Isoquinolines from Menispermaceae

A novel type of bisbenzylisoquinoline alkaloid containing one fully aromatic isoquinoline system is sciadoline, from Sciadotenia toxifera Kruhoff and A. C. Smith (Menispermaceae), which has been shown to have the structure (54) by spectroscopic studies.65 It is related to cycleanine (43 R1 = R2 = Me) and 7-nor-cycleanine (43 R1 = H, R2 = Me). 

Simple isoquinolines are not found in the Menispermaceae of South America. The isoquinolone thalifoline (1) was identified from Abuta pahni [32], Benzyltetrahydroisoquinolines are the biogenetic precursors for aporphines, proaporphines, and oxoaporphines. Yet the only such compound isolated from South American Menispermaceae is (+) coclaurine (2) obtained from Sciadotema eichleriam [52] and Caryomene olivascens [37-38]. The chemistry of simple isoquinolines [65], isoquinolones [66], and benzyltetrahydroisoquinolines [67] have been reviewed. 

An isoquinoline system condensed to a tropolone is the skeleton for a tropoloisoquinoline alkaloid. The general structure of the five alkaloids of this type known so far are derivatives of the tautomers of 10-hydroxy-9H-azuleno[l,2,3-i,j]isoquinolin-9-one (42) and 9-hydroxy-10H-azuleno[l,2,3 i,j]isoquinoline-10-one (43) [88]. Recently, the first tropone-isquinoline alkaloid, pareitropone (44) has been isolated from the roots of the South American Menispermaceae, Cissampebs pareira [48]. 

The aporphine alkaloids constitute a large subgroup of alkaloids derived from isoquinoline and are widely distributed especially in the Annonaceae, Lauraceae, Magnoliaceae and Menispermaceae. 

In the AmaryUidaceae the alkaloids seem to be confined to the subfamily Amaryllidoidae. Though the structural types are not uniform they seem to be confined to these monocotyledons with one remarkable exception, namely, the phenolic cocculine present in the Caucasian variety of CocctdMS laurifoUus DC. (Menispermaceae). This base, which appears to be absent from the East Asiatic varieties of the same species, apparently has the same ring skeleton as has lycorine, which is remotely related to the isoquinolines so common in the Dicotyledonae (193),... 

Most remarkable is the callus culture of Stephania cepharantha (Menispermaceae). Not only is it able to produce oxoaporphine alkaloids (Akasu et al. 1975) and bisben-zylisoquinolines (Akasu et al. 1976) but also two aristololactams which are only found in traces in the differentiated plants and are discussed as a hint for a possible systematic crosslink from the Menispermaceae to the Aristolochiaceae (Akasu et al. 1974). A further good example of the structure variability that can be produced by one culture is Fumaria capreolata (Fumariaceae) cultivated in our laboratory. Many structural types from a simple isoquinoline to a rather complicated structure like... 

Some families like the Cactaceae, Chenopodiaceae and Fabaceae are known to produce simple isoquinoline alkaloids. In the Menispermaceae they are very rare. Up to the moment, the only compounds of this type isolated from plants of this family were coiypalline and thalflavine from Menispermum dcnmcum, thalifoline from Abutapahni and 6,7-dimethoxy-2-methylisoquinolone from Stephania sasakii. 

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