Judul: Fractionation of Flavonoid Group from Kepel (Stelechocarpus burahol) Leaves as Antibacterial Agent
Abstrak: The objectives of this research was to separate flavonoids of kepel leavesfrom methanol extract as antibacterial agent. The bacteria used was Staphylococcus epidermidis that corresponds to body odor. The methanol extracts was fractionated in methanol:water (7:3), n-hexane and chloroform consecutively. Methanol:water (7:3) extract with the highest flavonoids content, fractionated by silica gel column chromatography (isocratic elution, with butanol:methanol:acetic acid 1:8:1 as eluent) to produce 7 fractions. All fractions were tested for antibacterial activity with a microplate method. Fraction V was the most active fraction with minimum inhibitory concentration (MIC) 0.06 mg/mL and minimum bactericidal concentration (MBC) of 0.50 mg/mL. Fraction V was further separated by preparative thin layer chromatography and gave three fractions. Fraction V3 was the most active fraction with MIC 1.00 mg/mL and MBC of 2.00 mg/mL. Identification of fraction V3 based on assessments on ultraviolet-visible and infrared spectrum belongs to flavones group.
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Judul: Detection of antibacterial compound from kesum leaves (Polygonum minus Huds) by TLC-bioautography method and the effect to escherichia coli and staphylococcus aureus membrane.
Abstrak: Kesum (Polygonum minus Huds) is the one of biodiversities from West Borneo and commonly used as flavouring ingredient for local culinary. Kesum leaves contain some bioactive compounds i.e high phenolic compounds, flavonoids, alkaloids, tannins and terpenoids which are potential as natural antibacterial agent. Detection of antimicrobial fractions of compounds from natural extracts could be done by TLC-bioautography. It is a combining method of chemical (thin layer cromatography/TLC) and microbology technique (antimicrobial activity assay) which allowed the localization of active compound. Generally, the kesum leaves extracts have been obtained by conventional maceration technique. This technique is often time consuming and requires relatively large amounts of solvent and sometimes diminishes the active compounds. Ultrasound assisted extraction (UAE) is one of the emerging technologies being developed in order to minimize the length of the extraction time, to reduce the cost, and to maximize the extract quality. The aims of this study are: 1) comparing extraction of kesum leaves maceration technique and UAE using some solvent with different polarity by multilevel extraction, 2) screening of extract based on antibacterial activity of kesum leaves extracts against E. coli and S. aureus, 3) fractination of kesum leaves extracts with the highest antibacterial activity by TLC, 4) to detect the active fraction of kesum leaves extracts with TLC-bioautography, and 5) to find out the mechanism inhibition of kesum leaves extracts against E. coli and S. aureus cell membrane. The experiment was conducted in four stages. The first stage covers extraction was done by steam distillation to obtain essential oils, followed multilevel extraction by maceration and UAE to obtain different extracts, i.e. polar, semipolar and nonpolar. The second stage covers qualitative analysis of phytochemical extracts, preparation of bacterial test and test the bacterial activity of extracts using disc – diffusion method and Minimum Inhibitory Concentration (MIC) using macrodilution method. The third stage was fractionation of extract with the highest antibacterial activity by TLC method. The fourth stage was detection the active fraction of kesum leaves extracts with TLC-bioautography, followed by TLC-bioautography. The last stage was study of mechanism inhibition of kesum leaves extracts against cell membrane by DNA probe staining using fluorescen microscopy and detection leakage of the cytoplasmic membrane has been analysed by spectrophotometer UV – Vis. This study exhibited that UAE provided higher extraction yields and shortened the extraction time, in comparison to the conventional maceration technique. Phytochemical analysis showed kesum leaves extract contain phenolics, alkaloids, flavonoids, triterpenoids, tannins and saponins. The ethanolic extract of kesum leaves were potential as source of antibacterial agent. The MIC of the ethanolic extract, was 25 mg/ml for E. coli and 30 mg/ml for S. aureus. Fractination by TLC showed six spots under UV light at λ 254 nm. TLC-bioautography with agar overlay technique effectively detected that fractions of ethanolic extract of kesum leaves with Rf4 = 0.30 and Rf5 = 0.37 demonstrated the most noticeable antibacterial activity for both E. coli and S. aureus. Inhibitory mechanism of kesum leaves extract against E. coli and S. aureus is the disruption cytoplasmic membrane permeability that causes leakage of cell materials.
Keyword: antibacterial, kesum, membrane permeability, TLC-bioautography, UAE

Judul: Analisis Dinamik Struktur Gedung Terhadap Beban Gempa (Studi Kasus Tower Altiz – Tangerang Selatan).
Abstrak: Penelitian ini bertujuan untuk melakukan pemodelan gedung, menganalisis besarnya periode getar dan kekakuan yang dimiliki gedung, menentukan mode shape dan partisipasi massa, serta menganalisis besarnya gaya geser dasar gempa. Objek penelitian adalah Tower Altiz. Prosedur penelitian mengacu kepada SNI 1727-2013, SNI 1726-2012, SNI 2847-2013, dan PPURG 1987. Berdasarkan hasil penelitian, pemodelan Tower Altiz telah berhasil dilakukan. Periode getar yang dialami Tower Altiz adalah 2.735 detik. Mode shape dari Tower Altiz telah berhasil didapatkan. Untuk besarnya partisipasi massa pada arah x yang lebih dari 90 %, didapat pada mode ke-10, sedangkan untuk partisipasi massa pada arah y didapat pada mode ke-11. Gaya geser dasar statik (Vstatik) sebesar 11359.164 kN sedangkan besarnya gaya geser dasar dinamik (Vdinamik) 8339.260 kN untuk arah gempa-x dan 7722.238 kN untuk arah gempa-y. Faktor skala desain untuk gaya geser dinamik (Vdinamik) sumbu-x adalah 1.15, sedangkan untuk sumbu-y adalah 1.25. Besarnya gaya geser dinamik (Vdinamik) yang diperoleh untuk sumbu-x dan sumbu-y adalah 9655.289 kN.
Keyword: gaya geser, gedung, gempa, struktur