 Biosynthesis involves the oxidation of indole-5,6-quinone by the tyrosinase type polyphenol oxidase from tyrosine and catecholamines leading to the formation of catechol melanin.Despite this many plants contain compounds which inhibit the production of melanins.The first step of the biosynthetic pathway for both eumelanins and pheomelanins is catalysed by tyrosinase.