Abstract
Of two cyanogenic glycosides in the leaves of Perilla frutescens var. acuta, prunasin ((R) -2-β-D-glucopyr anosyloxy phenylacetonitrile) was easily hydrolyzed with β-glucosidase (almond) and hesperidinase (Aspergillus niger) while the hydrolysis of (R) -2- (2-O-β-D-glucopyranosyl-β-D-glucopyranosyloxy) -phenylacetonitrile was achieved with hesperidinase (Asp. niger) but not with β-glucosidase (almond). By using β-glucosidase (almond) and hesperidinase (Asp. niger) as endogeneous enzyme, it was established that the dried leaves of P. frutescens var. acuta and its extract used commercially as a food-colorant contain the cyanogenic compounds corresponding to cyanide (CN) of at least 23. 4 mg/100 g (ca. 500 g of the fresh leaves) and 15.0 mg/100 g, respectively.
Sodium chloride used in the traditional treatment of perilla leaves was shown to be effective to remove the cyanogenic constituents without the liberation of cyanide and to inhibit the decomposition of polyphenols (to coloring matters) and anthocyanins during the treatment.
It was also demonstrated that linamarin (2-β-D-glucopyranosyloxy-2-methylpropionitrile), a cyanogenic compound in the bean of Phaseolus sp., is quantitatively hydrolyzed to cyanide by using a large amount of hesperidinase (Asp. niger).
