Picric acid converted it to acetylsalicylic acid, i.e., aspirin, to keep it from the Allies. See Great Phenol Plot. At the time, phenol was obtained from coal as a co-product of coke ovens and the manufacture of gas for gas lighting. Laclede Gas reports being asked to expand production of phenol (and toluene) to support the war effort. Both Monsanto and Dow Chemical undertook manufacture of synthetic phenol in 1915. Dow was the leading producer. Dow describes picric acid as “the main battlefield explosive used by the French. Large amounts [of phenol] also went to Japan, where it was made into picric
4-Aminosalicylic acid because aminosalicylic acid inhibits the synthesis of thyroid hormones. Drug interactions include elevated phenytoin levels. When taken with rifampicin, the levels of rifampicin in the blood fall by about half. The U.S. FDA assigned PAS to pregnancy category C, indicating that it is not known whether it will harm an unborn baby. With heat, aminosalicylic acid is decarboxylated to produce CO and 3-aminophenol. PAS has been shown to be a pro-drug and it is incorporated into the folate pathway by dihydropteroate synthase (DHPS) and dihydrofolate synthase (DHFS) to generate a hydroxyl dihydrofolate antimetabolite, which in turn inhibits dihydrofolate reductase (DHFR)