RESUMO
This study examined the in vitro effect of the Zizyphus joazeiro bark against gastrointestinal nematodes of goats and its cytotoxicity on Vero cells. The ovicidal activity of the crude hydroethanolic extract (CE), its partitioned hexane (HE) and aqueous extract (AE) and saponins fraction (SF), including betulinic acid (BA), a biogenetic compound from this plant found in HE, were investigated using the inhibition of egg hatch assay (EHA). Thereafter, the extracts and the SF were evaluated through the larval motility assay (LMA) and larval migration inhibition assay (LMIA). The AE and SF promoted a complete inhibition of the egg hatch, and the effective concentration to inhibit 50% (EC50) values was 1.9 and 1.3mg/mL, respectively. The highest percentages of inhibition in EHA observed after treatments with CE, HE and BA corresponded to 79, 48 and 17%, respectively. The extracts and SF did not show larvicidal activity in LMA and LMIA. The AE and SF demonstrated cytotoxic effects in 3-4,5-dimethylthiazol-2-yl, 2,5diphenyltetrazolium bromide (MTT) and trypan blue tests; however, SF was more toxic (50% inhibitory concentration, IC50=0.20mg/mL). The chemical characterization of the SF was made through Proton Nuclear Magnetic Resonance ((1)H NMR) and Electrospray Ionization Mass Spectrometry (ESI-MS) analyses, which led to the identification of two saponins known as Joazeiroside B and Lotoside A. The results obtained from the research of this saponin content provide important information about the biological activity, especially the anthelmintic effect present in the plant investigated. That also suggests the types of bioactive compounds that may be responsible for this antiparasitic activity exhibited by the plant extracts.
