C13H1807 SALICINUM

SALICIN  , the bitter principle of willow-bark, discovered by Leroux in 1831 . It exists in most species of Salix and Populus, and has been obtained to the extent of 3 or 4% from the bark of S. helix and S. pentandra . Salicin is prepared from a decoction o the bark by first precipitating the tannin by milk of lime, then evaporating the filtrate to a soft extract, and dissolving out the salicin by alcohol . As met with in commerce it is usually in the form of glossy white scales or needles . It is neutral, odourless, unaltered by exposure to the air, and has a bitter taste . It is soluble in about 30 parts of water and 8o parts of alcohol at the ordinary temperature, and in 0.7 of boiling water or in 2 parts of boiling alcohol, and more freely in alkaline liquids . It is also soluble in acetic acid without alteration, but is insoluble in chloroform and benzol . From phloridzin it is distinguished by its ammoniacal solution not becoming coloured when exposed to the air . Chemically, it is a glucoside derived from glucose and saligenin (o-oxy-benzyl alcohol), into which it is decomposed by the enzymes ptyaline and emulsin . Oxidation converts it into helicin (salicylaldehyde-glucose) . Populin, a benzoyl salicin, is a glucoside found in the leaves and bark of Populus tremula . Salicin is used in medicine for the same purposes as salicylic acid and the salicylates .

It is also used as a bitter tonic, i.e. a gastric stimulant, in doses of five grains . The ordinary dose may go up to

forty grains or more with perfect safety, though the British Pharmacopoeia limits it to twenty . The remote action of the drug is that of salicylic acid or the numerous compounds that contain it (see SALICYLIC ACID) .