Antioxidant effects of bis-indole alkaloid indigo and related signaling pathways in the experimental model of Duchenne muscular dystrophy

Indigo is a bis-indolic alkaloid that has antioxidant and anti-inflammatory effects reported in literature and is a promissory compound for treating chronic inflammatory diseases. This fact prompted to investigate the effects of this alkaloid in the experimental model of Duchenne muscular dystrophy. The main aim of this study was to evaluate the potential role of the indigo on oxidative stress and related signaling pathways in primary skeletal muscle cell cultures and in the diaphragm muscle from mdx mice. The MTT and Neutral Red assays showed no indigo dose-dependent toxicities in mdx muscle cells at concentrations analyzed (3.12, 6.25, 12.50, and 25.00 μg/mL). Antioxidant effect of indigo, in mdx muscle cells and diaphragm muscle, was demonstrated by reduction in 4-HNE content, H 2 O 2 levels, DHE reaction, and lipofuscin granules. A significant decrease in the inflammatory process was identified by a reduction on TNF and NF-κB levels, on inflammatory area, and on macrophage infiltration in the dystrophic sample, after indigo treatment. Upregulation of PGC-1α and SIRT1 in dystrophic muscle cells treated with indigo was also observed. These results suggest the potential of indigo as a therapeutic agent for muscular dystrophy, through their action anti-inflammatory, antioxidant, and modulator of SIRT1/PGC-1α pathway.