Figure 1. Effects of SG-Tang on Aβ aggregation, ROS, and neurite outgrowth in Aβ-GFP-expressing cells. (A) Experimental flow chart of Aβ-GFP SH-SY5Y cells. On day 1, cells were plated with retinoic acid (RA, 10 μM) added to the culture medium. On day 2, curcumin or SG-Tang was added to the cells for 8 h, followed by inducing Aβ-GFP expression with doxycycline (Dox, 5 μg/ml) for 6 days. On day 8, GFP fluorescence, cell number, ROS, Aβ-GFP RNA and neurite outgrowth were measured. (B) Assessment of GFP fluorescence and cell number with curcumin (1.2–5 μM) or SG-Tang (1–100 μg/ml) treatment (n = 3). The relative GFP fluorescence/cell number of untreated cells (Untr.) was normalized as 100%. (C) ROS assay with curcumin (1.2–5 μM) or SG-Tang (1–100 μg/ml) treatment (n = 3). The relative ROS of uninduced cells (Dox-) was normalized (100%). (D) Measurement of Aβ-GFP RNA levels in cells treated with 5 μM curcumin and 100 μg/ml SG-Tang by real-time PCR (n = 3). (E) Fluorescence microscopy images of differentiated Aβ-GFP SH-SY5Y cells uninduced (Dox-), untreated (Dox+) or treated with curcumin (5 μM) or SG-Tang (100 μg/ml). Neurite outgrowth and cell number were measured after TUBB3 (yellow) staining (n = 3). Nuclei were counterstained with DAPI (blue). The relative cell number of uninduced cells was normalized as 100%. P values: comparisons between induced (Dox+) vs. uninduced (Dox-) cells (###: P < 0.001), or treated (Dox+/curcumin or SG-Tang) vs. untreated (Dox+) cells (*: P < 0.05, **: P < 0.01, ***: P < 0.001). (B: GFP fluorescence and cell number: two-tailed Student’s t test; C–E: ROS, Aβ-GFP RNA and neurite outgrowth: one-way ANOVA with a post hoc Tukey test).