Vol 14, Issue 4, 2021 Online - 2455-3891 Print - 0974-2441 ANTIOXIDANT ACTIVITY OF METHANOL EXTRACT NATUNA MARINE SPONGE (PORIFERA) WITH DPPH METHODE Mitra Bunda Health Institute, Batam, Indonesia. Email: dellamayefis@gmail.com Received: 23 October 2020, Revised and Accepted: 02 March 2021 ABSTRACT Objective: Natuna sponge is a marine animal that contains a wide range of secondary metabolites that can be utilized in the field of pharmacy. The research aims to test the phytochemical content and antioxidant activity of the Natuna methanol marine sponge extract. Sample extraction is done by the maceration method with methanol solvent. Methods: Phytochemical tests include alkaloid testing, flavonoids, steroids, saponins, and tannins. Test antioxidant activity using the immersion DPPH method (1.1-diphenyl-2-picryl hydroxyl) measured absorption at a wavelength of 517 nm. Results: The phytochemical test results showing the sponge of Natuna contain secondary metabolites including alkaloids, flavonoids, steroids, saponins, and tannins. Conclusion: This Natuna sponge methanol extract has an antioxidant activity that is very strong with an IC 50 value of 52.91 ppm, and the comparator used is Vitamin C with an IC 50 value of 43,51 ppm. Keywords: Antioxidants, DPPH, Marine sponge, Phytochemical tests. INTRODUCTION Indonesian waters, especially the Riau Islands, have abundant marine biota wealth, their use has so far been focused on fish as a food product. One type of marine biota that can be used as medicine is a sponge. Not many studies about the benefits of marine life typical of the Riau Islands are used as medicinal ingredients, especially to ward off free radicals, namely antioxidants. Free radicals contained in the human body have the potential to inactivate various enzymes, oxidize fats, and disrupt the body’s DNA so that cell mutations occur which is the beginning of cancer [1]. Free radicals can be resisted by giving antioxidants [2]. So far, people only know the source of antioxidants from plants, such as the fruits, ginger, and others [3]. Meanwhile, the source of antioxidants from marine animals is not widely known [4]. However, along with the development of technology and science, the use of antioxidants derived from marine biota is also growing, one of them by utilizing sea sponges. Sponges from tropical Indonesian waters have very significant potential as bioactive compounds to be further developed into commodities of high economic value [5]. Sponges contain the most extensive bioactive compounds such as antibacterial activity which were isolated from Agelas clathrodes [6], antioxidant activity of Callyspongia sp. [7], and Lamellodysidea sp. [8] (Fig. 1). Although there have been studies of antioxidant activity in sponges with maceration extraction methods and it is proven that sponges have high antioxidant activity with IC 50 41.21 ppm [7,9,10], this test was carried out on sea sponges originating from the Thousand Islands with a different species from the sea sponge in Natuna. Giving rise to the thought that it is necessary to test the antioxidant activity of the Natuna marine sponge which is rich in marine biota as well as to find new medicinal ingredients. This study aims to determine the IC 50 value of the methanol extract of the Natuna sea sponge and test the activity of secondary metabolites contained therein. METHODS Tools and materials The tools used include glass tools for extraction, UV-visible Spectrophotometer (Shimadzu 265). Materials used include sponges obtained from Natuna waters, Riau Islands, DPPH, Vitamin C, methanol, Liebermann-Burchard reagents, Dragendorff, Mayer, and Bouchard at. The way of research Extraction Fresh samples of 4 kg sponges that have been washed, drained, chopped, and then macerated with methanol until completely submerged in brown glass bottles and stored in a light-protected place for 3 × 5 days while occasionally stirring and filtered with filter paper. The methanol macerate is combined and concentrated with a rotary evaporator until a thick extract is formed then weighed to obtain 99.74 g [11,12]. Phytochemical test extract [13] Alkaloid test As much as, 4 ml of sponge extract was put into a test tube then added 2 ml of chloroform and 5 ml of 10% ammonia and then added 10 drops of 2M sulfuric acid to clarify the separation of the formation of 2 different phases. The upper part of the formed phase is taken, and then, a Mayer reagent is added. The presence of alkaloids is characterized by the formation of red deposits. Flavonoid test Sponge extract is taken as much as 1 ml added with enough magnesium powder and 10 drops of concentrated hydrochloric acid. The presence of flavonoids is characterized by the formation of reddish-black, yellow, or orange. © 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.2021v14i4.40091. Journal homepage: https://innovareacademics.in/journals/index.php/ajpcr Research Article DELLADARI MAYEFIS*, SISKA WIDIASTUTI