International Journal of All Research Education and Scientific Methods (IJARESM), ISSN: 2455-6211 Volume 8, Issue 11, November-2020, Impact Factor: 7.429, Available online at: www.ijaresm.com IJARESM Publication, India >>>> www.ijaresm.com Page 1380 In Silico Studies of Selected Phytoconstituents from Sargassum wightii against COVID Main Protease R. Harini 1 , E. Selvakumari 2 , V. Gopal 3 1,2,3 Department of Pharmacognosy, College of Pharmacy, Mother Theresa Post Graduate and Research Institute of Health Sciences, Indira nagar, Gorimedu, Puducherry, India --------------------------------------------------------------*****************---------------------------------------------------------- ABSTRACT The aim of this present study is to analyze constituents present in dichloromethane fraction of brown seaweed Sargassum wightii by GCMS and to carry out docking studies on COVID-19 Main Protease. The brown seaweed was extracted by stasotto method and fraction has been subjected to GCMS analysis. The docking study, Lipinski rule of five and drug likeness score has been studied for the compounds identified in dichloromethane extract of the brown seaweed using the software AUTODOCK version 4.2 and Mol inspiration software respectively. The compounds Phenol, 2, 4- bis (1, 1-dimethylethyl)-, 8-heptadecene, 5-eicosene, (E)-, 1- heneicosanol, 1-heneicosyl formate, octadecyltrifluoroacetate, 17-pentatricontene, n-heptadecanol-1, 1- pentacontanol, sulphurous acid, octadecyl 2-propyl ester and eicosane 9- cyclohexylwere identified by GCMS analysis among them 5-Eicosene, (E)- was found to be in high concentration. The constituent SW1 showed higher binding affinity (binding energy -5.78 kcal/mol) when compared to the standard drug nelfinavir (binding energy -4.84 kcal/mol). Keywords: GCMS, Molecular docking, Sargassum wightii, QSAR study. I. INTRODUCTION Coronavirus disease 2019(COVID-19) is a contagious disease which was first reported in Wuhan, China [1], [2]. It is caused by Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) and most often spreads through small droplets while sneezing, coughing, talking and during close contact [2-5]. Commonly the positive cases suffer from fever, fatigue, cough, shortness of breath and sometimes experience loss of smell and taste [3], [6], [7]. But maximum cases result in multi-organ failure, distress syndrome, septic shock and blood clots [8-10]. The time from exposure to onset of manifestation usually ranges for the period of 2 to 14 days. This disease is diagnosed by real time reverse transcription polymerase chain reaction, a standard method to diagnose for which a swab of the nasopharynx is taken as sample [11]. Though chest CT imaging helps to diagnose the individual who is dubious for manifestation, guidelines do not recommend it for regime screening [12], [13]. Few preliminary studies explored that combination of protease inhibitors lopinavir, ritonavir and other antiviral treatments neuraminidase inhibitors, nucleoside analogues, umifenovir, remdesivir, tenofovir and lamivudine are used in the treatment of COVID 19 [14]. Based on the binding energy, Nelfinavir showed pre-eminent inhibitory activity against COVID-19 MPRO when compared to perampanel, pitavastatin and perampanel. Liu et al (2020) have crystallised main protease M PRO successfully from COVID 19 which act as a promising target for inhibiting CoV replication [15]. In silico studies serves as a tool to discover novel lead molecule which reduces cost and manpower [16]. Because of its diverse distribution marine algae plays a vital role in the development of novel drug moiety in therapy. Sargassum species are brown seaweed, a good source of secondary metabolites that are responsible for various pharmacological activities such as antioxidant properties [17], [18]. Through investigation of above said particulars, the current work focuses on analyzing the constituents present in the dichloromethane fraction of the brown seaweed Sargassum wightii by GCMS and to carry out docking studies on COVID-19 Main Protease. II. MATERIALS AND METHODS A. Collection, Processing and Authentication of Sample Fresh Sargassum wightii was collected from Mandapam, Rameswaram, Tamilnadu, India by hand picking method. The collected sample was identified and authenticated by a marine biologist at Centre of Advanced Study in Marine Biology, Annamalai University, Parangipettai, Tamilnadu, India. Then the samples were cleaned, washed and shade dried. The dried sample was comminuted and grounded to a fine powder.