Fig. 1

Dose and time-course of andrographolide’s effects on Nrf2. a Structure of andrographolide: 3-[2-[decahydro-6-hydroxy-5-(hydroxymethyl)-5,8a-dimethyl-2-methylene-1-napthalenyl]ethylidene]dihydro-4-hydroxy-2(3H)-furanone (CAS no. 5508-58-7). b Bar graphs depict mean ± S.E.M. Nrf2 immunoreactivities (optical density, OD fold changes normalized to β-actin) in rat primary astrocytes treated with andrographolide at the indicated concentrations for 1 h (with representative immunoblot of 3 independent experiments), with the vehicle-only (“0 μM”) group set at 1. c Cell viability (in mean ± S.E.M. % of vehicle-only from three independent experiments) of primary astrocytes after 24 h treatment with andrographolide at the indicated concentrations. d mRNA and e immunoreactivity changes of Nrf2 in primary astrocytes treated with andrographolide (50 μM) for the indicated time intervals, together with immunoreactivites in the f cytosolic and g nuclear fractions (with representative immunoblots). Bar graphs show mRNA or immunoreactivity expressed as mean ± S.E.M. fold change in transcript level or optical density (OD), respectively, with vehicle-only (“0 h”) group set as 1, from three to four independent experiments. Raw transcript values were normalized to mean expression of housekeeping genes (see the “Methods” section) prior to conversion to fold-change values while immunoreactivities were normalized to β-actin except for Nrf2 nuclear fractions, which were normalized to TATA-binding protein (TBP). *p < 0.05; **p < 0.01; and ***p < 0.001; significantly different from vehicle-only group (one-way ANOVA with Dunnett’s post hoc tests)