Alkaloids ofThalictrum collinum
The method of methanolic extraction was applied to the roots. After the methanol has been distilled off, the concentrated extract was treated with 10% sulfuric acid, the acid extracts were alkalinized to pH 9, and the alkaloids were extracted with ether and chloroform. The combined ether-soluble and chloroform-soluble alkaloids obtained were separated into phenolic and nonphenolic bases. The combined nonphenolic tertiary bases were chromat.graphed on a column of alumina (1:70, neutral, activity grade II). The alkaloids were eluted with benzene, benzene--chloroform, chloroform, ethyl acetate, and ethyl acetate-methanol.
Thalictrum alkaloids. V. Isolation.
The experimental procedure which led to the isolation of the new alkaloids thalifendlerine (I), thalifendine (II), thalidastine (III), thaliporphine (IV), preocoteine (V), and thalidezine (VI), from Thalictrum fendleri is described in detail. Known alkaloids also found in T. fendleri are berberine (VII), jatrorrhizine (VIII), glaucine (IX), magnoflorine (X), ocoteine (XI), hernandezine (XII), and thalicarpine (XIII). A completely new dimeric aporphinebenzylisoquinoline alkaloid of only partially elucidated structure is thaldimenne (XIV). A novel procedure for the separation of tertiary alkaloids consists of partition chromatography of the mixture of hydrochloride salts using a cellulose column in the system methyl ethyl ketone–water.
A peptide muscarinic toxin from the Green Mamba venom shows agonist-like action in an inhibitory avoidance learning task.
A peptide, muscarinic toxin 2 (MTX2), isolated from Dendroaspis angusticeps venom was previously shown to displace the specific binding of [3H]pirenzepine, a muscarinic M1 receptor ligand, from rat brain synaptosomal membranes. We have tested MTX2 for muscarinic agonist or antagonist actions in an inhibitory avoidance task in rats. Infusion of the muscarinic receptor antagonist scopolamine into the hippocampus of rats immediately after the training period produced amnesia, whereas the muscarinic agonist oxotremorine increased retention. When MTX2 was injected into the hippocampus of rats after the inhibitory avoidance task, it caused memory facilitation, which could be suppressed by the concomitant infusion of scopolamine. Hence, in this test, MTX2 showed muscarinic receptor agonist-like actions, which are probably mediated by the M1 subtype of muscarinic acetylcholine receptors.