© 2020 John and Chandrapragasam. This is an open access article distributed under the terms of the Creative Commons Attribution License -NonCommercial- ShareAlike Unported License (http://creativecommons.org/licenses/by-nc-sa/3.0/). In vitro antioxidant activity of Lactobacillus plantarum against hydrogen peroxide-induced neuronal damage on PC12 cells Shani Kunjamma John, Vani Chandrapragasam* Department of Biotechnology, Karunya Institute of Technology and Sciences, Karunya Nagar, Coimbatore, India. ABSTRACT Alzheimer’s disease (AD) is a progressive neurodegenerative disease of the central nervous system. Inflammatory injury and oxidative stress have been a hallmark for AD due to free radical production. The main objective of the present study is to identify the compounds having good antioxidant properties from Lactobacillus plantarum and its effect on neuronal cells. L. plantarum strain was cultured in De Man, Rogosa and Sharpe (MRS) medium supplemented with cinnamon and pantothenic acid (40 µg/ml and 4 µg/ml). Solvent extraction (ethyl acetate, chloroform, petroleum ether, and hexane) was done in the supernatant and tested for in vitro 2,2-diphenyl-1-2- picrylhydrazyl (DPPH), H 2 O 2 scavenging activity, and H 2 O 2 -induced cytotoxicity assessment in PC12 cell lines. The results obtained from the study showed that all the extracts have good antioxidant activity. It was observed that the stress-induced PC12 cell lines showed maximum protection of cells in the Media D (chloroform) extract, the IC 50 value was recorded as 23.71 µg/ml. Similarly, all solvent extracts showed significant antioxidant activity in DPPH assay with IC 50 value ranging from 23.59 to 106.8 µg/ml and IC 50 value in H 2 O 2 scavenging assay ranging from 37.39 to 107.7 µg/ml. Referring to the complex multifactorial etiology of AD, the findings from our work exhibited remarkable potentials of antioxidants activity. 1. INTRODUCTION Alzheimer’s disease (AD), a significant health complication in the civilized world, is a standard form of dotage-related neurodegenerative dementia. It is a progressive, neurodegenerative disease, the genesis of neurological decline and stands to be an ultimate and eventually a life-threatening disease unless the death is interceded by another cause [1]. AD affects mainly the parts of the brain associated with higher mental functions, specifically the neocortex and hippocampus [2]. AD is mainly characterized by abnormal deposition of extracellular amyloid- beta proteins (Aβ) and intracellular neurofibrillary tangles (tau proteins) and by comprehensive loss of neurons [3]. Etiology of AD is not fully understood because of the multifactorial mechanisms underlying the disease, and various studies suggested that free radicals were involved in the inflammatory injury and oxidative stress in AD [4,3]. The neuronal cell death is caused by the elevated production of reactive oxygen species (ROS) and nitrogen species such as hydrogen peroxide (H 2 O 2 ) and nitric oxide (NO) generated by Aβ in microglial cells [5,6]. Reactive oxygen species (ROS) play a key role in the pathogenesis of several diseases, including AD [7]. The human brain consumes *Corresponding Author: Vani Chandrapragasam, Department of Biotechnology, Karunya Institute of Technology and Sciences, Karunya Nagar, Coimbatore, India. E-mail: vani@karunya.edu ~20% of oxygen supply and is more susceptible to oxidative stress due to its high-energy consumption and increased oxidative stress has been reported in AD patients’ brain [8]. Oxidative stress is a condition caused by the imbalance between the ROS production and antioxidants levels causing damage to the cells by excessive production of ROS. ROS modulate the function of biomolecules and may target the cell substrates resulting in causing protein, DNA, RNA oxidation, or lipid peroxidation [9]. Lactobacillus plantarum MTCC 1325 strain was reported to have the competence of producing acetylcholine (Ach) neurotransmitter through both external and internal pathways and also holds significant antioxidant activity [10,11]. The studies on gut–brain axis communication depict that the bacteria (microbiome) present in the gastrointestinal tract possibly communicate with the brain and nervous system in different ways [12]. Pantothenic acid (Vitamin B5) is a water-soluble vitamin, with the main position for metabolic reactions due to its incorporation into coenzyme A (CoA) and intake of pantothenic acid is reported for the reduction of oxidative stress and improved brain damage caused in gamma-irradiated rats [13,14]. Cinnamon (Cinnamomum zeylanicum and Cinnamon cassia), known as the eternal tree of tropical medicine, belongs to the family Lauraceae, besides its antioxidant properties, they are also recorded to have anti-inflammatory, antimicrobial, antidiabetic, anticancer, and lipid-lowering and cardiovascular disease-lowering properties. They are also reported to have activity Journal of Applied Biology & Biotechnology Vol. 8(05), pp. 84-87, Sep-Oct, 2020 Available online at http://www.jabonline.in DOI: 10.7324/JABB.2020.80511 ARTICLE INFO Article history: Received on: April 23, 2020 Accepted on: August 09, 2020 Available online: September 12, 2020 Key words: Alzheimer’s disease, Lactobacillus plantarum, DPPH scavenging assay, H 2 O 2 scavenging assay, PC12 cell line