Judul: Total Fenolik, Flavonoid, dan Kapasitas Antioksidan Ekstrak Air Dari Tiga Aksesi Tanaman Gandarusa (Justicia gendarussa Burm.F).
Abstrak: Kadar fenolik dan flavonoid total serta kapasitas antioksidan pada tanaman obat seperti gandarusa (Justicia gendarussa Burm.F) dipengaruhi oleh banyak faktor, salah satunya perbedaan aksesi. Penelitian ini bertujuan menentukan nilai kadar fenolik dan flavonoid total serta kapasitas antioksidan dari tiga aksesi gandarusa yaitu aksesi Langkat, Malang dan Bekasi menggunakan air sebagai pelarut pengekstraksi. Penentuan kadar fenolik dilakukan dengan metode Follin- Ciocalteu, kadar flavonoid total ditentukan dengan metode AlCl3, dan kapasitas antioksidan dilakukan dengan metode FRAP (Ferric Reducing Antioxidant Power) dan DPPH (2,2’-difenil-1-pikrilhidrazil). Kadar fenolik total tertinggi sebesar 12,31 mg GAE g-1 bobot kering dan flavonoid total tertinggi sebesar 9,75 mg QE g-1 bobot kering serta kapasitas antioksidan (DPPH) tertinggi sebesar 8,04 μmol/g TEAC bobot kering ditemukan pada gandarusa aksesi Langkat. Sementara kapasitas antioksidan tertinggi dengan metode FRAP ditemukan pada gandarusa aksesi Bekasi sebesar 19,95 μmol TE g-1 bobot kering. Kadar fenolik dan flavonoid total memiliki korelasi signifikan dan sangat kuat terhadap kapasitas antioksidan secara statistika pada metode DPPH. Sementara kadar fenolik dan flavonoid total memiliki korelasi yang tidak signifikan terhadap kapasitas antioksidan pada metode FRAP. Simpulan hasil penelitian ini ditemukan bahwa aksesi gandarusa terbaik yaitu aksesi Langkat karena memiliki kadar nilai fenolik dan flavonoid total tertinggi serta nilai kapasitas antioksidan tertinggi menggunakan metode DPPH. Kata kunci: Aksesi, antioksidan, fenolik, flavonoid, gandarusa., Total phenolic and flavonoid levels as well as antioxidant capacity in medical plants such as gandarusa (Justicia gendarussa Burm. F) are influenced by many factors, one of which is accession differences. This study’s purpose is to determine the total phenolic and flavonoid levels and antioxidant capacity of three gandarusa accessions, namely the Langkat, Malang, and Bekasi using water as an extracting solvent. The phenolic content was determined by the Follin-Ciocalteu method, the total flavonoid content was determined by the AlCl3 method, and the antioxidant capacity was determined by the FRAP (Ferric Reducing Antioxidant Power) and DPPH (2,2’-diphenyl-1-pikrilhidrazyl) methods. Total phenolic content of 12.31 mg GAE g-1 dry weight and total flavonoids of 9.75 mg QE g-1 dry weight and the highest antioxidant capacity (DPPH) of 8.04 μmol TEAC g-1 dry weight were found in gandarusa accession Langkat. While the highest antioxidant capacity using the FRAP method was found in the gandarusa of the Bekasi highest antioxidant capacity using the FRAP method was found in the gandarusa of the Bekasi accession of 19.95 μmol TEAC g-1 dry weight. The levels of total phenolic and total flavonoids have a statistically significant and very strong correlation to antioxidant capacity in the DPPH method. Meanwhile, total phenolic and flavonoids level had no significant correlation to antioxidant capacity in the FRAP method. In conclusion, the result of this study found that the best gandarusa accession was the Langkat accession because it had the highest levels of total phenolic and flavonoid values and the highest antioxidant capacity values using the DPPH method. Keywords: Accession, antioxidant, flavonoid, gendarussa, phenolic.
Keyword: Accession, Antioxidant, Flavonoid, Gendarussa, Phenolic

Judul: Variasi Aksesi terhadap Total Fenolik, Flavonoid serta Aktivitas Antioksidan Daun Gandarusa Asal Indonesia
Abstrak: Gandarusa (Justicia gendarussa Burm. f.) merupakan tanaman obat yang memiliki kandungan metabolit sekunder sebagai antioksidan. Produksi metabolit sekunder tanaman dipengaruhi oleh banyak faktor salah satunya variasi aksesi. Penelitian ini bertujuan memperoleh aksesi terbaik gandarusa yang menghasilkan metabolit sekunder dan aktivitas antioksidan tertinggi. Ekstrak etil asetat daun gandarusa diukur kadar total fenoliknya dengan metode Folin-Ciocalteu, kadar total flavonoid dengan metode aluminium klorida, serta aktivitas antioksidan dengan metode FRAP (Ferric Reducing Antioxidant Power) dan DPPH (1,1-diphenyl-2-picrylhydrazyl). Aksesi Langkat menghasilkan kadar total fenolik tertinggi sedangkan aksesi Malang menghasilkan kadar total flavonoid tertinggi yang berturut-turut sebesar 12,048 mg GAE g-1 bobot kering dan 17,043 mg QE g-1 bobot kering. Aksesi Bekasi menghasilkan aktivitas antioksidan FRAP tertinggi sedangkan aksesi Langkat menghasilkan aktivitas antioksidan DPPH tertinggi dengan nilai berturut-turut 16,669 dan 0,257 μmol TE g-1 bobot kering. Adapun korelasi antar variabel tidak menunjukkan hasil yang signifikan., Gandarusa (Justicia gendarussa Burm. f.) is a medicinal plant that contains secondary metabolites as antioxidants. The production of secondary metabolites of plants is influenced by many factors, one of which is the variation in accession. This study aimed to obtain the best accession of gandarusa which produces secondary metabolites and the highest antioxidant activity. Ethyl acetate extract of gandarusa leaves measured its total phenolic levels by the Folin-Ciocalteu method, total flavonoid levels with the aluminum chloride method, as well as antioxidant activity with the FRAP and DPPH methods. The Langkat accession produced the highest total phenolic levels while the Malang accession produced the highest total flavonoid levels which were successively 12,048 mg GAE g-1 dry weight and 17,043 mg QE g-1 dry weight. The Bekasi accession produced the highest FRAP antioxidant activity while the Langkat accession produced the highest DPPH antioxidant activity with successive values of 16.669 and 0.257 μmol TE g-1 dry weight. As for the correlation between variables, it does not show any significant results.
Keyword: accession, antioxidant, flavonoid, Justicia gendarussa, phenolic

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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