Nitrogen-Doped Graphene Quantum Dot-Combined Sodium 10-Amino-2-methoxyundecanoate: Studies of Proinflammatory Gene Expression and Live Cell Imaging.

Marine cyanobacteria are renowned for producing bioactive secondary metabolites with great structural diversity via mixed biosynthetic pathways. Lyngbya sp., a marine cyanobacterium, produces many metabolites with anti-inflammatory potentials; nevertheless, its bioactive metabolites exercising providing protection against inflammation has been deciphered inadequate. In this study, the ethanolic fraction of the Lyngbya sp. extract was purified and identified as sodium 10-amino-2-methoxyundecanoate ( SAM ) using Fourier-transform infrared spectroscopy, nuclear magnetic resonance, and electron spray ionization-mass spectroscopy. SAM showed prominent inhibition of inflammation, which was analyzed by reactive oxygen species generation and nitric oxide (NO) inhibition assay. Furthermore, the anti-inflammatory potentials of SAM were evaluated in lipopolysaccharide (LPS)-induced RAW 264.7 macrophage cell lines by fluorescence-activated cell sorting analysis, which evidenced prominent decrease in COX-2 expression (∼90%) with SAM -treated cells than the control. Subsequently, a semiquantitative real-time polymerase chain reaction analysis also revealed the downregulation of COX -2, iNOS , TNF -α, NF -κß, IL -1α, IL -1ß, IL -4, and IL -6 gene expression in SAM -treated LPS-induced RAW 264.7 cells. To further enhance the delivery of SAM into the cells, it was combined with N-doped graphene quantum dots (N-GQDs) for the anti-inflammatory potentials. It resulted in improved downregulation of COX -2, iNOS , TNF -α, NF -κß, IL -1α, IL -1ß, IL -4, and IL -6 than cells treated with SAM alone. Conclusively, N-GQDs combined with SAM have the effective therapeutic potential as an inhibitor of inflammation by modulating the expression of different cytokine genes.