Introduction Phenolic compounds (flavonoids and phenolic acid derivatives) are the components of the resin which constitutes 50% of propolis, an important honeybees product, largely used as natural pharmacological remedy. Flavonoids are considered fundamental for its healing properties. Some caffeates, esters of one of the most representative phenolic acid, have instead shown allergenic properties. The purpose of this study is to achieve a selective determination of different classes of phenolic compounds on the basis of dissimilar fragmentation pathways and to characterize the ionization behaviour of these compounds. LC/ESI-triple quadrupole mass spectrometry appears to be the best technique for direct analysis of these samples. Method Sample preparation was based on methanol extraction / dilution of different pharmaceutical preparations or raw material coming from bee hives. LC-MS analyses were accomplished on a ion-trap (IT) and a triple quadrupole (TQ) instrument, both with electrospray interfaces, working in positive and negative ion mode. Chromatographic separations were achieved on octadecylsilica reversed phase column. Studied substances were found in all of the real propolis samples. Preliminary results A study of the fragmentation patterns of flavonoids and caffeic acid esters was accomplished both by IT and TQ mass analysers. The aim was to compare mass fragmentation behaviour with two mass analysers different either in terms of collision inducing device or in terms of potential applied. By comparison of fragmentation pathways in positive and negative ion modes, it has been possible to elucidate the mechanism of daughter ions formation due to the difference in charges stabilization. Chemical structure based pathways agree to use precursor ion scanning mode to selectively obtain single phenolic class chromatograms and to rapidly evaluate single class quantitation. This approach has been applied to the characterization of samples of different geographical origin and to the comparison of propolis samples and matching plant exudates samples. In both cases simplified chromatographic analysis of complex phenolic matrices was carried out. Novel aspects Selective determination of chemically similar compounds bearing opposite pharmacological / toxicological properties
Selective analytical determination of phenolic compounds in natural products by ESI-MS/MS precursor ion analysis
MEDANA, Claudio;BAIOCCHI, Claudio
2006-01-01
Abstract
Introduction Phenolic compounds (flavonoids and phenolic acid derivatives) are the components of the resin which constitutes 50% of propolis, an important honeybees product, largely used as natural pharmacological remedy. Flavonoids are considered fundamental for its healing properties. Some caffeates, esters of one of the most representative phenolic acid, have instead shown allergenic properties. The purpose of this study is to achieve a selective determination of different classes of phenolic compounds on the basis of dissimilar fragmentation pathways and to characterize the ionization behaviour of these compounds. LC/ESI-triple quadrupole mass spectrometry appears to be the best technique for direct analysis of these samples. Method Sample preparation was based on methanol extraction / dilution of different pharmaceutical preparations or raw material coming from bee hives. LC-MS analyses were accomplished on a ion-trap (IT) and a triple quadrupole (TQ) instrument, both with electrospray interfaces, working in positive and negative ion mode. Chromatographic separations were achieved on octadecylsilica reversed phase column. Studied substances were found in all of the real propolis samples. Preliminary results A study of the fragmentation patterns of flavonoids and caffeic acid esters was accomplished both by IT and TQ mass analysers. The aim was to compare mass fragmentation behaviour with two mass analysers different either in terms of collision inducing device or in terms of potential applied. By comparison of fragmentation pathways in positive and negative ion modes, it has been possible to elucidate the mechanism of daughter ions formation due to the difference in charges stabilization. Chemical structure based pathways agree to use precursor ion scanning mode to selectively obtain single phenolic class chromatograms and to rapidly evaluate single class quantitation. This approach has been applied to the characterization of samples of different geographical origin and to the comparison of propolis samples and matching plant exudates samples. In both cases simplified chromatographic analysis of complex phenolic matrices was carried out. Novel aspects Selective determination of chemically similar compounds bearing opposite pharmacological / toxicological properties
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