The quinones represent a class of organic compounds that are formally "derived from aromatic compounds [such as benzene or naphthalene] 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". The class includes some heterocyclic compounds. A large scale industrial application of quinones is for the production of hydrogen peroxide. Natural quinones show a biological or pharmacological activity, and some of them show anti-tumoral activity. They embody some claims in herbal medicine. Some quinone derivatives are used for coloring substances (dyes and pigments) and oxidizing agents.