|Salix daphnoides, European Violet Willow|
---Standard disclaimers: I am not a doctor. Read this information for entertainment value---
"Everybody knows" that willow bark is a good source of aspirin, right?
Well, it is never quite that simple. Some of the ancient Greeks referenced the use of willow bark to break fevers and then the knowledge seemed to disappear until Dr. Quinn Medicine Woman rediscovered in on Prime Time TV just in time to inform scientists in Europe.
There are several complications. One complication is that various species of willow have wildly varying amounts of salicin (and derivatives). A second complication is that the percentage of salicin varies modestly depending on the time-of-year. The third complication is that even the willow species with low concentrations of salicin contain "Flavonoids and polyphenols (that) contribute to the potent willow bark analgesic and anti-inflammatory effect."
Salicins as anticoagulants
You can make a credible case for the reduced mortality rate of ischemic events (heart attacks, strokes) in the US being attributable to the widespread use of anticoagulants prophylactically, That is, widespread use of low-dose (aka Baby) aspirin for at-risk patients.
The actual mechanics of an ischemic event is an obstruction in a vein or artery developing a clot and then the clot breaking loose and lodging in an artery where it branches, thereby causing the tissue downstream of the lodged clot to be deprived of oxygen and potentially dying.
Inflammation of the vessel walls are implicated in the sudden growth of clots. Obstructed blood vessels are a very minor issue and a person can not even know they have them. It is only when a clot starts to form and its growth accelerates.
So aspirin (a complex of acetic acid and salicylic acid) is effective from the anticlotting perspective because it binds to blood proteins .AND. reduces inflammation. Even though its pain and inflammation reducing effect has a half-life of four hours the anticlotting effect throws a much longer shadow and is still effective after 48 hours.
Salicin as a fever, inflammation and pain reducer
It is awesome if it is all you have. Contraindicated for young people with the flu due to Reyes syndrome. Contraindicated for people with underlying, bleeding disorders. Contraindicated for people with gastric ulcers or acid reflux issues.
Salicin as a percentage of bark, by species
This study is by no means exhaustive. There are hundreds of species of willow and they hybridize freely.
The four species that tipped the scales at over 5% salicin when sampled in the spring (by far the easiest time to "slip" the bark off the wood) were:
- Salix acutifolia at 10.8%
- Salix daphnoides at 9.5%
- Salix purpurea at 6.4%
- (Salix integra × Salix kochiana) at 5.9%
Many believe that willow is the natural source of aspirin. However, willow species contain only a low quantity of the prodrug salicin which is metabolized during absorption into various salicylate derivatives. If calculated as salicylic acid, the daily salicin dose is insufficient to produce analgesia. Salicylic acid concentrations following an analgesic dose of aspirin are an order of magnitude higher. Flavonoids and polyphenols contribute to the potent willow bark analgesic and anti-inflammatory effect. The multi-component active principle of willow bark provides a broader mechanism of action than aspirin and is devoid of serious adverse events. In contrast to synthetic aspirin, willow bark does not damage the gastrointestinal mucosa. An extract dose with 240 mg salicin had no major impact on blood clotting. In patients with known aspirin allergy willow bark products are contraindicated. Source
Bold and underlined is mine.
The underlined sentence is suspect until it is replicated.
The present study is a continuation of the research that was previously described by Sulima et al. (2017). The experimental materials comprised 29 S. purpurea genotypes that were selected from 91 genotypes acquired in 13 natural locations in north-eastern Poland. The genotypes used in the experiment were propagated in vitro, and were used to establish a field experiment in the Agricultural Experiment Station in Bałdy (N53°35′45.442″/E20°36′10.616″) operated by the University of Warmia and Mazury in Olsztyn.
Based on the results of the present study, genotypes OL 1/1 and ELK 2/2 were registered as cultivars ASPI and ASPIRA in the Research Center for Cultivar Testing. These cultivars are characterized by a very high (OL 1/1) and high (ELK 2/2) content of SG in the bark as well as supreme yield-related traits. Both genotypes were completely free of Melampsora spp. infection, which could suggest that they are highly resistant to leaf rust. In the group of the remaining S. purpurea genotypes, particular attention should be paid to genotypes ELK 1/1 (with only somewhat lower productivity) and ELK 2/9 (with somewhat lower SG content). The present findings validate the research hypothesis postulating that S. purpurea genotypes from natural locations are highly suitable for agricultural production of high-quality herbal raw material under controlled conditions.
A very simple method of detection of the free salicylic acid could be based on the different coordinating capacity of the salicylic derivatives with the octahedral Fe+3 cation. Thus, the yellow FeCl3 aqueous solution turns pale pink in contact with an aqueous solution of acetylsalicylic acid, but turns dark blue in the presence of a very light quantity of free salicylic acid.