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.
Clavulanic acid Clavulanic acid Clavulanic acid is a β-lactam drug that functions as a mechanism-based β-lactamase inhibitor. While not effective by itself as an antibiotic, when combined with penicillin-group antibiotics, it can overcome antibiotic resistance in bacteria that secrete β-lactamase, which otherwise inactivates most penicillins. In its most common form, the potassium salt potassium clavulanate is combined with: Clavulanic acid was patented in 1974. For the treatment of pyelonephritis during pregnancy, and for the treatment of pyelonephritis caused by gram-positive organisms, amoxicillin or amoxicillin-clavulanate potassium is preferred. The name is derived from strains of "Streptomyces clavuligerus", which produces clavulanic acid. Clavulanic acid