<![CDATA[Abstrak. Telah dilakukan penelitian uji aktivitas antioksidan daun gulma siam (Chromoleana odorata L.) dengan metode 1,1-difenil-2-pikrilhidrazil (DPPH). Tujuan penelitian ini untuk mengetahui kandungan senyawa metabolit sekunder, golongan flavonoid dan aktivitas antioksidan yang terdapat dalam daun gulma siam. Sebanyak 315 g daun gulma siam kering yang sudah dihaluskan, dimaserasi dengan etanol 95% diperoleh 100 g ekstrak kental etanol. Sebanyak 70 g ekstrak kental etanol difraksinasi dengan pelarut metanol dan n-heksana menghasilkan fraksi kental metanol 30,72 g dan n-heksana 14,62 g. Hasil skrining fitokimia ekstrak etanol menunjukkan positif mengandung senyawa alkaloid, flavonoid, saponin, tanin dan steroid. Fraksi metanol positif mengandung senyawa alkaloid, flavonoid, saponin, dan tanin. Fraksi metanol dilakukan isolasi dengan metode kromatografi kolom menggunakan eluen n-heksana : etil asetat : diklorometana (1:1:1) sebagai fase gerak pertama, kemudian ditingkatkan gradien kepolarannya untuk menghasilkan pemisahan secara sempurna. Hasil isolasi diperoleh 8 fraksi (A, B, C, D, E, F, G, H) dan hasil analisis secara KLT menunjukkan fraksi A dan B positif mengandung senyawa flavonoid. Senyawa flavonoid yang terkandung dalam fraksi A diperkirakan golongan isoflavon dan fraksi B diperkirakan golongan isoflavon, flavon, flavonol dan kalkon. Analisis FTIR menunjukkan fraksi A dan B mengandung gugus fungsi N-H, O-H (asam karboksilat), C=O (aldehid dan ester), C=C, C-H, C-X (flourida), C-O dan C-N. Hasil pengujian aktivitas antioksidan menggunakan metode DPPH, diperoleh Inhibitor concentrasi (IC50) untuk ekstrak etanol 15,5067 ppm, fraksi metanol 9,5671 ppm, fraksi A 82,7808 ppm dan fraksi B 16,2336 ppm, sedangkan untuk pembanding (asam askorbat) 0,8913 ppm. Dengan demikian, dapat disimpulkan aktivitas antioksidan yang paling kuat terdapat pada fraksi metanol.Kata kunci: daun gulma siam, Chromoleana odorata L., flavonoid, DPPH. Abstract. The antioxidant activity of siam weed leaf (Chromoleana odorata L.) has been done with 1,1-diphenyl-2-picrilhidrazil (DPPH) method. This study is intended to know the the content of secondary metabolite compounds, the group of flavonoid and antioxidant activity that found in siam weed leaf. The 315 g dry siam weed leaf that was refined, macerated with ethanol 96% produced 100 g of ethanol viscous extract. The 70 of ethanol viscous extract was fractionated with methanol and n-hexane solvent produced 30,72 g of methanol viscous fraction and 14,62 g n-hexane. The results of phytochemical screening of ethanol extract showed positive that contained compound of alkaloids, flavonoids, saponins, tannins and steroids. Methanol fraction showed positive that contained compound of alkaloids, flavonoids, saponins and tannins. The isolation in methanol fraction was made by coloumn chomatography method using eluent n-hexene : acetate ethyl : dichloromethane (1:1:1) as first mation phase. Then the polarity gradient was increased to produce complete separation. The result of isolation produced 8 fractions (A, B, C, D, E, F, G, H) and the analysis results with TLC showed fraction of A and B was positive contain flavonoids compound. Flaconoids compound that was contained in fraction A was estimated isoflvone group and fraction B was estimated group os isoflavone, flavone, flavonol and chalcone. Analysis FTIR showed that the fraction of A and B containing function group N-H, O-H (carboxylic acid), C=O (aldehyde and ester), C=C, C-H, C-X (flouride), C-O and C-N. The result of antioxidant activity test used DPPH method, obtained inhibitor concentration (IC50) for 15,5067 ppm of ethanol extract, 9,5671 of methanol fraction, 82,7808 ppm of fraction A and 16,2336 ppm of fraction B, while for comparison (ascorbic acid) is 0,8913 ppm. This, it can be concluded that strongert antioxidant activity was found in methanol fraction.Keywords: siam weed leaf, Chromoleana odorata L., DPPH.]]>
