130 Pacific Willow

Names

Common name – Pacific Willow

Scientific name – Salix lucida, subspecies lasiandra

Other names – Shining Willow, txálhpaz’

Fig 51.1: View of Pacific Willow (Salix lucida) leaves and branches.

Fig 51.2: Close-up view of Pacific Willow foliage.

General Information

Pacific Willow is a deciduous tree or large shrub of the Salicaceae (Willow) family, native to western North America ^[7]. This species has been extensively used by Indigenous peoples for medicinal purposes, particularly for pain relief and anti-inflammatory treatments ^{[2, 9]}. The Pacific Willow is one of several willow species traditionally utilized, all containing the bioactive compound salicin ^{[8, 12]}.

Traditional Medicinal Uses by Indigenous Peoples

The Elders spoke of Pacific Willow as one of the old medicines of the land – a tree whose spirit carried both strength and comfort ^[2]. Its bark, when chewed or brewed into tea, was known to ease pain throughout the body, calming headaches, joint aches, and the soreness that came after hard work ^{[2, 3]}. Those suffering from arthritis would boil the bark or make poultices to lay over swollen joints, feeling the pain ease as the medicine drew out the inflammation ^{[2, 13]}. The leaves, too, could be chewed to quiet everyday pains and bring relief when the body was tired ^[2]. When fevers came, a tea made from the bark helped to cool the body and restore balance, its medicine working gently but surely ^[2].

The people also used Pacific Willow for back pain and stiffness, drinking the decoction or applying it to sore muscles after long days of travel or work ^[2]. Its bark carried strong healing power – an anti-inflammatory gift that reached deep into the body to settle discomfort and bring rest ^[2]. Beyond its medicine, the bark had other uses: when stripped and prepared carefully, it could be made into strong twine, used for weaving or binding ^[6].

Biochemical Basis for Medicinal Properties

Primary Bioactive Compounds

Pacific Willow contains several classes of bioactive compounds, with phenolic glycosides being the most therapeutically significant:

1. Primary Active Compounds

• Salicin (β-D-salicin) – Primary bioactive compound (1-10% in bark) ^[12]
• Salicortin – Secondary salicylate glycoside ^[12]
• Tremulacin – Related phenolic glycoside ^[12]
• Populin – Supporting glycoside compound ^[12]
• Salicyl alcohol (Saligenin) – Metabolite of salicin ^[14]

2. Supporting Compounds

• Tannins – Astringent and anti-inflammatory properties ^[13]
• Flavonoids – Antioxidant and anti-inflammatory effects ^[13]
• Catechins – Polyphenolic compounds with bioactivity ^[13]
• Other phenolic acids – Supporting therapeutic compounds ^[13]

Chemical Structure and Properties of Key Compounds

Salicin (β-D-Salicin) – Primary Active Compound

Fig 51.3: Chemical structure of Salicin (β-D-Salicin), the primary active compound found in Pacific Willow.

Chemical Name: 2-(Hydroxymethyl)phenyl β-D-glucopyranoside ^[12]

Molecular Formula: C ₁₃ H ₁₈ O ₇ ^[12]

Molecular Weight: 286.28 g/mol ^[12]

Classification: Phenolic glycoside (salicylate glycoside)

Structural Features:

Salicin Structure:

– Glucose moiety (β-D-glucopyranoside)

– Phenolic aglycone (salicyl alcohol/saligenin)

– Glycosidic bond linking sugar to phenol

– Hydroxyl groups providing water solubility

– Aromatic benzene ring with ortho-hydroxymethyl substitution

Key Structural Components:

• Sugar Unit: β-D-glucose providing water solubility and stability
• Aglycone: Salicyl alcohol (2-hydroxybenzyl alcohol)
• Glycosidic Bond: β-1 linkage between glucose C1 and phenolic oxygen
• Functional Groups: Primary alcohol, phenolic OH, multiple secondary OH groups

Salicylic Acid – Active Metabolite

Fig 51.4: Chemical structure of Salicylic Acid, the active metabolite of salicin.

Molecular Formula: C ₇ H ₆ O ₃ Molecular Weight: 138.12 g/mol ^[12]

• Structure: Benzoic acid with ortho-hydroxyl substitution ^[12]
• Key feature: Carboxyl group (-COOH) and phenolic hydroxyl (-OH) ^[12]

Metabolic Pathway and Bioactivation

Salicin to Salicylic Acid Conversion

Step 1: Hydrolysis of Salicin

Salicin + H2O → β-D-Glucose + Salicyl alcohol (Saligenin)

Enzyme: β-glucosidase (intestinal or bacterial)

Location: Small intestine and colon

Mechanism: Cleavage of β-glycosidic bond

Step 2: Oxidation of Saligenin

Salicyl alcohol → Salicylaldehyde → Salicylic acid

Enzymes: Alcohol dehydrogenase, Aldehyde dehydrogenase

Location: Liver, intestinal mucosa

Mechanism: Two-step oxidation via aldehyde intermediate

Overall Conversion:

Salicin → [Hydrolysis] → Saligenin → [Oxidation] → Salicylic Acid ^[14]

Molecular Mechanisms of Action

1. Anti-inflammatory Mechanisms

Cyclooxygenase (COX) Inhibition:

Salicylic Acid → COX-1/COX-2 inhibition → Reduced prostaglandin synthesis ^{[11, 13]}

– Competitive inhibition of COX active site ^[11]

– Decreased PGE2, PGF2α, PGI2 production ^[11]

– Reduced inflammation, pain, and fever ^[13]

– Non-selective COX inhibition (unlike aspirin) ^[11]

Nuclear Factor κB (NF-κB) Suppression:

Salicylic Acid → NF-κB pathway inhibition → Reduced inflammatory gene expression ^{[4, 13]}

– Prevents NF-κB nuclear translocation ^[4]

– Decreased TNF-α, IL-1β, IL-6 production ^[13]

– Reduced inflammatory cytokine synthesis

– Anti-inflammatory gene regulation

2. Analgesic (Pain Relief) Mechanisms

Peripheral Pain Reduction:

Salicylic Acid → Prostaglandin inhibition → Reduced nociceptor sensitization ^{[11, 13]}

– Decreased PGE2 at nociceptors

– Reduced peripheral pain sensation

– Lower inflammatory pain signals

– Tissue-level analgesia

Central Pain Modulation:

Salicylic Acid → CNS effects → Central pain pathway modulation ^[13]

– Spinal cord anti-nociceptive effects

– Modulation of pain transmission

– Central analgesic mechanisms

– Enhanced pain threshold

3. Antipyretic (Fever Reduction) Mechanisms

Hypothalamic Thermoregulation:

Salicylic Acid → Hypothalamic PGE2 reduction → Temperature set-point normalization ^[11]

– Inhibition of COX in thermoregulatory center

– Reduced hypothalamic PGE2 levels

– Restoration of normal temperature set-point

– Enhanced heat loss mechanisms

Safety Considerations and Traditional Wisdom

Traditional Preparation Methods:

• Slow extraction (tea preparation) provides gradual salicin release ^[1]
• Lower gastric irritation compared to synthetic salicylates ^[13]
• Whole plant matrix effects enhance tolerance ^[13]
• Traditional dosing based on empirical knowledge ^[2]

Modern Safety Profile:

• Generally well-tolerated in traditional preparations ^[13]
• Lower incidence of gastric side effects vs. aspirin ^{[3, 13]}
• Contraindicated in salicylate sensitivity ^[13]
• Drug interactions similar to other salicylates ^[13]

References

1. Art of Manliness. (2021, June 1). Using willow bark as natural aspirin. https://www.artofmanliness.com/skills/outdoor-survival/how-to-harvest-and-use-natures-aspirin/
2. Elders and Community members of the Cayoose Creek Band of Sekw’el’was. (n.d.).
3. Healthline. (2024, September 30). Willow bark: Nature’s aspirin. https://www.healthline.com/health/willow-bark-natures-aspirin
4. Kopp, E., & Ghosh, S. (1994). Inhibition of NF-kappa B by sodium salicylate and aspirin. Science, 265 (5174), 956–959. https://doi.org/10.1126/science.8052854
5. McGill University Office for Science and Society. (2024, April 5). Sordid medicine shows exploited Indigenous cures. https://www.mcgill.ca/oss/article/medical-history/sordid-medicine-shows-exploited-indigenous-cures
6. Native Languages of the Americas. (n.d.). Native American Indian willow medicine, meaning and symbolism. http://www.native-languages.org/legends-willow.htm
7. Portland State University. (n.d.). Salix lucida (ssp. lasiandra) – Pacific willow. https://web.pdx.edu/~maserj/ESR410/SalixLucida.htm
8. Split Rock Environmental. (2025). Pacific willow (txálhpaz’). <a href="https://splitrockenvironmental.ca/products/pacific-willow-txalhpaz” rel=”noopener” target=”_new”> https://splitrockenvironmental.ca/products/pacific-willow-txalhpaz https://doi.org/10.1007/978-1-4020-4585-1_2743
9. The Pipettepen. (n.d.). The ample pharmacopeia of Indigenous medicine. https://www.thepipettepen.com/the-florid-pharmacopeia-of-indigenous-medicine/
10. U.S. Embassy & Consulates in Italy. (2021, November 19). Native Americans’ many contributions to medicine. https://it.usembassy.gov/native-americans-many-contributions-to-medicine/
11. Vane, J. R. (1971). Inhibition of prostaglandin synthesis as a mechanism of action for aspirin-like drugs. Nature New Biology, 231 (25), 232–235. https://doi.org/10.1038/newbio231232a0
12. Wikipedia. (2025, June 2). Salicin. https://en.wikipedia.org/wiki/Salicin
13. Wölfle, U., Strobach, D., & Schempp, C. M. (2023). Willow bark (Salix) used for pain relief in arthritis: A meta-analysis of randomized controlled trials. Phytotherapy Research, 37 (11), 5142–5155. https://doi.org/10.1002/ptr.8097
14. Xie, Y., Zhang, Y., & Xu, J. (2017). Biosynthesis and metabolism of β-D-salicin: A novel molecule that exerts biological function in humans and plants. Frontiers in Plant Science, 8, Article 925. https://doi.org/10.1016/j.btre.2014.08.005