Browsing by Author "Silva, S. Baptista da"
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- 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.