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Khalid Bashir Dar,1 Ishfaq Shafi Khan,2 Shajrul Amin,1 Aijaz Hassan Ganie,3 Aashiq Hussain Bhat,4 Showkat Ahmad Dar,5 Bilal Ahmad Reshi,6 Showkat Ahmad Ganie1 1Department of Clinical Biochemistry/Biochemistry, University of Kashmir, Srinagar, Jammu and Kashmir, India; 2Centre of Research for Development, University of Kashmir, Srinagar, Jammu and Kashmir, India; 3Department of Botany, University of Kashmir, Srinagar, Jammu and Kashmir, India; 4Cancer Research and Diagnostic Centre, SKIMS, Srinagar, Jammu and Kashmir, India; 5Regional Research Institute of Unani Medicine, Srinagar, Jammu and Kashmir, India; 6Department of Biotechnology, University of Kashmir, Srinagar, Jammu and Kashmir, IndiaCorrespondence: Showkat Ahmad GanieDepartment of Clinical Biochemistry/Biochemistry, University of Kashmir, Srinagar, Jammu and Kashmir 190006, IndiaTel +91 9419-972-678Email zubaidashowkat3@gmail.comIntroduction: Chronic inflammation is implicated in a multitude of diseases, including arthritis, neurodegeneration, autoimmune myositis, type 2 diabetes, rheumatic disorders, spondylitis, and cancer. Therefore, strategies to explore potent anti-inflammatory regimens are pivotal from a human-health perspective. Medicinal plants represent a vast unexplored treasure trove of therapeutically active constituents with diverse pharmacological activities, including anti-inflammatory properties. Herein, we evaluated Cousinia thomsonii, an edible medicinal herb, for its anti-inflammatory/immunomodulatory properties.Methods: Soxhlet extraction was used to obtain different solvent extracts (hexane, ethyl acetate, ethanol, methanol, and aqueous extract) in increasing order of polarity. In vitro anti-inflammatory assays were performed to investigate the effects of extracts on protein denaturation, proteinase activity, nitric oxide surge, and erythrocyte-membrane stabilization. The most effective extracts, ie, ethyl acetate (CTEA) and ethanol (CTE) extracts (150– 200 g) were selected for further in vivo analysis using albino Wistar rats. Wistar rats received varying concentrations of CTEA and CTE (25, 50, and 100 mg/kg) for 3 weeks, followed by a single subplantar injection of lipopolysaccharide. Dexamethasone served as positive control. Blood was obtained from the retro-orbital plexus and serum separated for estimation of proinflammatory cytokines (IL6, IL1β, IFNγ and TNFα). Western blotting was performed to study expression patterns of crucial proteins implicated in the NFκB pathway, ie, NFκB p65, NFκB1 p50, and NFκB2 p52. Histopathological examination was done and gas chromatography–mass spectrometry (GC-MS) carried out to reveal the identity of compounds responsible for ameliorating effects of C. thomsonii.Results: Among five tested extracts, CTEA and CTE showed marked inhibition of protein denaturation, proteinase activity, nitric oxide surge and erythrocyte-membrane hemolysis at 600 μg/mL (P< 0.001). Both these extracts showed no toxic effects up to a dose of 2,500 mg/kg. Extracts exhibited concentration-dependent reductions in expression of IL6, IL1β, IFNγ, TNFα, NFκB-p65, NFκB1, and NFκB2 (P< 0.05). Healing effects of extracts were evident from histopathological investigation. GC-MS analysis revealed the presence of important anti-inflammatory compounds, notably stigmast-5-en-3-ol, oleate, dotriacontane, ascorbic acid, n-hexadecanoic acid, and α-tocopherol, in C. thomsonii.Conclusion: C. thomsonii possesses significant anti-inflammatory/immunomodulatory potential by virtue of modifying levels of proinflammatory cytokines/markers and NFκB proteins.Keywords: chronic inflammation, interleukin, cytokine, immunoresponse, nitric oxide, compounds

Competing Interests: Disclosures None.

Ethnopharmacological Relevance: Cousinia thomsonii is traditionally known for treating various diseases including joint pain, swelling, body ache, asthma, dermatitis, cough and arthritis., Aim of the Study: This study employs lipopolysaccharide induced inflammatory wistar-rat model to evaluate efficacy of Cousinia thomsonii active-extracts on the expression of crucial inflammatory markers viz. iNOS, PPAR-γ, Rel-A, COX-2 and serum analysis of CRP., Materials and Methods: Methanol and aqueous extracts were administered orally at 25, 50, 100 mg/kg doses for 21 days. Serum was collected on 22nd day and rats were sacrificed to extract paw tissues. Dexamethasone (0.5 mg/kg) served as positive control. Immunoblotting and qPCR was used for expression analysis of iNOS, PPAR-γ, Rel-A, COX-2 respectively. ELISA was employed for evaluating CRP levels. Discovery-studio and Auto-Dock-Vina were used to check docking interactions of various identified compounds., Results: Both extracts caused dose-dependent decline in iNOS, Rel-A, COX-2 and CRP levels, while there was a dose-dependent increase in PPAR-γ expression. Methanol extract dominated immunomodulatory potential as compared with the aqueous extract. The results of the GCMS revealed the presence of ten compounds. Some of these compounds include 1-Octacosanol, Ethyl Linoleate, 1-Heptacosanol, 1-Hexadecanol, 1-Dodecanol and Behenic alcohol having strong anti-inflammatory, antimicrobial, anti-acne and anti-viral activities. Molecular Docking scores were calculated between each target protein and selected compounds. The best affinity/interactions were observed between 1-Octacosanol towards iNOS, PPAR-γ, Rel-A, COX-2 and CRP with binding energy of -10.4, -11.1, -8.6, -9.9 and -7.9 (kcal/mol) respectively. These compounds may act as strong inhibitors for iNOS, Rel-A, COX-2 and CRP or as agonists for PPAR-γ; thereby inducing anti-inflammatory/immuno-modulatory activities., Conclusions: The results indicate that Cousinia thomsonii contains therapeutically active compounds and thus could serve as potential therapeutic regimen against diverse inflammatory diseases., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier B.V.)

Orange red is a food and cosmetic coloring agent made by the amalgamation of two azo dyes carmoisine and sunset yellow. The current study demonstrates the effect of different concentrations of orange red on antioxidant status, inflammatory biomarkers (TNFα, IFNγ, IL1β, IL6, COX-2, iNOS, and NFκB/p65), biochemical enzymes, and liver histology. In totality, 25 male Wistar rats were procured and arbitrarily alienated into 5 different groups each with 5 animals. Group I was taken as the control. Groups II-V were designated as treatment groups. Groups II and III were administered with (5 and 25 mg/kg b.wt.) and groups IV and V with (150 and 300 mg/kg b.wt.) of orange red via oral gavage for 30 days. It was observed that both low and high concentrations of orange red (25, 150, and 300 mg/kg) remarkably augmented the levels of serum inflammatory cytokines (TNFα, IFNγ, IL1β, and IL6) and the protein and gene expression of COX-2, iNOS, and NFκB/p65. A significant decrease in glutathione reductase, glutathione peroxidase, glutathione- S -transferase, superoxidase dismutase, and catalase activity was observed with increasing concentration of orange red. Furthermore, an increase in the level of several vital biochemical parameters and damage severity to hepatic tissue was also found dose dependent.

Sodium benzoate is a widely used food and pharmaceutical preservative due to its antibacterial and antifungal activity. In the present study effect of different concentrations of sodium benzoate on hepatic antioxidants, inflammatory cytokines (TNF-α, IFN-γ, IL-1β and IL-6), biochemical markers and histopathology of liver was evaluated. Twenty five adult rats (aged 1-2 months) with 5 rats per group were randomly distributed into 5 groups. Group 1 rats were used as control and all groups (1-5) were provided with water and fed ad libitum . In addition to usual water and food, rats of group 2, 3, 4 and 5 were treated with 70, 200, 400 and 700 mg/kg b.wt of sodium benzoate once a day via oral gavage for 30 days. Our results showed that activity of glutathione peroxidase (GPx), catalase (CAT), glutathione-s-transferase (GST), glutathione reductase (GR) and superoxide dismutase (SOD) in rats decreased significantly when treated with 200, 400 and 700 mg/kg b.wt of sodium benzoate. Increase in the concentration of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, serum total protein, albumin, globulin, urea and creatinine was found to be dose dependent. Severe histopathological damage was observed in the hepatic tissue at higher concentrations of sodium benzoate. It was noticed that high concentrations of sodium benzoate (200, 400 and 700 mg/kg b.wt) produce significant increase in inflammatory cytokine markers (TNF-α, IFN-γ, IL-1β and IL-6) in comparison to control. Sodium benzoate at concentration of 70 mg/kg b.wt did not produce any significant changes in any of the above studied parameters.

Tricyclodecan-9-yl xanthogenate (D609) is a synthetic tricyclic compound possessing a xanthate group. This xanthogenate compound is known for its diverse pharmacological properties. Over the last three decades, many studies have reported the biological activities of D609, including antioxidant, antiapoptotic, anticholinergic, anti-tumor, anti-inflammatory, anti-viral, anti-proliferative, and neuroprotective activities. Its mechanism of action is extensively attributed to its ability to cause the competitive inhibition of phosphatidylcholine (PC)-specific phospholipase C (PC-PLC) and sphingomyelin synthase (SMS). The inhibition of PCPLC or SMS affects secondary messengers with a lipidic nature, i.e., 1,2-diacylglycerol (DAG) and ceramide. Various in vitro/in vivo studies suggest that PCPLC and SMS inhibition regulate the cell cycle, block cellular proliferation, and induce differentiation. D609 acts as a pro-inflammatory cytokine antagonist and diminishes Aβ-stimulated toxicity. PCPLC enzymatic activity essentially requires Zn 2+ , and D609 might act as a potential chelator of Zn 2+ , thereby blocking PCPLC enzymatic activity. D609 also demonstrates promising results in reducing atherosclerotic plaque formation, post-stroke cerebral infarction, and cancer progression. The present compilation provides a comprehensive mechanistic insight into D609, including its chemistry, mechanism of action, and regulation of various pharmacological activities.

Neurodegeneration entails progressive loss of neuronal structure as well as function leading to cognitive failure, apathy, anxiety, irregular body movements, mood swing and ageing. Proteomic dysregulation is considered the key factor for neurodegeneration. Mechanisms involving deregulated processing of proteins such as amyloid beta (Aβ) oligomerization; tau hyperphosphorylation, prion misfolding; α-synuclein accumulation/lewy body formation, chaperone deregulation, acetylcholine depletion, adenosine 2A (A2A) receptor hyperactivation, secretase deregulation, leucine-rich repeat kinase 2 (LRRK2) mutation and mitochondrial proteinopathies have deeper implications in neurodegenerative disorders. Better understanding of such pathological mechanisms is pivotal for exploring crucial drug targets. Herein, we provide a comprehensive outlook about the diverse proteomic irregularities in Alzheimer's, Parkinson's and Creutzfeldt Jakob disease (CJD). We explicate the role of key neuroproteomic drug targets notably Aβ, tau, alpha synuclein, prions, secretases, acetylcholinesterase (AchE), LRRK2, molecular chaperones, A2A receptors, muscarinic acetylcholine receptors (mAchR), N-methyl-D-aspartate receptor (NMDAR), glial cell line-derived neurotrophic factor (GDNF) family ligands (GFLs) and mitochondrial/oxidative stress-related proteins for combating neurodegeneration and associated cognitive and motor impairment. Cross talk between amyloidopathy, synucleinopathy, tauopathy and several other proteinopathies pinpoints the need to develop safe therapeutics with ability to strike multiple targets in the aetiology of the neurodegenerative disorders. Therapeutics like microtubule stabilisers, chaperones, kinase inhibitors, anti-aggregation agents and antibodies could serve promising regimens for treating neurodegeneration. However, drugs should be target specific, safe and able to penetrate blood-brain barrier.

This study evaluates the ameliorative potential of Rheum spiciformis methanolic (RS-MeOH) extract in reducing oxidative stress and hyperglycemia in albino rats along with characterization of possible therapeutic compound(s). Groups treated with 50 and 100 mg/kg bw plant extract (RS-MeOH ) decrease blood glucose levels from 359.9±8.2 to 209.5±8.5 mg/dl (50 mg/kg bw) and 354.7±13.3 to 162.5±7.4 mg/dl (100 mg/kg bw) on the 0 th and 14 th day (P<0.001) respectively. This reduction in blood glucose was significant as compared to glibenclamide (20 mg/dl) which reduced glucose levels from 297.7±11.39 to 132.9±8.74 mg/dl on 0 th and 14 th day respectively. Biochemical parameters triglycerdies, cholesterol, low density lipoprotein (LDL) and creatinine were also reduced in a dose dependent manner. Liver marker enzymes were positively modulated by administration of RS-MeOH (P<0.001). Antioxidant enzyme profile showed an enhanced/better pattern after the administration of RS-MeOH extracts for reduced glutathione, reduced glutathione (GR), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and superoxide dismutase (SOD) in both liver and pancreas. Moreover pancreatic histopathology reports revealed β-cell restorative effects with RS-MeOH, thereby potentiating its role in improving blood glucose levels. RS-MeOH purification and isolation studies involving GC-MS and NMR techniques revealed presence of emodin type compounds in RS-MeOH. Overall Rheum spiciformis showed ameliorative action on oxidative stress and hyperglycemia, however further studies to explore the mechanism of action of possible therapeutic compound in invivo clinical trials will prove beneficial for the advancement of new oral antidiabetic drug., Competing Interests: There is none to declare., (© Georg Thieme Verlag KG Stuttgart · New York.)

Protein-Protein Interactions (PPIs) drive major signalling cascades and play critical role in cell proliferation, apoptosis, angiogenesis and trafficking. Deregulated PPIs are implicated in multiple malignancies and represent the critical targets for treating cancer. Herein, we discuss the key protein-protein interacting domains implicated in cancer notably PDZ, SH2, SH3, LIM, PTB, SAM and PH. These domains are present in numerous enzymes/kinases, growth factors, transcription factors, adaptor proteins, receptors and scaffolding proteins and thus represent essential sites for targeting cancer. This review explores the candidature of various proteins involved in cellular trafficking (small GTPases, molecular motors, matrix-degrading enzymes, integrin), transcription (p53, cMyc), signalling (membrane receptor proteins), angiogenesis (VEGFs) and apoptosis (BCL-2family), which could possibly serve as targets for developing effective anti-cancer regimen. Interactions between Ras/Raf; X-linked inhibitor of apoptosis protein (XIAP)/second mitochondria-derived activator of caspases (Smac/DIABLO); Frizzled (FRZ)/Dishevelled (DVL) protein; beta-catenin/T Cell Factor (TCF) have also been studied as prospective anticancer targets. Efficacy of diverse molecules/ drugs targeting such PPIs although evaluated in various animal models/cell lines, there is an essential need for human-based clinical trials. Therapeutic strategies like the use of biologicals, high throughput screening (HTS) and fragment-based technology could play an imperative role in designing cancer therapeutics. Moreover, bioinformatic/computational strategies based on genome sequence, protein sequence/structure and domain data could serve as competent tools for predicting PPIs. Exploring hot spots in proteomic networks represents another approach for developing targetspecific therapeutics. Overall, this review lays emphasis on a productive amalgamation of proteomics, genomics, biochemistry, and molecular dynamics for successful treatment of cancer., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Dystrophin protein in association with several other cellular proteins and glycoproteins leads to the formation of a large multifaceted protein complex at the cell membrane referred to as dystrophin glycoprotein complex (DGC), that serves distinct functions in cell signaling and maintaining the membrane stability as well as integrity. In accordance with this, several findings suggest exquisite role of DGC in signaling pathways associated with cell development and/or maintenance of homeostasis. In the present review, we summarize the established facts about the various components of this complex with emphasis on recent insights into specific contribution of the DGC in cell signaling at the membrane. We have also discussed the recent advances made in exploring the molecular associations of DGC components within the cells and the functional implications of these interactions. Our review would help to comprehend the composition, role, and functioning of DGC and may lead to a deeper understanding of its role in several human diseases., (© 2017 Wiley Periodicals, Inc.)

Drug discovery is an exhaustive and time-consuming process involving numerous stages like target identification, validation, lead optimization, preclinical trials, clinical trials and finally postmarketing vigilance for drug safety. The application of computer-aided drug designing (CADD) is an indispensable approach for developing safe and effective drugs. Previous methods based on combinatorial chemistry (CC) and high throughput screening (HTS) consumed a lot of time as well as expenditure. CADD based approaches including pharmacophore modeling (PM), molecular docking (MD), inverse docking, chemical similarity (CS), quantitative structure-activity relationship (QSAR), virtual screening (VS) and molecular dynamics simulations have been quite productive in predicting the therapeutic outcome of candidate drugs/compounds besides saving precious time. CADD tools exploit structural and other information available regarding the target (enzyme/receptor) and the ligands to identify the compounds with the ability to treat diseases notably cancer, neurodegenerative disorders, malaria, Ebola, HIV-AIDS and many more. Computational approaches have led to the discovery of many drugs that have passed preclinical and clinical trials and become novel therapeutics in the treatment of a variety of diseases. Some notable examples of CADD derived novel drugs include dorzolamide, saquinavir, ritonavir, indinavir, captopril and tirofiban. CADD plays important role in predicting absorption, distribution, metabolism, excretion and toxicity (ADME/T) of candidate drugs. Overall, CADD represents an effective and much-needed strategy for designing therapeutically effective drugs to combat human diseases., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Introduction: Rheum spiciformis is a newly identified edible medicinal plant of genus Rheum . The plant is used to treat various diseases on traditional levels in Kashmir Valley, India., Aim: To evaluate the phytochemical screening, antibacterial and antifungal potential of aqueous and methanolic extracts of Rheum spiciformis , a traditionally used edible medicinal plant., Materials and Methods: Methanolic and aqueous extracts of Rheum spiciformis were tested for their antimicrobial activities against six bacterial strains namely Bacillus subtilis , Staphylococcus aureus , Klebsiella pneumoniae , Pseudomonas aeruginosa , Proteus vulgaris and Escherichia coli and four fungal strains Penicillium chrysogenum , Aspergillus fumigatus , Candida albicans and Saccharomyces cerevisiae. The susceptibility of microbial strains to the two extracts was determined using agar well diffusion method. Phytochemical screening was carried out by using various standard procedures., Results: Methanolic extract showed potent antimicrobial activity as compared to aqueous extract at the concentrations of 10, 30, 50, 80 and 100mg/ml. The most susceptible bacterial strains were Staphylococcus aureus with zone of inhibition (25±0.10mm), Klebsiella pneumonia (23±0.25mm), Proteus vulgaris (22±0.10mm) at the concentration of 100mg/ml. Aqueous extracts at the higher concentration were found effective against Proteus vulgaris and Bacillus subtilis with zone of inhibition (17±0.24mm) and (17±0.10mm), respectively. Among fungal strains the most susceptible were Aspergillus fumigatus (21±0.10mm), Saccharomyces cerevisiae (20±0.20mm) and Penicillium Chrysogenum (17±0.15mm) at the concentration of 100mg/ml methanol extract. The zone of inhibition for aqueous extract against fungal strains ranged between 14±0.13mm to 16±0.19mm at the highest concentration of plant extract. Phytochemical analysis revealed the presence of various secondary metabolites like flavonoids, saponins, volatile oils, phenols, steroids, terpenoids and alkaloids., Conclusion: Our results indicate that this plant has enough potential to serve as an excellent candidate for obtaining antimicrobial compounds to combat bacterial and fungal infections.

Context: Crataegus songarica K. Koch (Rosaceae) has been used in folk medicine to treat various diseases., Objective: This study evaluates the effect of C. songarica methanol extract on the kidney and heart tissue damage of albino rats, and to determine cytotoxic activity of various extracts of songarica on various human cancer cell lines., Materials and Methods: Rats were divided into six groups, Group I received water only; Group II received CCl4 (1 mL/kg b wt) intraperitoneal; C. songarica extract (at doses of 100, 200 and 300 mg/kg b wt) orally for 15 days. Cytotoxic activity was determined by SRB method using MCF-7, HeLa, HepG2, SF-295, SW480 and IMR-32 cell lines., Results: Compared with CCl4 group, administration of C. songarica extract at the dose of 300 mg/kg b wt, significantly decreases serum creatinine (59.74%), urea (40.23%) and cholesterol (54 mg/dL), MDA (0.007 nmol/mg protein) in kidney and (0.025 nmol/mg protein) in heart tissue, along with evaluation of GSH (209.79 ± 54.6), GR (111.45 ± 2.84), GPx (94.01 ± 14.80), GST (201.71) in kidney tissue and GSH (51.47 ± 1.47), GR (45.42 ± 6.69), GPx (77.19 ± 10.94), GST (49.89) in heart tissue. In addition, methanol, ethanol and ethyl acetate extracts exhibited potent anticancer activity on six cancer cell lines with IC50 values ranging from 28.57 to 85.106 µg/mL., Discussion and Conclusion: Crataegus songarica methanol extract has a potential antioxidant effect as it protects the kidney and heart tissue against CCl4-induced toxicity, prevents DNA damage and showed strong anticancer activity.

Mitochondria play a central role in cellular physiology. Besides their classic function of energy metabolism, mitochondria are involved in multiple cell functions, including energy distribution through the cell, energy/heat modulation, regulation of reactive oxygen species (ROS), calcium homeostasis, and control of apoptosis. Simultaneously, mitochondria are the main producer and target of ROS with the result that multiple mitochondrial diseases are related to ROS-induced mitochondrial injuries. Increased free radical generation, enhanced mitochondrial inducible nitric oxide synthase (iNOS) activity, enhanced nitric oxide (NO) production, decreased respiratory complex activity, impaired electron transport system, and opening of mitochondrial permeability transition pores have all been suggested as factors responsible for impaired mitochondrial function. Because of these, neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), Huntington's disease (HD), and aging, are caused by ROS-induced mitochondrial dysfunctions. Melatonin, the major hormone of the pineal gland, also acts as an anti-oxidant and as a regulator of mitochondrial bioenergetic function. Melatonin is selectively taken up by mitochondrial membranes, a function not shared by other anti-oxidants, and thus has emerged as a major potential therapeutic tool for treating neurodegenerative disorders. Multiple in vitro and in vivo experiments have shown the protective role of melatonin for preventing oxidative stress-induced mitochondrial dysfunction seen in experimental models of PD, AD, and HD. With these functions in mind, this article reviews the protective role of melatonin with mechanistic insights against mitochondrial diseases and suggests new avenues for safe and effective treatment modalities against these devastating neurodegenerative diseases. Future insights are also discussed.

Derailed inflammation causes severe damage to the normal tissues resulting in various pathological conditions such as auto-inflammatory disorders, neurodegenerative diseases and cancer. Cure of inflammatory diseases is a big challenge. Medicinal herbs used traditionally represent the best option for obtaining effective anti-inflammatory therapeutics. Present review provides a thorough insight about various pathways, consequences and therapeutic strategies of inflammation with prime focus to expose indigenous anti-inflammatory herbal compounds along with their structures and diverse range of mechanisms of action. Over hundred medicinal plants with scientifically reported anti-inflammatory properties were reviewed. Different parts of the plants like roots, stem, bark, leaves, flowers and seeds contain active compounds with potential anti-inflammatory properties. Such compounds act at multiple targets in the inflammatory response pathways and regulate multitude of chemical mediators, enzymes, genes or cellular functions to alleviate inflammation. Although a large number of antiinflammatory herbal compounds have been isolated but the mechanism of action of bulk of compounds has not been elucidated comprehensively. Besides there is need for conducting well designed clinical trials so that the promising compounds could be used as effective antiinflammatory therapeutic agents in future.

Mitochondria is one of the main source of oxidative stress (ROS), as it utilizes the oxygen for the energy production. ROS and RNS are normally generated by tightly regulated enzymes. Excessive stimulation of NAD(P)H and electron transport chain leads to the overproduction of ROS, results in oxidative stress, which is a good mediator to injure the cell structures, lipids, proteins, and DNA. Various oxidative events implicated in many diseases due to oxidative stress include alteration in mitochondrial proteins, mitochondrial lipids and mitochondrial DNA, Which in turn leads to the damage to nerve cell as they are metabolically very active. ROS/RNS at moderate concentrations also play roles in normal physiology of many processes like signaling pathways, induction of mitogenic response and in defense against infectious pathogens. Oxidative stress has been considered to be the main cause in the etiology of many diseases, which includes Parkinson's and Alzheimer diseases. Several PD associated genes have been found to be involved in mitochondrial function, dynamics and morphology as well. This review includes source of free radical generation, chemistry and biochemistry of ROS/RNS and mitochondrial dysfunction and the mechanism involved in neurodegenerative diseases., (Copyright © 2015 Elsevier Masson SAS. All rights reserved.)