AbstractContextThe genusGlauciumMill., one of the important Papaveraceae family plants, is rich in isoquinoline alkaloids and distributed worldwide.ObjectiveIsolation and identification of bioactive alkaloids fromGlaucium grandiflorumBoiss. & Huet. subsp.refractum(Nabelek) Mory var.torquatum(Cullen) Mory andG. corniculatum(L.) Rudolph var.corniculatum(Aslan2012),and investigation of their antioxidant and anticholinesterase activities.Materials and methodsThe aerial parts of each plant were dried, powdered, and percolated with methanol, then each extract was fractionated between 50% aqueous acetic acid and petroleum. Their aqueous acidic layer was adjusted to pH 7–8 with NH4OH and extracted with chloroform, the extract was subjected to CC separation and isolation. Structures of the isolated alkaloids were elucidated by 1D and 2D-NMR and mass spectral analyses. The alkaloid extracts and their pure alkaloids were tested for anti-cholinesterase (AChE and BuChE) and antioxidant (ABTS, CUPRAC, β-carotene linoleic acid tests) activitiesin vitro.ResultsMethanol extracts ofGlaucium grandiflorumsubsp.refractumvar.torquatumandG. corniculatumvar.corniculatumafforded a novel compound glauciumoline and seven known isoquinoline alkaloids three of which have an aporphine-type and the other five have a protopine-type skeleton. Among them,trans-protopinium (7) andcis-protopinium (8) were isolated from aGlauciumspecies for the first time. Tertiary amine extracts (TAEs) of both plants showed very strong acetylcholinesterase inhibitory activity. The TAE of the plants also showed strong antioxidant activity while the isolated alkaloids showed no meaningful activity in the anticholinesterase and antioxidant tests.Discussion and conclusionsGlauciumspecies are considered promising therapeutic agents in the treatment of Alzheimer’s disease.