Willow active extract of the bark, called salicin, was isolated to its crystalline form in 1828 by Henri Leroux, a French pharmacist, and Raffaele Piria, an Italian chemist, who then succeeded in separating out the compound in its pure state. In 1897, Felix Hoffmann created a synthetically altered version of salicin (in his case derived from the "Spiraea" plant), which caused less digestive upset than pure salicylic acid. The new drug, formally acetylsalicylic acid, was named Aspirin by Hoffmann's employer Bayer AG. This gave rise to the hugely important class of drugs known as nonsteroidal anti-inflammatory drugs (NSAIDs). Some of humans'
Acid-fastness Acid-fastness Acid-fastness is a physical property of certain bacterial and eukaryotic cells, as well as some sub-cellular structures, specifically their resistance to decolorization by acids during laboratory staining procedures. Once stained as part of a sample, these organisms can resist the acid and/or ethanol-based decolorization procedures common in many staining protocols, hence the name "acid-fast". The mechanisms of acid-fastness vary by species, although the most well-known example is in the genus "Mycobacterium", which includes the species responsible for tuberculosis and leprosy. The acid-fastness of "Mycobacteria" is due to the high mycolic acid content of their cell walls, which is responsible