chlorella, Nannochloropsis, Tetraselmis, Senedesmus and Phaeodactylum, respectively. CONCLUSION: The enzymatic hydrolysis allowed to produce extracts rich in proteins, with interesting antioxidant activity. The higher protein yield was obtained from the microalgae Chlorella (44%) and Senedesmus (52%), which coincides with the higher values of antioxidant activity. Therefore, the high protein content and the antioxidant activity of the enzymatic extracts from the microalgae Chlorella vulgaris and Senedesmus obliquus may be an interesting approach for the development of anti-aging ingredients.
- Potential chitosan-coated alginate nanoparticles for ocular delivery of daptomycinPublication . Costa, J. R.; Silva, N. C.; Sarmento, B.; Pintado, M.Daptomycin may offer an antibacterial alternative for the treatment of endophthalmitis caused by methicillin-resistant Staphylococcus aureus (MRSA) and other potential agents. In the present project, mucoadhesive chitosan-coated alginate (CS-ALG) nanoparticles are proposed as an effective delivery system for daptomycin permeation across ocular epithelia, with potential for the treatment of bacterial endophthalmitis. CS-ALG nanoparticles were prepared by ionotropic pre-gelation of an alginate core followed by chitosan polyelectrolyte complexation, and characterized regarding particle size, polydispersity, and zeta potential. The encapsulation efficiency was determined and antimicrobial activity was also tested after encapsulation of the antibiotic. Also, in vitro ocular permeability of free daptomycin and encapsulation into chitosan and CS-ALG nanoparticles was evaluated using ocular epithelial cell culture models. Formulated daptomycin-loaded CS-ALG nanoparticles were negatively charged, with a size range of 380–420 nm, suitable for ocular application. The encapsulation efficiency was between 79 and 92 %, with decreasing alginate:daptomycin mass ratios. The antibacterial activity of daptomycin against major microorganisms responsible for bacterial endophthalmitis was not affected by encapsulation into nanoparticles. Daptomycin permeability was up to 16 % (chitosan nanoparticles) and 9 % (CS-ALG nanoparticles) through corneal cell monolayer, and 18 % (chitosan nanoparticles) and 12 % (CS-ALG nanoparticles) for retinal cell monolayer after 4 h, demonstrating epithelial retention of the drug compared to free drug. The developed daptomycin-loaded CS-ALG nanoparticles seem to be an interesting and potential system for ocular daptomycin delivery and treatment of bacterial endophthalmitis.
- Prevention and treatment of diabetic retinopathy by natural antioxidant containing in chitosan-based nanomedicinesPublication . Silva, S. B. da; Carvalho, D.; Pintado, M.; Sarmento, B.Oxidative processes are critical factors in ocular conditions that may lead to pathologies such as Diabetic Retinopahty due to structural and functional modification of the tissues, apoptosis of capillary cells and retinal microvascular changes, making the loss of vision inevitable. Application of antioxidants may reduce apoptosis and restores partially functional tissues. Considering the multiple benefits of antioxidants in DR and that conjunctival drug permeability improvement is one of the major challenges in ocular drug delivery, the major topic of this work is to study the absorption capacity and consequent bioavailability of natural antioxidants incorporated in chitosan-based nanoparticles to prevent and treat DR. In this regards, it is proposed to characterize, quantify and compare the antioxidant potential of Salvia sp. and Satureja montana extracts and their main pure antioxidants: rutin, caffeic and clorogenic acid. Then, antioxidant compounds are encapsulated into different chitosan-based nanoparticles, nanoparticles and release profile characterized and ocular permeation evaluated using in vitro cell models. Finally, the effect of antioxidant nanomedicines across human ocular is evaluated in diabetic animal after topical administration in vivo.