Salix alba L.

Last updated: 25 Oct 2016

Scientific Name

Salix alba L.

Synonyms

Argorips alba Raf., Argorips cerulea Raf., Nectolis vitellina Raf., Salix alba var. alba, Salix alba f. ovalis Wimm., Salix aurea Salisb., Salix flexibilis Gilib., Salix kassanogluensis Kotschy ex Andersson, Salix libanotica Boiss., Salix pallida Salisb. [Illegitimate], Salix pameachiana Barratt, Salix regalis Wesm. [1]

Vernacular Name

English Cricket-bat willow, Huntingdon willow, swallow-tailed willow, [2] white willow [3]
China Bai liu [2]
India Mulching [2]
Saudi Arabia Safsaf abiad [2]

Geographical Distributions

Salix alba is native to Europe, central Asia, northern Africa [4], North America and China [5].

Botanical Description

S. alba is a member of the Salicaceae family [3]. It is a perennial tree that can grow up to 35 m tall [6].

The bark is dark grey and fissured. [6]

The young branches are erect or drooping, silky, later becoming glabrous. The buds are measures 6 x 1.5-2 mm, lanceolate-oblong, flattened, silky, and acute. [6]

The leaves are stipulate, stipules small, lanceolate, caducous. The petiole is measures of 5-8 mm, eglandular, lamina 5-10-(15) x 1-3 cm, narrowly lanceolate, acuminate, finely serrate, silky adpressed pilose when young, becoming subglabrescent. [6]

The catkins are appearing with leaves, dense, cylindrical, often bisexual, rachis densely pubescent, stalked with entire, oblong-obovate, obtusish bracts. The male catkin is measures of 25-50 x 3-4 mm that appear before anthesis. There are 2 stamens, free, filaments hairy towards the base, anthers 0.5-0.6 (-7) mm, yellow. Female catkin is measures of 3-5 x c. 0.6 cm, lax, have 1 or 2 glands, ovary ovoid, conical, obtuse, glabrous, and subsessile. [6]

The fruiting stipe is measures of 0.2-0.8 mm that equalling to its gland. [6]

Cultivation

No documentation.                                                                      

Chemical Constituent

The crude extract of S. alba bark has been reported to contain flavanoids (e.g. pure eriodictyol, 5,7‐dihydroxychromen‐4‐one, naringenin), [7] and tannin (e.g. procyanidin-B1) [8]

S. alba extract has been reported to contain glycosides and esters yielding salicylic acid (e.g. salicortin, salicin, and tremulacin). [9]

Plant Part Used

Bark [7][8]

Traditional Use

The Cree, Chippewa, Huron, Muhowk, and other American Indians have used S. alba in much the same way as aspirin to reduce fever, relieve headaches, treat arthritis and other pain, and fight inflammation. [10]

S. alba has also been used by some Native American tribes in order to prevent post-partum hemorrhage by using a low concentration, warm-water douche. [11]

An infusion of the bark of S. alba has been used for its perceived regulatory effect on the digestive system.  Most commonly, it has been used in order to promote healthy, regular bowels. The Cherokee also used S. alba as a respiratory tonic. This action in conjunction with its analgesic activity made it a useful tonic for athletes. Additionally, the bark of S. alba has been chewed, the juices swallowed, in order to treat hoarseness in the throat. [10]

Preclinical Data

Pharmacology

Antipyretic activity

The pharmacokinetic and in vivo pharmacological studies in rats indicate that salicin is able to act as an antipyretic agent without producing simultaneous gastric injury because salicin acts as a pro-drug for saligenin and salicylic acid formation. [12]

Anti-inflammatory activity

A standardized S. alba bark extract has been reported to exhibit anti-inflammatory activity in animal models. Results obtained show that S. alba extract was significantly raises GSH (reduced glutathione) levels, an effect which helps to limit lipid peroxidation. The extract was more potent than either ASA or celecoxib. Higher doses of the extract also reduced malondialdehyde levels and raised shows definite superiority to either ASA or celecoxib in protecting the body against oxidative stress. It is therefore evident that S. alba extract is at least as active as ASA on all the parameters of inflammatory mediators measured, when both are given on a similar mg/kg dose. [13]

The ethanolic Salix extract has been demonstrated to exhibit anti-inflammatory effect on human monocyte prostaglandin-E2 release, an important mediator of inflammation. The results indicated that Salix extract inhibited cyclooxygenase-2 mediated prostaglandin-E2 release independent of salicin and salicylate metabolites while also inhibiting lipopolysaccharide-induced release of inflammatory mediator tumour necrosis factor-alpha and interleukin-1beta. [14]

The hydroethanolic extract of S. alba possesses potent anti-inflammatory activity in in vitro studies employed ovine neutrophils. This mechanism appears to be attributable to its dose-dependent inhibitory actions on both neutrophil adhesion and superoxide production. Taken together, these findings indicate that multiple mechanisms of action underlie the anti-inflammatory action associated with S. alba extract. [15]

Toxicity

No documentation.

Clinical Data

Clinical findings

Pharmacokinetic activity

The serum collected from human volunteers following administration of a standardized S. alba bark extract corresponding to 240mg of salicin showed salicylic acid to be the primary metabolite with peak levels reached after 2 hours. [16]

Antirheumatic activity

S. alba extract has been reported to treat a chronic lower back pain and osteoarthritis in a randomized, double-blind, placebo-controlled study. Patients suffering from acute exacerbations of chronic low-back pain were given extract of S. alba standardized to 120 mg salicin, extract of S. alba standardized to 240 mg salicin or placebo for four weeks. Results obtained show that S. alba extract dose-dependently attenuated the perception of pain when compared to placebo. The percentage of pain-free patients in the last week of treatment was 39% for the 240 mg salicin group, 21% for the 120 mg salicin group and 6% for the placebo group with significantly more patients in the placebo group employing the rescue pain medication, tramadol, during the course of the study. [17]

In other experiment, S. alba extract standardized to 240 mg salicin was compared to that of 12.5 mg rofecoxib, the open, randomized, post-marketing study revealed improvements in the Arhus Low Back Pain Index, pain and physical impairment indices with no significant differences being found between the effectiveness of the two treatments at the doses employed. [18]

Anti-osteoarthritis activity

A double-blind, randomized, placebo-controlled clinical trial investigated the efficacy of S. alba extract, in a dose corresponding to 240 mg per day, in the treatment of knee/hip osteoarthritis. The S. alba extract demonstrated a moderate analgesic effect with a significant reduction observed in the measurement of pain by both patient and physician when compared to placebo. In addition, the S. alba extract was also well tolerated in patients and the study concluded that low-dose S. alba bark extract may be a suitable treatment for patients unable to take traditional non-steroidal anti-inflammatory agents due to their production of gastrointestinal adverse effects. [19]

Anti migraine activity

A ligand binding study showed that S. alba interacted with the serotonin-1D receptor subtype while also antagonizing the serotonin-2A/2C receptor subtypes. A completed prospective, open-label study examined the effectiveness of a daily dose of 600 mg S. alba, in combination with 600 mg Tanacetum parthenium, in migraine prophylaxis. The results indicated that attack frequency (57.2 and 61.7 percent reduction at six and twelve weeks, respectively), attack intensity (38.7 and 62.6 percent reduction at six and twelve weeks, respectively) and attack duration (67.2 and 76.2 percent reduction at six and twelve weeks, respectively) were reduced following the combination therapy for a twelve-week period with no adverse effects reported. The results of the ligand binding study indicate that S. alba interacts with serotonin receptors in a triptan-like manner. Hence, willow bark may reduce neuronal firing and the release of sensory neuropeptides and thereby inhibit the subsequent cranial vasodilatation and neurogenic inflammation characteristic of a migraine attack. [20]

Precautions

No documentation.

Side effects

S. alba is contraindicated in patients with a known allergy or hypersensitivity to members of the Salix species, to salicylates and to acetylsalicylic acid. [21]

Anaphylaxis requiring administration of epinephrine has been reported following ingestion of an herbal pollen compound predominately comprised of S. alba, Taraxacum officinalis and Artemisia vulgaris in an atopic patient. [22]

Caution is advised in patients with bleeding disorders and those taking supplements that may increase bleeding. The patients suffering from kidney, liver, immunosuppressive or chronic diseases (e.g. diabetes) also should used S. alba with caution. [23]

Pregnancy/Breast Feeding 

Patients planning to become pregnant, who are pregnant or breastfeeding should not use S. alba supplements without first consulting their medical practitioner. [24]

Maternal salicylate use during lactation may produce adverse events (e.g. rash, platelet abnormalities) in infants’ breastfed by mothers compliant with salicylate therapy. [25]

Age limitation

Salicylate-containing medications and herbal supplements are contraindicated in children due to the risk for Reye syndrome, a potentially life-threatening disorder characterized by acute non-inflammatory encephalopathy and hepatic failure. [26]

Adverse reaction

No documentation.

Interaction & Depletion

Interaction with drug

S. alba should be used with caution in those with medical conditions where the use of acetylsalicylic acid is contraindicated. Toxicities that should be considered before consumption of Salix species supplements as the salicylate constituents have a similar mechanism of action to that of acetylsalicylic acid and caution is advised accordingly. [20]

S. alba is contraindicated in patients with a known allergy or hypersensitivity to members of the Salix species, to salicylates and to acetylsalicylic acid. [26]

Interaction with other Herbs

Ingestion of an herbal pollen compound predominately comprised of S. alba, Taraxacum officinalis and Artemisia vulgaris in contraindicated in an atopic patient. [22]

Contraindications

No documentation.

Dosage

Dosage Range

Salicin equivalent to 120-240 mg suitable for the treatment of lower back pain. [17]

Salicin equivalent of 240 mg for osteoarthritis pain. [19]

Most Common Dosage

No documentation.

Standardisation

Standardized to 15% salicin. [24]

Poisonous Management

No documentation.

Line drawing

No documentation.

References

  1. The Plant List. Ver1.1. Salix alba L. [homepage on the Internet]. c2013 [updated 2012 Mar 26, cited 2016 Oct 25]. Available from: http://www.theplantlist.org/tpl1.1/record/kew-5001521.
  2. Quattrocchi U. CRC world dictionary of medicinal and poisonous plants: Common names, scientific names, eponyms, synonyms, and etymology. Volume V R-Z. Boca Raton, Florida: CRC Press, 2012; p. 129.
  3. United States Department of Agriculture. Natural Resources Conservation Service. Salix alba L. white willow. [homepage on the Internet]. No date [cited 2016 Oct 25]. Available from: http://plants.usda.gov/core/profile?symbol=SAAL2.
  4. Missouri Botanical Garden. Salix alba. [homepage on the Internet]. No date [cited 2016 Oct 25]. Available from: http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=c147.
  5. Botanical information of Salix alba. [homepage on the Internet]. No date [updated 2015 Aug 13, cited 2016 Oct 25]. Available from: https://www.mdidea.com/products/herbextract/salicin/data01.html.
  6. Flora of Pakistan. Salix alba Linnaeus. [homepage on the Internet]. No date [cited 2016 Oct 25]. Available from: http://www.efloras.org/florataxon.aspx?flora_id=5&taxon_id=200005744.
  7. Qizhen D, Gerold J, Peter W. Preparation of three flavanoids from the bark of Salix alba by high-speed countercurrent chromatographic separation. J Liq Chromatogr Relat Technol. 2004;27(20):3257-3264.
  8. Poblocka-Olech L, Krauze-Baranowska M. SPE-HPTLC of procyanidins from the barks of different species and clones of Salix. J Pharm Biomed Anal. 2008;48(3):965-968.
  9. Gruenwald J, Brendler T, Jaenicke C. PDR for herbal medicines. 2nd Edition. Montvale, New Jersey: Medical Economics Company, 2000; p. 807-809.
  10. Cichoke AJ. Secrets of Native American herbal remedies: A comprehensive guide to the Native American tradition of using herbs and the mind/body/spirit connection for improving health and well-being. New York: Penguin-Putnam Press, 2001.
  11. Moerman DE. Native American ethnobotany. Portland, OR: Timber Press, 1998.
  12. Akao T, Yoshino T, Kobashi K, Hottori M. Evaluation of salicin as an antipyretic prodrug that does not cause gastric injury. Planta Med. 2002;68(8):714-718.
  13. Khayyal MT, El-Ghazaly MA, Abdallah DM, Okpanyi SN, Kelber O, Weiser D. Mechanisms involved in the anti-inflammatory effect of a standardized willow bark extract. Arzneimittelforschung. 2005;55(11):677-687.
  14. Fiebich BL, Chrubasik S. Effects of an ethanolic Salix extract on the release of selected inflammatory mediators in vitro. Phytomedicine. 2004;11(2-3):135-138.
  15. Farinacci M, Colitti M, Sqorlon S, Stefanon B. Immunomodulatory activity of plant residues on ovine neutrophils. Vet Immunol Immunopathol. 2008;126(1-2):54-63.
  16. Schmid B, Kötter I, Heide L. Pharmacokinetics of salicin after oral administration of a standardised willow bark extract. Eur J Clin Pharmacol. 2001;57(5):387-391.
  17. Chrubasik S, Eisenberg E, Balan E, Weinberger T, Luzzati R, Conradt C. Treatment of low back pain exacerbations with willow bark extract: A randomized double-blind study. Am J Med. 2000;109(1):9-14.
  18. Chrubasik S, Künzel O, Model A, Conradt C, Black A. Treatment of low back pain with a herbal or synthetic anti-rheumatic: A randomized controlled study. Willow bark extract for low back pain. Rheumatology (Oxford). 2001;40(12):1388-1393.
  19. Schmid B, Lüdtke R, Selbmann HK, et al. Efficacy and tolerability of a standardized willow bark extract in patients with osteoarthritis: Randomized placebo-controlled, double blind clinical trial. Phytother Res. 2001;15(4):344-350.
  20. Shrivastava R, Pechadre JC, John GW. Tanacetum parthenium and Salix alba (Mig-RL) combination in migraine prophylaxis: A prospective, open-label study. Clin Drug Investig. 2006;26(5):287-296.
  21. Boullata JI, McDonnell PJ, Oliva CD. Anaphylactic reaction to a dietary supplement containing willow bark. Ann Pharmacother. 2003;37(6):832-835.
  22. Chivato T, Juan F, Montoro A, Laguna R. Anaphylaxis induced by ingestion of a pollen compound. J Investig Allergol Clin Immunol. 1996;6(3):208-209.
  23. Rainbow Food. Willow bark (Salix spp.). [homepage on the Internet]. c2011 [cited 2016 Oct 25]. Available from: http://www.rainbow-foods.org/ns/DisplayMonograph.asp?storeID=1b442e1b882b4d758be66a2594de9e62&DocID=bottomline-willowbark.
  24. Drug.com. Willow bark. [homepage on the Internet]. No date [updated 2016 Oct 02, cited 2016 Oct 25]. Available from: https://www.drugs.com/npp/willow-bark.html.
  25. Pray WS. Nonprescription products for the pregnant and breast-feeding patient. US Pharm. 2007;32(9):10-14.
  26. Schrör K. Aspirin and Reye syndrome: A review of the evidence. Paediatr Drugs. 2007;9(3):195-204.