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: Antidiabetic Activity In Vitro and Organoleptic Test from Combination Black Tea, Turmeric, and Ginger Extract
Abstrak: Teh hitam (Camellia sinensis L), kunyit (Curcuma longa L.), dan jahe (Zingiber officinale) merupakan tanaman yang berpotensi menjaga kadar gula darah pada penderita diabetes melitus. Namun, dasar ilmiah mengenai kombinasi teh hitam, kunyit, dan jahe dalam inhibisi enzim α-glukosidase masih terbatas. Oleh karena itu, penelitian ini bertujuan menentukan kombinasi ekstrak teh hitam, kunyit, dan jahe yang paling optimum terhadap inhibisi α-glukosidase serta uji organoleptik pada kombinasi aktivitas inhibisi α-glukosidase paling optimum. Metode penelitian meliputi analisis fitokimia, aktivitas inhibisi α-glukosidase, dan uji organoleptik. Ekstrak etanol kunyit sebagai ekstrak terbaik dengan nilai IC50 sebesar 9,48±0,05 μg/mL. Aktivitas inhibisi α-glukosidase tertinggi pada kombinasi F7 yang terdiri dari ekstrak teh hitam, kunyit, dan jahe sebesar 67,86±0,93 %. Uji organoleptik kombinasi F7 menunjukkan tingkat kesukaan tertinggi oleh P3 dan P2 pada warna, aroma, konsistensi, dan aftertaste, sedangkan rasa pada P3. Simpulan penelitian ini adanya kemampuan kombinasi ekstrak teh hitam, kunyit, dan jahe dalam inhibisi enzim α-glukosidase yang menunjukkan interkasi sinergis., Black tea (Camellia sinensis L), turmeric (Curcuma longa L.), and ginger (Zingiber officinale) are plants that have the potential to maintain blood sugar levels in diabetes mellitus sufferers. However, the scientific basis regarding the combination of black tea, turmeric, and ginger in α-glucosidase inhibition is still limited. Therefore, this study aims to determine the optimum combination of black tea extract, turmeric, and ginger for inhibition of the α-glucosidase and an organoleptic test on the optimum combination of α-glucosidase inhibition activity. The method of the research included phytochemical analysis, inhibitory activity of the α-glucosidase, and organoleptic tests. Turmeric ethanol extract was the best extract with an IC50 value of 9.48±0,05 μg/mL. The highest inhibitory activity of α-glucosidase in combination F7 consisting of black tea extract, turmeric, and ginger was 67.86±0.93 %. The organoleptic test of the combination F7 showed the highest level of preference by the P3 and P2 on the of color, aroma, consistency, and aftertaste, while the taste was in the P3. The conclusion of this study is the ability of the combination of black tea extract, turmeric, and ginger to inhibit the enzyme α-glucosidase which shows a synergistic interaction.
Keyword: black tea, ginger, α-glucosidase, organoleptic, turmeric

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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