Browsing by Author "Amaral, Maria Helena"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- Identification and quantification of stilbenes (piceatannol and resveratrol) in passiflora edulis by-productsPublication . Krambeck, Karolline; Oliveira, Ana; Santos, Delfim; Pintado, Maria Manuela; Baptista Silva, João Baptista; Lobo, José Manuel Sousa; Amaral, Maria HelenaRecently, studies on the by-products from the food industry, such as passion fruit seeds, have significantly increased, as these can have an added value, due to their properties, such as potential antioxidant activity. This study was conducted to determine the presence of piceatannol and resveratrol in various extracts of passion fruit (Passiflora edulis) seeds from Madeira Island and a commercial passion fruit oil was used as reference. The commercial oil and the extracts that were obtained by traditional Soxhlet method with ethanol and acetone did not reveal the presence of the two stilbenes, piceatannol and resveratrol. However, the extracts that were obtained by the ultrasound method showed significant amounts of piceatannol and resveratrol when compared with the commercial oil. The presence of these compounds indicates that this oil could have potential application in cosmetic and pharmaceutical industries, due to their proven antioxidant and anti-aging properties.
- Thermo-responsive microemulsions containing deep eutectic-based antibiotic formulations for improved treatment of resistant bacterial ocular infectionsPublication . Pedro, Sónia N.; Gomes, Ana T. P. C.; Vilela, Carla; Vitorino, Carla; Fernandes, Rosa; Almeida, Adelaide; Amaral, Maria Helena; Freire, Mara G.; Silvestre, Armando J. D.; Freire, Carmen S. R.The rise of antibiotic resistant strains, as methicillin-resistant Staphylococcus aureus (MRSA), challenges the current treatment of infections. In the case of ocular infections, antibiotic eye drops are commonly prescribed. However, their efficacy is usually compromised by the low viscosity of these formulations and the eye drainage. To overcome these drawbacks, deep eutectic solvent (DES)-based microemulsions with thermo-responsive character, that increase their viscosity upon contact with the eye have been developed. Using betaine-based DES aqueous solutions, it is possible to increase up to 140-fold the water solubility of the antibiotic chloramphenicol, typically used in ocular infections. The DES solutions containing the antibiotic are applied as water phases in water-in-oil-in-water (w/o/w) microemulsions, being stable up to 3 months. Furthermore, a sustained-release and a higher permeation of the antibiotic through the cornea than that of commercialized eye drops is achieved, while presenting comparable cytotoxicity profiles (cell viabilities > 88%). Higher antimicrobial activity and faster action of the antibiotic in case of infection with MRSA is observed compared to the commercialized formulations (7 log10 of inactivation in 48 h vs 72 h). Overall, these microemulsions comprising DES are a promising strategy to achieve higher antibiotic effectiveness in the treatment of resistant bacterial infections.