Judul: In Silico and In Vitro Analysis of α-Glucosidase Inhibition by Ethanol Extract of Red Ginger (Zingiber officinale var.  Rubrum) from Sukabumi
Abstrak: Indonesia menempati peringkat kelima penderita diabetes melitus terbanyak di dunia sehingga perlu adanya pengobatan antidiabetes yang efektif salah satunya dengan mekanisme penghambatan enzim α-glukosidase. Obat antidiabetes sintetik dalam jangka waktu panjang dapat memberikan efek samping. Oleh karena itu, penggunaan obat herbal perlu dilakukan karena dinilai lebih aman. Jahe merah telah banyak dimanfaatkan dalam bidang medis dan diharapkan berpotensi menghambat aktivitas enzim α-glukosidase. Penelitian ini bertujuan mengukur aktivitas inhibisi enzim α-glukosidase oleh ekstrak etanol jahe merah asal Sukabumi dan menentukan ligan terbaik melalui studi in silico. Penelitian ini dilakukan dengan maserasi dalam etanol 70% dan dilakukan pembacaan absorbansi inhibisi enzim, sedangkan studi in silico dilakukan dengan molecular docking. Hasil penelitian menunjukkan nilai IC50 penghambatan enzim α-glukosidase sebesar 50.139,719 ± 0,481 μg/mL dan didapatkan dua ligan terbaik yaitu 6- shogaol dan 6-gingerol yang memiliki nilai ΔG dan Ki mendekati akarbosa (ligan pembanding terbaik), lolos uji toksisitas, serta berinteraksi dengan banyak situs pengikatan dan situs katalitik yang terletak di dalam poket situs aktif, Indonesia is in the fifth position with the most diabetes mellitus sufferers globally, so effective antidiabetic treatment is needed, such as the mechanism of inhibiting the α-glucosidase enzyme. Synthetic antidiabetic drugs, in the long term, can have side effects. Therefore, the use of herbal medicines is necessary because they are considered safer. Red ginger has been widely used in the medical field, and it has expected to have the potential to inhibit the activity of α-glucosidase. This study aimed to measure the inhibitory activity of α-glucosidase enzyme by the ethanol extract of red ginger from Sukabumi and determine the best ligand through in silico study. This research was carried out by maceration in 70% ethanol and reading the absorbance of enzyme inhibition, while in silico studies were carried out by molecular docking. The results showed that the IC50 value for inhibition of α-glucosidase enzyme was 50.139,719 ± 0.481 μg/mL. Two best ligands were obtained, namely 6-shogaol and 6-gingerol, which had ΔG and Ki values close to acarbose (the best comparison ligand), passed toxicity testing and interacted with many binding sites and catalytic sites that were located in active site pocket
Keyword: α-Glucosidase, Diabetes mellitus, Red Ginger

Judul: α-Glucosidase Inhibition Activity and DPPH Free Radical Scavenging from Stratified Aqueous Extract of Red Ginger (Zingiber officinale Roxb. var Rubrum)
Abstrak: Jahe merah (Zingiber officinale Roxb. var. Rubrum) mengandung senyawa fenolik yang berpotensi menurunkan kadar glukosa darah (antihiperglikemik) pada pasien diabetes melitus. Penelitian ini bertujuan menentukan aktivitas inhibisi α-glukosidase, aktivitas antioksidan dalam meredam radikal bebas DPPH, dan kadar total fenolik ekstrak air jahe merah bertingkat (ekstrak ke-1, ekstrak residu ke-1, dan ekstrak residu ke-2). Metode penelitian yaitu ekstraksi jahe merah secara infundasi serta analisis dengan teknik uji spektronanometer yang meliputi analisis antidiabetes melalui aktivitas inhibisi α-glukosidase, aktivitas antioksidan metode DPPH, dan kadar total fenolik metode Folin-Ciocalteu. Aktivitas inhibisi α-glukosidase dan kadar total fenolik memiliki perbedaan nilai yang signifikan (p<0.05) dengan nilai tertinggi 97.729% (ekstrak ke-1) dan 27.624 mg GAE/g ekstrak (ekstrak residu ke-2). Aktivitas antioksidan dalam meredam radikal bebas DPPH memiliki perbedaan nilai yang tidak signifikan dengan nilai tertinggi 4.682 mg AAE/g ekstrak (ekstrak residu ke-1). Hasil analisis menunjukkan nilai aktivitas inhibisi α-glukosidase dan kadar fenolik total berbeda signifikan (p<0,05) dengan nilai tertinggi 97.729% (ekstrak ke-1) dan 27.624 mg GAE/g ekstrak (ekstrak residu ke-2). Hasil aktivitas antioksidan memiliki nilai yang tidak berbeda nyata (p>0,05) dengan nilai tertinggi 4.682 mg AAE/g ekstrak (ekstrak residu ke-1)., Red ginger (Zingiber officinale Roxb. var. Rubrum) contains phenolic compounds that have potential to reduce blood glucose levels (antihyperglycemic) in patients with diabetes mellitus. This study aimed to determine the inhibitory activity toward α-glucosidase, antioxidant activity in reducing DPPH free radicals, and total phenolic content from stratified aqueous extract of red ginger (1st extract, 1st residue extract, and 2nd residue extract). The red ginger was extracted by infundation and analyzed by spectronanometer test techniques which included analysis of antidiabetic through inhibitory activity of α-glucosidase, antioxidant activity using the DPPH method, and total phenolic content using the Folin-Ciocalteu method. The results of the analysis showed that the inhibitory activity of α-glucosidase and total phenolic content were significantly different (p<0.05) with the highest values 97.729% (1st extract) and 27.624 mg GAE/g extract (2nd residue extract). The result of antioxidant activity was not significantly different (p>0.05) with the highest value 4.682 mg AAE/g extract (1st residue extract).
Keyword: α-Glucosidase, Antioxidant, Diabetes Mellitus, Red Ginger

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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