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Penelusuran Aktivitas Antibakteri dari Kulit Akar Tumbuhan Medang Seluang (Litsea spathulata) terhadap Bakteri Uji Escherichia coli dan Shigella dysentriae
Get PDFScreening for antibacterial activity from root bark of Litsea spathulata had been done. Antibacterial test on each fraction showed that hexane had the highest activity followed by ethyl acetate and methanol. Major compound from antibacterial active fraction had been isolated. Identification of this compound was carried out applying phytochemistry assay and spectroscopic methods, i.e. ultraviolet (UV), infrared (IR), and Gas Chromatography- Mass Spectroscopic (GC-MS). Minimum inhibiting concentration (MIC) value of the active fraction was 780 mg/mL to Escherichia coli and 860 mg/mL to Shigella dysentriae
ARILASI 4-IODIDA ANISOL DENGAN t-BUTIL GERMANIUM MENGGUNAKAN KATALIS PALADIUM
Get PDFTelah dilakukan arilasi 4-iodida anisol dengan t-butil germanium menggunakan katalis paladium dalam pelarut tetrahidrofuran dengan kondisi atmosfir argon. Produk hasil arilasi dikarakterisasi melalui penentuan titik leleh, pengukuran menggunakan kromatografi gas-spektrometer massa (GC-MS), dan resonansi magnetik inti (NMR) proton dan karbon. Hasil penelitian menunjukkan bahwa produk arilasi adalah tris(4-metoksifenil)t-butil germanium (1) yang merupakan kristal putih dengan rendemen sebesar 35%. Penentuan titik leleh senyawa (1) menghasilkan nilai sebesar 113,5-114,5 oC dengan nilai m/z hasil pengukuran GC-MS sebesar 452. Spektra 1H NMR menunjukkan adanya tujuh puncak proton ekivalen dan spektra 13C NMR menghasilkan empat puncak karbon ekivalen. Hasil keseluruhan karakterisasi menunjukkan kecocokan dengan senyawa (1).
Kata kunci: arilasi, 4-iodida anisol, t-butil germanium, paladium.
The arylation of 4-iodo anisole with t-butyl germane using palladium as catalyst in tetrahydrofuran as a solvent in argon atmospheric condition was carried out. Product of arylation was characterized through determination of melting point, identification using gas chromatography-mass spectrometry (GC-MS), and nuclear magnetic resonance (NMR) proton and carbon. The results showed that product of arylation is tris(4-methoxyphenyl)t-butyl germane (1) which has white crystals in 35% yield. The determination of melting point compound (1) gave the value 113.5-114.5 oC with m/z 452 from GC-MS data. 1H NMR spectrum resulted seven peaks of equivalent proton and 13C NMR spectrum gave four peaks of equivalent carbon. All results of this characterization are appropriate with structure compound (1).Keywords: arylation, 4-iodo anisole, t-butyl germane, palladium
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
ANTIBACTERIAL ACTIVITY OF XANTHONE FROM ETHYL ACETATE EXTRACT OF THE STEAM BARK OF Garcinia picrorrhiza Miq
Get PDFA compound was isolated from the ethyl acetate extract of stem bark Garcinia picrorrhiza. The extraction was conducted by maseration. Separation and purification were done by chromatography method. The structure of compound was established using UV, IR, and 1H NMR spectroscopy. The antibacteria activity of the isolated compound was tested by paper disk difusion method and minimum inhibitory concentration (MIC) value was determined by using well difusion method examined against bacteria Escherechia coli, Salmonella typhi, Bacillus subtilis and Staphyloccocus aureus. The isolated compound was a yellow solids (43.8 mg) with melting point 171 – 172 oC. Based on spectroscopy data compared with data from the literature, the isolated compound is a known compound of oxygenated xanthone group with structure 1,4,5-trihydroxy-2-(3methylbut-2-enyl)xanthone. The compound exhibited an antibacterial activity against Bacillus subtilis only with MIC of 62.5 µg/mL
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
ISOLASI SENYAWA METABOLIT SEKUNDER DARI EKSTRAK n-HEKSANA BATANG TUMBUHAN BROTOWALI (Tinosporacrispa L.)
No full textTelah dilakukan isolasi satu senyawa metabolit sekunder dari ekstrak n-heksana batang Tinospora crispa. Ekstraksi dilakukan dengan metode maserasi. Pemisahan dan pemurnian dilakukan dengan teknik kromatografi. Terhadap senyawa hasil isolasi dilakukan uji aktivitas antioksidan menggunakan metode DPPH (1,1 - difenil-2-pikrilhidrazil) dengan variasi konsentrasi 1000, 500, 250, 125, 62,5, 31,25, 15,625 dan 7,8125 μg/mL. Senyawa hasil isolasi diperoleh dalam bentuk minyak berwarna kuning. Berdasarkan data spektroskopi NMR 1D dan dengan membandingkan data senyawa yang telah dilaporkan dari jamur endofitik batang brotowali pada literatur disimpulkan bahwa senyawa hasil isolasiadalah bis-(2-etilheksil)ftalat dengan rumus molekul C24O4H38. Uji aktivitas antioksidan dari senyawa hasil isolasi memberikan nilai IC50 sebesar 232,9 μg/mL dan dikategorikan tidak aktif antioksidan. </jats:p
Isolation and evaluation of the antioxidant actity of phenolic constituents of the Garcinia sizygiifolia
No full textGarcinia sizygiifolia is a native plant to the South Sulawesi region popularly known as sula and has been cultivated in several regions in Indonesia. The plant by local community use as a food and source of wood, but has not found information on chemical content and biological activity. Therefore, this study was carried out to Isolation and evaluation of the antioxidant activity of the phenolic constituent of the G. sizygiifolia. A 30.0 g portion of ethyl acetate extract of the stembark G. sizygiifolia were separated by column chromatography method using silica G 60 F254 (230-400 mesh), eluted gradient polarity mixtures of n-hexane-ethyl acetate were collected and sorted into fractions. Fraction F 1 (5.2 g) were separated and purified again by chromatography method until pure compound obtained. The structure of the isolated compound was determined using UV, IR, and NMR spectroscopy. The antioxidant activity was tested by DPPH method. The isolated pure compound was a yellow solid with melting point 148-149 oC. Base on spectroscopy data and by comparison with data from the literature, isolated compound is a known compound 2,4-dihydroxyphenylethanone. The compound exhibited antioxidant activity with IC50 96 µg/mL against DPPH.</jats:p
Isolation of Antioxidant Compound from Endophytic Fungi Acremonium sp. from the Twigs of Kandis Gajah
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