Vol 13, Issue 1, 2020 Online - 2455-3891 Print - 0974-2441 EFFECT OF SALACIA OBLONGA ROOT EXTRACT AGAINST CLINICAL ISOLATES STAPHYLOCOCCUS AUREUS ANANTHULA MOUNIKA 1 , BHARGAVI POKALA 2 , ZAHOORULLAH S MD. 3 , ANJANEYULU MUSINI 1 * 1 Centre for Biotechnology, Institute of Science and Technology, Jawaharlal Nehru Technological University, Hyderabad, Telangana, India. 2 Equine Veterinary Medical Centre, Qatar Foundation, Education City, Doha, Qatar. 3 Atal Incubation Centre, Aleap Wehub, Aleap Industrial Estate, Hyderabad, Telangana, India. Email: anjigen@gmail.com Received: 02 November 2019, Revised and Accepted: 25 November 2019 ABSTRACT Objective: Salacia oblonga Wall. is an important medicinal plant belonging to the family Celastraceae. The study reports the effect of S. oblonga root extracts against clinical isolate Staphylococcus aureus. Methods: Antibacterial activity was evaluated by agar diffusion method and assay for minimum inhibitory concentration (MIC) of extract. Further, the effect of S. oblonga extract determined by DNA fragmentation and respiratory dehydrogenase enzyme activity assays. Results: S. oblonga ethyl acetate root extract was evaluated for antibacterial activity towards clinical isolate S. aureus. Bacterial growth was determined in treated and control cells. Extract displayed good growth inhibition and MIC of the extract was 80 µg/ml. DNA fragmentation assay was carried out, this result has shown that treated bacterial cell has DNA damage compared to the control cell. Further, respiratory dehydrogenase enzyme activity was determined. In the treated cells, enzyme activity was low compared to the control cells. Conclusion: Salacia oblonga root extract inhibiting the growth of S. aureus by different modes of action. Keywords: Clinical isolate, Staphylococcus aureus, DNA fragmentation assay, Respiratory dehydrogenase, Salacia oblonga. INTRODUCTION Antimicrobial compounds are very important in reducing the worldwide burden of infectious diseases [1]. However, multidrug-resistant bacteria have become a significant public health risk and sometimes available antimicrobial agents are not effective toward infection caused by pathogenic bacteria. This has led to the search of new antibacterial compounds. From the past many years, plants have been used to treat infectious diseases and are considered as major source of new antimicrobial agents [2,3]. Numerous works have been done to study the antimicrobial effects of herbal plant extracts, including roots, stem, leaves, or flowers [4,5]. Many countries in the world have continued to encourage screening programs of plants used in traditional medicine and identification of their mode of action is important to authenticate their antimicrobial activities and possible inclusion in primary health care. Salacia oblonga is an important medicinal plant that has been extensively used in traditional Indian Ayurvedic medicine as a liver tonic, anti-inflammatory agent, anodyne amenorrhea, diabetes, and treatment of wounds. The root bark extracts are used for itches, asthma, thirst, and ear diseases [6,7]. The important phytoconstituents of S. oblonga include salacinol, mangiferin, and kotanlol, with proven biological activities, namely, nephroprotection, antimutagenic, anti-inflammatory, and antimicrobial [6,8,9]. The present study was undertaken to evaluate the effect of antibacterial activity of S. oblonga root extracts against clinical isolate Staphylococcus aureus. METHODS Chemical and reagents The analytical and high-performance liquid chromatography grade chemicals and reagents used in the study were procured from HiMedia and Merck. Amikacin antibiotic was obtained from Sigma-Aldrich (USA). Culture collection The clinical isolates of the human pathogen S. aureus collected from NICE Hospital, Mehdipatnam, Hyderabad, India, cultured in the laboratory by making use of the nutrient agar and activated in Luria Bertani (LB) broth at 37°C for 20 h before the experiment. For every fortnight, the culture was subjected to subculturing to maintain the pure cultures and stored glycerol stocks at a temperature of −90°C. Plant extract preparation Plants were collected from Western Ghats, Karnataka, India, and authenticated by Dr. N. Siddamallayya, Research Officer, Regional Research Institute, Bengaluru, India, as S. oblonga Wall. (RRCBI 7881). The plant was divided into aerial and root parts, washed properly, shade dried, and crushed to fine powder with the electric blender. The solvent used for the extraction was ethyl acetate (EtOAc). One hundred grams of dried root powder were used for extraction with the help of a Soxhlet apparatus and concentrated using a rotary evaporator (IKA RV 10) at 45°C. The extract was stored at 4°C for further use. Antibacterial assay The antimicrobial activity of plant extract was examined by agar well diffusion method [10]. The Mueller-Hinton agar (MHA) was poured onto the Petri plates with an inoculum size of 10 6 colony-forming unit (cfu)/ml of bacteria. The wells were prepared in the MHA plates with the help of a borer. Concentration of the extract 1 mg/ml was used for evaluating the antibacterial activity. A standard broad-spectrum antibiotic, amikacin (50 μg/ml) was used as a positive control, while the solvent served as negative control. The culture plates were incubated overnight at 37°C for allowing bacterial growth. After incubation, the antibacterial activity evaluated by observing zones of inhibition around the wells and measured. All the experiments were performed in triplicate. © 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.v13i1.36245 Research Article