Summary Of The Effect Of Honokiol On APP-CHO Cells

We first evaluated whether Honokiol treatment was toxic to the APP-CHO cell line. Cells were treated with various concentrations of Honokiol (0.5 μM, 1 μM, 2 μM, 5 μM, 10 μM and 20 μM) for 24 h and cell survival was determined by Prestoblue® assay (Fig.1A). As shown in Fig.1A, when exposed to Honokiol concentrations of 10 μM or lower, the viability of APP-CHO cells was the same as untreated control cells. However, a significant decrease in cell viability was observed with 20 μM Honokiol treatment. Validating the results, live-dead imaging showed (Fig.1B) no cell death up to 10 µM concentrations of Honokiol on staining. However, cells treated with 20 µM of Honokiol showed a relatively higher proportion of dead cells than the cells treated with lower concentrations. Consequently, two doses of 5 μM and 10 μM Honokiol were used in the subsequent experiments.

Figure 1. Effect of Honokiol on APP-CHO cell lines. A shows the dose dependent effect of Honokiol at various concentrations (0.5 μM, 1 μM, 2 μM, 5 μM, 10 μM and 20 μM). Up to 10 μM concentration, Honokiol did not induce toxicity after 24 h treatment, whereas significant toxicity was induced at 20 μM concentration. B Fluorescent viability stain shows dose-dependent effect of Honokiol treatment …show more content…
Increased oxidative stress is directly related to depletion of GSH [18]. Apoptosis due to ROS generation is significantly related to diminished GSH content [19]. Therefore, we sought to estimate the effect of Honokiol on the expression of GSH levels in APP-CHO cells using Glutathione Reductase Activity assay. High insulin exposure significantly reduced GSH content (72%) as compared to the control. Honokiol improved GSH content at both 5 and 10 μM doses, with statistically significant effect at 10 μM doses at 24 hours. There was no significant difference in GSH levels at 24 and 48 hours (Fig.