GLYCOSIDES IN Viola Tricolor L.

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CHAPTER 2: <strong>IN</strong>TRODUCTION Figure 2.13: Thestructure andorigin ofthe 1,3 A + fragmentin case ofO-andC- glycosides. (a)apigenin-7-O-glucoside; (b) isovitexin (apigenin-6-C-glucoside). The 1,3 A + fragment appears at different m/z values for O- and C-glycosides, since in the case ofC-glycosides it contains a partofthe sugarmoiety. 35
CHAPTER 2: <strong>IN</strong>TRODUCTION hand, contradictory conclusions were drawn about the role of the (Y0-H) −• ion in the differentiation of flavonoid classes. As the 2,3-double bond adjacent to the carbonyl group in position 4 was considered to be essential for its stabi- lization, the presence of the (Yi-H) −• ion was thought to be opposing to the fla- vanonestructure [126]. However,thisionwaslaterobservedintheproduction spectra ofthe flavanoneshesperetin and naringenin [113]. 2.4.3.5 Samplederivatization and complex formationmethods At the early days of MS based analysis of flavonoids, derivatization (such as methylation, trimethylsilylation, or acetylation) was inevitable, since electron impactandchemicalionizationneededtheanalytetobeinthegasphase. Inad- dition, only limited structural information could be obtained about the derivatized flavonoid glycosides [127–129], and this methods often lead to difficul- tieswithrespecttointerpretation ofthefragmentation patterns, andrequired a time-consumingsamplepreparationstep. Anotherdisadvantageofthemethod was the problem of side reactions [130]. With the introduction of more mod- ernionization techniques,theanalysisofflavonoidglycosides becamepossible withoutderivatization,andnowitisappliedonlyrarelytoobtainadditionalor complementary information. Acetylation,forexample,canstillbeusefulinthestructuralcharacterization of glycoside residues and reportedly allowed differentiation between terminal glucose, galactose and mannose residues of naturally occurring glycosides [131]. Followingthesameapproach,Cuyckensetal. [132]developedamethod- ology to differentiate and characterize terminal monosaccharide residues of flavonoidO-glycosides. AccordingtotheirFABandESIdata,athorough study of some characteristic fragment intensities provided means of differentiation for hexose and pentose isomers. On the other hand, it was demonstrated that the fragmentation behavior of permethylated flavonoid glycosides (the experi- mentsdidnotincludeflavanones)dependedontheglycosidiclinkagebetween the sugars units [133]. Contrary to non-derivatized glycosides, the Y ∗ ion was observed for both flavones and flavonols, but the rearrangement yielding the Y ∗ fragment occurred only for1→6 linkeddisaccharides. Complexation also proved to provide complementary information to struc- ture elucidation. Studies have suggested that certain structural features are re- quired for metal chelation of flavonoids. Proposed chelation sites include the 36
Page 1 and 2: ANTIOXIDANT FLAVONOID GLYCOSIDES IN
Page 3 and 4: Összefoglaló Avadárvácska(Viola
Page 5 and 6: CONTENTS 3.10 Anthocyanidin and fla
Page 7 and 8: CONTENTS R Recoveryin the fortified
Page 9 and 10: CHAPTER 1: PRELIMINARIES AND AIMS O
Page 11 and 12: CHAPTER 1: PRELIMINARIES AND AIMS O
Page 13 and 14: CHAPTER 2: INTRODUCTION Table2.1: S
Page 15 and 16: CHAPTER 2: INTRODUCTION A number of
Page 17 and 18: CHAPTER 2: INTRODUCTION charides, v
Page 19 and 20: 14 Figure 2.4: Biosynthesis ofthe m
Page 21 and 22: CHAPTER 2: INTRODUCTION or acetonit
Page 23 and 24: CHAPTER 2: INTRODUCTION 2.4.1 Instr
Page 25 and 26: CHAPTER 2: INTRODUCTION Figure 2.6:
Page 27 and 28: CHAPTER 2: INTRODUCTION cyanidins w
Page 29 and 30: CHAPTER 2: INTRODUCTION Table 2.2:
Page 31 and 32: CHAPTER 2: INTRODUCTION Figure 2.8:
Page 33 and 34: CHAPTER 2: INTRODUCTION icant Y −
Page 35 and 36: CHAPTER 2: INTRODUCTION Figure 2.10
Page 37 and 38: CHAPTER 2: INTRODUCTION ide) more e
Page 39: CHAPTER 2: INTRODUCTION dance for b
Page 43 and 44: CHAPTER 3 Material and methods 3.1
Page 45 and 46: CHAPTER 3: MATERIAL AND METHODS 3.5
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Page 51 and 52: CHAPTER 4: RESULTS AND DISCUSSION 4
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Page 71 and 72: 66 Table 4.3: Principal ESI-MS/MS p
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Page 81 and 82: 76 Table 4.6: The antocyanidin and
Page 83 and 84: CHAPTER 5 Conclusion Although heart
Page 85 and 86: CHAPTER 5: CONCLUSION proposedtober
Page 87 and 88: CHAPTER 5: CONCLUSION UIBK-HorvathL
Page 89 and 90: BIBLIOGRAPHY insulinresistanceanddi
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BIBLIOGRAPHY [28] N. Saito, C. F. T
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BIBLIOGRAPHY electrospray ionizatio
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BIBLIOGRAPHY [138] C. T. da Costa,
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Listof publications Papersrelatedto
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BIBLIOGRAPHY The antioxidant activi
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was evaporated to dryness under red
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151, 135, 119, and 103 ( 1,3 B + )
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Anal Bioanal Chem DOI 10.1007/s0021
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Anal Bioanal Chem The eluate was co
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Anal Bioanal Chem Column chromatogr
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Anal Bioanal Chem a HO OH d HO OH O
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Anal Bioanal Chem 3. Witkowska-Bana
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12 V. Vukics et al. / J. Chromatogr
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Table 2 Principal ESI-MS/MS product
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