Vol 13, Issue 10, 2020 Online - 2455-3891 Print - 0974-2441 EVALUATION OF ANTIOXIDANT AND ANTIBACTERIAL ACTIVITY OF GLYCYRRHIZA GLABRA ROOT EXTRACTS SHUSHIL BHUSAL, KHAGA RAJ SHARMA* Central Department of Chemistry, Tribhuvan University, Kirtipur, Kathmandu, Nepal. Email: Khagaraj_sharma33@yahoo.com Received: 06 July 2020, Revised and Accepted: 18 August 2020 ABSTRACT Objectives: The present study was designed to investigate the phytochemical analysis, antioxidant potential, and antibacterial activities of the traditionally used medicinal plant Glycyrrhiza glabra. Methods: The plant secondary metabolites were extracted through cold percolation using methanol (MeOH) as a solvent. The MeOH extract was further fractionated in different solvents in increasing order of polarity. The antioxidant activity was evaluated by 2,2-diphenyl-1-picrylhydrazyl assay. The antibacterial activity was studied by agar well diffusion method. Results: The antioxidant potential IC 50 was found 43.13, 104.83, and 200.11 µg/ml for ethyl acetate (EtOAc), MeOH, and chloroform (CHCl 3 ) extracts, respectively. The EtOAc fraction showed the potent antioxidant with IC 50 43.13 µg/ml compared to the standard ascorbic acid 58.76 µg/ml. The antimicrobial activity exhibited by MeOH extract against Bacillus subtilis (ATCC 6051) and Staphylococcus aureus (ATCC 6538P) zone of inhibition was 18 mm and 17 mm, for chloroform extracts 15 mm and 13 mm, and for EtOAc fraction 11 mm against Bacillus subtilis. The highest dilution that yielded no single bacteria colony on the nutrient agar plates for Bacillus subtilis and S. aureus of MeOH extract was found 0.39 mg/ml and 6.25 mg/ml, for chloroform extract 3.125 mg/ml and 6.25 mg/ml and EtOAc fraction against Bacillus subtilis was 12.50 mg/ml as minimum bactericidal concentration. Conclusion: The plant extracts showed potent antioxidant and antibacterial activity. The results support for using the G. glabra in bacterial infection which provides partial scientific validation for using the plant against bacterial infections. Keywords: Glycyrrhiza glabra, zone of inhibition, Minimum bactericidal concentration, Antioxidant, Antibacterial, Medicinal plant. INTRODUCTION Nepal is regarded as the country of a showroom of biodiversity in terms of species richness at the global and continental level, respectively. Within its narrow stripe, it includes diverse physiographic structures, a wide range of climatic conditions, varied topography, and abundant ecological habitats. Nepal has prosperous biodiversity of flora and fauna. Around 7000 plant species are found in Nepal, among them, 1800 species are currently in use for folk medicine [1,2]. Despite our rich heritage and knowledge of the uses of medicinal plants to cure different diseases as drugs, little attention has been paid to harness the inexpensive remedies to modern requirements. Natural product is the high-value chemical entities derived from plant or microbial sources [3]. Natural product concerns to the primary and secondary metabolites. Since the origin of life, human beings are depending on nature for their basic needs such as shelter, food, clothing, means of transportation, and medicines [4]. Through trial and error, traditional healers found that some plants had healing power, and this knowledge was passed down through the generations. This knowledge is systematized and used in Ayurveda, Tibetan medicine, homeopathy, and Unani system [5]. Medicinal plants have minimal toxicity, are cost- effective, and pharmacologically active hence they provide an easy remedy for many human ailments as compared to the synthetic drugs which are a subject of adulteration and side effects [6]. Thus, biologically active phytochemicals can be isolated from the crude plant extract and after its isolation, dose-based activity can be determined in in-vitro and in in-vivo conditions to develop a novel drug. Partially purified samples of medicinal plants are used for the management of different diseases as antioxidant, anticancer, antibiotic, antidiabetic, etc. Oxidative stress is the state of imbalance between the generation of reactive oxygen species and detoxification of the reactive intermediates or repairing of the resulting damage. Oxidative stress is produced during the normal metabolic process in the body as well as induced by a variety of environmental factors and chemicals [7]. These antioxidants play a vital role in delaying, intercepting, or preventing oxidative reactions, catalyzed by free radical through scavenging or chelating process. This antioxidant activity might be due to the presence of polyphenolic compounds such as flavonoids, phenolic acids, and phenolic diterpenes [8]. Antibiotics are a type of chemical compound used in the treatment and prevention of bacterial infections in animals and human beings by killing or inhibiting the growth of microorganisms. Due to extensive and haphazard use of commercial antimicrobial drugs in the treatment of infectious diseases, multiple drug resistance has developed, making it a global growing problem [9]. Natural products found in high altitudes may give a new source of antimicrobial agents with possible novel drug candidates with a new mechanism of action. Thus, screening of plant extracts from higher plants can be the solution to this global problem [10]. The present study focused on the collection of traditionally used medicinal plant Glycyrrhiza glabra, extraction of plant secondary metabolites, and performed the antioxidant and antibacterial activity. METHODS Chemicals Most of the chemicals used were of analytical grade. Methanol (MeOH) (Collagen Scientific), hexane (Merck), ethyl acetate (EtOAc) (Merck), and chloroform (Merck) were purchased from the market. Ascorbic acid, 2,2-diphenyl-1-picrylhydrazyl (DPPH), sodium nitrite, aluminum chloride, potassium hydroxide, and sodium hydroxide were available in the laboratory. Reagents and solvents used during phytochemical analysis were prepared in the laboratory with the chemicals provided in the laboratory. © 2020 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.2020.v13i10.38950 Research Article