Judul: Potensi Abu dan Simplisia Pelepah Aren (Arenga pinnata.Merr) sebagai Inhibitor Tirosinase
Abstrak: Abu pelepah aren merupakan hasil samping dari pemanfaatan pohon aren yang diambil niranya untuk bahan baku industri gula aren. Abu tesebut telah biasa digunakan oleh kalangan masyarakat sebagai pencerah kulit atau penghambat pigmentasi kulit. Tirosinase merupakan enzim kunci dalam proses melanogenesis atau proses pigmentasi kulit. Penelitian ini bertujuan mempelajari aktivitas inhibisi tirosinase dari ekstrak pelepah aren. Pengujian aktivitas inhibisi tirosinase menggunakan metode kit assay dan analisis logam menggunakan Atomic Absorption Spectrophotometer (AAS). Dari hasil pengujian aktivitas tirosinase diperoleh nilai IC50 sebesar 1458.98 μg/mL untuk ekstrak abu pelarut akuades dan 1960.91 μg/mL untuk ekstrak abu pelarut etanol 96%. Sedangkan ekstrak simplisia dalam pelarut etanol 96% dan etanol 70% tidak memiliki aktivitas inhibisi tirosinase (nilai IC50 > 2000 μg/mL ). Analisis logam menunjukan adanya kandungan logam mineral seperti Al, Mg, Fe, Zn, dan Cu dalam abu pelepah aren yang diduga memiliki peran dalam proses inhibisi tirosinase.
Keyword: Aren, IC50, Logam, Mineral, Tirosinase

Judul: Aktivitas Antioksidan Ekstrak Pelepah Pohon Aren (Arenga pinnata Merr.)
Abstrak: Stem sugar palm has been reported to contain tannin compound, however, there is no scientific information about its potential as antioxidant. Hence, the objective of this research was to measure the antioxidant activity of stem sugar palm extract (Arenga pinnata Merr.) in vitro. This research used water, ethanol 70% and ethanol 96% as solvents. The stem sugar palm was extracted in water solvent by boiling method and by maceration in ethanol 70% and 96% solvents. Bioactive compounds in the extracts were determined by phytochemical method. Antioxidant activity of stem sugar palm extracts were determined by 1,1-diphenyl-2-picrylhydrazyl radical absorption method (DPPH) and the content of the total phenolic measured in colometric with Folin-Ciocalteu method. The result showed that the stem sugar palm extracts contained saponin, tannin and phenol, and steroids and triterpenoid. Analysis of antioxidant activity showed that both ethanol 70% and 96% stem sugar palm extracts were potential as natural antioxidant. The highest antioxidant activity and the total phenolic value were showed by ethanol 96% extract (IC50 = 2.570 μgL-1; 3.75 GAE mgg-1).
Keyword: phenolic, phytochemical, stem sugar palm, DPPH, Antioxidant

Judul: Construction of Strongly Optimal Binary Linear Code with Minimum Distance 9 and 11
Abstrak: A binary linear code of length n over q F is a subspace of n q F . A code has three parameters that attached to it, namely length, dimension, and minimum distance. A code with length n, dimension k and minimum distance d is often called [n, k, d ]-code. Usually, when two parameters are given, then we want to find a code that has the best value for the last parameter. Based on Gilbert- Varshamov bound, if a [n, k, d ]-code exists and can not be expanded, we call it a strongly optimal code. In this paper, we construct strongly optimal code with minimum distance 9 and 11. In constructing the code, we created a theorem and algorithm based on Gilbert-Varshamov bound before we implement the algorithm to MAPLE programming language. Because of computational limitations, the program can only construct up to k = 10 for d = 9 and k = 12 for d = 11.
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