The treatment of chronic wounds is considered a public health problem. When the condition affects at-risk groups such as those with diabetics, it becomes a great clinical challenge. In this work, we evaluated the healing effects of a new zinc complex, [Zn(phen)(van)2], identified as ZPV, which was synthesized, characterized and associated with chitosan (CS) membranes and tested on cutaneous wounds of diabetic rats. Chitosan membranes were modified by Schiff base reaction with the complex under two experimental conditions (14 and 21 days), resulting in membranes with concentrations of complex equal to 0.736 μmol cm-2 (CS-ZPV1) and 1.22 μmol cm-2 (CS-ZPV2). Release assays in aqueous medium indicated that the membranes release the complex gradually when exposed to an aqueous medium. Diabetes was inducted in Wistar rats using 40 mg/kg (i.v.) streptozotocin. On the 7th day after diabetic induction, a circular excision on the skin (1.0 cm) was performed with a punch. The lesions were treated with the pure chitosan membrane and the membrane associated with the zinc-vanillin complex in two different doses. Skin samples were subjected to macroscopic and histopathological analyses, cytokine (TNF-α, IL-1β, and IL-10) quantification and reverse transcriptase polymerase chain reaction (TGF-β and VEGF) assays. The analyses showed a decrease in wound size, reepithelialization, angiogenic stimulus, collagen deposition, and reduced levels of TNF-α and IL-1β as well as increased IL-10 and gene expression of TGF-β and VEGF. The evaluated parameters suggest that CS-ZPV in the two concentrations tested may be effective in the treatment of chronic wounds.
3 complex. Chromatographic studies were carried out and showed that immediately after nitrite complex was dissolved only one species was present with retention time(t R ) of 6.81 minutes. Addition of H 3 O + to nitrite complex led to the formation of one major peak with t R of 3.92 min supporting nitrosyl complex formation. The reaction of nitrosyl complex with cysteine was also monitored by HPLC and it showed clearly the formation and followed decrease of a peak at 3.38 minute with maximum absorption at 380 nm, consistent with an intermediate complex. Later, it was observed the appearance of a peak at 4.15 minute with absorption band at 470 nm. In contrast to the reaction with cysteine, methionine did not show the formation of any intermediate. The use of HPLC was an important tool to support mechanistic assumptions for nitrosyl reactions.
A quitosana é um biopolímero derivado da quitina, o segundo polissacarídeo mais abundante na natureza, existente principalmente nas carapaças de crustáceos. Devido as suas diversas propriedades químicas e biológicas é frequente mente usado como objeto de pesquisa. A quitosana apresenta uma grande quantidade de grupos amino reativos em sua cadeia, possibilitando modificações químicas, como por exemplo a base de Schiff. As esferas de quitosana purificada, e de quitosana desacetilada, foram preparadas e modificadas para o estudo de novas aplicações. A reação de modificação de Base de Schiff é evidenciada pela presença do estiramento C=N, característico da função imina, pela presença das bandas referentes às ligações em compostos aromáticos pelo IV, e pelas bandas da vanilina presentes nos espectros eletrônicos. O estudo cinético realizado sobre a incorporação do complexo de cobre nas esferas mostra uma maior capacidade de adsorção para as esferas modificadas de quitosana desacetilada.
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