Bisbenzylisoquinoline alkaloids

More than 225 different bisbenzylisoquinoline alkaloids are known and have been isolated.

The bisbenzylisoquinoline alkaloids are considered the largest group within the isoquinoline alkaloids.{{citation|author=Peter Nuhn|date=2006|edition=4|isbn=9783777613635|location=Stuttgart|pages=603f|publisher=S.Hirzel Verlag|title=Naturstoffchemie}} The best-known representative of this group is tubocurarine chloride. Other representatives include dauricin, oxyacanthin, tetrandrine, and tiliacorin.

Dauricine Structural Formula V3a.svg|dauricine

Oxyacanthine Structural Formula V3a.svg|Oxyacanthine

Tiliacorine Structural Formula V3a.svg|Tiliacorine

Tubocurarine Structural Formula V6a.svg|Tubocurarine

Bisbenzylisoquinoline alkaloids are characterized by their structure. Typically, they consist of two benzyl-tetrahydroquinoline units linked by ether groups, and occasionally by C-C bonds. Multiple ether bridges are often present.{{citation|author=H. Latscha, U. Kazmaier|date=2016|edition=4|isbn=9783662477830|location=Berlin Heidelberg|pages=691|publisher=Springer Spektrum|title=Chemie für Biologen}} These alkaloids can be categorized into three groups, using the nomenclature head for the 1,2,3,4-tetrahydroisoquinoline unit and tail for the 1-benzyl residue:

• head-head
• tail-tail-
• head-tail-linked bisbenzylisoquinoline alkaloids.{{citation|author=Eberhard Breitmaier|date=1997|isbn=9783519035428|location=Wiesbaden|pages=63f|publisher=Springer Fachmedien|title=Alkaloide}}

Dauricine is the simplest representative with a tail-to-tail linkage. Oxyacanthine and Tetrandrin contain both head-head and tail-tail linkages, while Tiliacorine features one tail-tail linkage and two head-head linkages linking to a dibenzodioxin moiety. Tubocurarine chloride is characterized by two head-tail linkages of the tetrahydroisoquinoline units. In the following structural formulae, the tail linkages are marked red and the head linkages are marked blue:

Dauricine Structural Formula V3b.svg|Dauricine

Oxyacanthine Structural Formula V3b.svg|Oxyacanthine

Tiliacorine Structural Formula V3b.svg|Tiliacorine

Tubocurarine Structural Formula V6b.svg|Tubocurarine

The alkaloids belonging to the bisbenzylisoquinoline group are generally toxic and exhibit curarizing effects. Oxyacanthine serves as a sympatholytic agent, an antagonist to epinephrine, and a vasodilator. Tubocurarine, a potent curarizing poison, stands as the oldest known muscle relaxant. South American indigenous populations have traditionally employed it as an arrow poison (see curare).

Tetrandine, found as an ingredient in the Chinese medicine "han-fang-shi," possesses analgesic and antipyretic properties.

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Category:Alkaloids