Quercetin, Kaempferol and Capsaicin Counteract the TGF-β1-Induced Upregulation of αSMA and Collagen in Myoblasts

Two-day-differentiated C2C12 cells were treated with TGF-β1 for 48 h to induce myofibroblast differentiation. Twenty-four hours before (pre-treatment) and for forty-eight hours with (co-treatment) TGF-β1 treatment, cells were exposed to quercetin (25, 50 µM), kaempferol (10, 25, 50 µM) or capsaicin (25, 50 µM).

The immunofluorescence intensity of alpha smooth muscle actin (αSMA) and collagen type I/III gene expression were assessed as myofibroblast markers. MyoD immunofluorescence intensity was measured as a myogenic marker. Co-treatment of TGF-β1 with the phy-tochemicals was most effective, resulting in a decreased number of αSMA-positive cells (all three compounds), decreased collagen type I (kaempferol, capsaicin) and type III (kaempferol) gene expression, and increased MyoD (kaempferol, capsaicin) protein ex-pression compared to TGF-β1 treatment.