[Evaluation of the anti-inflammatory activity and phytochemical screening of Annona senegalensis leaves]

Abstract

Objective: This study aims to highlight the anti-inflammatory activity of ethanol extract of Annona senegalensis and do its phytochemical screening.

Methods: Rats were divided into three groups. The first group received only saline injection and instillation by intraperitoneal injection on days D0 and D7. This phase was the sensitization of that group. Then, on days D21, D22 and D23, the rats of the same group (Group 1) were injected with saline under anesthesia. The second group (Group 2) was composed of rats had not undergone treatment with the extract of Annona senegalensis. The rats in this batch have been sensitized by intraperitoneal injection (50 μL) of a solution of albumin (50 mg/rat) dissolved in aluminum hydroxide on days 0 and 7. Then during the challenge phase, saline containing 0.9% sodium chloride were injected intraperitoneally on days D21, D22 and D23. The sacrifice took place at D24 or 24 hours after the last challenge to ovalbumin. Similarly, rats of the third group (Group 3) have been sensitized by ovalbumin combined with aluminum hydroxide on days D0 and day D7. Then during the stage of provocation, rats in this batch received at days D21, D22 and D23, conjugated injection of albumin and ethanol extract of Annona senegalensis (injection of 0.4 mL of 7.10(-2) mg/kg body weight). The aqueous extract of Annona senegalensis has been previously prepared in saline. Twenty four hours after the last injection corresponding to D23, the rats were sacrificed under anesthesia. Secondary metabolites have been characterized by physico-chemical properties.

Results: Rats in the control (Group 1) gave an average of 24 ± 0.02 mast cells, 7 ± 0.1 macrophages, 9 ± 0.05 eosinophils. In the control group was not revealed the presence of neutrophils. Following the steps of provocation and awareness albumin (Group 2), we observed a significant increase in the number of inflammatory cells compared to control group (p < 0.001). Indeed, mast cells and macrophages have suffered increased respectively to 164 ± 0.01 and 253 ± 0.04. While eosinophils have increased from 9 ± 0.05 to 81 ± 0.01. There were 31 ± 0.02 neutrophils in Group 2. Group 3 treated with Annona senegalensis (7.10(-2) mg/kg) induced a significant decrease in the number of inflammatory cells compared to control group (p < 0.001). Indeed, mast cells decreased from 164 ± 0.01 to 89 ± 0.03. Similarly, the number of macrophages decreased from 253 ± 0.04 to 175 ± 0.06 and neutrophils decreased from 31 ± 0.02 to 10 ± 0.05. Finally, the eosinophils have suffered a decrease (from 81 ± 0.01 to 61 ± 0.08). However, after treatment with the extract, the values of different cell types have always been significantly higher (p < 0.001) compared to those in the control group (except neutrophils). This result indicates that the extract of Annona senegalensis did not completely inhibit the inflammatory effect induced by albumin. The major classes of secondary metabolites, terpenoids, coumarins, flavonoids and tannins were detected in the leaves of the plant. However, they are low in alkaloids and substances quinone.

Conclusion: The extract induced a significant decrease in the number of inflammatory cells. This effect is likely due to higher concentrations of tannins and phenolic compounds in the extract of plant. Thus this study provides a scientific validation of the use of this plant against asthma and cough in the Ivorian pharmacopoeia. However, its mechanism of action remains to be elucidated.