Judul: (In Vitro) Inhibition of α-Amylase, α-Glucosidase and Lipase by Roselle (Hibiscus Sabdariffa) Extracts by In Vitro Method
Abstrak: Obesity is caused as the result of an imbalance between energy intake and expenditure. Moreover, obesity is a strong risk factor for various diseases, such as hypertension, arteriosclerosis, diabetes mellitus. The aim of the present study is to evaluate the ability of roselle aqueous extract (RAE) to inhibit porcine pancreas lipase, S. Cerevisiae α-glucosidase, Bacillus. sp α-amylase and porcine pancreas α-amylase activity in vitro. Fresh roselle flower was extracted by aquadest at 70, 85 and 100o C for 15 and 30 minutes. We also analyzed total soluble phenolic content of the extract by the Folin-Ciocalteu reagent and total acidity by titratable acidity methods. The results indicated that RAE without pH treatment had more than 80% inhibitory activity for lipase, α-glucosidase and both α-amylase. Next we treated the pH of RAE similiar to intestinal digestion condition as follow : the pH was reduced to pH 2 for 30 minutes and than increased to pH 6,8. The pH treated RAE had no effect on α-glucosidase and low inhibition on lipase activity but it showed the highest inhibition activity against α-amylase. Kinetic studies revealed uncompetitive inhibition of RAE on α-amylase porcine pancreas. Based on its strong α-amylase inhibitory RAE seems promising to be an anty obesity agent, although needs further study to proof in vivo efficacy.
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Judul: Khasiat Ekstrak Rimpang Kunci Pepet dan Buah Asam Gelugur sebagai Pelangsing secara In Vitro dan In Vivo
Abstrak: Garcinia atroviridis (gelugor) fruits and Kaempferia angustifolia (kunci pepet) rhizomes have been traditionally used as herbal medicine to reduce body weight. The extract of these plants has been shown (in vitro) to have antiobesity activity. The objectives of this research is to evaluate the activity of the combination of these herbs‟ ethanol extracts towards human pancreatic lipase activity by in vitro analysis (pH = 8.0, incubation time = 45 minutes, and temperature = 40 °C) and mouse pancreatic lipase by in vivo analysis. The combined extracts activity towards human pancreatic lipase was analyzed using lipase concentration of 1.4 х 10-6 μg/μL with sesame oil (0.243 μg/μL) as the substrate. The in vivo test were conducted to female mice by investigating their body weight and feed consumption changes before and after the combined extract administration. The in vitro test results showed that the 1:1 gelugor–kunci pepet ethanol extract combination had the highest inhibition activity towards human pancreatic lipase (75.69%) at 20 ppm concentration. The lowest body weight average of (171.38 g) was observed in the mice group that had been admistered with 564 mg combined extract per 200 g body weight. Their average feed consumption decreased from 30.13 g to 19.87 g per day. These results gave conclusion that the combined gelugor–kunci pepet ethanol extract is able to inhibit human pancreatic lipase activity, decrease mouse body weigth and appetite.
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Judul: Desain Sistem Transfer Energi Nirkabel Berbasiskan Tesla Coil
Abstrak: Tesla coil merupakan alat yang ditemukan oleh Nikola Tesla yang dapat mentransmisikan daya tanpa kabel dengan memanfaatkan prinsip induksi elektromagnetik. Pada penelitian ini dibuat sebuah prototype Tesla Coil dengan menggunakan transistor C1970 dan receiver menggunakan rangkaian LC. Identifikasi alat meliputi pengaruh daya input transmitter terhadap receiver, bentuk signal yang dipancarkan transmitter, pengaruh jarak transmitter dan receiver, nilai efisiensi serta efek alat terhadap perangkat lain. Hasil pengamatan menunjukkan bahwa semakin besar daya input maka semakin besar daya yang dipancarkan oleh transmitter. Bentuk sinyal yang dipancarkan oleh transmitter berupa gelombang listrik AC sinusoidal dengan frekuensi ~2.9 MHz. Semakin jauh jarak receiver terhadap transmitter maka semakin kecil amplitudo gelombang AC yang diterima oleh receiver, menyebabkan semakin kecil daya yang diterima oleh receiver. Adapun nilai efisiensi terbesar penangkapan daya oleh receiver yaitu sebesar 0.00516 % serta terdapat gangguan pada alat-alat tertentu seperti monitor komputer dan radio.
Keyword: rangkaian LC, receiver, tesla coil, transistor C1970, transmitter