Judul: Produksi dan Karakterisasi Senyawa Inhibitor alfa-Glukosidase Streptomyces sp. BWA
Abstrak: Endophitic Streptomyces sp. BWA 65 from brotowali (Tinospora crispa) produces α-glucosidase inhibitor compound that acts as antidiabetic. This study aimed to produce and characterize α-glucosidase inhibitory compound of Streptomyces sp. BWA 65 and assay its biological function as antidiabetic based on α-glucosidase inhibitory activity. Streptomyces sp. BWA 65 which was rejuvenated in Yeast Soluble Starch Agar (YSA) for 7 until 10 days, was then cultured in a liquid medium for 7 days, and produced in International Streptomyces Project-2 (ISP-2) for: 5, 10, 15, and 20 days. Then, supernatant was extracted with ethyl acetate and was assayed for α-glucosidase inhibition activity. The ethyl acetate extract of Streptomyces sp. BWA 65 was also assayed for its Inhibitor Concentration 50 (IC50) value. The characteristics of α-glucosidase inhibitor profile compounds which contained in the ethyl acetate extract was analyzed by Gas Chromatography–Mass Spectroscopy (GC-MS). The results showed that the highest α-glucosidase inhibitor activity was 98.50% when the Streptomyces sp. BWA 65 was grown on ISP-2 10 days production time. The IC50 of ethyl acetate extract of Streptomyces sp. BWA 65 was 0.047 μg ml-1. The results of GC-MS analysis were interpreted with OPCWTEST.M database showed that the ethyl acetate extract of Streptomyces sp. BWA 65 contained 7 peaks with 7 components obtained. The chemical components of ethyl acetate extract of Streptomyces sp. BWA 65, were: 9-octadecenoic acid, (E)-, oleic acid, dan 6-octadecenoic acid, (Z)-.
Keyword: Bogor Agricultural University (IPB), Streptomyces sp. BWA 65, GC-MS, IC50, α-glukosidase inhibitor

Judul: Karakterisasi ekstrak asal Streptomyces sp. IPBCC.B.15.1539 yang berfungsi sebagai inhibitor alfa-glukosidase
Abstrak: Penderita diabetes melitus (DM) di Indonesia pada tahun 2013 diperkirakan mencapai 6.9% atau sekitar 12 juta jiwa. Lebih dari 95% penderita diabetes merupakan penderita DM tipe 2 dan salah satu metode pengobatannya adalah dengan cara menghambat aktivitas enzim α-glukosidase. Streptomyces sp. IPBCC.B.15.1539 asal brotowali merupakan isolat yang menghasilkan inhibitor α-glukosidase. Besarnya potensi Streptomyces sp. IPBCC.B.15.1539 dalam menghasilkan senyawa inhibitor α-glukosidase, menjadikan karakterisasi ekstrak asal Streptomyces sp. IPBCC.B.15.1539 dinilai penting. Tujuan penelitian ini adalah mengkaji karakter ekstrak Streptomyces sp. IPBCC.B.15.1539 dengan metode kromatografi lapis tipis (KLT), mengukur nilai penghambatan terhadap enzim α-glukosidase (IC50) secara in vitro, dan nilai LC50 menggunakan metode brine shrimp letality test (BSLT). Streptomyces sp. IPBCC.B.15.1539 yang ditumbuhkan pada media ISP-2 selama 10 hari pada suhu 20-25 oC dengan kecepatan 100 rpm menghasilkan biomassa sebesar 2.22 ± 0.03 mg mL-1 dan menghasilkan 28.38% ekstrak etil asetat. Ekstrak ini mengandung 7 komponen utama penyusun ekstrak yang diduga mengandung kelompok senyawa flavonoid dan antosianidin. Ekstrak etil asetat Streptomyces sp. IPBCC.B.15.1539 memiliki nilai IC50 terhadap enzim α-glukosidase sebesar 145.51 μg mL-1 dan nilai LC50 terhadap larva Artemia salina sebesar 517.23 μg mL-1. Nilai LC50 ini dinyatakan toksik terhadap larva A. salina. Karakter ekstrak IPBCC.B.15.1539 tersebut dapat menjadi dasar identifikasi senyawa aktif inhibitor α-glukosidase.
Keyword: characterization, diabetes mellitus, ethyl acetate extract, inhibitor of α- glucosidase, Streptomyces sp

Judul: Approximation of the Median of Poisson Distribution Using the Relation of Poisson-Gamma Distribution
Abstrak: A major drawback of median is that median cannot usually be defined in closed form, even in the cases where their distribution functions are known. This study gives an approximation of the closed form for the median of the Poisson distribution by using the relation of Poisson-Gamma distribution. The approximation uses elementary techniques based on the monotonicity of certain sequences involving tail probabilities of the Poisson distribution and the Central Limit Theorem. Furthermore, a closed form expression for the mean absolute deviation 􀜧|􀜰􀰒 􀵆 􀜯􀝁􀝀􁈺􀜰􀰒􁈻| is also studied. The median is relevant because of the fact that it minimizes the mean absolute deviation of a Poisson random variable (􀜰􀰒􁈻 by considering median as central tendency.
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