Cyanogenic Glycosides and Related Compounds

Many plants accumulate compounds capable of liberating hydrogen cyanide upon acid or enzymatic hydrolysis. Two types of compounds, cyanogenic glycosides and 

Linustatin (66) and neolinustatin (67) are disaccharide derivatives extracted from seeds of Linum usitatissimum (119). Their structural features are closely related to linamarin and lotaustralin, respectively. 

Biosynthesis of linamarin and lotaustralin has been studied by Conn et al. (19, 149). On the basis of highly effective incorporation of C-labelled L-valine into linamarin and of L-isoleucine into lotaustralin, they concluded that these amino acids are precursors of the two cyanoglucosides. Since the glucosyl transferase (UDP-glucose ketone cyanohydrin-yff-D-glucosyltransferase) was shown to be unable to distinguish between the two possible enantiomers - (i ,S)-2-hydroxy-2-methyl-butyro-nitriles - L-isoleucine ([3S]-Ls-isoleucine), which supplies the / -enantiomer, must be the sole precursor for naturally occurring (/ )-lotaustralin (149). It is quite possible that L-leucine is the precursor of acacipetalin, proacacipetalin, epiproacacipetalin, and cardiospermin. 

Deidaclin (70), first called daidamin, was obtained from Deidamia clematoides (Passifloraceae) (139). The structure of deidaclin was established as 

Tetraphyllin A (71) (mp 116° to 118°C, [a] -14.0°) was first isolated in a crystalline form from Tetrapathaea tetrandra (Passifloraceae) (104). The structure of this compound, determined from spectroscopic evidence derived from itself and its derivatives, was similar to that of deidaclin (70). These two cyanogens were shown to be epimers to each other by NMR spectral studies (110, 113). The stereochemistry at the chiral centers of these compounds was determined by X-ray chrystallography to be (i ) in deidaclin and (S) in tetraphyllin A, respectively (54). 

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Methods for the isolation, purification, and characterization of cyanogenic glycosides and related compounds have been reviewed (Brimer, 1988 Brinker and Seigler, 1989,... 

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