Judul: Fractionation and identification of toxic compound group from ethyl acetate fraction of pond apple extract (Annona glabra)
Abstrak: Fraksi etil asetat buah sirsak hutan (Annona glabra) telah dilaporkan menunjukkan sitotoksisitas tertinggi dibandingkan dengan fraksi etanol dan air. Dalam penelitian ini, fraksi etil asetat difraksionasi lebih lanjut dengan metode kromatografi lapis tipis preparatif dan dihasilkan 5 noda (rentang Rf 0.27–0.95) di bawah sinar ultraviolet 254 nm. Fraksi dengan Rf = 0.66 mengandung kristal berbentuk jarum dan berwarna putih. Spektrum ultraviolet fraksi tersebut menunjukkan puncak serapan pada 206 nm. Kenampakan fisis, panjang gelombang serapan ultraviolet serta spektrum inframerah yang memperlihatkan serapan khas, yaitu gugus OH (3396 cm-1), C=O (1737 cm-1), C=C (1561 cm-1), dan C–O (1384 cm-1) menunjukkan ciri khas golongan senyawa asetogenin. Serapan C=O dan C–O diduga sebagai penciri keberadaan cincin lakton yang lazim ditemukan dalam struktur asetogenin. Sitotoksisitas asetogenin telah dilaporkan berhubungan dengan adanya lakton tersebut, gugus OH, dan rantai karbon takjenuhnya. Kata kunci: asetogenin, inframerah, kromatografi, sirsak hutan., Ethyl acetate fraction of pond apple has been reported as the most cytotoxic fraction compared with ethanol and water fractions. In this study the ethyl acetate fraction was further fractionated using preparative thin layer chromatography and the resulted five fractions showed Rf range from 0.27 to 0.95 under ultraviolet irradiation at 254 nm. Fraction having Rf = 0.66 was a white needle shape crystal. The ultraviolet spectrum of this fraction showed absorption peak at 206 nm. The physical appearance, absorption wavelengh and infrared spectrum, including OH group (3396 cm-1), C=O (1737 cm-1), C=C (1561 cm-1), and C-O (1383 cm-1) was further showed characteristic absorptions of acetogenin compound, The lactone ring which is common in acetogenin structures was predicted from the C=O and C–O absorptions. The cytotoxicity of acetogenins has been reported as related with this lactone, as well as the OH groups and the unsaturated hydrocarbon. Key words: acetogenin, infrared, chromatography, pond apple
Keyword: asetogenin, inframerah, kromatografi, sirsak hutan

Judul: Isolasi dan Identifikasi Senyawa Alkaloid dalam Ekstrak Daun Sirsak Hutan (Annona glabra)
Abstrak: Sirsak hutan (Annona glabra), is a plant that has been traditionally used as medicine. In previous studies, ethanol extract of A. glabra leaves has been reported to be toxic against brine shrimp and zebrafish embryo. The result of phytochemical test showed dominant presence of alkaloids in the chloroform fraction, which was the most active fraction of the extract. This study was intended to isolate alkaloids from the chloroform fraction. The total alkaloid extract was obtained as much as 0.95 g (0.1%). Fractionation using column chromatography showed the presence of alkaloids in D fraction obtained by CHCl3-MeOH (90:10) as the eluent. This fraction exhibited 6 spots that were detected as alkaloids based on thin layer chromatography analysis with CHCl3- MeOH (85:15) eluent. Following separation of these spots on preparative thin layer chromatography, there were only 3 spots (D3; 1.1%, D4; 2.1%, and D5; 1.5%) with good separation based on ultraviolet spectrum at 254 nm. Based on spectra of liquid chromatography-mass spectrometer, Fourier transformed infrared, and ultraviolet, the D3 spot was predicted to be similar with armepavine.
Keyword: Bogor Agricultural University (IPB), isoquinoline, Annona glabra, alkaloids

Judul: Query Expansion based on Bilingual Dictionary Using Conditional Probability
Abstrak: Query expansion is a technique that can be used to bridge vocabulary gaps between queries and documents in the collection. With query expansion, user will be helped to formulate queries well so that user will optimize the search result. In this study, the expansion term was resulted from the translation of bilingual dictionary. Subsequently, several terms of expansion were elected based on the closeness of its relationship with the original query. This research showed that conditional probability can be used to select expansion term in bilingual translation method query expansion. The result of 1000 documents was more than 97% relevan document can be retrieved by this system. The more expansion term used, the larger number relevan document was retrieved.
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