Salicylic acid Salicylic acid Salicylic acid (from Latin "salix", "willow tree") is a lipophilic monohydroxybenzoic acid, a type of phenolic acid, and a beta hydroxy acid (BHA). It has the formula CHO. This colorless crystalline organic acid is widely used in organic synthesis and functions as a plant hormone. It is derived from the metabolism of salicin. In addition to serving as an important active metabolite of aspirin ("acetylsalicylic acid"), which acts in part as a prodrug to salicylic acid, it is probably best known for its use as a key ingredient in topical anti-acne products. The salts and esters of salicylic
4-Aminosalicylic acid enzymatic activity. PAS was first synthesized by Seidel and Bittner in 1902. It was rediscovered by the Swedish chemist Jörgen Lehmann upon the report that the tuberculosis bacterium avidly metabolized salicylic acid. Lehmann first tried PAS as an oral TB therapy late in 1944. The first patient made a dramatic recovery. The drug proved better than streptomycin, which had nerve toxicity and to which TB could easily develop resistance. In the 1948, researchers at Britain's Medical Research Council demonstrated that combined treatment with streptomycin and PAS was superior to either drug alone, and established the principle of combination therapy for