Acetylcholinesterase inhibitory activity from Amaryllis belladonna growing in Chile: enzymatic and molecular docking studies.

Alkaloid profiles from Amaryllis belladonna plants collected in Chile were examined by GC-MS to assess their inhibitory activity on acetylcholinesterase (AChE) using in vitro and in silico methodologies. The alkaloid extract was roughly separated by column chromatography on silica gel. AChE inhibitory activities from extracts and purified alkaloids were tested by the Ellman method and a molecular docking study was performed to assess the interaction between AChE and purified alkaloids. Sixteen alkaloids were found from hexane and chloroform extracts, and three were isolated and identified as buphanidrine, acetylcaranine and lycorine. Chloroform extract showed the greatest AChE inhibitory activity with IC50 value 8.89 µg/mL, whereas buphanidrine exhibited the highest inhibitory activity, with IC50 value 17.56 µg/mL. Inhibition kinetics showed that buphanidrine acts as a mixed inhibitor and molecular docking supports this inhibition mechanism. Overall, our study supports the potential use of A. belladonna as an alkaloid source with AChE inhibitory activity.[Formula: see text].

Galanthamine and other Amaryllidaceae related alkaloids are inhibitors of α7, α4β2 and α3β4 nicotinic acetylcholine receptors

Abstract Galanthamine is an Amaryllidaceae-derived acetylcholinesterase inhibitor used to treat memory impairment in Alzheimer's disease and vascular dementia. There is evidence that galanthamine, in addition to its effects on acetylcholinesterase, may enhance or inhibit brain nicotinic acetylcholine receptors, which could increase or decrease the therapeutic efficacy of galanthamine, respectively. Here, we evaluated the effects of galanthamine and two others Amaryllidaceae acetylcholinesterase inhibitors (haemanthamine and tazettine) analyzed by gas chromatography-mass spectrometry and identified by comparing their mass fragmentation patterns with literature and database NIST vs.2.0 on the agonist responses of brain nicotinic acetylcholine receptors α7, α3β4, (α4)2(β2)3 and (α4)3(β2)2. Using nicotinic acetylcholine receptors expressed heterologously in Xenopus oocytes, in conjunction with two-electrode voltage clamping, we found that galanthamine inhibits the function of nicotinic acetylcholine receptors assayed through a mix competitive and non-competitevely. Nicotinic acetylcholine receptor α7 were significantly more sensitive to inhibition (17 ± 0.6 µM) than the heteromeric receptor, α3β4 (90 ± 3.4 µM). Neither haemanthamine nor tazettine were more potent than galanthamine.

Rhodolirium andicola: a new renewable source of alkaloids with acetylcholinesterase inhibitory activity, a study from nature to molecular docking

ABSTRACT Acetylcholinesterase is an important target for control of neurodegenerative diseases causing cholinergic signaling deficit. Traditionally, galanthamine has been used as an Amaryllidaceae-derived acetylcholinesterase inhibitor, although new Amaryllidaceae plants could serve as source for better acetylcholinesterase inhibitors. Therefore, the objective of this study was to characterize the alkaloid composition from bulbs of Rhodolirium andicola (Poepp.) Traub, a native Chilean Amaryllidaceae specie, and assess their inhibitory activity on acetylcholinesterase by in vitro and in silico methodologies. Alkaloidal extracts from R. andicola exhibited an inhibitory activity with IC50 values between 11.25 ± 0.04 and 57.78 ± 1.92 µg/ml that included isolated alkaloid, galanthamine (2.3 ± 0.18 µg/ml), Additionally, 12 alkaloids were detected using gas chromatography-mass spectrometry and identified by comparing their mass fragmentation patterns with literature and database NIST vs.2.0. To better understand the bioactivity of isolated compounds and alkaloidal extracts against acetylcholinesterase, a molecular docking approach was performed. Results suggested that alkaloids such as lycoramine, norpluvine diacetate and 6α-deoxy-tazettine expand the list of potential acetylcholinesterase inhibitors to not only galanthamine. The role of R. andicola as a source for acetylcholinesterase inhibitors is further discussed in this study.