ABSTRACT
Objective: The aim of the present study was to encapsulate vancomycin in different liposomal formulations and compare the in vitro antimicrobial activity against Staphylococcus aureus biofilms. Methods: Large unilamellar vesicles of conventional (LUV VAN), fusogenic (LUVfuso VAN), and cationic (LUVcat VAN) liposomes encapsulating VAN were characterized in terms of size, polydispersity index, zeta potential, morphology, encapsulation efficiency (%EE) and in vitro release kinetics. The formulations were tested for their Minimum Inhibitory Concentration (MIC) and inhibitory activity on biofilm formation and viability, using methicillin-susceptible S. aureus ATCC 29213 and methicillin-resistant S. aureus ATCC 43300 strains. Key Findings: LUV VAN showed better %EE (32.5%) and sustained release than LUVfuso VAN, LUVcat VAN, and free VAN. The formulations were stable over 180 days at 4°C, except for LUV VAN, which was stable up to 120 days. The MIC values for liposomal formulations and free VAN ranged from 0.78 to 1.56 µg/ml against both tested strains, with no difference in the inhibition of biofilm formation as compared to free VAN. However, when treating mature biofilm, encapsulated LUVfuso VAN increased the antimicrobial efficacy as compared to the other liposomal formulations and to free VAN, demonstrating a better ability to penetrate the biofilm. Conclusion: Vancomycin encapsulated in fusogenic liposomes demonstrated enhanced antimicrobial activity against mature S. aureus biofilms.
ABSTRACT
Purpose: Bothrops snakes are responsible for more than 70 % of snakebites every year in Brazil and their venoms cause severe local and systemic damages. The pharmacological properties of medicinal plants have been widely investigated in order to discover new alternative treatments for different classes of diseases including neglected tropical diseases as envenomation by snakebites. In this work, we have investigated the ability of Vochysia haenkeana stem barks extract (VhE) to neutralize the neuromuscular effects caused by Bothropstoxin-I (BthTX-I), the major phospholipase A2 (PLA2) myotoxin from B. jararacussu venom. Methods: The biological compounds of VhE were analysed under thin layer chromatography (TLC) and its neutralizing ability against BthTX-I was assessed through twitch-tension recordings and histological analysis in mouse phrenic nerve-diaphragm (PND) preparations. The antimicrobial activity of VhE was assessed against S. aureus, E. coli and P. aeruginosa strains. The aggregation activity of VhE was analysed under protein precipitation assay. Results: VhE showed the presence of phenolic compound visualized by blue trace under TLC. VhE abolished the neuromuscular blockade caused by BthTX-I applying the pre-toxin incubation treatment and partially neutralized the BthTX-I action under post-toxin incubation treatment; VhE contributed slightly to decrease the myotoxicity induced by BthTX-I. The neutralizing mechanism of VhE may be related to protein aggregation. VhE showed no antimicrobial activity. Conclusion: V. haenkeana extract which has no antimicrobial activity exhibited neutralizing ability against the neuromuscular blockade caused by BthTX-I and also contributed to decrease its myotoxicity. Protein aggregation involving phenolic compounds may be related in these protective effects.
ABSTRACT
The purpose of this work was to determine the proximate composition and fatty acid profiles of the Gastrocnemius pars interna intramuscular fat (IMF) of rhea (Rhea americana) thighs. The birds were bred in captivity, fed with balanced feed (Nutriavestruz Crescimento - Purina) and kept in a pen with grass ad lib. The birds of both sexes used in the research weighed 23 kg on average and were aged about twelve (12) months old. They were subjected to hydric diet (12 h) before slaughtering by electric shock. The rhea meat showed an average moisture, protein, ash and total lipid contents of 74.1%, 22.8%, 1.5% and 1.6%, respectively. It was noticed the predominance of monounsaturated fatty acids (MUFA) in intramuscular fat (IMF), 42.3% and a high percentage of polyunsaturated fatty acids (PUFA), 29.7%. The fatty acids found in higher proportion in rhea IMF were: 18:2n-6 (24.33%), 18: ln-9 (19.25%), 16:0 (13.70%), 22: ln9 (11.40%), 18:0 (10.66%), 15: ln-10 (8.62%), 24: ln-9 (2.90%) and 20:4n-6 (1.72%). The PUFA/SFA and n-6/n-3 ratios were 1.06 and 31.30, respectively. The consumption of rhea meat is a healthy alternative to red meat as it points to a lower susceptibility to cardiovascular diseases caused by the high consumption of fat comparatively to the consumption of meat from most domesticated animals.
