Melanins are enigmatic pigments and biological macromolecules that are produced by a wide variety of
microorganisms including several species of bacteria and fungi. The present study was carried out on isolation
and characterization of melanin from marine actinobacteria, Actinoalloteichus sp. MA-32. Medium
composition and culture conditions for the melanin production by Actinoalloteichus sp. MA-32 were
optimized using two statistical methods: Plackett–Burman design applied to find the key ingredients
and conditions for the best yield of melanin production and central composite design used to optimize
the concentration of the four significant variables: glycerol, l-tyrosine, NaCl and trace salt solution. The
melanin was optimally active at pH 7–9 and temperature 45–60 ◦C and it was most stable up to pH 11
and 4% of NaCl concentration. Melanin was examined by UV–vis absorption spectroscopy and infrared
spectrometry. Melanin has potential antibacterial activity as it showed greater antagonistic and it has
a strong antioxidant potential observed in the in vitro evaluation of its DPPH radical-scavenging activity,
superoxide radical-scavenging activity, nitric oxide-scavenging activity, reducing power and metal
chelating activity. The observed activities indicate that melanin might be a novel potential antioxidant.
This study suggested that the melanin could potentially be used as a natural antioxidant in the food,
cosmetic and pharmaceutical industries.