Abstract
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.
Highlights
Parasitic diseases impair livestock health and can cause high mortality rate in cattle herds if parasitism rates are high
The solvent was evaporated under reduced pressure and the remaining plant material was subsequently extracted with methanol (MeOH) (9 L), using the same procedure
The MS/MS fragmentation pattern obtained from this alkaloid showed fragment ions at m/z 298.32 [M-18+H]+ and 280.33 [M-36+H]+, which were formed by the loss of one and two molecules of water, respectively
Summary
Parasitic diseases impair livestock health and can cause high mortality rate in cattle herds if parasitism rates are high. Popularly known as “algaroba” and “algarobeira”, is a shrub belonging to the Fabaceae family that is native to arid and semi-arid regions This species was introduced into northeastern Brazil more than 50 years ago and is used as a food source for humans and animals because of its high production of pods and the high palatability and nutritional value of the pods (Pegado et al, 2006). Several types of biological activity have been reported for this plant, such as anthelmintic (Lima et al, 2017), insecticidal (Dhivya et al, 2018) and antibacterial (Odhiambo et al, 2015) These effects have been attributed to the alkaloids that are present in this species. The alkaloids of greatest pharmacological importance are juliprosopine and juliprosine (Silva et al, 2013)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
