Judul: Purification of Gendarusa Antioxidant  Compound (Justicia gendarussa Burm. f.) by Column Chromatography Method
Abstrak: Gandarusa (Justicia gendarussa Burm. f.) merupakan salah satu tanaman yang berpotensi sebagai sumber antioksidan karena kandungan metabolit sekundernya. Gandarusa termasuk ke dalam tanaman liar dan sudah lama dimanfaatkan sebagai tanaman obat. Penelitian ini bertujuan menentukan aktivitas antioksidan dengan metode DPPH hasil purifikasi ekstrak gandarusa menggunakan kromatografi kolom. Metode penelitian ini terdiri atas ekstraksi dengan maserasi bertingkat, optimasi pelarut dengan Kromatografi Lapis Tipis (KLT), purifikasi dengan kromatografi kolom, dan analisis antioksidan kualitatif dengan metode KLT bioautografi dan kuantitatif dengan metode DPPH. Pelarut n-heksana:etil asetat (6:4) dapat memisahkan ekstrak gandarusa dengan baik. Hasil purifikasi dengan kromatografi kolom menghasilkan 8 fraksi. Fraksi 3.2 memiliki aktivitas antioksidan tertinggi dengan nilai IC50 sebesar 617,34 µg/mL, sedangkan ekstrak kasarnya sebesar 2551,30 µg/mL. Purifikasi gandarusa dengan kromatografi kolom menghasilkan fraksi dengan aktivitas antioksidan lebih kuat dibandingkan dengan kondisi campurannya (ekstrak kasar)., Gandarusa (Justicia gendarussa Burm. f.) is a plant with potential as an antioxidant source due to its secondary metabolite content. Gandarusa is considered a wild plant and has long been used as a medicinal plant. This research aimed to determine the antioxidant activity using the DPPH method of purified gandarusa extract obtained through column chromatography. The research methods include extraction through stepwise maceration, solvent optimization using Thin Layer Chromatography (TLC), purification with column chromatography, and qualitative antioxidant analysis using TLC bioautography and quantitative analysis using the DPPH method. The n-hexane:acetate (6:4) solvent can effectively separate gandarusa extract. The purification results from column chromatography produced 8 fractions. Fraction 3.2 exhibited the highest antioxidant activity with an IC50 value of 617.34 µg/mL, while the crude extract had an IC50 value of 2551.30 µg/mL. Purification of gandarusa using column chromatography yielded fractions with stronger antioxidant activity compared to the mixed state (crude extract).
Keyword: antioxidant, column chromatography, gendarussa, purification, TLC

Judul: a-Glucosidase Inhibitory Activity of Purified Gandarusa by Column Chromatography
Abstrak: Gandarusa (Justicia gendarussa Burm. f.) merupakan herbal sumber daya lokal Indonesia yang berpotensi sebagai obat herbal antidiabetes. Penelitian ini bertujuan menentukan aktivitas inhibisi a-glukosidase dari senyawa yang terkandung pada fraksi hasil purifikasi ekstrak metanol gandarusa menggunakan kromatografi kolom. Simplisia gandarusa dimaserasi bertingkat dengan n-heksana, etil asetat, dan metanol. Ekstrak gandarusa difraksinasi dengan kromatografi kolom menggunakan pelarut optimal (etil asetat:n-heksana 4:6 v/v). Ekstrak kasar dan 8 fraksi hasil purifikasi dipekatkan kemudian ditentukan aktivitas antioksidannya dengan menggunakan KLT bioautografi dan aktivitas inhibisi a-glukosidasenya secara in vitro. Hasil penelitian menunjukkan bahwa purifikasi gandarusa menghasilkan fraksi kolom yang memiliki aktivitas antioksidan dan dapat menghambat a-glukosidase lebih baik dibandingkan ekstrak kasar tanamannya. Aktivitas inhibisi a-glukosidase tertinggi dimiliki oleh F2 (IC50 99,34 ppm), lebih tinggi dibandingkan dengan obat komersial akarbosa. Secara keseluruhan, fraksi gandarusa berpotensi untuk dikembangkan lebih lanjut sebagai obat herbal antidiabetes., Gandarusa (Justicia gendarussa Burm. f.) is a local Indonesian herbal resource with potential as an herbal antidiabetic remedy. This study aimed to determine the inhibitory activity of a-glucosidase from compounds present in the purified fractions of methanolic extract of gandarusa using column chromatography. Simplified gandarusa was extracted in stages with n-hexane, ethyl acetate, and methanol. The gandarusa extract was fractionated using column chromatography with an optimal solvent (ethyl acetate:n-hexane 4:6 v/v). The crude extract and eight purified fractions were then concentrated and evaluated for antioxidant activity using bioautographic thin-layer chromatography and in vitro a-glucosidase inhibitory activity. The results showed that the purification of gandarusa yielded a column fraction with antioxidant activity and better a-glucosidase inhibition compared to the crude extract of the plant. The highest inhibitory activity of a-glucosidase was found in F2 (IC50 99,34 ppm), which was higher than that of the commercial drug acarbose. Overall, the gandarusa fraction has potential for further development as an herbal antidiabetic remedy.
Keyword: a-glucosidase, antidiabetic, column chromatography, Justicia gendarussa

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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