Abstract
Currently 75–88% of fungal infections are caused by Candida species, and Candida albicans is the main microorganism that causes these infections, especially oral candidiasis. An option for treatment involves the use of the antifungal peptide Histatin 5 (Hst 5), which is naturally found in human saliva but undergoes rapid degradation when present in the oral cavity, its site of action. For this reason, it is important to develop a way of applying this peptide to the oral lesions, which promotes the gradual release of the peptide. In the present study, we have evaluated the development of liposomes of different lipid compositions, loaded with the peptide as a way to promote its release slowly and gradually, preserving its antifungal potential. For this, the peptide 0WHistatin 5, an analog of the peptide Hst 5, was synthesized, which contains the amino acid tryptophan in its sequence. The solid phase synthesis method was used, followed by cleavage and purification. The liposomes were produced by thin film hydration technique in three different lipid compositions, F1, F2, and F3 and were submitted to an extrusion and sonication process to standardize the size and study the best technique for their production. The liposomes were characterized by dynamic light scattering, and tests were performed to determine the encapsulation efficiency, release kinetics, stability, and evaluation of antifungal activity. The extruded liposomes presented average size in the range of 100 nm, while sonicated liposomes presented a smaller size in the range of 80 nm. The encapsulation efficiency was higher for the sonicated liposomes, being 34.5% for F1. The sonicated F3 presented better stability when stored for 60 days at 4°C. The liposomes showed the ability to release the peptide for the total time of 96 h, with the first peak after 5 h, and a further increase of the released after 30 h. Time-kill assay showed that the liposomes were able to control yeast growth for 72 h. The data suggest that the liposomes loaded with 0WHistatin 5 maintained the action of the peptide and were able to limit the growth of C. albicans, being a suitable system for use in the treatment of oral candidiasis.
Highlights
In recent decades, there has been an increase in mortality caused by fungal infections which have gone from isolated and rare cases to one of the greatest global public health problems especially among immunocompromised individuals (Robbins et al, 2016)
Nine milliliters of Sabouraud Dextrose Broth (SDB) prepared with the microorganism were added in an Erlenmeyer for the growth control, 512 μg ml−1 of fluconazole was used for the positive control and for testing the systems produced 1 ml of the liposomal system encapsulated or not with 0WHistatin 5 (0WHst 5) was added
To determine the amount of extrusion cycles and sonication time required for the formation of the liposomes, periodic measurements were made in a spectrophotometer (Chorilli et al, 2013)
Summary
There has been an increase in mortality caused by fungal infections which have gone from isolated and rare cases to one of the greatest global public health problems especially among immunocompromised individuals (Robbins et al, 2016). Liposomes encapsulated with peptide ghrelin, used to treat cachexia, characterized as extreme weakness in patients afflicted with chronic diseases, showed that liposomes were able to protect the peptide from the attack of trypsin and carboxylesterase enzymes by 20 and 81%, respectively (Salade et al, 2017) These positive aspects about the use of liposomes motivated us to elaborate a system to apply Histatin 5, with the main interest in increasing peptide availability at the site of action, causing its fungicidal effect to be preserved and intensified over a longer period, optimizing treatment against C. albicans
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