Vol 14, Issue 4, 2021 Online - 2455-3891 Print - 0974-2441 CARDIOPROTECTIVE POTENTIAL OF QUERCETIN AGAINST DIESEL OR PETROL EXHAUST NANOPARTICLE INDUCED TOXICITY: A PROSPECTIVE IN VITRO PHARMACOLOGICAL STUDY IN H9C2 CELLS MOHAN DURGA 1 *, THIYAGARAJAN DEVASENA 2 1 Department of Biochemistry and Bioinformatics, Dr MGR Janaki College of Arts and Science for Women, Chennai, Tamil Nadu, India. 2 Centre for Nanoscience and Technology, Anna University, Chennai, Tamil Nadu, India. Email: durgam2k7@gmail.com Received: 22 January 2021, Revised and Accepted: 02 March 2021 ABSTRACT Objective: Phytochemicals are known to elicit potential antioxidant activity. This study examined the cardioprotective effects of quercetin against oxidative damage to rat cardiomyocyte cells (H9c2) after treatment with Diesel Exhaust Nanoparticles (DEPs) or Petrol Exhaust Nanoparticles (PEPs). Methods: Cardiomyocyte cells were exposed to DEPs or PEPs alone and in a combination with quercetin for 24 h. Results: Results showed that quercetin had no lethal effect on H9c2 cells up to a concentration of 1.0 µg/ml. Exposure to DEPs (4.0 µg/ml) or PEPs (10.0 µg/ml) induced cytotoxicity, oxidative stress, and inflammation (p<0.05). It also provoked lipid peroxidation by an increase in MDA and a decrease in SOD activity and glutathione activity (p<0.05). Simultaneous addition of quercetin restored these parameters to near normal. Conclusion: These results thus specify that quercetin plays a protective role in cardiac cells exposed to DEPs and PEPs. Keywords: Diesel exhaust nanoparticles, Petrol exhaust nanoparticles, H9c2, Antioxidants, Quercetin, Inflammation. INTRODUCTION Flavonoids are a group of natural, polyphenolic compounds found widely in fruits, flowers, vegetables, stem, wine, and tea. Nearly 400 different flavonoids have been discovered till date. Quercetin (3, 5, 7, 3, 4 - pentoxy flavones) is one of the best illustrated flavonoids with potential antioxidant properties [1]. Quercetin was found in its glycosylated form in apples, onions, broccoli, and French beans [2]. Studies revealed that quercetin intake showed decreased frequency of neoplastic and cardiovascular diseases [3-5]. Studies by Tieppo et al., 2007, reported that quercetin increased the genomic stability and hence enhanced the antioxidant defense system in rat models [6]. Studies also showed that quercetin inhibited the expression of nitric oxide (NO) synthase, cyclooxygenase, lipid peroxidation (LPO), and xanthine oxidase [7]. Farombi and Onyema, 2006, indicated that dietary antioxidants such as quercetin, Vitamin E, and Vitamin C played a protective role against oxidative stress induced by monosodium glutamate in the brain, liver, and kidney of rats [8]. Studies showed that quercetin prevented different disorders caused by environmental contaminants [9]. Environmental contaminants such as diesel exhaust nanoparticles (DEPs) and petrol exhaust nanoparticles (PEPs), pose a great threat to human health because of their small size and cause dangerous effects such as asthma, bronchitis, various allergies, and lung cancer [10]. As a component of particulate matter (PM), DEPs were seen to exhibit lethal effects on cardiac cells both in vivo and in vitro. In vitro studies showed that different cell types took up DEPs and induced inflammation and oxidative stress in various cell types [11]. DEPs evoked cardiac failure in rats [12]. Other studies showed that DEPs induced reactive oxygen species (ROS) formation and hence oxidative stress and inflammation in the lung and respiratory tract of rats [13]. Studies also showed that DEPs induced toxicity by the production of hydroxyl radicals [14]. Reproductive toxicity evoked by DEPs in rats was treated by quercetin [15]. Other studies showed that quercetin exhibited ameliorating effects on reproductive toxicity induced by 3-methyl-4-nitrophenol (PNMC) (a vital component of DEPs) in chicken embryos [16]. Available data’s on PEP toxicity are insufficient and hence need to be studied in detail. To the finest of our acquaintance, there are no data’s in the available literature reporting the protective effect of quercetin on DEP/PEP- induced cardiotoxicity. The current study was thus, undertaken to investigate the anti-toxic and antioxidant effects of quercetin in DEP/ PEP-induced cardiotoxicity in vitro. METHODS Chemicals Quercetin (98.5%) was purchased from Sigma-Aldrich Pvt. Ltd., Bengaluru, India. All other analytical grade chemicals were purchased from HiMedia Laboratories, Mumbai, India. Collection and characterization of nanoparticles The collection and characterization of nanoparticles were done according to our previous study [17]. Cell culture and MTT assay H9c2 cells (Rat cardiomyocyte cell line) were used for the determination of cytotoxic end-points. The cell lines were purchased from National Centre for Cell Science, Pune. Cytotoxicity determination (IC 50 ) of DEPs and PEPs was performed by MTT assay according to our previous study [17]. The different concentrations of Quercetin (Q) were added to the cells in 100 µL of medium and incubated for 24 h. After 24 h of incubation, 10 µL MTT was added to each well and incubated further for 4 h. 100 ml of DMSO solution was added to each well for the formazan crystal solubilization. The wells were then quantified by measuring absorbance of the solution at 570 nm using a microplate reader (BIO- RAD, USA). The IC 50 value was calculated from the absorbance. Experimental design for cardioprotective activity The cells were incubated in medium containing DEP or PEP with or without prior treatment with quercetin. 1/25 th IC 50 value of DEP © 2021 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open access article under the CC BY license (http://creativecommons.org/ licenses/by/4.0/) DOI: http://dx.doi.org/10.22159/ajpcr.2021v14i4.40858. Journal homepage: https://innovareacademics.in/journals/index.php/ajpcr Research Article