Judul: Aktivitas Inhibisi Enzim α-Glukosidase dan Toksisitas Ekstrak Air dan Ekstrak Etanol Daun Sengon (Paraserianthes falcataria (L) Nielsen)
Abstrak: Paraserianthes falcataria (L) Nielsen has been shown to have a high bioactivity. Utilization of sengon leaf as a antidiabetic has not been done. This study aims to examine the antidiabetic activity and toxicity of water and ethanol extracts of the sengon leaves. Antidiabetic activity of the extracts was tested by the method of inhibition against α-glucosidase enzyme. Cytotoxicity of Paraserianthes falcataria (L) Nielsen. extracts was conducted by BSLT. Extraction of Paraserianthes falcataria (L) Nielsen. Inhibition of α-glucosidase enzyme extract water, ethanol 70%, and 96% had IC50 values, respectively for 1541.667 and 1213.090 ppm, the IC50 of water extract could not be calculatet because its inhibition activity is less than 50%. IC50 values for acarbose as a comparison is 0.311 ppm. The test results in 70% and 96% ethanol extract showed Paraserianthes falcataria (L) Nielsen. not have an antidiabetic. Toxicity testing of water extract, ethanol 70%, and 96% gain in a row LC50 value of of 499 677 , 373 342 and 383 270 ppm. Means that all the tested extracts are toxic.
Keyword: Bogor Agricultural University (IPB), Totoxicity, Inhibition, α-Glucosidase, Sengon

Judul: Aktivitas antidiabetes ekstrak air dan etanol daun sirsak secara in vitro melalui inhibisi enzim α-glukosidase
Abstrak: Soursop leaf is a part of the soursop plant used in traditional medicine and proven for antidiabetic agent through decrease in blood glucose level. However, the mechanism of decrease in blood glucose level has not been determined. The research was done to determine the activity of aqueous and ethanol extract of soursop leaf at 1, 1.50, 2% as α-glucosidase inhibitor, compared their activities with acarbose 1% as positive control and determine the mechanism of inhibition. Soursop leaf were extracted with ethanol 70% using maceration method and boiling water method. Aqueous and ethanol extract of soursop leaf were used for phytochemical assay and used for α-glucosidase inhibition method. The α- glucosidase activity was determined by measuring the p-nitrophenol release from the reaction of the enzyme and substrate p-nitrophenil- α-D-glucopiranoside (p- NPG) at 400 nm. The phytochemical analysis indicates that aqueous extract and ethanol extract contained alkaloid, flavonoid, saponin, tannin, and steroid. Both of them can inhibit α-glucosidase activity, but the mechanism of inhibition of the extract has not been able to determined. Aqueous extract can inhibit α-glucosidase activity up to 41.91%, and ethanol extract can inhibit α-glucosidase activity up to 89.33%. Acarbose as positive control can inhibit 93.84% of α-glucosidase activity.
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Judul: Pemodelan Nilai Tukar Rupiah Terhadap US Dollar Menggunakan Deret  Waktu Hidden Markov Dua Waktu Sebelumnya
Abstrak: Nilai tukar Rupiah terhadap US Dollar mengalami perubahan setiap waktunya dalam periode yang panjang dan perubahan yang terjadi mungkin terjadi kembali di masa mendatang. Jika penyebab kejadiannya tidak diamati secara langsung dan membentuk suatu rantai Markov maka perubahan nilai tukar Rupiah dapat dimodelkan dengan model deret waktu hidden Markov. Untuk menggambarkan perilaku nilai tukar Rupiah terhadap US Dollar, dalam karya ilmiah ini digunakan model deret waktu hidden Markov dua waktu sebelumnya. Model ini mengasumsikan bahwa nilai tukar Rupiah terhadap US Dollar bergantung pada rantai Markov yang merupakan penyebab kejadian yang tidak diamati dan nilai tukar Rupiah dua waktu sebelumnya.
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