Enigmatic secondary metabolites: Microbial melanins and their applications

Melanin is a biomacromolecule found in all kingdoms of life that ranges from dark brown to black pigment. Eumelanin, allomelanin, neuromelanin, and pheomelanin are all types of melanin. They possess a wide range of bioactive properties, including antioxidant, radioprotective, antimicrobial, antiviral, antiinflammatory, antiproliferative, and photoprotective properties. Melanin has anticancer and antimicrobial properties that make it useful in pharmacology and medicine. In addition, it has applications in cosmetics; to mimic the natural process of these compounds in the skin, many manufacturers have embraced the use of melanin in sunscreens. Furthermore, due to the absorption of ultraviolet rays, mixed electronic-ionic conductivity, and hydration state-dependent electrical properties of melanin, it is used in organic electronics such as solar cells, batteries, and biosensors. This review examines the various functions and applications of this biological pigment, as well as its distinct physicochemical, chemical, bioactive, and anticorrosive properties.