RESUMO
This study aimed to evaluate the in vitro activity of D. insularis extracts and fractions against gastrointestinal nematodes of goats and its cytotoxicity on Vero cells. The egg hatch (EHT) and larval motility (LMT) tests were conducted to investigate the anthelmintic effects of the crude hydroethanolic (CH), ethyl acetate (EA), butanolic (BT) and residual hydroethanolic (RH) extracts. The elution of the active extract (EA) on column chromatography (SiO2) using organic solvents furnished six fractions (FR1 to FR6), which were also tested. Cytotoxicity was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Trypan Blue exclusion assays. All extracts, FR2 and FR3, inhibited egg hatching in a concentration-dependent manner. The EHT led to EC50 values (effective concentration 50%) of 0.64; 0.69; 0.77; 0.96; 0.27 and 0.65mg/mL for CH, EA, BT, RH, FR2 and FR3, respectively. However, the extracts exhibited low effect on the motility of L3. In the cytotoxicity evaluation (MTT assay), the IC50 (inhibitory concentration 50%) was 1.18 (EA), 1.65 (FR2) and 1.59mg/mL (FR3), which was relatively high (low toxicity) in comparison to the EC50 values in EHT, mainly for FR2. The chemical analyses of most active fractions (FR2) by Liquid Chromatography coupled to Mass Spectrometry (LC-MS) led the characterization of the flavones tricin and diosmetin. These results showed the high anthelmintic effect and low cytotoxicity of D. insularis and also that the flavones can be probably responsible for the nematocidal activity of this plant.
