New acetylcholinesterase inhibitors isolated from Delphinium uncinatum

[Display omitted] •Four (1–4) norditerpenoids have been isolated from D. uncinatum.•Structures of (1–4) were deduced based on spectroscopic technique.•All the compounds (1–4) were evaluated for their acetylcholinesterase inhibitory potential followed by molecular docking studies.•The isolated compounds showed promising acetylcholinesterase inhibition activities. The inhibition of acetylcholinesterase (AChE), the key enzyme in the breakdown of acetylcholine, is presently the most common pharmacological approach available for Alzheimer’s disease (AD). Despite research on the molecular bases of AD, potent therapeutic agent against its expansion is still needed. In searching for natural cholinesterase inhibitors, the present study was focused on the isolation of three new norditerpenoid alkaloids, uncinatine B-D together with known virescenine from Delphinium uncinatum. Chemical structures for all the isolated norditerpenoids (1–4) were established using latest spectroscopic techniques. The isolated undescribed compounds along with known virescenine were testified for their acetylcholinesterase inhibitory activity supported by docking analyses. Molecular docking simulation showed that the isolated compounds (1–4) were observed to adhered in the active site of AChE with docking scores − 13.5322 (1), −11.8173 (2), −12.4240 (3) and − 8.9352 (4) respectively. Overall results demonstrated that these natural norditerpenoids compounds were found as selective inhibitors of AChE. This is the first report regarding the use of bioactive ingredients of Delphinium uncinatum in testing against Alzheimer's disease.