Percorrer por autor "Malcata, Francisco Xavier"
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- Anti-inflammatory activity of chitooligosaccharides in vivoPublication . Fernandes, João C.; Spindola, Humberto; Sousa, Vanessa de; Santos-Silva, Alice; Pintado, Manuela E.; Malcata, Francisco Xavier; Carvalho, João E.All the reports to date on the anti-inflammatory activity of chitooligosaccharides (COS) are mostly based on in vitro methods. In this work, the anti-inflammatory activity of two COS mixtures is characterized in vivo (using balb/c mice), following the carrageenan-induced paw edema method. This is a widely accepted animal model of acute inflammation to evaluate the anti-inflammatory effect of drugs. Our data suggest that COS possess anti-inflammatory activity, which is dependent on dose and, at higher doses, also on the molecular weight. A single dose of 500 mg/kg b.w. weight may be suitable to treat acute inflammation cases; however, further studies are needed to ascertain the effect upon longer inflammation periods as well as studies upon the bioavailability of these compounds.
- Influence of abiotic factors on the antimicrobial activity of chitosanPublication . Tavaria, Freni K.; Costa, Eduardo M.; Gens, Eduardo J.; Malcata, Francisco Xavier; Pintado, Manuela E.In an effort to bypass the adverse secondary effects attributed to the traditional therapeutic approaches used to treat skin disorders (such as atopic dermatitis), alternative antimicrobials have recently been suggested. One such antimicrobial is chitosan, owing to the already proved biological properties associated with its use. However, the influence of abiotic factors on such activities warrants evaluation. This research effort assessed the antimicrobial activity of chitosan upon skin microorganisms (Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli) in vitro when subject to a combination of different abiotic factors such as pH, ionic strength, organic acids and free fatty acids. Free fatty acids, ionic strength and pH significantly affected chitosan's capability of reducing the viable numbers of S.aureus. This antimicrobial action was potentiated in the presence of palmitic acid and a lower ionic strength (0.2% NaCl), while a higher ionic strength (0.4% NaCl) favored chitosan's action upon the reduction of viable numbers of S.epidermidis and E.coli. Although further studies are needed, these preliminary results advocate that chitosan can in the future be potentially considered as an antimicrobial of choice when handling symptoms associated with atopic dermatitis.
- Medium factors affecting extracellular protease activity by Bacillus sp. HTS 102—A novel wild strain isolated from Portuguese merino woolPublication . Queiroga, Ana Catarina; Pintado, Manuela Estevez; Malcata, Francisco XavierThe synthesis of an extracellular protease by Bacillus sp. HTS102—a wild strain recently isolated from the wool of Portuguese Merino ewes, was optimized. This protease is thermostable and particularly resistant to harsh environmental conditions—and appears to bear a unique ability to hydrolyze keratin-rich solid materials. Following a preliminary screening for the most relevant medium factors involved in processing, a fractional factorial design (2VI 6-1) was applied to ascertain the effects of six relevant parameters— viz. yeast extract concentration, peptone level, inoculum size, stirring rate, temperature and pH. The concentrations of yeast extract and peptone, as well as the incubation temperature and pH were found to play significant roles; and the 2-factor interaction between yeast extract level and pH was also significant. A 2.2-fold increase in the overall level of protease synthesis was eventually attained, with the improved medium relative to the basal medium—which is noteworthy when compared with competing proteases and previous optimization efforts.