Isoquinolines natural occurrence

Much of the interest in these heterocycles is associated with their natural occurrence as alkaloids, an area which has been reviewed (M. Sharma, The Isoquinoline Alkaloids, Academic Press, New York, 1972, p 315 V. Simanek, Alkaloids (Academic Press), 1985, 2, 1859 S.D, Phillips and R.N. Castle- J. heterocyclic Chem., 1981, 18, 223). The fully aromatised benzo[c]phenanthridine alk doids, exemplified by nitidine (120), show anti— leukaemic activity (F.R. Stermitz et al, J. med. Chem., 1975, 1, 708) and have been obtained from... 

The pavine and isopavine alkaloids of the Papaveraceae have been discussed in Vols. 4, 10, 12, and 17 of this treatise (2-5), and only brief references have been made to occurrences outside this botanical family. Individual chapters have been devoted to the pavine and isopavine alkaloids in the two books by Shamma (6,7), covering developments until 1977, and also in Rodd s Chemistry of Carbon Compounds (8), published in 1978. A listing of naturally known pavines and isopavines up to 1975, with references to physical and spectral data, appeared in Kametani s Chemistry of the Isoquinoline Alkaloids 9,10). A more recent compilation by Gozler and co-workers 11) has covered references to mid-1982. Relevant literature has also been summarized regularly in Vols. I-XIII of Spe-... 

Since the late 1950s PMR spectroscopy has contributed immensely to many areas of the chemistry of alkaloids (7). With the advent of Fourier transform spectrometers CMR has rapidly approached the level of PMR in its application to problems of structural elucidation and stereochemistry. In the case of the alkaloids many classes of the isoquinoline family have been studied. These alkaloids are of particular interest not only because of their widespread occurrence in nature but also because of their pharmacological activity (2-5). Wenkert et al. (6) were the first to review progress in this area. More recently, Shamma and Hindenlang (7) have made an extensive compilation of chemical shift data on amines and alkaloids that includes many... 

In another study, plants were examined both for their effect on larvae and for the presence of alkaloids although no correlation was obtained. The occurrence and chemistry of alkaloids of Central Asian plants have been surveyed. Sections on the chemistry of isoquinoline alkaloids are included in two books on natural product... 

Comparatively few simple isoquinoline alkaloids have been found to occur naturally. Until now such compounds have been encountered in three or four species of the Cactaceae, in a Chenopodiaceae [Salsola arbuscula Pall. (S. richteri Karel)], in three species belonging to the family of the Fumari-aceae [Corydalis pallida (Thunb.) Pers.,C. awrea Willd., C. tvherosa DC.] and in one Papaveraceae Papaver somniferum L.). While no doubt exists as to the native occurrence of the anhalonium and salsola isoquinolines, hy-drohydrastinine and hydrocotarnine may have been artifacts from the benzylisoquinoline alkaloids of Corydalis tuberosa and Papaver somniferum. 

While isoquinolines are elaborated by a number of natural orders, there are only two exceptions to the statement that the protopine bases are found only in the Papaveraceae. These exceptions are the occurrence of a-al-locryptopine ( S-homochelidonine) in Zanthoxylum brachyacanthum F. Miill. and in Z. coco Gill. Fagara coco (Gill.) Engl.), plants belonging to the Rutaceae, and of protopine in Nandina domestica Thunb. (Berberidaceae). 

The cularines are a group of isoquinoline alkaloids with the general structure (1), which incorporates an oxepine system in its molecular skeleton. If the nitrogen is secondary the alkaloid can be called a norcularine. The occurrence of cularine alkaloids in nature seems to be associated mainly with the Fumariaceae family (Sham-ma 1972, Shamma and Moniot 1978). 

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