| Summary: | 碩士 === 靜宜大學 === 應用化學研究所 === 93 === Much attention was paid on flavanone because of their potentials in the prevention against cardiovascular diseases and cancer. However, many previous papers had focused on the analysis of flavanones whereas few dealt with the migration and retention of flavanones. For investigation of separation mechanism, we selected nine compounds with identical skeleton of flavanone in this study.
The optimum separation of LC with C18 column was performed by gradient of acetonitrile and 5 mM phosphate buffer (pH 6.9). About capillary electrophoresis, we adopted CZE mode for its simple and convenient. The optimum electrolyte buffer of CZE was 32 mM sodium tetraborate buffer (pH 9.2), 4.5 mM SDS, and apply 15 kV. It can also be achieved for separating of isomers.
Generally, more hydroxyl groups will increase the polarity of compounds. For flavanones with dual adjacent hydroxyl groups, their pKa are less than singular substituent. Nevertheless, the compounds with hydroxy at C3 would cause adverse elution order of flavone and flavanone in LC. In addition, the polarity would be reduced because of forming intramolecular hydrogen bond within hydroxy at C5 and carbonyl group at C4. Moreover, in single substituted compounds, the polarity of flavanone with hydroxy at C6 is the smallest, and compounds with hydroxy at C4''and C7 are closely. But the pKa of flavanone with hydroxy at C7 is the smallest for its easier dissociation.
Through the discussion on mechanism, we not only demonstrated the effect of substituent, but also found a reasonable explanation for the contradictory results of Wulf et al. and Wang et al. was due to whether the hydroxy sustituent at C3 exist.
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