Judul: Aktivitas Antioksidan Dan Potensi Hayati Dari Kombinasi Ekstrak Empat Jenis Tanaman Obat Indonesia
Abstrak: The crude ethanol extracts combination of four Indonesia medicinal plants namely Curcuma xanthorriza, Phyllanthus niruri, Andrographis paniculata, and Curcuma aeruginosa were examined for their antioxidant (radical scavenging) activity using 2,2-diphenyl-1-picrylhidrazyl (DPPH) free radical and biological activities or cytotoxicity using brine shrimp lethality test (BSLT). IC50 values for DPPH radical scavengeing activity ranged from 1.923 to 211.127 ppm, with extract combination of Curcuma xanthorriza and Curcuma aeruginosa (1:0:0:1) having the lowest value and therefore the most potent, and extract combination of Phyllanthus niruri, Andrographis paniculata, and Curcuma aeruginosa (0:1:1:1) having the highest value. LC50 values for BSLT ranged from 31.796 to 620.165 ppm, with extract combination of Curcuma xanthorriza, Phyllanthus niruri, Andrographis paniculata, and Curcuma aeruginosa (1:1:1:1) having lowest value and therefore the most potent, and extract of Curcuma aeruginosa (0:0:0:1) having the highest value. A positive correlation between antioxidant and biological activities of extract combination was obtained from combination (1:1:1:1), with antioxidant and biological or cytotoxicity values were 41.87 and 31.79 ppm, respectively.
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Judul: Pengukuran Aktivitas Antioksidan dengan Metode Cuprac, DPPH, dan Frap serta Korelasinya dengan Fenol dan Flavonoid pada Enam Tanaman
Abstrak: Oxidative stress is the imbalance condition between free radical and antioxidants that can cause oxidative damage in cell, tissues, organ, accelerates the aging process, and emergence of diseases. This study aims to determine the antioxidant capacity of 6 herbs, and the relationship between phenol and flavonoids content with their antioxidant activity and relationship between phenol and flavonoids content in the ethanol extract of some Indonesian herb, there are Orthosiphon stamineus, Sonchus avensis, Sida rhombifolia, Guazuma umifolia, Andrographis paniculata, and Parkia biglobosa. The measurement of antioxidant activity use 3 methods, that are CUPRAC (cupric ion reducing antioxidant capacity), DPPH (2,2-diphenyl-1-pickrylhidrazyl), and FRAP (ferric reducing antioxidant power). The research of the six herbs showed antioxidant activity. Statistic test from three method antioxidant showed that measurement antioxidant activity with CUPRAC, DPPH, and FRAP gave a significantly different result, but CUPRAC and FRAP give the same response of the six herbs. The phenol has no correlation with flavonoids content but have highly correlation with their antioxidant activity. Flavonoids have no correlation with antioxidant activity.
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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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