Canadine

("S")-Canadine, also known as ("S")-tetrahydroberberine and xanthopuccine, is a benzylisoquinoline alkaloid (BIA), of the protoberberine structural subgroup, and is present in many plants from the family Papaveraceae, such as "Corydalis yanhusuo" and "C. turtschaninovii".
Biosynthesis.
Metabolically, ("S")-canadine is derived from ("S")-reticuline, a pivotal intermediate in the biosynthesis of numerous BIA structural subgroups, through three enzymatic steps: 1) Berberine bridge enzyme to ("S")-scoulerine; 2) ("S")-scoulerine 9-"O"-methyltransferase to ("S")-tetrahydrocolumbamine; and 3) ("S")-canadine synthase/CYP719A21 to ("S")-canadine.
("S")-Canadine is the immediate metabolic precursor of berberine, which is obtained through the action of the enzyme ("S")-tetrahydroprotoberberine oxidase. It is also an intermediate in the complex biosynthesis of noscapine, which is likewise a benzylisoquinoline alkaloid, but of the phthalideisoquinoline structural subgroup.
("S")-Canadine, berberine, palmatine, and hydrastine are the major alkaloids present in goldenseal.
Effects.
A number of "in vitro" effects of ("S")-canadine have been reported. It stimulates myogenesis and inhibits muscle protein degradation. ("S")-Canadine blocks K(ATP) channels in dopamine neurons. ("S")-Canadine has displayed antioxidant activity: though it lacked any demonstrable cytotoxic effect in three unique cell cultures, it was observed to possess antioxidant activity against free radical-induced oxidative injury. ("S")-Canadine can block voltage-dependent calcium channels, but at a level significantly lower than that of verapamil.