Judul: Isolasi senyawa golongan flavonoid sebagai antioksidan dari daun dandang gendis (Clinacanthus nutans)
Abstrak: The leaves of dandang gendis (Clinacanthus nutans) exhibit antioxidant activity. The objective of this study is to investigate the highest antioxidant activity from flavonoid extract of the leaves. Antioxidant activities were determined by radical scavenging assay using 1,1-diphenyl-1-pycryl-hydrazyl radical. The result showed that ethyl acetate extract had antioxidant activity with IC50 value of 178.40 mg L-1. The ethyl acetate extract was fractionated further using preparative thin layer chromatography with eluent of n-buthanol:acetic acid: water (4:1:5) and produced 3 fractions. The most active fraction was fraction 2 with IC50 value of 52.93 mg L-1, which was lower than that of butylated hydroxy toluene (IC50 16.71 mg L-1). Flavonoid assay of fraction 2 showed that it contained flavonol and flavon. The ultraviolet-visible spectrum of fraction 2 in methanol solvent showed a maximum absorption at 332 in band 1 and 274 nm in band 2. In MeOH+MeONa and MeOH+AlCl3-HCl solvents there was a bathochromic shift, indicated the presence of 4'-OH and 5-OH. The new peak at 326.5 nm showed the presence of 7-OH substituent.
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Judul: Isolation of Phenolic Active Compounds as Antioxidant from Dandang Gendis (Clinachantus nutans) Leaves.
Abstrak: Daun dandang gendis (Clinacanthus nutans) merupakan salah satu tanaman obat yang berpotensi sebagai antioksidan. Tujuan penelitian ini ialah mengisolasi senyawa bioaktif dari tanaman yang termasuk famili Acantaceae untuk mendapatkan komponen aktif senyawa fenolik dengan aktivitas antioksidan yang tinggi. Aktivitas antioksidan ditentukan dengan metode penggaitan radikal bebas 1,1-difenil-2-pikrilhidrazil. Dari hasil fraksinasi menggunakan kromatografi lapis tipis preparatif dengan eluen n-butanol:air:asam asetat (4:5:1) diperoleh 3 fraksi. Fraksi teraktif ialah fraksi 2 dengan nilai konsentrasi hambat 50% (IC50) 89.50 mg L-1, sedangkan IC50 untuk senyawa kontrol, hidroksi toluena terbutilasi (BHT) sebesar 6.87 mg L-1. Hasil ini menyimpulkan bahwa aktivitas antioksidan fraksi 2 jauh lebih rendah bila dibandingkan dengan aktivitas BHT. Uji senyawa fenolik dilakukan dengan kromatografi gas‒spektrometer massa dan diduga terdapat 3 senyawa fenolik, yaitu p-isopropenilfenol, o-hidroksiasetofenon, dan p-hidroksiasetofenon.
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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