Judul: Potensi Buah Makasar (Brucea javanica (L.) Merr) sebagai Inhibitor Enzim α-Glukosidase
Abstrak: Buah makasar merupakan salah satu tanaman obat Indonesia yang kaya akan manfaat. Secara empiris buah makasar dapat menurunkan kadar gula darah pada penderita diabetes melitus. Ekstrak buah makasar fraksi air dan heksana diteliti untuk mengetahui potensinya sebagai antidiabetes pada konsentrasi 1% dan dibandingkan dengan acarbose 1% sebagai kontrol positif. Uji antidiabetes dengan ekstrak buah makasar fraksi air ini dilakukan dengan metode inhibisi enzim á-glukosidase. Aktivitas antidiabetes diukur berdasarkan terbentuknya produk berupa p-nitrofenol dari reaksi enzim á-glukosidase dan substratnya pnitrofenil- á-D-glukopiranosida (p-NPG) yang diukur dengan spektrofotometer pada panjang gelombang 400 nm. Uji fitokimia menunjukkan bahwa fraksi air mengandung senyawa alkaloid dan flavonoid, sedangkan fraksi heksana mengandung senyawa alkaloid. Hasil penelitian menunjukkan bahwa fraksi air dan heksana ekstrak buah makasar pada konsentrasi 1% (b/v) dapat menghambat aktivitas enzim á-glukosidase sebesar 14.32% dan 12.76%, lebih rendah dari kontrol positif (Acarbose) dengan hambatan terhadap aktivitas enzim á- glukosidase sebesar 81.15%.
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Judul: Potensi Buah Makasar (Brucea javanica (L.) Merr) sebagai Inhibitor Enzim α-Glukosidae
Abstrak: Brucea fruit is one Indonesian medicine plants which rich in advantages. Empirically, brucea fruit can decrease blood glucose concentration for patient of diabetes mellitus. Water fraction of brucea fruit extract have been observed to determine its ability as antidiabetic would be compared with acarbose as positive control in same concentration (1%). Antidiabetic test in water and hexane fraction of brucea fruit extract use α-glucosidase inhibition method. Antidiabetic activity has been measured by formation of p-nitrophenol from enzymatic reaction of nitrophenil--D-glucopyranose (p-NPG) which is catalyze by α-glucosidase enzyme. The formation of p-nitrophenol was measured by spectrophotometer at λ=400 nm. Phytochemistry test showed that water fraction contains alkaloid and flavonoid, whereas hexane fraction only contain alkaloid. The result of this research is water fraction and hexane of brucea fruit (Brucea javanica (L.) Merr) at concentration 1% (b/v) can inhibit α-glucosidase enzyme activity 14.32% and 12.76%, whereas Acarbose as positive control can inhibit α-glucosidase enzyme activity 81.15%.
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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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