Judul: Antioxidant Capacity and Inhibition of Pancreatic Lipase  from Fractionated Asam Gelugur (Garcinia atroviridis) In vitro
Abstrak: Obesitas adalah penyakit dengan penimbunan lemak dalam jangka panjang yang mengakibatkan timbulnya penyakit degeneratif. Asam gelugur dapat bermanfaat sebagai antioksidan dan inhibitor lipase pankreas. Penelitian ini bertujuan mengukur kapasitas antioksidan, kadar fenolik dan flavonoid total, serta inhibisi lipase pankreas ekstrak kasar dan hasil fraksinasi asam gelugur. Ekstraksi dengan metode sonikasi pelarut etanol 70% kemudian difraksinasi bertingkat dengan pelarut n-heksan, etil asetat, kloroform, dan akuades. Kadar fenolik total asam gelugur tertinggi dimiliki fraksi akuades 535,80 mg GAE/g ekstrak. Kadar flavonoid total tertinggi pada fraksi kloroform 751,04 mg QE/g ekstrak. Kapasitas antioksidan tertinggi pada metode FRAP ekstrak kasar dan pada DPPH fraksi akuades dengan nilai berurut yaitu 339,82 mg TE/ g ekstrak dan 936,52 mg TE/ g ekstrak. Inhibisi lipase pankreas pada konsentrasi 1000 mg/mL tertinggi dimiliki fraksi n-heksan sebesar 91,33% dan tidak berbeda nyata dengan orlistat 88,46%. Korelasi positif diperoleh antara kapasitas antioksidan metode DPPH dengan senyawa fenolik maupun flavonoid. Inhibisi lipase pankreas dengan kadar fenolik dan flavonoid total serta kapasitas antioksidan tidak berkorelasi., Obesity is caused by long-term fatty accumulation leads to degenerative diseases. Asam gelugur can be useful as an antioxidant and pancreatic lipase inhibitor. This study aimed to measure total phenolic and flavonoid content, the antioxidant capacity, and pancreatic lipase inhibitor of crude extract and fractionated. Sonication method is used with ethanol 70% solvent and then multistage fractionation with n-hexane, ethyl acetate, chloroform, and aquades. The highest total phenolic content was observed in aquades fraction 535,80 mg GAE/g extract. The highest total flavonoid content was in the chloroform fraction 751,04 mg QE/g extract. The highest antioxidant capacity was obtained in FRAP method of crude extract and in DPPH of aquades method by aquades fraction with values of 339,82 mg TE/g extract and 936,52 mg TE/g extract. Inhibition of pancreatic lipase at 1000 mg/mL was highest in the n-hexane fraction at 91.33%. A positive correlation was found between the antioxidant capacity of DPPH method and phenolic and flavonoid contents. Pancreatic lipase inhibition with total phenolic and flavonoid and antioxidant capacity were not significantly correlated.
Keyword: fractionation, Antioxidant, pancreatic lipase inhibitor., Garcinia antroviridis

Judul: In Vitro Assay of Water and Ethanol Extracts of Asam Gelugur Fruits, Lengkuas, and Kencur Rhizomes as Inhibitor of Pancreatic Lipase Activity.
Abstrak: Asam gelugur fruits of Garcinia oftenly used to reduce body weight. Lengkuas and kencur are traditional herbal that potential as inexpensive and available antiobesity because they had been studied could reduce the level of phospholipids, triglycerides, and cholesterol. This research evaluated the potencies of these herbal as antiobesity by their water and ethanol extracts capabilities in inhibiting pancreatic lipase activity in vitro at pH 8,0, incubation time 45 minutes, and temperature 40°C. This research used human pancreatic lipase (1,4 × 10-5 μg/μL) and sesame oil (16,2 μg/μL) as substrate. The water and ethanol extracts of asam gelugur fruits contained saponins and alkaliods, respectively. The water extract of lengkuas rhizomes contained alkaloids, flavonoids, saponins, dan quinones, while the ethanol extract contained alkaloids, flavonoids, saponins, and steroids. The water extract of kencur rhizomes contained saponins and quinones, while the ethanol extract contained alkaloids, flavonoids, steroids, and quinones. These plants have potencies as antiobesity based on in vitro assay in inhibiting pancreatic lipase activity. The highest inhibitory effect of all extracs was obtained from the ethanol extract of asam gelugur fruits with value of 86,3% at 150 ppm. The highest inhibitory effect of lengkuas extracts was from the ethanol extract at 200 ppm, which was about 56,2%. The highest inhibitory effect of kencur was showed by the ethanol extract with the value 37,6% at 300 ppm. These values were higher than the inhibitory effect of the positive control (Xenical®) at 100 ppm, about 10,6%.
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Judul: Bifurkasi Hopf pada Model Siklus Bisnis Kaldor Kalecki tanpa dan dengan Waktu Tunda
Abstrak: Business cycle model is one of dynamical system models in economic. One of the business cycles model is Kaldor-Kalecki model. Kaldor-Kalecki business cycle model that is written in delayed defferential equations, is a business cycle model that involves gross product and capital stock of a company. In this paper Kaldor-Kalecki business cycle model is analyzed using both nondelay and delay in time of capital stock. By Taylor expansion for the time delayed model, an analysis of stability around the fixed points has been done. Furthermore, by using Hopf bifurcation theorem, it can be shown that there exists periodic orbits and limit cycle. In the nondelayed model, changing the parameter of goods market could lead to the occurrence of Hopf bifurcation and the existence of limit cycle. Similarly, for the delayed model, it has been shown that changing the time delay parameter may result in the occurrence of Hopf bifurcation and limit cycle.
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