Study On The Chemical Constituents Of Aloe: Isolation, Structure Characterization And Antioxygenic Property

This thesis deals with the study on the chemical constituents of Aloe, a Chinese traditional herb proved to have many pharmacological activities. Modern techniques combined with traditional methods, especially the column chromatography over polyamide and silica gel were adopted in the experiment. Using various separating and purifying techniques such as solvent partition, thin-layer preparative chromatography and recrystallization, ten phenolic compounds have been isolated. They are aloe-emodin (A), physicion (B), chrysophanol (C), emodin (D), rhein (E), 1,8-dihydroxy-9,10- anthraquinone- 3-methyl -(2- hydroxy) propionate ester (named as aloe-emodin ester) (F), 3,4-dihydro -6,8- dihyroxyl -3-(2'acetyl- 3'-hydroxyl-5'- methoxyphenyl) methyl- 1H- [2]benzoplyran- 1-one (named as Aloe dihydroisocoumarin A) (G), 3,4-dihydro-6- methoxy - 8 - dihyroxyl-3-(2'acetyl-3'-hydroxyl-5'- methoxyphenyl) methyl- 1H -[2] benzoplyran -1-one (named as Aloe dihydroisocoumarin B) (H), Aloe dihydrocomarin (I) and 8-C-β-D -[2-O (E)-p-coumaroyl] glucopyranosyl -2-[2- hydroxy] propyl- 7- methoxy -5-methyl-chromone (J). The compounds F, G, H and I are novel.In the structure elucidating of these unknown compounds, 2DNMR techniques such as 1H-1H COSY, HMQC/HSQC HMBC and NOESY, 1DNMR, UV, IR, MS, XRSCD, CD and molecular model calculation were employed. On the basis of 2DNMR spectral analysis, the structures of compounds E to I were discussed in detail. Additionally, the free radical scavenging activities of compounds G and H with an H2O2/NaOH/DMSO system by Electron Spin Resonance were briefly studied.