Judul: Isolasi dan Karakterisasi Kandidat Peptida Antimikroba dari Daun Pegagan (Centella asiatica)
Abstrak: Peptida antimikroba (AMP) memiliki aktivitas spektrum luas dan dapat membunuh bakteri yang resistan terhadap antibiotik. AMP dapat diisolasi dari berbagai sumber salah satunya tumbuhan. Centella asiatica (pegagan) memiliki kandungan yang mampu menghambat bakteri, berpotensi digunakan dalam pengobatan pengganti antibiotik. Namun, belum diketahui adanya senyawa AMP pada pegagan sebagai antimikroba. Penelitian ini bertujuan mengisolasi dan mengkarakterisasi senyawa peptida antimikroba yang terdapat pada daun pegagan, yang berpotensi dalam pengobatan jerawat. Metode yang digunakan dalam penelitian ini meliputi isolasi sampel, presipitasi amonium sulfat dan dialisis, analisis bobot molekul dan kadar protein sampel, serta uji aktivitas antibakteri. Proses isolasi AMP daun pegagan menggunakan CH3COOH 10% memiliki kondisi optimal dengan ukuran 250 mesh dan tambahan sonikasi. Identifikasi peptida menggunakan metode SDS-PAGE menunjukkan bobot molekul peptida terduga sebesar 13 kDa. Presipitasi yang dilakukan meningkatkan kadar protein dua kali lipat sebesar 0,449 mg/ml dibandingkan ekstrak kasar. Pengujian aktivitas antibakteri hasil pemurnian sampel pegagan terhadap E. coli dan P. acnes tidak menunjukkan adanya daya hambat., Antimicrobial peptides (AMPs) had broad-spectrum activity and could kill antibiotic-resistant bacteria. AMPs could be isolated from various sources, one of which was plant. Centella asiatica (pegagan) contained compounds that could inhibit bacteria, potentially serving as a substitute for antibiotics. However, it was not yet known whether AMP compounds in pegagan acted as antimicrobials. This research aimed to isolate and characterize antimicrobial peptide compounds found in pegagan leaves for potential application in acne treatment. The methods employed included sample isolation, ammonium sulfate precipitation, dialysis, analysis of sample molecular weight and protein content, and antibacterial activity tests. The optimal conditions for AMP isolation from pegagan leaves involved using 10% CH3COOH, a 250 mesh size, and additional sonication. Peptide identification using SDS-PAGE indicated that the molecular weight of the predicted peptide was 13 kDa. The precipitation process doubled the protein content to 0.449 mg/mL compared to the crude extract. However, purified pegagan samples did not exhibit any inhibitory effect in tests against E. coli and P. acnes.
Keyword: peptida antimikroba, pegagan, antibiotik, bakteri

Judul: Isolasi dan Fraksinasi Peptida Antimikroba  Putatif dari Rimpang Temu Hitam (Curcuma aeruginosa)
Abstrak: Peptida antimikroba (AMP) merupakan salah satu alternatif yang dapat digunakan untuk mengatasi resistensi antibiotik. Optimasi ekstraksi AMP temu hitam sudah pernah dilakukan. Penelitian ini bertujuan mengidentifikasi serta menentukan aktivitas AMP putatif hasil isolasi dan fraksinasi dari rimpang temu hitam. Metode yang digunakan pada penelitian ini yaitu ekstraksi rimpang temu hitam dengan asam asetat 5%, pengendapan amonium sulfat 80%, dialisis, pengukuran kadar protein metode Bradford, identifikasi AMP putatif dengan SDS PAGE, dan uji aktivitas AMP putatif metode sumuran. Hasil dari identifikasi fraksi dialisis dan ekstrak kasar rimpang temu hitam didapatkan pita yang merupakan AMP terduga dengan bobot molekul 12,59 kDa. Kadar total protein menunjukkan hasil sebesar 0,0853 mg/mL untuk ekstrak kasar dan 0,819 mg/mL untuk fraksi dialisis. Namun tidak terdapat aktivitas antimikroba fraksi dialisis terhadap Escherichia coli, Staphylococcus aureus, Propionibacterium acne, dan Aspergillus niger., Antimicrobial peptides (AMP) are an alternative that can be used to overcome antibiotic resistance. Optimization of black ginger AMP extraction has been carried out. This research aimed to identify and determine the activity of putative AMPs resulting from isolation and fractionation of temu hitam rhizomes. The method used in this research are extraction of temu hitam with 5% acetic acid, precipitation 80% ammonium sulfate, dialysis, measurement of protein content using Bradford method, identification of putative AMPs with SDS-PAGE, and testing of putative AMP activity using well method. The results of identifying the dialysis fraction and crude extract of temu hitam rhizomes showed a band which was a suspected AMP with a molecular weight of 12.59 kDa. The total protein content showed results of 0.0853 mg/mL for the crude extract and 0.819 mg/mL for dialysis fraction. However, there was no antimicrobial activity of dialysis fraction against Escherichia coli, Staphylococcus aureus, Propionibacterium acne, and Aspergillus niger.
Keyword: ammonium sulfate fractionation, antimicrobial, antimicrobial peptide, Curcuma aeruginosa, dialysis

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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