Judul: Isolasi Senyawa Aktif dari Cyanobacteria Laut Symploca sp. Asal Ujung Kulon
Abstrak: Symploca sp. adalah suatu jenis Cyanobacteria laut yang mempunyai ragam metabolit sekunder dan aktivitas hayati unik yang berpotensi dijadikan sebagai sumber obat baru. Penelitian ini bertujuan mengisolasi senyawa aktif terhadap Artemia salina dari Cyanobacteria laut Symploca sp. asal Ujung Kulon. Pemisahan ekstrak MeOH Symploca sp. menghasilkan fraksi SN-1, SN-2, dan SN-3. Fraksi SN-2 (0,12 g) adalah fraksi paling ampuh (LC50 0,32 μg/mL) terhadap A. salina. Pemurnian SN-2 lebih lanjut menghasilkan tiga subfraksi: SN- 2.1, SN-2.2, dan SN-2.3. Subfraksi SN-2.2 (36,5 mg) menunjukkan toksisitas paling ampuh (LC50 0.10 μg/mL). Berdasarkan analisis HPLC, subfraksi teraktif mempunyai dua komponen senyawa aktif: SN-2.2.3.1.1 dan SN-2.2.3.1.2., Symploca sp. is a marine Cyanobacteria possessing diverse and unique secondary metabolites and biological activities which can be used as a source of new drugs. The study aimed to isolate the active molecules against Artemia salina from a marine Cyanobacteria Symploca sp. from Ujung Kulon. Separation of MeOH extract of the Symploca sp. gave SN-1, SN-2, and SN-3 fractions. The SN- 2 (0,12 g) was the most potent fraction (LC50 0,32 μg/mL) against A. salina. Further purification of SN-2 resulted three subfractions: SN-2.1, SN-2.2, and SN- 2.3. The subfraction SN-2.2 (36,5 mg) reveals the most potent toxicity (LC50 0.10 μg/mL). Based on HPLC analysis, the most active subfractions has two components of the active compound: SN-2.2.3.1.1 and SN-2.2.3.1.2.
Keyword: A. salina, Cyanobacteria, secondary metabolite, Symploca sp., toxicity

Judul: Uji Toksisitas Senyawa Bioaktif dari Bakteri yang Berasosiasi dengan Spons
Abstrak: Marine bacteria associated with sponges have been known as a source of bioactive compounds. Toxicity test of this compounds was done as initial test to determine the potency of bioactive compounds in pharmaceuticals development. The aim of this study was to extract and fractionate bioactive compounds from marine bacteria associated with sponges and to test its toxicity toward Artemia salina. Bacterial isolate of SAB E-31, SAB E-41, SAB E-57, HAL-13, HAL-74, and HAA-01 isolated from sponge were used as source of bioactive compounds. The bioactive compounds were extracted by using ethyl acetate. The ethyl acetate extract of SAB E-31, SAB E-41, SAB E-57, HAL-13, and HAA-01 were active with the lowest LC50 was 251.18 μg mL-1 from ethyl acetate extract of SAB E-41. The three of best ethyl acetate extract, SAB E-31, SAB E-41, and SAB E-57 were fractionated by preparative thin layer chromatography (PTLC) using eluent of nbutanol: ethyl acetate (3:7). Fractionation results of the three best ethyl acetate extract obtained 19 fractions, and 9 fraction among them were active fraction with the lowest LC50 from the fraction was 46.74 μg mL-1 come from SAB E-57.
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Judul: igenvalues and Eigenvectors of Tridiagonal Matrix with Non Constant and Recurrent Diagonal Entries.
Abstrak: Matriks tridiagonal adalah suatu matriks yang mempunyai entri-entri bernilai nol kecuali pada diagonal utama, di bawah diagonal utama (subdiagonal) dan di atas diagonal utama (superdiagonal). Entri pada diagonal utama tidak konstan dan berulang. Setiap entri pada matriks tridiagonal ini adalah bilangan kompleks. Dalam karya ilmiah ini, akan dibuktikan 3 teorema untuk menentukan nilai eigen dengan 2 kasus dan 1 teorema untuk menentukan vektor eigen. Teorema pertama menentukan polinomial karakteristik dari matriks tridiagonal. Polinomial karakteristik dari matriks tridiagonal tersebut digunakan untuk menentukan nilai eigen pada teorema kedua dan ketiga serta menentukan vektor eigen pada teorema keempat
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