Judul: Aktivitas antimikroba ekstrak jahe (Zingiber officinale Roscoe) terhadap beberapa bakteri patogen
Abstrak: hazards to the human health. Ginger (Zingiber officinale Roscoe) is commonly used as traditional medicine. It has a potential as antimicrobial agent by inhibit or kill microbes in dose dependent manner. The principle compounds of ginger are essential oils and non volatile compounds which maximum have antimicrobial activity. The objectives of this research are: (1) to study the yield of ginger extracts by multistage maceration with different polarity solvents, (2) to study antimicrobial activity of hexane, ethyl acetate and ethanol extract of ginger against foodborne pathogen such as Staphylococcus aureus, Bacillus cereus and Salmonella enterica serovar Typhimurium. Ginger extracts were prepared by multistage maceration method using solvent hexane, ethyl acetate and ethanol. The ginger extracts were assayed for antimicrobial activity by agar well diffusion method with Diameter Inhibition Zone (DIZ) and dillution broth method. The yield of hexane, ethyl acetate and ethanol ginger extracts from multistage maceration were respectively 3,57; 3,17; 3,02 g/100 g dry ginger. The DIZ value for Staphylococcus aureus were 5,0; 5,7; 1,3 mm with hexane, ethyl acetate and ethanol ginger extracts respectively 6,1; 6,6; 6,0 mm for Bacillus cereus and Salmonella Typhimurium were show no inhibitory zone. This results showed that the ginger extracts from multistage maceration have a weak antimicrobial activity (1,3 – 6,6 mm) against Gram-positive bacterial. The inhibition activity was determined for ethyl acetate ginger extract that showed the relatively highest inhibition zone. The minimum inhibition concentration did not reach in a range concentration between 5 – 20 mg/ml against Staphylococcus aureus and Bacillus cereus, therefore ginger extracts from multistage maceration with rotavapor temperature 50 o C and freeze dry process were not efficient to developed as natural antimicrobial.
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Judul: α-Glucosidase Inhibition Activity and DPPH Free Radical Scavenging from Stratified Aqueous Extract of Red Ginger (Zingiber officinale Roxb. var Rubrum)
Abstrak: Jahe merah (Zingiber officinale Roxb. var. Rubrum) mengandung senyawa fenolik yang berpotensi menurunkan kadar glukosa darah (antihiperglikemik) pada pasien diabetes melitus. Penelitian ini bertujuan menentukan aktivitas inhibisi α-glukosidase, aktivitas antioksidan dalam meredam radikal bebas DPPH, dan kadar total fenolik ekstrak air jahe merah bertingkat (ekstrak ke-1, ekstrak residu ke-1, dan ekstrak residu ke-2). Metode penelitian yaitu ekstraksi jahe merah secara infundasi serta analisis dengan teknik uji spektronanometer yang meliputi analisis antidiabetes melalui aktivitas inhibisi α-glukosidase, aktivitas antioksidan metode DPPH, dan kadar total fenolik metode Folin-Ciocalteu. Aktivitas inhibisi α-glukosidase dan kadar total fenolik memiliki perbedaan nilai yang signifikan (p<0.05) dengan nilai tertinggi 97.729% (ekstrak ke-1) dan 27.624 mg GAE/g ekstrak (ekstrak residu ke-2). Aktivitas antioksidan dalam meredam radikal bebas DPPH memiliki perbedaan nilai yang tidak signifikan dengan nilai tertinggi 4.682 mg AAE/g ekstrak (ekstrak residu ke-1). Hasil analisis menunjukkan nilai aktivitas inhibisi α-glukosidase dan kadar fenolik total berbeda signifikan (p<0,05) dengan nilai tertinggi 97.729% (ekstrak ke-1) dan 27.624 mg GAE/g ekstrak (ekstrak residu ke-2). Hasil aktivitas antioksidan memiliki nilai yang tidak berbeda nyata (p>0,05) dengan nilai tertinggi 4.682 mg AAE/g ekstrak (ekstrak residu ke-1)., Red ginger (Zingiber officinale Roxb. var. Rubrum) contains phenolic compounds that have potential to reduce blood glucose levels (antihyperglycemic) in patients with diabetes mellitus. This study aimed to determine the inhibitory activity toward α-glucosidase, antioxidant activity in reducing DPPH free radicals, and total phenolic content from stratified aqueous extract of red ginger (1st extract, 1st residue extract, and 2nd residue extract). The red ginger was extracted by infundation and analyzed by spectronanometer test techniques which included analysis of antidiabetic through inhibitory activity of α-glucosidase, antioxidant activity using the DPPH method, and total phenolic content using the Folin-Ciocalteu method. The results of the analysis showed that the inhibitory activity of α-glucosidase and total phenolic content were significantly different (p<0.05) with the highest values 97.729% (1st extract) and 27.624 mg GAE/g extract (2nd residue extract). The result of antioxidant activity was not significantly different (p>0.05) with the highest value 4.682 mg AAE/g extract (1st residue extract).
Keyword: α-Glucosidase, Antioxidant, Diabetes Mellitus, Red Ginger

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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