Judul: Profil Fitokimia dan Aktivitas Antikalkuli Ekstrak Air Daun Tapak Dara (Catharanthus roseus) secara In Vitro dan In Vivo
Abstrak: Catharanthus roseus leaves have been traditionally used for kidney stone’s treatment, but scientifically study about it hasnot been done. This study aims to analyze the phytochemical component and examine the anticalculi activity aqueous extract of Catharanthus roseus in vitro and in vivo. Phytochemical analysis is conducted qualitatively. In vitro anticalculi activity carried out to observe the decay of calcium oxalate in various concentration of extract. In vivo testing using aqueous extract with dose 100 mg/kg and 300 mg/kg in induced Sprague dawley rats by ethylene glycol 0.75% and ammonium chloride 1% ad libitum for 10 days. Phytochemical components contained in aqueous extract of Catharanthus roseus include of alkaloids, phenolic, flavonoids, tannins, saponins and triterpenoids. Aqueous extract with 5% concentration has the highest ability to decay calcium oxalate that is equal to 262.13 ± 12.36 ppm. Aqueous extract could increase body weight and decrease serum creatinine along with the rat kidney’s calcium, but it couldn’t reduce the number of renal crystal deposition. This indicates that aqueous extract of Catharanthus roseu leaves don’t have anticalculi activity.
Keyword: Bogor Agricultural University (IPB), anticalculi, kidney stones, aqueous extract, Catharanthus roseus

Judul: In Vitro Inhibition of Xanthine Oxidase by Roselle (Hibiscus sabdariffa) and Ciplukan (Physalis angulata) Extracts.
Abstrak: The enzyme xanthine oxidase catalyses xanthine oxidation into uric acid, which plays a crucial role in gout. Roselle and ciplukan as common medicine herbs used in many traditional treatment because it contains secondary metabolite compounds potentially as xanthine oxidase inhibitory. In this research, to water and ethanol extracts from roselle and ciplukan was conducted phytochemical assay, toxicity to Artemia salina , herbs, extract assay, and inhibition assay to xanthine oxidase activity by in vitro, and than to compared allopurinol as positive control. Uric acid crystal growth rate from saturated solution with turbidimetry method was also observed. Ciplukan phytochemical assay showed that flavonoid, tannin, saponin, alkaloid, and steroid compounds but alkaloid and steroid were not detected in roselle extract. Probit analysis to water and ethanol extracts from roselle calyxes and ciplukan herbs showed lethal concentration 50 value (LC50) of 96.95, 40.03, 252.79, and 63.83 ppm, respectively. Ethanol and water extracts from ciplukan (70.08% and 43.66%) showed higher inhibition activity than ethanol and water roselle extracts (35.53% and 20.42%) but still lower than alloprinol (98.63%) in concentration 100 ppm. Among 4 extracts, only ciplukan ethanol extract had the lowest Inhibition concentration 50 value as 74.49 ppm indicated that it is potential to be developed as medicine. Turbidimetry method was not successful for observing uric acid crystal growth.
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Judul: Best Difference Equation Aproximation to Duffing 's Equation
Abstrak: Persamaan Duffing merupakan persamaan yang sering muncul sebagai model masalah sistem ayun mekanis atau pada masalah rangkaian listrik. Umumnya penyelesaian persamaan ini secara numerik memberikan hampiran dengan gala! yang tinggi, seperti dengan metode Runge-Kutta. Tulisan ini mengkonstruksi suatu persamaan beda untuk menghampiri persamaan Duffing tersebut. Penyelesaian dari persamaan beda ini melibatkan fungsi-fungsi eliptik Jacobi. Berdasarkan penyelesaian ini diperoleh basil bahwa penyelesaian hampirannya persis sama dengan penyelesaian analitiknya. Penyelesaian analitik yang diperolehjuga melibalkan fungsi-fungsi eliptik Jacobi.
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