LAUSR

Melanins are a ubiquitous group of pigments widely acclaimed as potent free-radical scavengers. The present study proposed to harness this property of melanins for anti-inflammatory and anti-cancer applications. Pyomelanin, a potent form of melanin analogous to alkaptomelanin in humans, was derived from Pseudoalteromonas species and fabricated into ultra-small pyomelanin nanogranules (PNGs) by facile routes. These melanin nanogranules were characterized for various physicochemical attributes using DLS, TEM, FTIR, EPR, XRD, and TGDA. Additionally, elemental analysis and long-term particle stability study was also conducted. The ultra-small particles were ~ 5–7 nm in size through TEM with a very strict size distribution. The free-radical scavenging activity of PNG assessed through the DPPH assay was comparable with that of ascorbic acid. Significant inflammatory markers viz., cyclooxygenase, lipoxygenase, myeloperoxidase, and cellular nitrate levels estimated in lipopolysaccharide-triggered RAW264.7 cells were reduced upon PNG treatment. The cancer cell kill effect of PNG was estimated in lung carcinoma cells in comparison with normal fibroblasts, wherein percentage inhibition in cancer cells was ~ 2-fold higher than that observed in normal fibroblasts. Overall, our results demonstrate the proof-of-principle of using pyomelanin nanogranules for therapeutic applications.