Laetrile is synthesized from amygdalin by hydrolysis. Laetrile (patented 1961) is a simpler semisynthetic derivative of amygdalin. Prunasin is a cyanogenic glycoside related to amygdalin. The most important cyanogenic glucoside is amygdalin, which occurs in bitter almonds. Related cyanogenic glycosides are known, such as amygdalin. Mandelonitrile is the aglycone part of the cyanogenic glycosides prunasin and amygdalin. Peach pits contain amygdalin, which is metabolized into cyanide. The origin of cyanide content in bitter almonds is via the enzymatic hydrolysis of amygdalin. Apricot kernels (seeds) contain amygdalin, a poisonous compound. Almonds, apricots, apples, and cherry kernels contain significant amounts of amygdalin. P450 monooxygenases are involved in the amygdalin biosynthetic pathway. These enzymes include amygdalin beta-glucosidase, prunasin beta-glucosidase and mandelonitrile lyase. On average, bitter apricot kernels contain about 5% amygdalin and sweet kernels about 0.9% amygdalin. It is known for containing amygdalin, a poisonous compound. Ripe plums have much lower amygdalin content.