Salix. Willow-bark

United States Dispensatory 1926 Pt I & 2
Potter�s New Cyclopedia of Botanical Drugs and Preparations

Compiled by Ivor Hughes

Salix. Willow-bark. Weidewinde, G. Ecorce de Saule, Fr.

Most of the species of the large genus Salix are possessed of similar medicinal properties. (For elaborate study of various willow barks see Wellcome Chemical Research Laboratory Report, No. 39.) S. fragilis L. or Crack Willow, which has been introduced into this country from Europe, is said by Sir James Smith to be the most valuable species. S. purpurea L., the Basket Willow, a European species, is stated by Lindley to be the most bitter, and S. pentandra L., or Laurel-leaf Willow, is preferred by Nees von Esen-beck. Many native species are in all probability equally active with the foreign.


Salix alba L., the species formerly recognized by the U. S. Pharmacopoeia (1880), is the common European or white willow. It has sparingly escaped from cultivation, growing from New Brunswick and Ontario southward to Pennsylvania. It is a large tree with a rough grayish bark, the twigs being brittle at the base, and in this respect somewhat resembling S. fragilis. The leaves are pubescent on both surfaces and finely serrulate. It hybridizes with other species of Salix. It flowers in April and May, and the bark is easily separable throughout the summer.

That obtained from the branches rolls up when dried into the form of a quill, from 0.5 to 1 mm. thick, has a brown, more or less finely warty periderm, is flexible, fibrous, and of difficult pulverization. The inner surface is brownish-white, and smooth, separating in thin layers.

Willow bark has a feebly aromatic odor and a peculiar bitter astringent taste. It yields its active properties to water, with which it forms a reddish-brown decoction. Pelletier and Caventou found among its ingredients, tannin, resin, a bitter yellow coloring matter, a green fatty matter, gum, wax, lignin, and an organic acid combined with magnesia. The proportion of tannin is so considerable that the bark has been used for tanning leather. The characteristic constituent of all species of willow, however, is salicin. (See Salicinum.) Robert W. Beck (A. J. P., 1891, 581) has determined the-relative percentages of salicin and tannin as follows:




Leaves of S.lucida Muhl.



Bark of S. lucida Muhl



Bark of S. alba L.



Bark of Salix nigra L.




Jowett and Potter made an examination of thirty-three samples of willow and poplar, and found in but one (Salia; discolor Muhl.) the related glucoside salinigrin, which Jowett had previously discovered in an unknown sample of willow bark. This compound has the formula C13H16O7, and on hydrolysis yields glucose and meta-hydroxybenzaldehyde. (Wellcome Chem. -Research Laboratory Report, No. 28.)

The green aments or floral buds have been recommended by certain eclectic practitioners as a sexual depressant, useful in Spermatorrhoea, and other forms of sexual excitement, and in the nervous disturbances of the menstrual period. From twenty to thirty minims (1.3-1.8 cc.) of the fluidextract are to be given four times a day.

SALICINUM. U. S., Br. SALICIN Salicin. USD Part 1.

" A glucoside [C13H18O7] obtained from several species of Salix and Populus (Fam. Salic-acece)." U. S. "Salicin, C12H18O7, is a crystalline glucoside, which may be obtained from the bark of various species of Salix, and of Populus." Br.

Orthohydroxybenzylglucoside; Salicine, Fr.; Salioin, Q.; Salicina, It.

The discovery of salicin is claimed by Buchner of Germany, and Fontana and Rigatelli of Italy; but Leroux of France deserves the credit of having first accurately investigated its properties. .Salicin is a glucoside of ortho-hydroxy-benzyl-alcohol, and is found in the bark of Salix Helix, S. pentandra, S. prcecox and probably some other species of willow and of the Populus tremuloides and P. tremula (see Populi Gemmae). Salix nigra yields a different principle (see below).

To prepare saliein the ground bark is extracted with boiling water, concentrated in a vacuum still and the extract purified by precipitation with lead acetate. The excess of lead is removed by hydrogen sulphide and the filtrate is neutralized with ammonia and carefully concentrated to the crystallizing point. The crude salicin is decolorized with animal charcoal and recrystallization from water and finally from alcohol. Merck obtained 251 grains from 16 ounces of the bark and young twigs of Salix Helix, and Erdmann 300 grains from the same quantity of the bark of Salix pentandra. It may probably be obtained from any of the willow barks having a bitter taste. T. Fawssett states that the best material for preparing salicin is undoubtedly the willow peelings, obtained as refuse from a basket factory, and known in Belgium as " rood schors." David Brown states that the peelings are produced from Salix fra-gilis, while Crispo considers the source to be Salix purpurea. These peelings should be used soon after they are stripped from the twigs. (P. J., June 6, 1903, 784.) A new glucoside called salinigrin, C13H16O7, has been isolated from black willow bark. It has been shown to be a glucoside of metahydroxybenzaldehyde. Its melting point is 195� C. For a.paper by Jowett on the percentage of salicin obtained from various kinds of willow bark, see T. B. P., 1902, 483, and 1903, 474.

Description and Physical Properties.

Colorless, silky, shining needles or prisms, or a white, crystalline powder. It is odorless and has a very bitter taste. One Gm. of Salicin is soluble in 23.5 cc. of water and in 88.5 cc. of alcohol, at 25� C. One Gm. is soluble in 3.3 cc. of water at 80� C., and in 30 cc. of alcohol at 60� C. It is insoluble in chloroform and in ether.

"Salicin melts between 199� and 202" C. Its aqueous solution (1 in 30) is neutral to litmus paper, and is levorotatory. Heat a small portion of Salicin in a test tube until it turns brown, add a few cc. of distilled water, and a drop of ferric chloride T.S.: a violet color is produced. With sulphuric acid Salicin gives a red color which disappears on the addition of distilled water. Heat gently about 0.1 Gm. of Salicin with about 0.2 Gm. of potassium dichromate and 2 cc. of diluted sulphuric acid: the fragrant odor of salicylic aldehyde is developed.

" Ash: not more than 0.05 per cent. Ten cc. portions of an aqueous solution of Salicin (1 in 50) yield no precipitate on the addition of 1 ce. of tannic acid T.S., picric acid T.S., or mercuric potassium iodide T.S. (alkaloids), and another 10 cc. portion is not colored violet by a drop of ferric chloride T.S. (salicylic acid). An aqueous solution of Salicin meets the requirements of the test for heavy metals. " Preserve in well-closed containers." U. S.

"Colorless, shining, trimetric, tabular crystals, or white, crystalline powder. Taste very bitter. Soluble in 28 parts of water, and in 80 parts of alcohol (90 per cent.); insoluble in ether. Melting point from 200� to 201� C. Colored red by sulphuric acid. When 0.1 gramme is gently heated with 0.2 gramme of potassium bichromate and 2 millilitres of diluted sulphuric acid an odor recalling meadowsweet is developed. No appreciable ash." Br.

Salicin gives with concentrated sulphuric acid a bright red color; this is known as the rutilin reaction. It belongs to the class of glucosides, being resolved by boiling with diluted hydrochloric and sulphuric acids into grape sugar and saligenin, according to the reaction:

C13H18O7 + H2O = C6H12O6 + C7H8O2

Saligenin, which is ortho-oxybenzyl alcohol, C6H4(OH)CH20H, is converted by further boiling with dilute acids into a resinous body, saliretin, C14H14O2; this is a polymerized aldehyde of saligenin. Nitric acid produces with salicin at first two principles called respectively helicin, C13H16O2, and helicoidin, C26H34O14, and afterwards picric and oxalic acids. (J. P. C., xxx, 43.) Distilled with potassium diehro-mate and sulphuric acid, saliein yields, among other products, a volatile oleaginous liquid, identical with one of the components of oil of spiraea, and recognized as salicyl aldehyde, C7H6O2 (incorrectly called salicylous acid), while saligenin, C7H8O2, is the alcohol, and salicylic acid, C7H6C3, the acid corresponding. The synthesis of salicin has been effected by Michael (A. J. P., 1879), who obtained first helicin by the reaction of acetoehlorhydrose and salicyl aldehyde, and, by the action of nascent hydrogen upon this, salicin.

Saligenin (salicyl alcohol) has recently become a commercial article, a proprietary form being known as salicaine. Saligenin occurs as a white crystalline powder permanent in the air, soluble in water, alcohol, ether or the oils, melting at 85� to 86� C. Its taste is at first pungent and followed by a sense of numbness.

Uses.�Salicin acts upon the stomach probably as a simple bitter, and after absorption as a feeble and uncertain form of salicylic acid, since it is rapidly, although not completely, decomposed in the system, the products of its change appearing in the urine fifteen to thirty minutes after the ingestion of a single dose.

The elimination is partly as salicin, partly as salicylic acid, partly as a salicyluric acid, and partly as saligenin. It has been highly recommended 'as a substitute for salicylic acid in rheumatism by Maclagan and others, but since it owes its activity to its conversion in the blood into salicylic acid and since this conversion is uncertain, salicin is inferior in power to the salicylates. By some it is believed to be less liable to upset the stomach. Salicin has been used as an antiperiodic. One or two drachms may be given in the intermission. Hirschfelder (/. A. M. A., 1920, Ixxv, 1770) has shown that saligenin possesses marked local anesthetic powers and has used it with satisfaction as a clinical anesthetic in strengths of from 4 to 10 per cent. It has the great advantage of being practically non-toxic.

Dose, of salicin, from ten to thirty grains (0.65-2.0 Gm.).


Potter�s New Cyclopedia of Botanical Drugs and Preparations

WILLOW Salix'alba L. S.fragilis L. S. cinerea L. and other species

Fam. Salicaceae

Synonyms: White Willow, European Willow. Habitat: Indigenous to Britain, Central and Southern Europe.

Description: The bark occurs in thin channeled pieces up to about 2cm wide and 2 mm thick. Outer surface glossy in young bark, wrinkled and duller in older bark, greenish or greyish brown; inner surface striated, fibrous, yellowish or reddish brown.

Taste, astringent and bitter;.odour, faint.

Part Used: Bark.

Constituents: (i) Phenolic glycosides; salicin, picein and triandrin, with esters of salicylic acid and salicyl alcohol, acetylated salicin, salicortin andsaiireposide; concentrations etc. depending on species [2, 4, 386] (ii) Miscellaneous; tannins, catechin, p-coutnaric acid and flavonoids [2, 386].

Medicinal Use: Analgesic, anti-inflammatory, febrifuge, tonic. Willow is an gout, fevers and aches and pains of all kinds. It is usually considered to be the natural form and origin of the modern aspirin.

Potter's Products: Rheumatism Mixture No. 92A, Sciatica Mixture No. 124A, Herbprin Tablets. Regulatory Status: GSL.

Biblical References: Leviticus 23 :40; Job 40 :22; Psalm 137 :2; Isaiah 15:7 and 44:4; Ezekiel 17:5.

If you did not find what you were seeking, use the site search box at the top right hand of the page or browse the site library and images.