Alkaloids from Erythrina crista-galli flowers inhibit acetylcholinesterase

Alkaloids isolated from Erythrina crista-galli flowers inhibited acetylcholinesterase in laboratory experiments, with cristamidine showing the strongest activity among four compounds tested. The study combined in vitro assays with molecular docking and molecular dynamics simulations to examine the compounds’ inhibitory activities and their interactions with the enzyme. Acetylcholinesterase, abbreviated AChE, is a hydrolytic enzyme that breaks down acetylcholine into choline and acetate.

The researchers noted that increased AChE activity in patients with Alzheimer’s disease may contribute to early degeneration of cholinergic neurons in the basal forebrain and to impaired cholinergic signalling. The experiments reported here evaluated enzyme inhibition, not effects on patients or on Alzheimer’s disease outcomes. Four alkaloids were isolated from E. crista-galli flowers: cristamidine, erythrinine, erythraline and 8-oxoerythrinine.

The researchers confirmed their structures using high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy. These methods established the identities and structural features of the compounds before their inhibitory activity was assessed. In the in vitro assay, the four compounds were tested at a concentration of 50 micrograms per millilitre.

Cristamidine produced the highest inhibition effect, followed by 8-oxoerythrinine, erythrinine and erythraline. The supplied study abstract does not report exact inhibition percentages, concentration-response measurements or numerical values for the lower-ranking compounds, so the reported result establishes a ranking at the tested concentration rather than a complete pharmacological profile. The researchers then used molecular docking to investigate how the compounds might interact with AChE.

The simulations showed that both cristamidine and 8-oxoerythrinine formed stable interactions with AChE’s active pocket, linking the two strongest laboratory performers with computationally predicted binding behaviour. In the study, this analysis supported the observation that cristamidine and 8-oxoerythrinine formed stable interactions with the active pocket. The computational results are model-based findings and therefore complement, rather than independently establish, the measured inhibition seen in the laboratory assay.

The in vitro results show that the isolated alkaloids affected AChE under the assay conditions, while the in silico analyses indicate that two of the compounds, particularly cristamidine and 8-oxoerythrinine, interacted with the enzyme’s active site in the models. The authors identified E. crista-galli as a possible natural source of AChE inhibitors on the basis of these findings. The results remain confined to laboratory and computational studies.

No animal experiments, clinical studies or human outcomes were reported in the supplied material, and the findings do not demonstrate that the compounds or flowers treat Alzheimer’s disease or any other condition in people. The study instead establishes a set of chemically identified flower alkaloids with measured AChE inhibition and model-based evidence of stable interactions for two leading compounds.

Subject of Research: In vitro and in silico assessment of Erythrina crista-galli flower alkaloids as acetylcholinesterase inhibitors

Article Title: Alkaloids from Erythrina crista-galli flowers and their inhibitory activities against acetylcholinesterase: in vitro and in silico studies

Article References: Herlina, T., Akili, A. W. R., Hardianto, A., Fajriah, S., Handayani, S., Mayanti, T., Julaeha, E., & Latip, J. (2026). Alkaloids from Erythrina crista-galli flowers and their inhibitory activities against acetylcholinesterase: in vitro and in silico studies. Scientific Reports. https://doi.org/10.1038/s41598-026-76749-6

Image Credits: AI Generated

DOI: 10.1038/s41598-026-76749-6

Keywords: Erythrina crista-galli, acetylcholinesterase, plant alkaloids, cristamidine, 8-oxoerythrinine, in vitro assay, molecular docking, molecular dynamics, natural products, Alkaloids, Erythrina, crista-galli