Judul: Kajian inhibitor α-Glukosidase aktinomiset endofit asal brotowali (Tinospora crispa)
Abstrak: Pengobatan diabetes secara tradisional pada umumnya adalah dengan memanfaatkan berbagai jenis tanaman yang memiliki kandungan bahan aktif yang dapat menurunkan kadar gula dalam darah, diantaranya adalah senyawa yang dapat menghambat enzim α-glukosidas. Eksplorasi mikrob endofit diharapkan dapat menghasilkan metabolit sekunder penting yang memiliki khasiat sama dengan metabolit yang dihasilkan tanaman inangnya. Tanaman obat diabetes merupakan sumber mikrob potensial pengahsil inhibitor α-glukosidase. Isolat potensial dari tanaman obat tersebut diharapkan dapat digunakan untuk memproduksi senyawa inhibitor α-glukosidase secara mikrobiologis.
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Judul: Isolation of Endophytic Actinomycetes in Medicinal Plants and Their Potency as an Antidiabetes Based on α-glucosidase Activity.
Abstrak: Endophytic actimomycetes lives in plant tissues without causing a negative impact on plant. Several medicinal endophytic microbes are able to produce the same bioactive compounds as produced by the host. Inhibition of α-glucosidase is one of antidiabetes mechanism. The potency of endophytic actinomycetes from medicinal plant as α-glucosidase inhibitor needs to be elucidated. Temulawak (Curcuma xanthorrhiza), ciplukan (Physalis minima) and brotowali (Tinospora crispa) were surface sterilized and crushed, then plated on humic acid vitamin B. Actinomycetes colonies were purified and produced on International Streptomyces Project No. 4 followed by α-glucosidase assay. Crude extracts with the highest inhibition of α-glucosidase were freeze dried, then diluted at 0.07%, 0.1%, 0.3%, 0.5% (w/v) with dimethylsulfoxide and assayed. Commercial inhibitor, acarbose (Glucobay; Bayer) were used as a comparation. Fourty six isolates were classified into 29 isolates Gram positive and 17 isolates Gram negative. Fifteen isolates were actinomycetes which 11 isolates obtained from brotowali stem, and 4 isolates from temulawak rhizome. The highest inhibition (61.27%) were shown by Cx-10.1 temulawak isolate at 0.07% (w/v) concentration compared with Glucobay 0.1% (w/v) which was only 39.70%. At 0.07% (b/v) concentration, Tc-2.1 from brotowali produce low activity (24.16%). Endophytic Cx-10.1 isolate could be potential to produce higher activity of α-glucosidase inhibitor compared with Glucobay.
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Judul: The Construction of Greedy SVP LLL Algorithm
Abstrak: A lattice is a set of all integer linear combination of a set of linearly independent vectors in ℝ𝑛���. The independent vectors are called bases of lattice. Any lattice can be generated from many bases, and these bases have the same cardinality. In the lattice, the most fundamental and renowned problem is the Shortest Vector Problem (SVP). SVP is a tracking problem of the shortest nonzero vector in a lattice with equivalent bases. In two dimensions, SVP problem has resolved exactly by Gauss’ algorithm. When the lattice dimension is higher than two, A.K. Lenstra, H.W. Lenstra and L. Lovasz gave a LLL algorithm to compute approximation of nonzero shortest vector in the lattice. Reduced bases solution obtained from LLL algorithm still be an approximation and has polynomial running time of arbitrary dimension which large enough. In 1994, Schnoor and Euchner modified this LLL algorithm as a new variant which later was named deep insertion LLL algorithm. This algorithm is a modified version of the LLL algorithm to the terms of the exchange step to improve the accuracy of output of LLL reduced bases and applying it to the subset sum problem. The purpose of this research are: (1) Reconstruct the LLL algorithm and deep insertion LLL algorithm using a geometric approach. (2) Construct a greedy SVP LLL algorithm. (3) Implement the three algorithms in a symbolic programming language, and evaluate them experimentally. A bases ℬ=[𝐛���1,𝐛���2,…,𝐛���𝑛���] in ℝ𝑚��� is called reduced LLL with parameter 𝛿��� if satisfies: (a) |𝜇���𝑗���𝑖���|≤12, for every integer 𝑖���,𝑗��� with 1≤𝑖���<𝑗���<𝑛���. (b)𝛿���‖𝜋���𝑗���(𝐛���𝑗���)‖2≤‖𝜋���𝑗���(𝐛���𝑗���+1)‖2, for 𝑗���=1,2,…,𝑛���−1,where 𝛿��� is a reduced parameter of real numbers with 14<𝛿���<1. The first requirement is the reduced basis 𝛿��� must “nearly orthogonal” and in its computation case, this requirement can be reached out by using the Gram-Schmidt’s orthogonalization. While the second requirement is called exchange step, or used to called as Lovasz condition. By using both of these requirements, then they establish the LLL algorithm. Then, Schnoor and Euchner modify the LLL algorithm based on the requirements of the exchange step called the deep insertion LLL algorithm, where the exchange step is based on the comparison of the projected vector in orthogonal complement [𝐛���1,𝐛���2,…,𝐛���𝑘���−1]⊥ after j-th reduction. To construct greedy SVP LLL algorithm, the requirements of the exchange step is based on purely by comparing norm of lattice 𝐛���𝑗��� with norm lattice 𝐛���𝑖��� for 𝑖���=1,2,3…,𝑗���−1. The process of insertion reduced vector after the exchange step also has done greedily. Then, we calculate the number of arithmetic operation in greedy SVP LLL algorithm for further analysis. The result of our exprimentation for three algorithms on the certain matrix size shows that the running time of the three algorithms increases propotional to the size of the matrix. The result also shows that by using 𝛿���=34 for the LLL algorithm and the deep insertion LLL algorithm, and the greedy SVP LLL algorithm which is a new variant made by using no parameter of 𝛿���, outperform of the other of two previous algorithm in terms of speed with the same output.
Keyword: LLL algorithm, LLL deep insertion algorithm, greedy SVP LLL algorithm