Annonaceae isoquinoline-type alkaloids

The family Annonaceae comprises some 2000 species and only about 150 have been investigated for their chemical constituents. Studies during the past decade have indicated that this family can perform biosynthetic sequences which yield an array of isoquinolines. As examples of the more unique types of isoquinolines, Erythrina alkaloids and the cularines form the subjects of two separate chapters. Relatively little information exists on the pharmacology of the cularines. There are now about 225 bisbenzyl-... 

The known chemistry of the Annonaceae is mainly based on the work of Cave and Leboeuf on the benzyhsoquinoline alkaloids. After this work, several papers were published which evidenced the presence of alkaloids derivatives of isoquinolines. Approximately 800 alkaloids of the types isoquinolines, protoberberine, aporphine, and others were isolated from different genera of the Aimonaceae. Previous chemical and pharmacological investigations have indicated that bisbenzylisoquinolines are important bioactive components existing in plants of the Annonaceae family. Other terpenes, flavonoids, Hgnans, acetogenins, and some aromatic compounds are also found in the family but the alkaloids are the major chemical constituents. 

From the benzylisoquinolines are derived all the types of isoquinoline alkaloids found in the Annonaceae (Fig. 3) berberines, aporphines, oxoaporphines, phenanthrenes, cularines, morphinanedienones, isoquinolones, dimethylaminoethyl-benziles and bisbenzylisoquinolines. 

This type of alkaloid is new, not only in the Annonaceae, but in the plant kingdom. Although about 20 bisbenzylisoquinoline alkaloids have been described so far with a biphenyl bond joining their benzyl rings, all of them also possess one or two diaryl ether bridges between their isoquinoline moieties. 

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