GLYCOSIDES IN Viola Tricolor L.

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CHAPTER 2: <strong>IN</strong>TRODUCTION Figure 2.11: Differentiation of 6-C- and 8-C-glycosides. Product ion spectra of protonated (a)vitexin and(b) isovitexin, aswell asthe MS 3 spectra of the 0,2 X + fragment for (c)vitexin and(d) isovitexin [100]. scribed the E1 − ion as being characteristic also for the 8-C isomer vitexin. Sim- ilarly, the same authors reported higher abundance of the 0,3 X − ion for the 6-C isomers than for the 8-C-glycosides [111]. Moreover, different small molecule loss patterns were observed in the positive ion MS 3 spectra of the 0,2 X + frag- mentsfor6-C-and8-C-glycosyl isomers. Usingthesamefragmentationenergy, more pronounced fragmentation occurred in case of C-6 glycosides, resulting in 0,2 X + –H2O, 0,2 X + –CHO, 0,2 X + –H2O–COfragments, whereasinthespectra of the 8-C-glycosyl isomers only the 0,2 X + –CHO fragment was present (Fig. 2.11c and d). Thisobservation wasalso confirmed by Vukics etal. [112]. Inaddition, the 1,3 A + and 1,3 A + –COfragments were exclusively present in the positive MS 3 spectraofthe 0,2 X + ionforthe6-Cisomers, suchasswertiajaponin (7-methoxy- luteolin-6-C-glucoside), isoorientin andisovitexin [115, 116]. On the other hand, in the product ion spectra of hexose and pentose1 con- tainingasymmetricaldi-C-glycosides,suchasschaftoside(apigenin-6-C-glucoside-8-C-arabinoside) and isoschaftoside (apigenin-6-C-arabinoside-8-C-glucos- 31
CHAPTER 2: <strong>IN</strong>TRODUCTION ide) more extensive fragmentation was found for the C-6 sugar moiety. Con- sequently, fragments 0,2 X + P, 1,5 X + P, 0,2 X + H–H2O and 0,2 X + H–2H2O appeared only for the C-6 pentose isomer, while 0,4 X + H–2H2O, 0,2 X + P–H2O, and 0,1 X + H were observed only for the C-8 pentose variant [98, 112]. Please note that the product ion spectra ofhexose and deoxyhexose containing di-C-glycosides did not exhibitthe same differences [112]. OnthesubjectofthedifferentiationofpositionalC,O-glycosylisomers,only scarceinformation isavailable. Examining53flavonoidglycoside isomers,Fer- reresetal.[96]observedthatinthenegativeionMS n spectraacertainfragment ratiowasalwayshigherfortheC-6isomers. Thesefragmentswereverysimilar in structure to flavonoid aglycones (Ag), namely, [Ag+41] − and [Ag+71] − for mono-C-glycosides and[Ag+83] − and[Ag+113] − for di-C-glycosides. 2.4.3.4 Natureof the aglycone Identification of the aglycone part of flavonoid O-glycosides can be achieved by thorough analyses of the MS 3 spectra obtained for the Y0 fragment, or by their comparison (i) with the corresponding spectra of reference molecules, (ii) orwithliteraturedata[92,94,99,101,117–121]. IncaseofC-glycosides,thelack of an abundant Y0 fragment renders the direct comparison of spectra impossi- ble. Still, a thorough analysis of the MS 3 spectra of i,j X or i,j X–H2O fragments, which are similar in structure to the aglycone, can provide sufficient informa- tionfortheidentification. Iftheinstrumentation doesnotallowtheregistration ofMS 3 spectra,applicationofhigherfragmentationenergyisrecommended,as thenthefragmentionscharacteristicoftheaglyconemayappearintheMS/MS spectra [109]. The basic structure of the aglycone part, including the number and nature of substituents, can be assumed from the molecular mass corresponding to the aglycone. Forexample,forapigenin-7-O-glucoside,the molecularmassofMW = 270 can be calculated from the m/z value for the Y0 fragment either in the positive or in the negative ion mode. This fact suggests that it possesses a 2,3 double bond and three hydroxyl substituents connected to a flavone, flavonol or isoflavone skeleton, as no other relevant combination of basic skeletons and substituents addsupthesamemolecularweight. Thestructures offlavoneand isoflavone isomers differ only in the connection points of the B-ring, they have the same molecular mass. However, asfaras theirdifferentiation isconcerned, 32
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
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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: CHAPTER 2: INTRODUCTION Figure 2.10
Page 39 and 40: CHAPTER 2: INTRODUCTION dance for b
Page 41 and 42: CHAPTER 2: INTRODUCTION hand, contr
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 83 and 84: CHAPTER 5 Conclusion Although heart
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CHAPTER 5: CONCLUSION UIBK-HorvathL
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BIBLIOGRAPHY insulinresistanceanddi
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BIBLIOGRAPHY [28] N. Saito, C. F. T
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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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