Judul: Identification of Compounds in Purslane Stem (Portulaca oleracea L.) and Its Potential as Superoxide Dismutase Activator using In Silico Method
Abstrak: Superoksida dismutase (SOD) merupakan enzim yang berfungsi sebagai antioksidan dalam tubuh. Antioksidan dapat menangkal radikal bebas yang ada dalam tubuh. Krokot merupakan bahan alternatif yang telah terbukti memiliki sifat antioksidan, namun belum diketahui apakah batang krokot dapat meningkatkan aktivitas SOD dan jenis senyawa yang berperan dalam meningkatkan aktivitas tersebut. Penelitian ini bertujuan mengetahui potensi batang krokot terhadap aktivitas SOD dan jenis senyawa pada batang krokot yang berperan dalam meningkatkan aktivitas tersebut melalui penambatan molekuler terhadap reseptor SOD PDB ID 1CB4. Penelitian ini dilakukan dengan mengidentifikasi senyawa pada batang krokot menggunakan LC-MS/MS QTOF, kemudian memprediksi bioavailabilitas dan toksisitasnya, dan dilanjutkan dengan penambatan molekuler. Hasil penambatan molekuler diidentifikasi melalui parameter energi bebas Gibbs (∆G), konstanta disosiasi (Kd), dan residu yang berikatan antara reseptor dengan ligan. Xanthosine memiliki potensi terbaik dalam meningkatkan aktivitas SOD dengan nilai (∆G) sebesar -7.00 kkal/mol dan Kd sebesar 7.37 µM. Selain itu, hasil identifikasi residu yang berikatan antara reseptor dengan ligan menunjukkan bahwa xanthosine terikat pada situs aktivator alosterik enzim. Simpulan penelitian ini adalah batang krokot dapat menjadi aktivator superoksida dismutase secara in silico., Superoxide dismutase (SOD) is an enzyme that functions as an antioxidant in the body. Antioxidants can counteract free radicals in the body. Purslane is an alternative material that has been proven to have antioxidant properties, but it is not yet known whether purslane stems can increase SOD activity and the types of compounds that play a role in increasing this activity. This study aims to determine the potential of purslane stems on SOD activity and the types of compounds in purslane stems that play a role in increasing this activity through molecular binding to the SOD PDB ID 1CB4 receptor. This research was conducted by analyzing the compounds in purslane stems using LC-MS/MS QTOF, then predicting their bioavailability and toxicity, and followed by molecular docking. Molecular docking results were analyzed using Gibbs free energy (∆G), dissociation constant (Kd), and binding residue between the receptor and the ligand. Xanthosine has the best potential to increase SOD activity with a value (∆G) of -7.00 kcal/mol and a Kd of 7.37 µM. In addition, analysis of the residue binding between the receptor and the ligand shows that xanthosine binds to allosteric sites of the enzyme activator. The conclusion of this study is that purslane stems can be an activator of superoxide dismutase in silico.
Keyword: antioxidant, molecular docking, purslane stems, superoxide dismutase

Judul: Total Phenolic, Flavonoid, and Antioxidant Activity Content of Purslane (Portulaca oleracea L.) Resulting from Streptomycin Mutation
Abstrak: Krokot (Portulaca oleracea L.) merupakan tanaman yang mengandung polifenol, seperti asam fenolik dan flavonoid yang berperan sebagai sumber antioksidan dalam alternatif pengobatan penyakit degeneratif. Penelitian ini bertujuan menentukan konsentrasi dan durasi perendaman streptomycin yang optimum untuk menghasilkan mutan putatif dengan kandungan fitokimia serta aktivitas antioksidan terbaik. Krokot diekstraksi secara basah menggunakan metode MAE dengan pelarut etanol 96%. Uji kadar total fenolik dan flavonoid ditentukan menggunakan metode Folin-Ciocalteu dan AlCl3 serta aktivitas antioksidan menggunakan metode DPPH juga FRAP. Kadar total fenolik dan aktivitas antioksidan DPPH tertinggi terdapat pada sampel A1B1 dan A2B2 (0,4507 ± 0,0115 mg GAE g¯? bb dan 0,0062 ± 0,0002 µmol TE g¯? bb) dengan peningkatan sebesar 3,59 kali dan 1,41 kali dibandingkan kontrol. Kadar total flavonoid dan aktivitas antioksidan FRAP tertinggi terdapat pada sampel A1B4 (2,3383 ± 0,0493 mg QE g¯? bb dan 5,5622 ± 0,0909 µmol TE g¯? bb) dengan peningkatan 4,4 kali dan 5,42 kali dibandingkan kontrol. Hasil karakteristik stomata dengan analisis dendogram menunjukkan bahwa A1B4 terbukti mengalami mutasi ditandai fenomena kimera., Purslane (Portulaca oleracea L.) contains polyphenols like phenolic acids and flavonoids, serving as antioxidants for treating degenerative diseases. This study aimed to determine the optimal concentration and duration of streptomycin soaking to produce mutants with the best phytochemical content and antioxidant activity. Wet extraction was performed using the MAE method with 96% ethanol. Total phenolic and flavonoid contents were measured using the Folin-Ciocalteu and AlCl3 methods, and antioxidant activity using DPPH and FRAP methods. The highest phenolic content and DPPH activity were in samples A1B1 and A2B2 (0,4507 ± 0,0115 mg GAE g¯? bb and 0,0062 ± 0,0002 µmol TE g¯? bb), showing increases of 3,59 and 1,41 times compared to the control. The highest flavonoid content and FRAP activity were in sample A1B4 (2,3383 ± 0,0493 mg QE g¯? bb and 5,5622 ± 0,0909 µmol TE g¯? bb), with increases of 4,4 and 5,42 times compared to the control. The dendrogram analysis of stomatal characteristics indicates that A1B4 has undergone mutation, as evidenced by the presence of chimera phenomena.
Keyword: antioxidant, flavonoid, phenolic, chimera, mutation, streptomycin

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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