Atividade cicatrizante de três espécies adaptadas ao cerrado brasileiro em modelo experimental de úlceras dérmicas em coelhos com análise imunohistológica e morfológica

Abstract

The Brazilian cerrado is one of the planet’s major biological diversity biomes, hosting a wide variety of medicinal plants used as part of the tradition and customs of local communities. The objectives of this study were to determine the levels of polyphenols and flavonoids; evaluate the antioxidant activity; correlate the levels of polyphenols and flavonoids among themselves and with the antioxidant activity and to evaluate the healing activity of the ethanol extracts (EE) of three species of the cerrado: Lippia sidoides, Synadenium grantii and Stachytarpheta gesnerioides. With the ethanol extracts (EE), obtained from leaves, it were spectrophotometrically quantified the concentrations of polyphenols and flavonoids, and it was also evaluated the antioxidant activity (DPPH) and their correlations. The EE obtained from the leaves were incorporated into the cream base (10% of L. sidoides, 10% of Synadenium grantii and 10% of Stachytarpheta gesnerioides) and their healing activity was evalluated. It was used as experimental model the induction of dermal ulcers in New Zealand albino rabbits (males 1.5-2.0 kg; n = 6). The ulcers were analyzed for the appearance of the lesion and the contraction of the wound area during 10 days. After this period, the histology was conducted using histological sections stained with hematoxylin-eosin to compare the number of inflammatory cells, fibroblasts and blood vessels and immunohistochemistry to compare the number of myofibroblasts among the experimental groups. Descriptive statistics analysis were conducted and, to assess the significance of differences between the mean results of groups, It was also applied the analysis of variance (ANOVA) and Tukey's post hoc test, using SPSS version 14.0 and p <0.05. It was evaluated the Pearson correlation between the levels of polyphenols and flavonoids and between these levels and the antioxidant activity. All the EE of the used species showed the presence of polyphenols, flavonoids and antioxidant activity. It was demonstrated a positive correlation among these constituents and antioxidant activity. No difference was observed in the contraction of the lesion when compared to the control and treated groups. At microscopic analysis, treatment with L. sidoides showed the number of blood vessels, collagen area and area of extracellular matrix similar to the positive control; the number of fibroblasts and inflammatory cells was 24% (p = 0.002) and 54% (p <0.001) lower, respectively, compared to positive control. Treatment with Synadenium grantii presented number of fibroblasts, collagen area and area of extracellular matrix similar to the positive control and reduced the number of inflammatory cells (61%) and blood vessels (54%) (p <0.001 for both) compared the positive control. Treatment with Stachytarpheta gesnerioides presented number of fibroblasts, collagen area and area of extracellular matrix similar to the positive control and reduced the number of inflammatory cells (65%, p <0.001) and blood vessels (42%, p = 0.005) compared the positive control. In relation to the myofibroblasts, all treatments presented number of myofibroblasts similar to the positive control A combined analysis of these results suggest to perform further scientific studies related to healing activity of L. sidoides.