Bioactive DOPA melanin isolated and characterised from a marine actinobacterium <i>Streptomyces</i> sp. MVCS6 from Versova coast

<div><p>The melanin pigment produced from <i>Streptomyces</i> sp., MVCS6 was isolated and dihydroxyphenyalanine (DOPA) melanin compound was biochemically identified and spectroscopically characterised (ultraviolet and FT-IR). DOPA melanin showed a promising activity as an antibacterial natural product against 12 pathogenic bacteria from hospital isolations, particularly, against <i>Pseudomonas aeruginosa</i> RMMH7 (inhibition zone of 18 ± 0.02 at 30 μg/disc, and MIC of 10 ± 0.02 μg/mL) and <i>Vibrio parahaemolytics</i> RMMH12 (inhibition zone of 15 mm ± 0.03 at 30 μg/disc, and MIC of 14 ± 0.02 μg/mL). Moreover, <i>in vitro</i> evaluation of reducing power (Ascorbic Acid Equivalent (160 μg/mL)), DPPH radical-scavenging (89%), NO-scavenging (72%) and lipid peroxidation activities (89.6%) were determined. Cytotoxicity of DOPA melanin against cervical cancer cell line showed a dose–response activity, and IC₅₀ value was found to be 300 μg/mL. These results would open the way to propose <i>Streptomyces</i> sp. MVCS6 as a promising source of bioactive eumelanin with therapeutic potential in medicine.</p></div