The apricot, Prunus armeniaca, is a species of Prunus, classified with the plum in the subgenus Prunus. The native range is somewhat uncertain due to its extensive prehistoric cultivation. Cyanogenic glycosides (found in most stone fruit seeds, bark, and leaves) are found in high concentration in apricot seeds. Laetrile, a purported alternative treatment for cancer, is extracted from apricot seeds. Apricot seeds "were used against tumors as early as A.D. 502. In England during the seventeenth century, apricot oil was also used against tumors, swellings, and ulcers". The isolated compounds were identified with the help of spectroscopic techniques and bioassays. β-Sito-sterol, 2,6-dihydroxy-4-methoxyacetophenone and kaempferol were isolated from a petroleum extract whereas aromadendrin, quercetin, β-sitosterol-β--glucoside, pleoside and tannins (four proanthocyanidins – A-type) were characterized from an ethyl acetate extract.