Judul: In Silico Study of Chemical  Constituent in Lemongrass (Cymbopogon citratus) Against Monoamine Oxidase A
Abstrak: Inhibitor dari salah satu isoform enzim monoamin oksidase, yakni monoamin oksidase A (MAO-A), memiliki pengaruh terhadap beberapa kondisi psikiatris seperti kecemasan, sehingga inhibitor MAOA dijadikan sebagai salah satu jenis obat antidepresan. Beberapa penelitian pada tanaman serai menunjukkan adanya efek antidepresan. Penelitian ini bertujuan mendeteksi adanya potensi senyawa senyawa aktif tanaman serai (Cymbopogon citratus) dalam menghambat aktivitas enzim MAO-A yang merupakan salah satu pengobatan yang bersifat antidepresan dengan metode docking atau penambatan molekuler. Penelitian ini menggunakan metode penambatan molekuler dengan perangkat lunak YASARA Structure, preparasi protein dan visualisasi tiga dimensi menggunakan Discovery Studio, dan visualisasi dua dimensi menggunakan LigPlus. Dari 56 senyawa yang ditemukan, sebanyak 5 senyawa bioaktif pada tanaman serai berpotensi sebagai inhibitor monoamin oksidase A, yakni limonene, linalool, neral, beta-myrcene, dan trans citral setelah melalui tahap penapisan virtual, analisis farmakokinetik dan prediksi toksisitas. Berdasarkan analisis penambatan molekuler, limonene dengan energi bebas ikatan sebesar -4.921 kkal/mol dan konstanta inhibisi sebesar 244.83 µM memiliki potensi terbaik untuk menginhibisi aktivitas monoamin oksidase A., Monoamine oxidase A (MAOA) inhibitors have an effect to several psychiatric condition such as anxiety, so that MAOA inhibitor could be used as antidepressant drug. This research aims to detect potential bioactive of lemongrass (Cymbopogon citratus) in order to inhibit MAOA enzyme activity that is served as one of antidepressant treatment. This research used YASARA Structure as molecular docking software, Discovery Studio as protein preparation and three dimensional visualization, and LigPlot as three-dimensional visualization. Based on 56 constituent found in lemongrass, 5 constituents had found to be potential on inhibiting MAOA, namely limonene, linalool, neral, beta-myrcene, and trans-citral after conduting virtual screening, pharmacokinetic and toxicity prediction. Based on molecular docking analysis, limonene is found to be the most potential ligand to inhibit MAOA activity with -4,921 kkal/mol binding free energy and 244.83 µM inhibition constant.
Keyword: antidepresan, limonene, MAOA, penambatan molekuler, tanaman serai

Judul: Analysis in silico of the interaction of the noni (Morinda citrifolia) bioactive compounds as an antistress candidates inhibit the Monoamine Oxidase A (MAO-A) receptors
Abstrak: Monoamin oksidase (MAO) merupakan famili enzim yang menggunakan oksigen untuk memotong gugus amina neurotransmitter monoamine. Enzim MAO berfungsi untuk menonaktifkan neurotransmitter monoamine, terkhusus MAO-A yang memecah serotonin, epinefrin dan norepinefrin sebagai biomarker stres. Pencegahan stres dapat menggunakan senyawa aktif flavonoid, lignan dan kumarin yang memiliki potensi sebagai antistres/antidepresi. Mengkudu (Morinda citrifolia) merupakan salah satu tanaman yang memiliki kandungan senyawa aktif flavonoid dan lignan. Senyawa turunan yang terdapat pada mengkudu diantaranya adalah quercetin, 3,3'-bisdemethyltanegool, pinoresinol, (-)-3,3'-bisdemethylpinoresinol, kaempferol, scopoletin, isoscopoletin, dan vanillin. Penelitian ini bertujuan untuk mengidentifikasi senyawa bioaktif mengkudu (Morinda citrifolia) yang memiliki potensi paling efektif terhadap MAO-A sebagai kandidat antistres secara In silico. Jenis penelitian yang digunakan adalah deskriptif eksploratif yang dilakukan melalui beberapa tahap meliputi: preparasi ligan, preparasi protein reseptor, penambatan molekuler (Molecular docking) dan visualisasi hasil docking. Data hasil docking dianalisis dengan cara mengelompokkan model ligan yang memiliki energi ikatan paling rendah dan jenis ikatan yang terbentuk. Hasil penelitian menunjukkan senyawa yang terdapat pada buah mengkudu terbukti memiliki potensi menghambat aktivitas enzim MAO-A. Kata kunci: antistres, MAO-A, mengkudu, penambatan molekuler, Monoamine oxidase (MAO) is a family of enzymes that use oxygen to cleave the amine group of the monoamine neurotransmitter. MAO functions to deactivate monoamine neurotransmitters, especially MAO-A which breaks down serotonin, epinephrine and norepinephrine as stress biomarkers. Depression or stress can be prevented using the active compounds of flavonoids, lignans and coumarins which have potential as antistress/antidepressants. Noni (Morinda citrifolia) is a plant that contains active compounds of flavonoids and lignans. Derivative compounds found in noni include quercetin, 3,3'-bisdemethyltanegool, pinoresinol, (-)-3,3'- bisdemethylpinoresinol, kaempferol, scopoletin, isoscopoletin, and vanillin. This study aims to determine the bioactive compound of noni which has the most effective potential inhibit MAO-A as an In silico antistress candidate. The type of research used is descriptive exploratory which is carried out through several stages including: ligand preparation, receptor protein preparation, molecular docking and visualization of docking results. The docking data were analyzed by grouping the ligand model with the lowest bond energy and the type of bond formed. The results showed that the compounds contained in the noni fruit (Morinda citifolia) proved to have the potential to inhibit the activity of the MAO-A enzyme.
Keyword: antistress, MAO-A, moleculer docking, noni

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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