Judul: Optimization of Extraction of Antimicrobial Peptide from Gandarusa Leaves Using the Box-Behnken Design
Abstrak: Antimicrobial Peptide (AMP) memiliki aktivitas spektrum luas dan dapat membunuh bakteri yang resistan terhadap berbagai obat. Daun gandarusa (Justicia gendarussa Burm. F.) memiliki aktivitas antibakteri namun kajian terkait antimicrobial peptide pada tanaman tersebut belum dilakukan. Penelitian ini bertujuan menentukan kondisi optimum ekstraksi serta mengidentifikasi AMP daun gandarusa yang berpotensi memiliki aktivitas antibakteri. Rancangan optimasi ekstraksi dibuat menggunakan Box-Behnken Design. Kadar total protein diukur dengan metode Bradford, identifikasi AMP dilakukan dengan metode SDS-PAGE, dan pengujian aktivitas antibakteri dilakukan dengan metode difusi sumuran. Hasil penelitian menunjukkan kondisi optimum ekstraksi diperoleh dari kombinasi konsentrasi pelarut 14,997%, waktu ekstraksi 2,998 jam, dan rasio antara sampel dengan pelarut yaitu 1:3. Identifikasi dengan SDS-PAGE menunjukkan AMP terduga dari daun gandarusa memiliki berat molekul sebesar 11 kDa, pengujian aktivitas antibakteri ekstrak kasar terhadap Escherichia coli dan Staphylococcus aureus tidak menunjukkan adanya daya hambat., Antimicrobial Peptide (AMP) has broad-spectrum activity and can kill multidrug-resistant bacteria. Gandarusa leaves (Justicia gendarussa Burm. F.) have antibacterial activity, but studies regarding antimicrobial peptides in this plant have not been carried out. This study aimed to determine the optimum conditions of extraction and identify AMPs of gandarusa leaves that have potential antibacterial activity. Extraction optimization design was made using Box-Behnken Design. Total protein levels were measured by the Bradford method, AMP identification was carried out by the SDS-PAGE method, and antibacterial activity testing was carried out by the well diffusion method. The results showed that the optimum extraction conditions were obtained from a combination of 14,997% solvent concentration, 2,998 hours extraction time, and the ratio between sample and solvent of 1:3. Identification with SDS-PAGE showed that AMP from gandarusa leaves has a molecular weight of 11 kDa, testing the antibacterial activity of crude extracts against Escherichia coli and Staphylococcus aureus showed no inhibition.
Keyword: antimicrobial peptide, Box-Behnken design, Gandarusa leaves, optimization

Judul: Fractionation of Antimicrobial Peptide Candidates from Gandarusa  (Justicia gendarussa) Leaves
Abstrak: Peptida antimikroba adalah senyawa yang ditemukan pada organisme hidup dan berfungsi sebagai komponen penting dalam sistem pertahanan tubuh. Keunggulan peptida antimikroba adalah memiliki sprektum luas membunuh bakteri patogen dan bakteri yang resistan. Daun gandarusa (Justicia gendarussa Burm. F.) memiliki aktivitas antibakteri namun kajian terkait peptida antimikroba pada tanaman tersebut masih terbatas. Penelitian ini bertujuan untuk memfraksinasi peptida antimikroba dari daun gandarusa serta menguji aktivitas antimikrobanya. Ekstraksi peptida daun gandarusa menggunakan pelarut asam asetat 10% dan waktu ekstraksi 2 jam. Kadar total protein diukur dengan metode Bradford, identifikasi kandidat peptida antimikroba dilakukan dengan metode SDS-PAGE, dan pengujian aktivitas antibakteri dilakukan dengan metode difusi sumuran. Hasil penelitian menunjukkan sampel optimum ekstraksi terhadap bobot molekul dan kadar protein daun gandarusa adalah sampel 100 mesh dengan sonikasi. Identifikasidengan SDS-PAGE menunjukkan peptida antimikroba dari daun gandarusa memiliki berat molekul berkisar 10-12 kDa. Uji aktivitas antibakteri Fraksi peptida daun gandarusa terhadap Escherichia coli dan Propionibacterium acnes tidak menunjukkan adanya daya hambat., Antimicrobial peptides are compounds found in living organisms that function as crucial components of the body's defense system. The advantage of antimicrobial peptides lies in their broad spectrum of activity, capable of killing pathogenic bacteria and antibiotic-resistant bacteria. Justicia gendarussa Burm. F. leaves are known to have antibacterial activity; however, research on antimicrobial peptides from this plant is still limited. This study aims to isolate and fractionate antimicrobial peptides from Justicia gendarussa leaves and evaluate their antimicrobial activity. The extraction of peptides from Justicia gendarussa leaves was performed using 10% acetic acid solvent with an extraction time of 2 hours. The total protein content was measured using the Bradford method, antimicrobial peptide candidates were identified using SDS-PAGE, and antibacterial activity was tested using the well diffusion method. The results showed that the optimal sample for extraction, in terms of molecular weight and protein content, was 100 mesh with sonication. Identification with SDS-PAGE indicated that the antimicrobial peptides from Justicia gendarussa leaves have a molecular weight ranging from 10-12 kDa. However, the antibacterial activity test of the peptites fraction of Justicia gendarussa leaves against Escherichia coli and Propionibacterium acnes did not show any inhibitory effect.
Keyword: antibakteri, Justicia gendarussa, peptida antimikroba, dialisis, SDS-PAGE

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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