Judul: Molecular Docking of Turmeric (Curcuma longa L) and Black Tea (Camellia sinensis) Active Compound Against Asparagine Endopeptidase Enzyme
Abstrak: Asparagin Endopeptidase (AEP) memiliki peran dalam penyakit Alzheimer (PA) untuk membelah protein prekursor amiloid dan protein tau sehingga menyebabkan plak Aβ dan Tangels, keduanya merupakan penyebab utama PA. Penelitian ini bertujuan untuk menguji aktivitas senyawa aktif dari kunyit dan teh hitam pada AEP melalui penambatan molekuler. Bioavalibilitas ligan diprediksi berdasarkan karakteristik molekuler pada aturan Lipinski. Prediksi toksisitas ligan dilakukan pada laman ADMET properties. Reseptor diperoleh dari database PDB:5LUB. Ligan uji berasal dari senyawa aktif teh hitam dan kunyit. Hasil penambatan dengan binding energy tertinggi yang berasal dari teh hitam adalah asam galat (3,1330 kkal/mol), kaempferol (3,1800 kkal/mol) dan katekin (2,4170 kkal/mol), sementara itu ligan uji kunyit diantaranya, prokurkumadiol (4,0060 kkal/mol), epiprokurkumenol (2,3430 kkal/mol) dan dehidrokurdion (4,4560 kkal/mol). Kebanyakan ligan memiliki interaksi dengan residu sisi aktif, oleh karena itu, beberapa senyawa aktif tersebut diprediksi berpotensi besar menghambat AEP., Asparagine Endopeptidase (AEP) have a role in Alzheimer's disease (AD) which cleaves amyloid precursor protein (APP) and tau causing production of Aβ plaque and Tangels, which are main cause of AD. This study aims to examine the inhibition activity of the active compounds of turmeric and black in AEP through molecular docking. The bioavalibility of ligands is predicted based on the molecular characteristics of the Lipinski rule. The prediction of ligand toxicity was carried out on the ADMET properties. The receptors are obtained from the PDB:5LUB. The test ligands are derived from the active compounds of black tea and turmeric. The highest binding energy from black tea are (3,133gallic acid kcal/mol), kaempferol (3,1800 kcal/mol) and catechin (2,4170 kcal/mol), also ligans from turmeric are procurcumadiol (4,0060 kkal/mol), epiprocurcumenol (2,3430 kkal/mol) and dehydrocurcudione (4,4560 kkal/mol). Mostly ligands have interactions with active site residues, therefore, some of these active compounds are predicted to have great potential to inhibit AEP.
Keyword: Alzheimer, Asparagin Endopeptidase (AEP), kunyit, teh hitam, Alzheimer, Asparagine endopeptidase (AEP), black tea, turmeric

Judul: Bioactive Compounds Screening of Cinnamon (Cinnamomum burmannii) as Inhibitor of Acetylcholinesterase Enzyme In Silico
Abstrak: Alzheimer merupakan penyakit progresif dan neurodegeneratif yang banyak menyerang populasi lansia di atas 65 tahun. Patofisiologi Alzheimer dapat terkait dengan penipisan neurotransmitter asetilkolin (ACh) yang disebabkan karena adanya plak beta amiloid dan neurofibrillary tangles. Metabolit sekunder yang terdapat pada kulit kayu manis (Cinnamomum burmannii) berpotensi sebagai antikolinesterase untuk menangani gejala Alzheimer. Penelitian ini bertujuan menapis senyawa bioaktif yang berasal dari kulit kayu manis (Cinnamomum burmannii) secara in silico dengan metode virtual screening dan molecular docking melalui analisis energi ikatan, konstanta inhibisi, dan jenis interaksi. Penelitian menunjukkan bahwa senyawa aktif epicatechin dan medioresinol memiliki potensi terbaik dalam inhibisi AChE dengan afinitas mendekati dengan ligan alami atau pembanding. Epicatechin memiliki energi bebas ikatan sebesar -10,0 kkal/mol dan konstanta inhibisi sebesar 0,0459 μM dengan empat ikatan hidrogen dan tujuh ikatan hidrofobik. Sementara medioresinol memiliki energi bebas ikatan sebesar -9,9 kkal/mol dan nilai Ki sebesar 0,0543 μM dengan satu ikatan hidrogen dan tiga belas ikatan hidrofobik., Alzheimer is a progressive and neurodegenerative disease that mainly affects the elderly population over 65 years. The pathophysiology of Alzheimer's may be related to the depletion of the neurotransmitter acetylcholine (ACh) caused by the presence of beta amyloid plaques and neurofibrillary tangles. Secondary metabolites found in cinnamon (Cinnamomum burmannii) have potential as anticholinesterases to treat Alzheimer's symptoms. This study aims to screen bioactive compounds derived from cinnamon (Cinnamomum burmannii) in silico with virtual screening and molecular docking methods through analysis of bond energies, inhibition constants, and types of interactions. Research shows that the active compounds epicatechin and medioresinol have the best potential for AChE inhibition with affinity close to that of natural or comparison ligands. Epicatechin has an affinity energy of -10,0 kcal/mol and an inhibition constant of 0,0459 M with four hidrogen bonds and seven hydrophobic bonds. Meanwhile, medioresinol has an affinity energy of -9,9 kcal/mol and a Ki value of 0,0543 M with one hidrogen bond and thirteen hydrophobic bonds.
Keyword: Alzheimer, acetylcholinesterase, cinnamon, molecular docking

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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