Determination of the potential of solid lipid nanoparticles containing green propolis rich in artepelin C in vitro and in the topical therapy of wounds diabetic rats infected with methicillin-resistant Staphylococcus aureus

Abstract

The difficulty of wound healing is one of the main complications due to Diabetes Mellitus (DM), caused by the high level of oxidative stress and the persistence of the inflammatory process. This process may be more compromised when associated with bacterial infection, such as Methicillin-Resistant Staphylococcus Aureus (MRSA), worsening the condition, which is responsible for a large number of amputations. Thus, the search for new therapeutic agents is paramount, and the use of plants and natural products of plant origin, have become an alternative to the use of antibiotics and conventional healing. The green propolis, originating from the alecrim-do-campo (Baccharis dracunculifolia), is distinguished by the composition of about 16 phenolic compounds with the major presence of flavonoids, such as Artepelin C, which has been the object of several pharmacological studies due to their varied biological properties, as antioxidant, anti-inflammatory and anti-tumor, being considered an important therapeutic alternative from the economic point of view, being pharmacologically efficient and easy to obtain. However, due to unfavorable physical-chemical characteristics, its direct use in topical formulation may be restricted. In this way, the use of nanotechnology becomes an ally to overcome these limitations and enable the encapsulation of extracts of plants and/or isolated substances. In this project, the cicatrizing action of solid lipid nanoparticles (NLS) containing fraction of Artepelin C rich green propolis (PVArtC) in experimental models in vitro and in vivo will be investigated. Initially, tests of cytotoxicity, wound healing, retention and skin permeation in vitro will be performed. After in vitro assays, in vivo studies will be performed using male Wistar rats that will be randomly divided into seven experimental groups (n=7). Experimental induction of diabetes will be by single intraperitoneal application of streptozotocin at a dose of 55 mg/kg. After the diabetic state of the animals has been proven, anesthesia will be performed and, later, the wounds will be made in the dorsal region with the aid of a punch 3 cm in diameter. Then, the bacterial inoculum (methicillin-resistant S. aureus (ATCC 25923)) will be injected into the surgical lesion of the animals and after 24 hours of inoculation, the first swab will be collected for evidence of wound contamination. The lesions will be treated twice a day for 21 days. The area of the wounds will be measured daily to verify macroscopic reduction and clinical appearance of the lesions. After euthanasia, the wounds will be used for histopathological, biochemical, immunoenzymatic and molecular analysis. This work is an integral part of the thematic project approved by FAPESP (Process FAPESP: 2017/04138-8): "Attainment of chemical, analytical, biological, pharmacological and technological studies to fill the gaps on the development of the Brazilian propolis sector". (AU)