The development of antibiotics generated a revolution in the way we look and treat bacterial infections. In spite of the initial success, new problems came along and raised allergic reactions, bacterial resistance and ecological problems. These consequences have encouraged research on alternative solutions based on sustainable sources. In this way, antibacterial agents that do not comprise metals or synthetic molecules are appealing. Among those alternatives, we found the (+)-usnic acid, a strong lichen metabolite that has been progressively applied as active material in commercial products (such as creams, toothpaste, deodorant and sunscreen). These products take advantage of antiviral (Influenza A), antimicrobial, antifungal, anti-inflammatory, antiproliferative, analgesic, antiprotozoal and antipyretic properties of this natural product. The aggregation level of active material represents an important aspect to be circumvented to optimize the activity of usnic acid derivatives. In this work, the novelty related with encapsulation of usnic acid in electrospun fibers of poly(vinyl pyrrolidone) and Eudragit L -100 is explained. This encapsulation process favors the homogeneous distribution of active material in beads-free electrospun fibers, minimizing the aggregation level, providing reasonable surface area for diffusion of material along fiber walls and contributing to massive production of active available surface. An additional advantage is offered by loaded enteric electrospun fibers, that favors the development of new pH-controlled release antibacterial materials. The effective bactericidal activity of usnic acid was verified against different bacteria in a time dependent controlled diffusion process in which usnic acid acquires a controlled release rate from polymeric matrix (inhibition halo measurement reveals convenient activity of usnic acid). This property can be conveniently explored as a secondary therapy in the diabetics wound healing treatment due to the strong mechanical properties of fibers and adequate release profile of usnic acid.
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Reference: Araújo, E.; (2016). Bactericidal Activity of Usnic Acid-Loaded Electrospun Fibers. Recent Patents on Nanotechnology., DOI: 10.2174/1872210510666160517160144