Standardization of Germinated Oat Extracts and Their Neuroprotective Effects Against Aβ1-42 Induced Cytotoxicity in SH-SY5Y Cells

Abstract

The present study aimed to standardize germinated oat extracts (GOEs) by profiling avenanthramides (AVNs) and phenolic acids and evaluate their neuroprotective effects against Aβ_1-42-induced cytotoxicity in human neuroblastoma (SH-SY5Y) cells. GOEs were standardized to contain 1652.56 ± 3.37 µg/g dry weight (dw) of total AVNs, including 468.52 ± 17.69 µg/g AVN A, 390.33 ± 10.26 µg/g AVN B, and 641.22 ± 13.89 µg/g AVN C, along with 490.03 ± 7.83 µg/g dw of ferulic acid, using a validated analytical method. Treatment with AVN C and GOEs significantly inhibited Aβ_1-42-induced cytotoxicity (p < 0.05). Furthermore, both AVNs and GOEs markedly reduced Aβ_1-42-induced reactive oxygen species (ROS) generation in SH-SY5Y cells, showing significant scavenging activity at concentrations of 25 μg/mL (AVNs) and 50 μg/mL (GOEs) (p < 0.05). RT-PCR analysis revealed that AVNs and GOEs effectively downregulated the expression of inflammation- and apoptosis-related genes triggered by Aβ_1-42 exposure. These findings suggest that GOEs rich in AVNs may serve as a potential functional ingredient for enhancing memory function through the inhibition of neuroinflammation and oxidative stress.

Keywords: Aβ1-42; avenanthramides; germinated oat extracts; human neuroblastoma cell; memory improvement.

Figure 1

UV chromatograms of AVNs in the standard solution (A) and oat extracts (B), along with the quantification of AVNs (C) and phenolic acids (D) from the oat extracts, where peaks 1, 2, and 3 correspond to AVN C, A, and B, respectively. Data are presented as mean ± standard deviation (SD) of [n = 3] independent experiments. Statistical significance among treatment groups was determined using one-way ANOVA (or two-way ANOVA where applicable), followed by Tukey’s honestly significant difference (HSD) post hoc test. Different letters (a, b, c) above the bars indicate statistically significant differences among groups (p < 0.05). N/D means not detected, which is below the limit of detection.

Figure 2

Inhibitory effects (% of control) of the AVNs (A) and oat extracts (GOEs) and (B) against Aβ_1-42-induced cytotoxicity in the SH-SY5Y cell. The different letters (a, b) indicate significant differences among concentrations (p < 0.05). An asterisk (*) indicates significant differences between the Aβ_1-42 and each treatment group (p < 0.05). Significant difference (HSD) post hoc test.

Figure 3

Inhibitory effect of AVNs (A) and oat extracts (GOEs) (B) on intracellular ROS production induced by Aβ_1-42. The different letters (a, b) indicate significant differences among concentrations (p < 0.05). An asterisk (*) indicates significant differences between the Aβ_1-42 and each treatment group (p < 0.05). Data are presented as mean ± standard deviation (SD) of [n = 3] independent experiments. Statistical significance among treatment groups was determined using one-way ANOVA (or two-way ANOVA where applicable), followed by Tukey’s honestly significant difference (HSD) post hoc test.

Figure 4

Expression levels of NF-κB, Bax, and Bcl-2 mRNA in SH-SY5Y cells with the sample treatment for 24 h, and Aβ_1-42 (1 μM) was inoculated for a further 24 h. (A–E) The relative expression levels of NF-κB (p50), NF-kB (p65), Bax, Bcl-2, and Bax/Bcl-2 ratio. The data was presented as mean ± SD. The different letters (a, b, c) indicate significant differences among each treatment group (p < 0.05). Data are presented as mean ± standard deviation (SD) of [n = 3] independent experiments. Statistical significance among treatment groups was determined using one-way ANOVA (or two-way ANOVA where applicable), followed by Tukey’s honestly significant difference (HSD) post hoc test.