Neuroprotective Effect of Peanut Hairy Root Extract Against Oxidative Stress in PC12 Derived Neurons

Abstract

Oxidative stress resulting in neurodegeneration in specific areas of the brain leading to disorders such as Parkinson’s disease (PD) has been well documented. A specific treatment, however, that can address oxidative stress and thus arrest the progression of PD is unavailable to date. In the present study, using neuronally differentiated rat pheochromocytoma (PC12) cells, a well-established model for studying neuroprotection, we have investigated the protective efficiency of a peanut hairy root extract (PHRE) consisting of resveratrol and other natural resveratrol analogs on hydrogen peroxide (H2O2)-induced neurodegeneration. PHRE is a highly defined and stilbenoid enriched product obtained from elicited-peanut hairy root cultures. PC12-derived neurons were treated with 300 μM H2O2 to expose them to oxidative stress. The cells underwent marked degeneration as determined by characteristic morphological features of degeneration and lactate dehydrogenase (LDH) assay. Pretreatment with PHRE containing 15 μM of resveratrol and additional resveratrol analogs attenuated hydrogen peroxide-induced cytotoxicity of PC12 neurons. Even at 20 or 30 μM concentration, however, synthetic/commercial resveratrol alone did not protect the PC12 neurons from the H2O2 induced neurodegeneration that matched the level of protection provided by PHRE. Our results suggest that PHRE derived resveratrol along with other constituents in the extract have more potential as neuroprotectant than the synthetic/commercial resveratrol alone to prevent oxidative stress-induced cell death. INTRODUCTION The hallmark of Parkinson’s disease is the selective and progressive degeneration of the dopaminergic (DA) neurons in the substantia nigra pars compacta (de Lau et al., 2006). Among the many causes including genetic and environmental factors, oxidative stress is reported to be one of the major causes leading to PD (Abou-Sleiman et al., 2006; Jenner and Olanow, 1998). Oxidative stress occurs due to excessive exposure to reactive oxygen species (ROS) which can lead to impaired cellular functions and cell death (Halliwell, 2001). Hydrogen peroxide (H2O2) is a common strong oxidant, and is also one of the major reactive oxygen species (ROS) which is used in in vitro models to create oxidative stress and toxicity (Stadtman and Berlett, 1991). The rat pheochromocytoma (PC12) cells can be differentiated into neurons with nerve growth factor (NGF) (Gunning et al., 1981). PC12 cells were used by us to determine if NGF-coupled nanotubes could deliver NGF to these cells and differentiate them into neurons (Xie et al., 2008). PC12-derived neurons have been used routinely as a dopaminergic neuronal model because the differentiated PC12 cells syn-the Prabhu et al.: Neuroprotective Effect of Peanut Hairy Root Extract Against Oxid