Judul: Potensi Biopigment Asal Streptomyces sebagai Antioksidan, Antibakteri dan Antikanker
Abstrak: Actinomycetes, are known for their abilities to produce diverse secondary metabolites. About 100,000 active compounds of secondary metabolites are known to be produced by actinomycetes. This amount includes 45% of all active compounds of secondary metabolites produced by microorganisms. Streptomyces, one of the actinomycetes genus are able to produce various types of pigment. Pigments, as one of the secondary metabolites, have different biological activities such as antioxidant, anticancer, and antimicrobial activity. Soil actinomycetes ARK19 and ARK86 produced pink-purple and yellow intracellular pigment which potentially has pharmaceutical properties. Here, we assessed the antioxidant, antibacterial and anticancer activity of the crude pigment extract and its active fraction and the detection of polyketide synthases (PKS) and non-ribosomal peptide synthetases (NRPS) genes. In our study, ARK19 has the closest similarity with Streptomyces yangpuensis fd-2tb (99%). The actinomycetes showed the best growth and pigment production in ISP4 medium supplemented with starch as a carbon source. The pigment extracts were extracted using methanol solvent resulted yield 7.54% and 6.21% (w/w) for S. yangpuensis ARK19 and S. polychromogenes ARK86, respectively. Based on the UV-Vis analysis, the S. yangpuensis ARK19’s pink-purple pigment was indicated as prodigiosin, while the S. polychromogenes ARK86’s yellow pigment indicated as carotenoid. The crude pigment extracts were tested for their cytotoxic activity by Brine Shrimp Lethality Test (BSLT). The LC50 of each extract was recorded at 182.88 μg/ml and 116 μg/ml for S. yangpuensis ARK19 and S. polychromogenes, respectively. The result suggests that the pigment extracts were classified as a cytotoxic compound and might have anticancer activity. These findings were supported by a cytotoxicity test by MTT assay against a human breast cell line. S. polychromogenes crude pigment extract showed the best cytotoxic activity with an IC50 value of 289.07 μg/mL and 271.27 μg/mL for MCF-7 and MCF-12A cell lines, respectively. Furthermore, to understand the possible chemical compounds involved in their biological activities, we identified the chemical composition of the pigment extracts by GC-MS analysis. Our result revealed that the most dominant compound in the crude pigment extract were 6-Octadecanoid acid and 2-p-nitrophenyl-1,3,4-oxadiazol-5- in S. yangpuensis ARK19 and S. polychromogenes ARK86, respectively. The active fraction was obtained by Thin-Layer Chromatography separation. The antioxidant and antibacterial active fractions of the extracts was determined by bioautography test followed by preparative-TLC. Our result showed that the crude pigment extract as well as their active fraction have in vitro antioxidant activity against DPPH radical. The antibacterial activity was assayed by the disc diffusion method exhibited broad spectrum activity against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The active fraction of S. polychromogenes ARK86 extract resulted changes in morphology of B. subtilis as a result of antibacterial activity. Metabolite profiling using LC-MS analysis showed that active fraction of S. yangpuensis ARK19 was rich in dextromethorphan, while S. polychromogenes ARK86 major compounds was morphine. This compound was reported to have anti-oxidative stress and antiproliferative activity. Moreover, PCR-based gene detection revealed the presence of marker genes of both PKS and NRPS clusters, the common secondary metabolite synthesis mechanism in microbes. The results showed that the crude pigment extract and the active
Keyword: Antibacterial, Anticancer, Antioxidant, Biopigment, NRPS/PKS

Judul: Antimicrobial, Antioxidant, and Toxicity Activity of Marine Actinomycetes Biopigment Extract
Abstrak: Aktinomiset merupakan bakteri Gram-positif yang mempunyai potensi sebagai sumber metabolit sekunder baru. Salah satu metabolit sekunder tersebut adalah biopigmen. Biopigmen yang dihasilkan oleh aktinomiset mempunyai berbagai aktivitas biologis. Penelitian ini bertujuan menguji kemampuan antimikrob, antioksidan, dan toksisitas ekstrak biopigmen aktinomiset laut kode HV11.P3 dan SCA54.P2. Aktivitas antimikrob diuji terhadap beberapa mikrob patogen dan menunjukkan hasil terbaik dalam menghambat pertumbuhan Bacillus subtilis ATCC 19659 untuk ekstrak HV11.P3 kemudian Escherichia coli ATCC 8739 untuk SCA54.P2.Aktivitas antioksidan terhadap radikal DPPH menunjukkan nilai IC50 231,084 μg/ml untuk HV11.P3 dan 369,296 μg/ml untuk SCA54.P2. Hasil uji toksisitas berupa nilai LC50 yaitu 94,603 μg/ml untuk HV11.P3 dan 131,220 μg/ml untuk SCA54.P2 menggunakan metode Brine Shrimp Lethality Test (BSLT). Senyawa kimia penyusun ekstrak diidentifikasi menggunakan GC-MS. Hasilnya senyawa 1H-Purine-2,6-dione, 3,7-dihydro-1,3,7-trimethyl- (CAS) menjadi penyusun dominan ekstrak HV11.P3 dengan peak area 44,65% dan 5-Methoxypyrrolidin-2-one dengan luas peak area 30,23% untuk ekstrak biopigmen SCA54.P2. Analisis gen 16S rRNA menunjukkan bahwa HV11.P3 memiliki kesamaan terdekat dengan Micromonospora chalcea strain 1464-217L dan SCA54.P2 dengan Micromonospora tulbaghiae strain TVU1., Actinomycetes are Gram-positive bacteria that have potency as a source of new secondary metabolites. One of those secondary metabolites is biopigments. Biopigments produced by actinomycetes have various biological activities. This study aimed to determine antimicrobial, antioxidant, and toxicity activity from marine actinomycetes biopigment extract coded as HV11.P3 and SCA54.P2. Antimicrobial activities were tested against several pathogenic bacteria and showed the best result for inhibiting Bacillus subtilis ATCC 19659 for HV11.P3 and Escherichia coliATCC 8739 for SCA54.P2. The antioxidant activity against DPPH radical showed IC50 value 231,084 μg/ ml for HV11.P3 and 369,296 μg/ ml for SCA54.P2. The toxicity test results (LC50) based on Brine Shrimp Lethality Test (BSLT) were 94,603 μg/ ml and 131,220 μg/ ml for HV11.P3 and SCA54.P2, respectively. The major chemical compounds of HV11.P3 extract were identified as 1H-Purine-2,6-dione, 3,7-dihydro-1,3,7-trimethyl- (CAS) (peak area 44,65%) and 5-Methoxypyrrolidin-2-one for SCA54.P2 (peak area 30,23%). The 16S rRNA gene analysis showed that HV11.P3 had the closest similarity with Micromonospora chalcea strain 1464-217L and SCA54.P2 with Micromonospora tulbaghiae strain TVU1.
Keyword: BSLT, DPPH, Extract, GC-MS, 16S rRNA gene

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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