Dhurrin, C14H17O7N, is another glucoside of fairly general occurrence in plants, which yields HCN as one of the products of its hydrolysis. It is found in the leaves and stems of several species of millets and sorghums. Frequent cases of poisoning of cattle from eating of these plants as forage have been reported. On hydrolysis, dhurrin first yields glucose and paraoxy-mandelo nitrile; the latter then breaks down into paraoxy-benzaldehyde and HCN.
Vicianin, C19H25O10N, is a cyanophoric glucoside, found in the seeds of wild vetch, etc. On hydrolysis, it yields glucose, arabinose, and d-mandelo nitrile. It is, therefore, similar to amygdalin, except that one glucose molecule is replaced by arabinose.
THE MUSTARD OIL GLUCOSIDES
The seeds of several species of plants of the Cruciferæ or mustard family contain glucosides in which the other characteristic group is a sulfur-containing compound. These glucosides yield "mustard oils" when they are hydrolyzed by the enzyme myrosin, which accompanies them in the plant. The following glucosides, found in the seeds of white and black mustard, are the best-known representatives of this class.
Sinigrin, C10H16O9NS2K, found in black mustard seeds, when hydrolyzed yields glucose, acid potassium sulfate, and allyl isosulfocyanide (mustard oil), as indicated by the equation.
C10H16O9NS2K + H2O = C6H12O6 + C3H5≡N=C=S+KHSO4.
The acid potassium sulfate group separates first and most readily, leaving a compound known as merosinigrin, for which the following formula has been suggested:
This compound usually breaks down into glucose and mustard oil; but by special treatment it is possible to obtain from it thioglucose, C6H11O5·SH. This indicates that in the original glucoside the glucose is linked with the mustard oil through the sulfur atom.
Sinalbin, C30H42O15N2S2, from white mustard seeds, when hydrolyzed by myrosin, yields glucose, sinalbin mustard oil (a paraoxybenzyl derivative of allyl isosulfocyanide) and sinapin acid sulfate; according to the equation