Atividade anti-inflamatória do extrato aquoso das folhas da Annona crassiflora (araticum) DC em modelos experimentais in vivo e in vitro

Abstract

The Brazilian Cerrado has numerous species of popular use, including Annona crassiflora (AC) from the Annonaceae family. Bioactive compounds such as flavonoids, tannins and alkaloids were identified in extracts of leaves, seeds, bark and fruits of A. crassiflora, which have been associated with bactericidal, antimalarial, larvicidal, nematicidal, anti-Leishmanial, analgesic and anti-inflammatory activities. However, there are no studies in the literature that evaluated the anti-inflammatory potential of the aqueous extract of the leaves of this species. Thus, the present study aimed to investigate the possible anti-inflammatory effects of the freeze-dried aqueous extract of A. crassiflora leaves (EAAC) using in vivo and in vitro experimental models, of peritoneal inflammation induced by carrageenan (CGN) and quantification the production of nitric oxide (NO) in culture supernatants of RAW 264.7 cells, respectively. In the in vivo experimental model, BALB/c mice were divided into four groups (G 1 - 4) and treated orally (p.o.) with: G1 = 0.5% carboxymethyl cellulose (CBX); G3 = EAAC 30 mg / kg; G4 = EAAC 55 mg / kg; G5 = EAAC 100 mg / kg. After sixty minutes, the animals received an intraperitoneal (i.p.) injection of 1% CGN to induce peritoneal inflammation. Four hours after the CGN injection, the animals were anesthetized and killed by cervical dislocation. Then, an incision was made in the abdomen and the peritoneal cavity was gently washed with phosphate buffered saline (PBS), pH 7.2, and the peritoneal lavage was collected for total and differential leukocyte counts. The results obtained showed that EAAC, at a dose of 30 mg / kg, significantly reduced the migration of total leukocytes to the peritoneal cavity, compared to the control group treated only with the 0.5% CBX vehicle. In addition, at this dose, there was a reduction in the population of mononuclear cells (monocytes / macrophages), but not of neutrophils and lymphocytes, as observed in the differential count. In the highest doses (55 and 100 mg / kg), EAAC reduced the populations of neutrophils and monocytes / macrophages, although it did not decrease the total leukocyte migration, in relation to the control group. Considering that EAAC (30 mg / kg) reduced the number of monocytes / macrophages in the peritoneal inflammatory response induced by CGN 1%, we investigated its effect on the production of nitric oxide (NO) in RAW 264.7 cells. RAW 264.7 cells were treated with RPMI medium only (control) or with different concentrations of EAAC (0.488 to 1000.0 μg / mL) for 24 hours, and then NO production was quantified in culture supernatants using the method of Griess. The results obtained suggest that the extract, in its highest concentrations (62 to 1000 μg / mL), tends to induce NO production in a dose-dependent manner, as demonstrated by the greater amount of NO determined in supernatants of the cultures of RAW 264.7 cells, although there were no statistically significant differences in relation to the control group. The results obtained suggest that the EAAC has dose-dependent anti- or pro-inflammatory properties, thus presenting a dual effect on the modulation of inflammatory responses.