Die UV-Dimerisation von 1.3-Dimethyluracil in der Eismatrix / UV-Dimerization of 1,3-Dimethyluracil in Ice-Matrix

1972 ◽  
Vol 27 (12) ◽  
pp. 1475-1480 ◽  
Author(s):  
Egon Fahr ◽  
Gerhard Fürst ◽  
Peter Maul ◽  
Heinz Wieser

UV irradiation of 1,3-dimethyluracil in ice-matrix yields four dimeric dimethyluracils (2 c) - (5 c), which could be isolated by preparative thin-layer chromatography. Attemps for structure elucidation of these four dimers by UV, IR, NMR and mass-spectrometric methodes pointed out, that only NMR-spectra give structural evidences; by IR - not by mass-spectra - certain identification of dimers is possible.In accordance with dimeric thymines and dimeric uracils the syn-dimeric dimethyluracils (3 c) and (5 c) are stable in 6 N HCl, the anti-dimers are monomerisized. Investigations of stability in HCl gives informations about structures of cyclobutane pyrimidine dimers

2018 ◽  
Vol 1 (1) ◽  
pp. 264-270
Author(s):  
Hady Wiraputra ◽  
Marline Nainggolan ◽  
Panal Sitorus

Tanaman buni (Antidesma bunius (L.) Spreng.) secara tradisional telah digunakan untuk hipertensi, takikardia, anemia, sifilis, antikanker, antioksidan, sumber pewarna alami dan antidiabetes. Saponin merupakan senyawa fitokimia yang mempunyai kemampuan membentuk busa dan mengandung aglikon polisiklik yang berikatan dengan satu atau lebih gula. Penelitian ini bertujuan untuk melakukan karakterisasi senyawa saponin hasil isolasi dari daun buni dengan spektrofotometer ultraviolet dan inframerah. Simplisia daun buni dilakukan karakterisasi kemudian diekstraksi dengan cara maserasi bertingkat menggunakan pelarut n-heksana dan etanol 80%. Selanjutnya ekstrak etanol dihidrolisis dengan HCl 2N kemudian difraksi dengan pelarut kloroform. Isolasi dilakukan terhadap fraksi kloroform dengan cara kromatografi lapis tipis preparatif menggunakan fase diam silika gel GF254 dan fase gerak yang sesuai. Isolat yang diperoleh diuji kemurnian dengan KLT 2 arah dan dikarakterisasi menggunakan spektrofotometer ultraviolet dan inframerah. Hasil pemeriksaan karakterisasi simplisia diperoleh kadar air 7,32%, kadar sari larut dalam etanol 52,70%, kadar sari larut dalam air 23,25%, kadar abu total 6,86% dan kadar abu tidak larut dalam asam 0,94%. Pemisahan fraksi kloroform dengan KLT menggunakan fase gerak n-heksana-etilasetat perbandingan 5:5 diperoleh noda 13 dan hasil KLT preparatif diperoleh 2 isolat murni yaitu isolat 1 (ungu merah) dengan Rf 0,92 dan isolat 2 (biru) dengan Rf 0,78. Hasil karakterisasi isolat 1 diperoleh panjang gelombang maksimum pada 208 nm dan dijumpai adanya gugus hidroksil, gugus -CH alifatis, ikatan C=C, gugus –CH2, gugus –CH3, dan gugus C-O. Hasil karakterisasi isolat 2 diperoleh panjang gelombang maksimum pada 204 nm dan adanya gugus hidroksil, gugus -CH alifatis, gugus –CH2, gugus –CH3, dan gugus C-O. Buni (Antidesmabunius (L.) Spreng.) has been traditionally used for the treatment of hypertension, tachycardia, anemia, syphilis, and used asanti-cancer, anti-oxidant, natural dye, and anti-diabetic. Saponin is a phytochemical compound which has capability in forming foam and contains polycyclic aglycone that binds with one or more glucose. This research aimed to conduct the characterization of saponin compound from buni leaves with ultraviolet spectrophotometer and infrared. Buni leaves simplicia was characterizedand extracted using sequential maceration method with n-hexane and 80% ethanol. The ethanol extract was hydrolyzed with HCl 2N and fractionized using chloroform solvent. Isolation of chloroform fraction was done using preparative thin-layer chromatography using silent phase of silica gel GF 254 and suitable mobile phase. Isolates obtained was taken into purity test with two dimensions thin-layer chromatography and characterized using ultraviolet spectrophotometer and infrared. The characterized simplicia resulted with 7.32% of water content, 52.70% of dissolved content in ethanol, 23.25% of dissolvedcontent in water, 6.86% of total ash content, and 0.94% of undissolved ash content in acid. Fractinationof chloroform fraction with thin-layer chromatography using mobile phase ofn-hexane-ethyl acetate with 5:5 ration resulted with 13 spotsand the result of the preparative thin-layer chromatography resulted 2 pure isolates which are isolate 1 (purple-red) with Rf 0.92 and isolate 2 (blue) with Rf 0.78. The characterization of isolate 1 resulted that the maximum wave lengthwas 208 nm with hydroxyl group, –CH aliphatic group, C=C bond, –CH2 group, –CH3 group, and C–O group. The characterization of isolate 2 resulted that the maximum wave lengthwas204 nm with hydroxyl group, –CH aliphatic group, –CH2 group, –CH3 group, and C–O group.


1967 ◽  
Vol 50 (4) ◽  
pp. 934-938
Author(s):  
Paul E Corneliussen

Abstract A rapid method for determining biphenyl in citrus fruits has been developed and was studied collaboratively. Biphenyl is separated from fruit tissue by steam liquidliquid extraction. The ra-heptane extract is subjected to preparative thin layer chromatography (TLC) on plates coated with silica gel containing phosphors for ready visibility of the biphenyl spots under UV light. The spots are removed from the plate and extracted with alcohol for spectrophotometric measurement at 248 mμ. The TLC cleanup adds specificity to the method; o-phenylphenol, if present, does not interfere and crop blanks are insignificant. The average of 36 recoveries (12 each at abovit 100, 50, and 10 ppm) was 96.7% with a mean deviation of 10.7%. It is recommended that the method be adopted as official, first action.


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