Willow Tree - Salicin - Salicylic Acid
Epitheal focus on high value bioactive extractives (salicins) for medical applications while using the bark-free pulp for manufacturing food packaging materials with any waste and residues used for biogas and biofertilizers. Willow bark is one of the few plant materials to contain substances (salicins ) which are as effective as synthetic equivalents for analgesic & anti-inflammatory properties, with fewer undesirable side effects. Salicin is approved for use in dermatology products by the European Medicines Agency. The EU market for natural medicines is growing at 7.2% pa and will exceed $ 200B globally by 2024, focussing the pharma sector on natural products. Willow is currently not grown for commercial salicin production while salicin concentration differs among willow varieties & cultivation practice.
The bark of willow tree possesses many medicinal properties. The active ingredient present in the willow bark, known as salicin, was crystallized by Leroux in 1829 and salicylic acid was isolated by Pina in 1836. Kolbe synthesized salicylic acid and by 1874 the industrial production was undertaken. Salicylic acid was used for the treatment of rheumatic fever, gout, and as an antipyretic. However, due to the emergence of adverse gastrointestinal effects, it became difficult to tolerate salicylic acid for more than short periods of time. This prompted Hoffman, a chemist at Bayer, to conduct experiments in order to improve the safety profile. He used the earlier work of Gerhardt, a French chemist who had used acetylated salicylic acid to reduce adverse effects. Bayer began testing acetylsalicylic acid in animals by 1899; this was the first time a drug was tested on animals in an industrial setting. Later, it proceeded to clinical studies and then was finally marketed as aspirin (Brunton et al., 2006).
Salicylic acid has keratolytic properties and is applied topically for the treatment of hyperkeratotic and scaling skin conditions such as dandruff and seborrheic dermatitis, ichthyosis, psoriasis, and acne. Salicylic acid produces desquamation of hyperkeratotic epithelium by dissolving the intercellular cement, which, in turn, causes cornified tissue to swell, soften, macerate, and desquamate. Salicylic acid is keratolytic at concentrations of 3%–6%. It is destructive to tissue at concentrations above 6%. Concentrations of 6%–60% are used to remove corns and warts and in the treatment of psoriasis and other hyperkeratotic disorders (Insel, 1990). Systemically, salicylic acid acts as a nonsteroidal, antiinflammatory agent with analgesic, antiinflammatory, and antipyretic actions similar to those of aspirin. Magnesium salicylate is taken orally for the treatment of pain and fever and in the management of inflammatory conditions such as osteoarthritis, rheumatoid arthritis, bursitis, and other musculoskeletal disorders (Hutchison, 2003).