Analysis And Characterization Of Phenolic Compounds In Domestic Olive Leaves

Numerous in vitro studies have shown that the phenolic compounds present in olives（Olea Europaea L.） have various biochemical roles.There were several studies and paperswhere high-performance liquid chromatography coupled with mass spectrometry （HPLC-MS）was used for the systematic separation and identification of phenolic compounds in oliveleaves in foreign countries. But there were no papers where HPLC-MS was used for theisolation and structure elucidation of phenolic compounds in domestic olive leaves.In this paper, olive leaves, produced in Gansu olive base, was used as the research objectto elucidate the substantial foundation of olives with systemetical separation andcharacterization. The separation and characterization were carried out with standard operatingprotocol employing the modern analytical and detective techniques. The MS/MSfragmentation pathways of phenolic compounds in olives were investigated in detail and thefragmentation pathway rules were summarized.In this work, high-performance liquid chromatography （HPLC） coupled to electrospraytime-of-flight mass spectromery （ESI-TOF-MS） has been applied to screen phenoliccompounds in olive leaves extracts. The use of small particle size C₁₈column provided greatresolution and made separation of a lot of isomers possible. The structural characterizationwas based on accurate mass data and the nature of fragment ions obtained by ESI-TOF-MS.Several phenolic compounds from the methanol extracts of domestic olive leaves wereidentified systematically by analyzing UV characteristics, total ion chromatogram （TIC） andMS fragmentation patterns on negative ion mode. Two phenolic alcohols, nine secoiridoids,one cinnamic acid derivative, three flavonoids displayed by total ion chromatogram （TIC）directly were identified. Totally, fifty phenolic compounds displayed by extract ionchromatogram （EIC） were assigned or tentatively assigned, respectively from severalimportant families （phenolic alcohols, secoiridoids, lignans, phenolic acids, cinnamic acidderivative and flavonoids） of the polar fraction of olive oil. Among them, three compoundswere probably new or firstly reported and the structure of one new phenolic compoundpresent in Olea europaea L. has been tentatively confirmed by matching their MS spectra with known phenolic compounds present in Olea europaea. This new compound was dehydrationcondensation content of elenolic acid glucoside and phloretic acid. Furthermore,2”-hydroxy-oleuropein was probably first detected in olive leaves.The MS/MS fragmentation pathways of secoiridoids, cinnamic acid derivatives andphenolic alcohols in olives were investigated in detail and the fragmentation pathway ruleswere summarized by combining the fragmentation pathway of the literature with the data ofultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry（UPLC/Q-TOF-MS）. The fragmentation rules obtained from the fragmentation pathways laidtheory foundation for the later analysis and structure identification of phenolic compounds inolives with high-performance liquid chromatography coupled with mass spectrometry（HPLC-MS）.