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: Aktivitas Antioksidan dan Sitotoksisitas Ekstrak Pigmen yang Berasal dari Bakteri yang Berasosisasi dengan Spons Laut
Abstrak: Poor lifestyle and environmental factors, including free radicals exposure, can cause degenerative diseases. Free radicals such as Reactive Oxygen Species (ROS) are naturally generated in the cells during metabolism. ROS is stabilized by indigenous antioxidants that are naturally present in the cells. Besides indigenous antioxidants, dietary antioxidant intake protects the body from free radicals that can trigger degenerative diseases. One of the antioxidant sources is bio-pigment, which can be produced by plants and microbes, including bacteria. The production of pigment from bacteria has advantages such as faster production and being environmentally friendly. The pigmented bacteria can live in various habitats, including in the oceans. Marine bacteria can form a symbiotic mutualism relationship with other organisms, such as sponges. Bacteria associated with sponges produce secondary metabolites similar to the hosts. The colored body of the sponge is thought to be caused by the presence of the associated pigmented bacteria. Several previous studies have reported various biological activities of pigments produced by bacteria associated with sponges, such as antimicrobial, anticancer, and antioxidant. In this study, isolate AGS112 and SAB E-64 produce yellow-red and bright yellow intracellular pigments, respectively, that might have antioxidant activity. Thus, this study aimed to determine the antioxidant and cytotoxicity activity of pigments derived from marine sponge-associated bacteria, followed by its function in the antioxidative genes expression regulation in the model organism Schizosaccharomyces pombe. This study was initiated by the rejuvenation of 2 bacterial isolates, AGS112 and SAB E-64. AGS112 was identified based on 16S rRNA. Meanwhile, SAB E64 had been identified in previous studies as Kocuria marina, which belongs to the actinobacteria group. Furthermore, the production and extraction of pigment produced by B. haikouensis AGS112 and K. marina SAB E-64 were carried out using chloroform and methanol, respectively. The crude pigment extracts were then analyzed using UV-Vis to determine the maximum wavelength absorption of each pigment, followed by the total phenolic and flavonoid measurements. In addition, the cytotoxicity activity test was carried out using the Brine Shrimp Lethality Test (BSLT) method. The two crude pigment extracts were then fractionated using the Thin Layer Chromatography (TLC) method, followed by bio-autography TLC analysis. The selected active fraction was isolated using the TLC-preparative method. Then, both crude pigment extracts and the active fraction extracts were tested for their antioxidant activity against DPPH radicals. The pigment extract with more potent antioxidant activity was then selected to be analyzed in vivo using model organism S. pombe through oxidative stress response assay (spot assay and TPC method), followed by relative gene expression analysis of sod1 and ctt1 genes using qRT-PCR. The metabolite profiling of the selected active fraction extract was analyzed using Liquid Chromatography Mass-Spectrophotometry (LC-MS). Based on the 16S rRNA gene, AGS112 has the closest similarity to Bacillus haikouensis C-89 (99%). The yields of crude pigment extracts of B. haikouensis AGS112 and K. marina SAB E-64 were 12.57% and 19.7% (w/v), respectively. The BSLT results showed that the LC50 values of each crude pigment extract were <1000 µg/mL that indicated the crude pigment extracts at certain concentrations is classified as cytotoxic compound and may have
Keyword: Antioxidant, DPPH, Pigment, Schizosaccharomyces pombe, Sponge-associated bacteria

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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