Ethyl acetate extract of germinated brown rice attenuates hydrogen peroxide-induced oxidative stress in human SH-SY5Y neuroblastoma cells: role of anti-apoptotic, pro-survival and antioxidant genes

Nur Hanisah Azmi,Norsharina Ismail,Maznah Ismail,Mustapha Umar Imam

doi:10.1186/1472-6882-13-177

Nur Hanisah Azmi, Norsharina Ismail + Show 2 more

Open Access

https://doi.org/10.1186/1472-6882-13-177

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Abstract

BackgroundThere are reports of improved metabolic outcomes due to consumption of germinated brown rice (GBR). Many of the functional effects of GBR can be linked to its high amounts of antioxidants. Interestingly, dietary components with high antioxidants have shown promise in the prevention of neurodegenerative diseases like Alzheimer’s disease (AD). This effect of dietary components is mostly based on their ability to prevent apoptosis, which is believed to link oxidative damage to pathological changes in AD. In view of the rich antioxidant content of GBR, we studied its potential to modulate processes leading up to AD.MethodsThe total phenolic content and antioxidant capacity of the ethyl acetate extract of GBR were compared to that of brown rice (BR), and the cytotoxicity of both extracts were determined on human SH-SY5Y neuronal cells using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) Assay. Based on its higher antioxidant potentials, the effect of the GBR extract on morphological changes due to hydrogen peroxide (H2O2)-induced oxidative damage in human SH-SY5Y neuronal cells was examined using inverted light microscope and fluorescence microscope by means of acridine orange-propidium iodide (AO/PI) staining. Also, evaluation of the transcriptional regulation of antioxidant and apoptotic genes was carried out using Multiplex Gene Expression System.ResultsThe ethyl acetate extract of GBR had higher total phenolic content and antioxidant capacity compared to BR. The cytotoxicity results showed that GBR extract did not cause any damage to the human SH-SY5Y neuronal cells at concentrations of up to 20 ppm, and the morphological analyses showed that the GBR extract (up to 10 ppm) prevented H2O2-induced apoptotic changes in the cells. Furthermore, multiplex gene expression analyses showed that the protection of the cells by the GBR extract was linked to its ability to induce transcriptional changes in antioxidant (SOD 1, SOD 2 and catalase) and apoptotic (AKT, NF-Kβ, ERK1/2, JNK, p53 and p38 MAPK) genes that tended towards survival.ConclusionsTaken together, the results of our study showed that the ethyl acetate extract of GBR, with high antioxidant potentials, could prevent H2O2-induced oxidative damage in SH-SY5Y cells. The potential of GBR and its neuroprotective mechanism in ameliorating oxidative stress-related cytotoxicity is therefore worth exploring further.

Highlights

There are reports of improved metabolic outcomes due to consumption of germinated brown rice (GBR)
We have reported a higher antioxidant capacity for methanolic extract of GBR compared to BR [13], while in two other studies we have demonstrated that the ethanolic extracts of GBR possessed higher antioxidant capacities [14,15]
GBR has been shown to possess high antioxidant capacity, as we have demonstrated in the current study

Summary

Introduction

There are reports of improved metabolic outcomes due to consumption of germinated brown rice (GBR). Dietary components with high antioxidants have shown promise in the prevention of neurodegenerative diseases like Alzheimer’s disease (AD) This effect of dietary components is mostly based on their ability to prevent apoptosis, which is believed to link oxidative damage to pathological changes in AD. Reactive oxygen species (ROS) produced in excess due to endogenous and/or exogenous stimuli would normally induce signal transduction that may result in mitochondrial dysfunction, cell death or cell survival [3] The outcome of such insults on cells depends largely on the enormity of the insult and the ability of the cells to contain the insults or remove accumulating ROS. When ROS accumulate, oxidative damage is normally prevented by induction of protective factors like antioxidants, which may not be effective if the insult is too overwhelming In such cases, apoptotic mechanisms set in to remove neurons deemed unsalvageable [1,5]. Loss of neurons through these apoptotic deaths results in severe morphological and functional deficits, which manifest with progressive memory and cognitive decline

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