MCS-18, a novel natural plant product prevents autoimmune diabetes

► MCS-18, a natural product isolated from the plant Helleborus purpurascens increases diabetes free survival using the NOD-mouse model. ► MCS-18 treatment significantly reduces islet T-cell infiltrates as well as the rate of T-cell proliferation. ► Periinsular infiltrates in the MCS-18 treated animals show an enhanced number of Foxp3+ CD25+ regulatory T cells. ► MCS-18 exerts an efficient immunosuppressive activity.