Immunomodulation induced by the aqueous extract obtained from Ampelozizyphus amazonicus

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Ampelozizyphus amazonicus Ducke (Rhamnaceae) (popularly known as “Saracura-mirá”) is a medicinal plant from Amazonia (Brazil). An aqueous drink is prepared from its barks and roots which displays a very bitter taste and forms abundant foam when shaken, due to the high content of dammarane-type saponins in the species. The plant is used in the region to treat and prevent malaria, as well as a stimulant and energetic. Previous studies did not show a direct action of this plant on Plasmodium blood forms, however, it is effective on controlling infection induced by sporozoite forms. In this study, we investigated whether the aqueous extract (SM) obtained from the stem barks of A. amazonicus collected in “quilombola” communities of Oriximiná (Para), Brazil, could control malaria infection through an overall augmentation of the immunological response. Daily oral treatment and dose of SM was based on its traditional use (Peçanha et al. 2013). Oral treatment with SM induces an increase in both IgM and IgG antibody titers in mice immunized with the T-independent type 2 (TI-2) antigen TNP-ficoll. We investigated the effect of SM treatment on the course of B cell response in P. chabaudi-infected mice and observed that SM treatment induced an increase in the levels of circulating total IgM and IgG in Plasmodium-infected mice when compared to infected untreated animals. There was, however, a decrease in the number of antibody-producing plasma cells (CD138+ cells) in the spleen of P. chabaudi-infected SM-treated mice. The data obtained in our study indicates that SM could amplify the response of murine B cells to a TI-2 antigen and could also increase immunoglobulin production during malaria infection and regulate the emergence of antibody secreting cells. Future studies on the role of saponins isolated from SM on both B cell response and resistance to malaria infection will be performed.