Catecholic berberine

Alkaloids which inhibit acetylcholine esterase, monoamine oxidase and catechol-O-methyltransferase are tabulated in Table 11. Potent ACE blocker are indole alkaloids of the physostigmine type (e.g., eseramine, geneserine, physovenine, eserine), protoberberine alkaloids (e.g., berberine, columbamine, coptisine, jatrorrhizine, palmatine), steroidal alkaloids (leptine I, solanine, solamargine, and tomatidine), galanthamine and others. A plausible structure-function relationship is not apparent, except that all these alkaloids have a quaternary N under physiological conditions, and that an oxygen can be traced 2 to 4 carbons adjacent to the N, similar to the situation in acetylcholine. 

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