Aucubin is an iridoid glycoside that has been found in E. ulmoides with diverse biological activities.^1,2 Aucubin (0.001-1 μg/ml) dose-dependently inhibits the IgE-stimulated secretion of IL-6 and TNF-α by RBL-2H3 mast cells (IC50s = 0.19 and 0.1 μg/ml, respectively).¹ It reduces UVB-induced expression of matrix metalloproteinase-1 (MMP-1) in HS68 human foreskin fibroblasts by 57% when used at a concentration of 0.01 μg/ml.² Aucubin (0.01-1 μg/ml) also dose-dependently reduces production of reactive oxygen species (ROS) and malondialdehyde (MDA) levels, a marker of lipid peroxidation. In a mouse model of pulmonary fibrosis induced by bleomycin , aucubin (5 mg/kg, i.p.) decreases the breathing frequency, increases lung dynamic compliance, alleviates parenchymal fibrotic changes, and reduces expression of TGF-β1 and α-smooth muscle actin (α-SMA).³ Aucubin (5 mg/kg, i.p.) reduces blood glucose levels and lipid peroxidation in the liver and kidneys of rats with diabetes induced by streptozotocin .⁴ It also reduces the number of errors made in a Y-maze and enhances neuronal survival by approximately 7- and 4-fold, respectively, in rats with streptozotocin-induced diabetes.⁵