Judul: Korelasi kadar kurkuminoid dan aktivitas antioksidan ekstrak kunyit (Curcuma longa Linn) melalui modifikasi ekstraksi
Abstrak: Kunyit (Curcuma longa Linn) diketahui mempunyai aktivitas biologis sebagai antioksidan yang berasal dari kandungan kurkuminoidnya. Aktivitas antioksidan dan kadar kurkuminoid kunyit dipengaruhi oleh proses ekstraksi. Penelitian ini bertujuan membandingkan kadar kurkuminoid ekstrak kunyit segar dan ekstrak simplisia berdasarkan teknik ekstraksi maserasi konvensional dan modifikasi ekstraksi secara sonikasi dan gelombang mikro dengan menggunakan pelarut etanol 70%. Hasil penelitian menunjukkan bahwa rendemen ekstrak simplisia sebesar 18.77-30.39%, sedangkan rendemen ekstrak segar yaitu 26.17- 43.04%. Kedua jenis ekstrak memiliki rendemen tertinggi pada perlakuan maserasi. Kadar kurkuminoid ekstrak simplisia yang dihasilkan berkisar antara 7.17-17.91(%b/b), sedangkan ekstrak segarnya berkisar antara 1.89-2.45(%b/b). Adapun nilai IC50 ekstrak simplisia berkisar antara 35.44-61.53ppm, sedangkan ekstrak segarnya berkisar antara 69.24-215.32ppm. Kadar kurkuminoid dan aktivitas antioksidan tertinggi terdapat pada perlakuan ekstrak kunyit simplisia melalui sonikasi. Pola kromatografi lapis tipis ekstrak dengan eluen kloroform:diklorometan (32.5:67.5 v/v) menunjukkan bahwa ekstrak terpisah menjadi 4 senyawa, dengan 3 senyawa diidentifikasi sebagai kurkumin, demetoksikurkumin, dan bisdemetoksikurkumin. Kadar kurkuminoid ekstrak kunyit segar dan ekstrak simplisia melalui maserasi serta modifikasi ekstraksi berkorelasi positif terhadap aktivitas antioksidannya.
Keyword: Turmeric, Modification extraction, Curcuminoid, Antioxidant

Judul: Kandungan Kurkuminoid, Inhibisi a-Glukosidase dan Sitotoksisitas Ekstrak dari Beberapa Aksesi Kunyit (Curcuma domestica Val.)
Abstrak: Turmeric (Curcuma domestica Val.) is a medicinal plant family Zingiberaceae with curcuminoid content of the rhizome. This study aims to determine the content of curcuminoid, α-glucosidase inhibitory activity, and cytotoxicity test curcuminoids of turmeric extracts from several accessions. Curcuminoid content analysis was performed using HPLC. Inhibition of α- glucosidase performed in vitro with the substrate p-NPG. The cytotoxicity of curcuminoid extract of turmeric using BSLT method. The highest levels of curcuminoid owned by Ngawi, followed by Ciemas, Wonogiri, and Nagrak. Levels curcuminoids Ngawi of 24.50%. Turmeric extract the highest bioactivvity as α-glucosidase inhibitor activity is Nagrak accession with IC50 values of 207.093 μg/mL. Cytotoxycity test results showed that all samples have bioactivity and accession have the best LC50 value is Karanganyar at 19.090 μg/mL. Nagrak, Wonogiri, and Ngawi, has the potential to be developed into new varieties of turmeric with high bioactivity in inhibition α-glucosidase with IC50 moderate level.
Keyword: Bogor Agricultural University (IPB), turmeric, cytotoxicity, curcuminoids, α-glucosidase

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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