Natural product to modern discovery of their active ingredients and eventually to the development of new drugs. A large number of currently prescribed drugs have been either directly derived from or inspired by natural products. A few representative examples are listed below. Some of the oldest natural product based drugs are analgesics. The bark of the willow tree has been known from antiquity to have pain relieving properties. This is due to presence of the natural product salicin which in turn may be hydrolyzed into salicylic acid. A synthetic derivative acetylsalicylic acid better known as aspirin is a widely used pain reliever.
Salix alba from the wood was important for gunpowder manufacture. The bark tannin was used in the past for tanning leather. The wood is used to make cricket bats. "S. alba" wood has a low density and a lower transverse compressive strength. This allows the wood to bend, which is why it can be used to make baskets. Willow bark contains Indole-3-butyric acid, which is a plant hormone stimulating root growth; willow trimmings are sometimes used to clone rootstock in place of commercially synthesized root stimulator. It is also used for ritual purposes by Jews on the holiday of Sukkot. Hippocrates, Galen,