Judul: Kajian Metabolomik dan Density Functional Theory Terhadap Kapasitas Antioksidan Justicia gendarussa Pada Dosis Pupuk Nitrogen Berbeda
Abstrak: Justicia gendarussa, also known as gendarussa, is a plant that has the potential to be an antioxidant. J. gendarussa can grow wild as a bush, especially in forested settings and along river dams. These wild growth conditions will cause inconsistent secondary metabolite production and change biological activity, so it is necessary to cultivate J. gendarussa plants to maintain consistent secondary metabolite content. Plant cultivation treatments that can be carried out include different doses of nitrogen fertilizer. These metabolite changes can be observed using a metabolomics approach. Additionally, metabolomics can be used to identify active compounds. Then, to ensure the ability of the active compound, a computational density functional theory (DFT) chemistry study can be carried out. Therefore, this research aims to determine the optimal nitrogen fertilizer dose on J. gendarussa antioxidant capacity and metabolites using a metabolomics approach. Then, identify its antioxidant compounds in the J. gendarussa fraction with nitrogen fertilizer dose of the highest harvest weight using metabolomics and DFT. The research method begins with cultivating J. gendarussa plants at different doses of nitrogen fertilizer (0, 90, 180, 270 kg/ha), sample preparation, extraction, determination of extract antioxidant capacity, identification of extract metabolites, fractionation, determination of fraction antioxidant capacity, identification of fraction metabolites, DFT studies, and data analysis. The highest harvest weight with a mass of 11 g/plant was produced by plants given 270 kg/ha of nitrogen fertilizer. Antioxidant capacity was shown to be insignificantly different between treatments measured. Based on the metabolomics approach, variations in nitrogen fertilizer made metabolites at doses of 90 kg/ha and 180 kg/ha had higher relative concentrations of metabolites compared to doses of 270 kg/ha. So, 90 kg/ha are the optimal nitrogen fertilizer dose. The ethyl acetate and n-butanol fractions from the nitrogen fertilizer dose with the highest harvest weight had the highest antioxidant capacity. Principal component analysis (PCA) and heatmap succeeded in differentiating metabolites based on polarity. Orthogonal partial least square-discriminant analysis (OPLS-DA) succeeded in identifying six active compounds and 14 unknown compounds that had the potential to be isolated in the ethyl acetate fraction. DFT studies proves that 6-{[(Benzyloxy)carbonyl]amino}-6-deoxy-1,2-O-isopropylidene-alpha-D-glucofuranose and gendarusin A has a smaller gap energy than trolox standard, indicating its antioxidant activity is higher than trolox. Additional tests in vitro or in vivo research on the isolation results need to be carried out to prove the research results further.
Keyword: Cultivation, Gendarussa, Heatmap, PCA, OPLS-DA

Judul: Phenolic Content and Antioxidant Activity of Gendarussa Ethanolic Extract Cultivated with Manure and NPK Fertilizer
Abstrak: Nutrisi dapat mempengaruhi kandungan fenolik tanaman Justicia gendarussa Burm f. (gandarusa). Penelitian ini bertujuan memperoleh informasi komposisi pemupukan gandarusa dengan kadar total fenolik dan aktivitas antioksidan tertinggi, dan menganalisis korelasi antara kadar fenolik dan aktivitas antioksidan yang diperoleh. Pupuk yang digunakan adalah pupuk kandang, NPK, dan kontrol tanpa pemupukan. Laju aplikasi pemupukan 10% dan 50%. Sampel dimaserasi dengan etanol. Kadar total fenolik diukur dengan metode Folin-Ciocalteu. Aktivitas antioksidan diukur dengan metode Ferric Reducing Antioxidant Power (FRAP) dan 2,2’-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). Korelasi dianalisis dengan uji Pearson’s. Kadar total fenolik daun dan batang tertinggi diperoleh pada perlakuan 50% pupuk kandang dan 50% pupuk NPK sebesar 8 dan 5 mg EAG g-1 bobot kering. Aktivitas antioksidan tertinggi diperoleh pada sampel daun perlakuan 50% pupuk kandang dan 50% pupuk NPK (FRAP) dan perlakuan pupuk NPK (ABTS), serta sampel batang perlakuan pupuk NPK (FRAP) dan kontrol (ABTS), dengan nilai berturut-turut 21, 25, 12 dan 27 µmol KAET g-1 bobot kering. Kadar total fenolik daun dan aktivitas antioksidannya berkorelasi positif, sedangkan korelasi pada batang tidak bersifat signifikan secara statistik., Nutrient can affect gendarussa plant’s phenolic content. The objective of the research is to obtain the fertilizing condition yielding the highest phenolic content and antioxidant activity on gendarussa, and analyze the correlation between the obtained phenolic content and antioxidant activity. Fertilizers used were manure, NPK, and no fertilizer being the control. Fertilizing application rate were 10% and 50%. Sample was macerated with ethanol. Total phenolic content was measured with Folin-Ciocalteu method. Antioxidant activity was measured with FRAP and ABTS assay. Correlation was analyzed with Pearson’s test. The highest phenolic contents were 8 and 5 mg GAE g-1 dry weight obtained from treatment 50% manure and 50% NPK of leaf and stem sample. The highest antioxidant activity were 21, 25, 12 and 27 µmol TEAC g-1 dry weight obtained from leaf 50% manure and 50% NPK (FRAP) and NPK sample (ABTS), and stem’s NPK (FRAP) and control (ABTS) sample. Leaf’s phenolic content and antioxidant activity were positively correlated, while that of the stem were insignificant.
Keyword: Pupuk, Nutrisi tanaman, Gandarusa, Fenolik, Aktivitas antioksidan, Antioxidant activity, Fertilizer, Gendarussa, Phenolic, Plant nutrition

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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