BIODIVERSITAS ISSN: 1412-033X Volume 22, Number 10, October 2021 E-ISSN: 2085-4722 Pages: 4440-4447 DOI: 10.13057/biodiv/d221037 Methanol pigment extracts derived from two marine actinomycetes exhibit antibacterial and antioxidant activities DOVA KELVIN MESRIAN 1 , WIDYA ESTI PURWANINGTYAS 1 , RIKA INDRI ASTUTI 1 , AKHMAD ENDANG ZAINAL HASAN 2 , ARIS TRI WAHYUDI 1, ♥ 1 Department of Biology, Faculty of Mathematics and Natural Sciences, Institut Pertanian Bogor. Jl. Agatis, Bogor, 16680, West Java, Indonesia, Tel./fax.: +62-251-8622833,  email: ariswa@apps.ipb.ac.id. 2 Department of Biochemistry, Faculty of Mathematics and Natural Sciences, Institut Pertanian Bogor. Jl. Tanjung, Bogor, 16680, West Java, Indonesia Manuscript received: 4 September 2021. Revision accepted: 25 September 2021. Abstract. Mesrian DK, Purwaningtyas WE, Astuti RI, Hasan AEZ, Wahyudi AT. 2021. Methanol pigment extracts derived from two marine actinomycetes exhibit antibacterial and antioxidant activities. Biodiversitas 22: 4440-4447. In recent years, natural pigments produced by marine microorganisms, especially actinomycetes, have become an important source of medically valuable drugs and other active compounds. Based on that crucial fact, this study aimed to determine the toxicity, antimicrobial, and antioxidant activities of methanolic pigment extract derived from marine actinomycetes HV11.P3 and SCA54.P2. Both extracts exhibited high toxicity activity based on Brine Shrimp Lethality Test (BSLT). The results showed the lethal concentration 50% (LC50) values of actinomycetes HV11.P3 and SCA54.P2 pigment crude extracts were 94.60 μg/mL and 131.22 mg/mL, respectively. The antimicrobial activity of those extracts was also tested against several microbes and showed the best results for inhibiting against Bacillus subtilis and Escherichia coli. Furthermore, we assessed the antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals and the results showed the inhibitory concentration 50% (IC50) values of actinomycetes HV11.P3 and SCA54.P2 pigment crude extracts were 231.08 μg/mL and 369.3 μg/mL, respectively. By using GC-MS analysis, we identified chemical compounds of actinomycete pigment crude extracts, revealing that the most dominant compounds were 1H-Purine-2,6-dione, 3,7-dihydro-1,3,7-trimethyl- (CAS) (44.65%) for HV11.P3 and 5-Methoxypyrrolidin-2-one (30.23%) for SCA54.P2. The 16S rRNA gene sequence analysis showed that actinomycete HV11.P3 and actinomycete SCA54.P2 had the closest similarity to Micromonospora chalcea strain 1464-217L and Micromonospora tulbaghiae strain TVU1, respectively. This study revealed that two pigment crude extracts derived from actinimycetes HV11.P3 and SVA54.P2 had antibacterial, antioxidant, and toxicity activities. The actinomycete SCA54.P2 pigment crude extract had the best activity as an antibacterial against E. coli ATCC 8739, while actnomycete HV11.P3 pigment crude extract had the best activity as an antioxidant. Keywords: Actinomycetes, antimicrobial, antioxidant, pigment, toxicity INTRODUCTION In recent years, various problems in the health sector have emerged and attracted the attention of the world. These include resistance to several types of pathogens microbial and increased deaths due to infection with degenerative diseases (Prestinaci et al. 2015; Kharirie and Andriani 2020). Resistance occurs when bacteria, viruses, fungi, and parasites change continuously and reduce the effectiveness of the commonly used antimicrobial agent (Founou et al. 2017). Furthermore, infections that are difficult to treat will increase the risk of disease spread, disease severity, and mortality which have a long-term impact (Roope et al. 2019). Chronic bacterial, viral, and fungal infections might be causative factors for inflammatory and worsen degenerative diseases. Therefore, the discovery of new antimicrobial compounds should be considered in the present and the future. Degenerative diseases as a result of cell damage due to the aging process or various other factors that affect the number of free radicals in the body (Sahardi and Makpol 2019). The accumulation of free radicals will initiate multiple diseases such as Alzheimer's, Parkinson's, atherosclerosis, cardiovascular disorders, hypertension, and diabetes mellitus type 2 (Stambler 2017). Naturally, the human body can reduce free radicals in a certain amount by antioxidant compounds that have been formed in the body. However, if oxidative stress occurs, which is an imbalance between the number of free radicals and the number of antioxidants in the body, the body needs an external source of antioxidants to prevent the oxidation of the essential constituents of cells (Al-Snafi 2017). The other bioactive compound that can act as a tool against degenerative disease is the toxic compound. It has been proven that the toxic compound tested with the brine shrimp lethality test (BSLT) has a good correlation with cytotoxic activity in some solid human tumors (Mclaughlin et al. 1998). Actinomycetes are Gram-positive, filamentous aerobic bacteria with high G+C composition (Gong et al. 2018; Bhakyashree and Kannabiran 2018). Actinomycetes isolated from terrestrial were extensively researched, leading to the rediscovery of natural products that have been reported. On the other hand, marine actinomycetes are primarily a new resource of secondary metabolites including terpenes, peptides, sterols, fatty acids, alkaloids, amino acids and their derivatives (Liao et al. 2016; Pudi et al. 2016). The marine environment is capable of producing all of these compounds due to the enormous biodiversity