CYANOGENETIC SUBSTANCES 1 89 



particular the skeletal form of the disease. The active principle is 

 ^-aminopropionitrile. The compound is absent from L. sativus, L. 

 cicera, L. latifolius, L. strictus, L. splendens, and others (Strong, 

 1956). However, most of these latter species are positive for the form 

 known as "neurolathyrism." This fact merely confirms what has been 

 suspected, namely, that the two forms of lathyrism result from two 

 different agents. Among the species reported by Selye hardly any 

 (these exceptions were also doubtful) were positive for both forms of 

 lathyrism. More recently, Ressler et al. (1961) have identified a neuro- 

 lathyrus factor from L. latifolius as L-a, y-diamino butyric acid. This 

 finding has led to a very interesting speculation that the two types of 

 lathyrus factors are derived from a common precursor. Apparently, 

 they do not occur together in a plant. The hypothetical scheme in 

 which the lathyrus factors stem from a parent substance, asparagine, 

 is shown in Fig. 10-1. Further support for the pathway illustrated in 

 Fig. 10-1 was provided by the subsequent discovery of the hypothet- 

 ical intermediate, /3-cyano-L-alanine, in related species, Vicia saliva 

 and V. angustifolia (Ressler, 1962). 



CH2NH2 

 CH2 

 COOH — (a)/-C-N 



CHNH2 



CH2 



CONH3 teN ^COOH 



asparagine /^-cyano-L-alanine CHNH2 



CH2 

 CH2NH2 



Fig. 10-1. Hypothetical pathway in (a) Lathyrus odoratus and 

 (b) L. latifolius (after Ressler, Redstone and Erenberg, 1961; 

 reprinted from SCIENCE by permission). 



Hegnauer (1959a) has investigated the distribution of cyano- 

 genetic substances among species of Taxus and certain related genera 

 {Cephalotaxus and Torreya). The other genera were acyanogenetic as 

 were certain species of Taxus. In certain cyanogenetic species, 

 varieties were found to be either negative (T. baccata var. aurea), 

 weakly cyanogenetic (var. dovastoniana), or strongly cyanogenetic 

 (var. baccata). According to Hegnauer: 



It is interesting, in chemotaxonomic relationship, that the genera 

 Taxus and Cephalotaxus are clearly phytochemically different. Both 

 contain alkaloid but the bases are different. Cyanogenesis is found 

 only in Taxus. 



