Anti-tick effect and cholinesterase inhibition caused by Prosopis juliflora alkaloids: in vitro and in silico studies.

We investigated the in vitro acaricide activity of the methanolic extract (ME) and alkaloid-rich fraction (AF) of Prosopis juliflora on Rhipicephalus microplus and correlated this effect with acetylcholinesterase (AChE) inhibition. The acaricide activity was evaluated using adult and larval immersion tests. Also, we studied the possible interaction mechanism of the major alkaloids present in this fraction via molecular docking at the active site of R. microplus AChE1 (RmAChE1). Higher reproductive inhibitory activity of the AF was recorded, with effective concentration (EC50) four times lower than that of the ME (31.6 versus 121 mg/mL). The AF caused mortality of tick larvae, with lethal concentration 50% (LC50) of 13.8 mg/mL. Both ME and AF were seen to have anticholinesterase activity on AChE of R. microplus larvae, while AF was more active with half-maximal inhibitory concentration (IC50) of 0.041 mg/mL. The LC-MS/MS analyses on the AF led to identification of three alkaloids: prosopine (1), juliprosinine (2) and juliprosopine (3). The molecular docking studies revealed that these alkaloids had interactions at the active site of the RmAChE1, mainly relating to hydrogen bonds and cation-pi interactions. We concluded that the alkaloids of P. juliflora showed acaricide activity on R. microplus and acted through an anticholinesterase mechanism.

In vitro ovicidal and larvicidal activities of some saponins and flavonoids against parasitic nematodes of goats.

This study assessed the anthelmintic activity of plant-derived compounds against gastrointestinal nematodes of goats using the egg hatch and larval motility assays. The compounds tested were saponins (digitonin and aescin) and their respective sapogenins (aglycones), hecogenin acetate and flavonoids (catechin, hesperidin, isocordoin and a mixture of isocordoin and cordoin). Additionally, cytotoxicity of active substances was analysed on Vero cell through 3-4,5-dimethylthiazol-2-yl,2,5diphenyltetrazolium bromide (MTT) and propidium iodide (PI) tests. Significant reduction on the egg hatching (P 90%). Nevertheless, higher cytotoxicity was observed in the MTT assay, with IC50 of 0.20 mg mL-1 (aescin) and 0.0074 mg mL-1 (digitonin). Aescin and digitonin have a pronounced in vitro anthelmintic effect and the glycone portion of these saponins plays an important role in this activity.

In vitro acaricide and anticholinesterase activities of digitaria insularis (Poaceae) against Rhipicephalus (Boophilus) microplus.

Medicinal plants have been proposed as an alternative for acaricide control, aiming to develop lower-cost and eco-friendly ectoparasiticide products. The aim of this study was to evaluate the in vitro activity of the extracts and fractions obtained from the leaves of Digitaria insularis on the reproductive efficacy of the bovine tick Rhipicephalus (Boophilus) microplus. Also, we investigated the possible relation with the anticholinesterase mechanism. The effect of the crude hydroethanolic (CH), hexanic (HE), ethyl acetate (EA), butanolic (BT) and residual hydroethanolic (RH) extracts, as well as four fractions of HE, were evaluated using adult immersion test. Only the HE and EA extracts (50 mg/mL) and fraction 2 (Fr2) (12.5 mg/mL) promoted reduction of the reproductive parameters (oviposition and hatching rate) greater than 90% and were not statistically different from the positive control. Higher reproductive activity was recorded in Fr2 with a lower effective concentration (EC50) value (6.65 mg/mL) than in HE (17.8 mg/mL) and EA (23.97 mg/mL). The anticholinesterase activity was assessed through spectrophotometry in microtiter assays, with enzymatic inhibition of 34.8, 43.2 and 57.9% of the HE, AE and Fr2, respectively. The chemical evaluation of the Fr2 was carried through Gas Chromatography coupled to Mass Spectrometry (GC-MS) and led to the characterization of nine compounds classified as fatty acids (3), esterified fatty acids with long-chain alcohol (4) and terpene (1). The effect of D. insularis extracts and fractions was focused on female reproductive parameters such as oviposition and hatching rates. The results obtained in this study suggest that D. insularis shows an in vitro acaricidal activity against R. (B.) microplus. Such action might be associated with the presence of secondary metabolites identified in the Fr2.

In vitro anthelmintic and cytotoxicity activities the Digitaria insularis (Poaceae).

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.

In vitro anthelmintic activity of the Zizyphus joazeiro bark against gastrointestinal nematodes of goats and its cytotoxicity on Vero cells.

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.