Isoxazole is a liquid heterocyclic compound C3H3NO isomeric with oxazole and having a penetrating odor like that of pyridine. Isoxazoles belong to an important class of five-membered aromatic heterocycles containing two electronegative heteroatoms, nitrogen and oxygen, in a 1,2-relationship and three regular sp2 carbon atoms. These molecules are found to be key components in various synthetic products in daily use and also present as a pharmacophore essential for biological activity in many drugs and bioactive natural products. In addition, isoxazoles have demonstrated their ability to exhibit hydrogen bond donor/acceptor interactions with a variety of enzymes and receptors.
The quinones are a class of organic compounds that are formally derived from aromatic compounds by conversion of an even number of –CH= groups into –C(=O)– groups with any necessary rearrangement of double bonds, resulting in a fully conjugated cyclic dione structure. Quinones exhibit numerous biological activities such as neurological, antibacterial, antiplasmodial, antioxidantal, trypanocidal, antitumor, and anti-HIV, and these activities have been proven to be related to the redox properties of their carbonyl functions.