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

• Published in: Natural product research 2015-11, Vol.29 (22), p.2117-2121
• Main Authors: Sivaperumal, P., Kamala, K., Rajaram, R.
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - isolation & purification; antibacterial; antioxidant; Antioxidants - chemistry; Antioxidants - isolation & purification; Cell Line, Tumor - drug effects; cytotoxicity activity; Dihydroxyphenylalanine - analogs & derivatives; Dihydroxyphenylalanine - chemistry; Dihydroxyphenylalanine - isolation & purification; FT-IR; Humans; India; melanin; Microbial Sensitivity Tests; Pseudomonas aeruginosa - drug effects; Seawater - microbiology; Streptomyces - chemistry; Vibrio parahaemolyticus - drug effects
• ISSN: 1478-6419; 1478-6427
• DOI: 10.1080/14786419.2014.988712

The melanin pigment produced from Streptomyces 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 Pseudomonas aeruginosa RMMH7 (inhibition zone of 18 ± 0.02 at 30 μg/disc, and MIC of 10 ± 0.02 μg/mL) and Vibrio parahaemolytics RMMH12 (inhibition zone of 15 mm ± 0.03 at 30 μg/disc, and MIC of 14 ± 0.02 μg/mL). Moreover, in vitro 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 IC 50 value was found to be 300 μg/mL. These results would open the way to propose Streptomyces sp. MVCS6 as a promising source of bioactive eumelanin with therapeutic potential in medicine.