Neuroprotective activity and acetylcholinesterase inhibition of five Amaryllidaceae species: A comparative study

Abstract Aims Amaryllidaceae alkaloids exhibit a wide range of physiological effects, of which the acetylcholinesterase (AChE) inhibitory activity is the most relevant. However, scientific evidence related to their neuroprotective effectiveness against glutamate-induced toxicity has been lacking. Thus, the purpose of this study was to conduct a comparative study of the neuroprotective activity and the AChE inhibitory activity of species of Amaryllidaceae. Main methods The neuroprotective activity against glutamate-induced toxicity was measured in rat cortical neurons and the Ellman method was employed for the quantification of acetylcholinesterase inhibitory activity of alkaloidal extracts of five species of Amaryllidaceae ( Crinum jagus , Crinum bulbispermum , Hippeastrum barbatum , Hippeastrum puniceum and Zephyranthes carinata ). The alkaloid Amaryllidaceae patterns based on GC/MS analyses were also investigated. Key findings The results showed that the alkaloidal extract from C. jagus presented a high neuroprotective activity in both pre- and post-treatments against a glutamate excitotoxic stimulus. Furthermore, the alkaloid extracts from C. jagus and Z. carinata revealed an inhibitory activity of AChE from the electric eel with IC 50 values of 18.28 ± 0.29 and 17.96 ± 1.22 μg/mL, respectively. In addition, 46 alkaloids were detected by GC/MS, and 20 of them were identified based on their mass spectra and retention index. The results suggest that the neuroprotective effects might be associated with lycorine and crinine-type alkaloids, whereas the acetylcholinesterase enzyme inhibitory activity could be related to galanthamine and lycorine-type alkaloids, although not based on synergistic processes. Significance In summary, Amaryllidaceae species are sources of alkaloids with potential use for Alzheimer's disease.