Navigation Links
Structural Determination of Flavonoids Using MSn

Jack Cunniff, Philip Tiller, Michael Harvey, and Adrian Land,
Thermo Finnigan

Natural Product Analysis

The data presented here can be acquired using the Thermo Finnigan LCQ Series of ion trap mass spectrometers.

Introduction

For more than five thousand years tea has been used in China as an herbal remedy. In recent years pharmacological studies have supported some of these health claims. Flavonoids, a class of polyphenolic compounds, found in tea, plants and many fruits have shown some promising results related to anti-cancer as well as antiinflammatory and anti-allergy properties. For these reasons, there has been renewed interest in both detecting and characterizing these compounds.

In many instances, flavonoids exist as their glycosylated conjugate. In a typical MS/MS experiment, glycosylated moieties may be cleaved from the molecular precursor with a resulting MS/MS spectrum which is difficult to relate back to a hypothetical structure. The primary reason for the difficulty is the fact that first generation fragment ions may undergo further fragmentation, which can result in a very complex spectrum. Third and fourth generation product ions can not readily be distinguished from second generation product ions.

The LCQ Series of mass spectrometers can perform MSn, so precursor ions are isolated before a subsequent MS/MS experiment is performed. Due to this isolation step, fragmentation spectra are generally less complex and ambiguous than traditional MS/MS spectra. Through successive MS/MS steps, product origins can be assigned. As the following experiments will show, the LCQ may remove glycosylated side chains in a controlled, step-by-step manner using the power of MSn. Eventually, a core structure is exposed. A final fragmentation spectrum of the core structure yields a classic fingerprint which may then be referenced against a library MS/MS spectrum of the base component. In this way, a compound may be unequivocally classified.

Goal

This experiment demonstrates:
The utility of MSn for structural determination and unambiguous classification of a suspected flavonoid compound.
The utility of MSn for the unambiguous determination of product origin.

Experimental Conditions

Thermo Finnigan LCQ fitted with ESI probe
Infusion: 3 L/min using integrated syringe pump
Capillary temp: 150 C
Needle voltage: +4.2 kV
Sheath gas: 45 units
Auxiliary gas flow: 10 units

Results

Apiginin (Figure 1) (mw 270.2) is a base component of a class of flavonoids. The MS/MS spectrum of apiginin is rich in detail (Figure 2). Because the
LCQ imparts energy solely onto the precursor molecule, variations in collision energy generally have very little impact on the relative ratios of the product ions. The MS/MS spectrum of apiginin will be used as our library spectrum or fingerprint for the classification of Compound X whose full-scan mass spectrum is shown in Figure 3.


Figure 1. Structure and full-scan mass spectrum of apiginin.



Figure 2. Full-scan MS/MS (m/z 271) spectrum of apiginin.



Figure 3. Full -scan mass spectrum of Compound X.

From the spectrum in Figure 3, it is clear that compound X has an [M+H]+ ion at 579 and an [M+Na]+ ion at 601. The MS/MS spectrum of the [M+H]+ ion of Compound X (Figure 4) indicates a loss of 146 and also exhibits an ion of m/z 271the m/z of the [M+H]+ ion of apiginin. The loss of 146 is often indicative of the loss of a deoxy-hexose sugar and the m/z 271.1 ion is indicative of the base component: apiginin.

At this point it is possible to do MS3 on the 271.1 ion and compare the spectrum with that of the MS/MS spectrum of apiginin. Before we do this, however, we shall first endeavor to determine whether the m/z 271 ion is related to the m/z 433 ion. To accomplish this, an MS3 experiment was performed on the m/z 433 ion and the spectrum is illustrated in Figure 5. The hypothesis that the m/z 271 originated from the m/z 433 ion has been confirmed. The difference in the two masses (162 amu) is also indicative of the loss of a hexose sugar.


Figure 4. Full-scan MS/MS (m/z 579) mass spectrum of Compound X.



Figure 5. Full-scan MS3 (579>433>) mass spectrum of Compound X.



Figure 6. Full-scan MS4 (579>433>271>) mass spectrum of Compound X.

Up to now, the only evidence that Compound X belongs to the flavonoid class is the presence of the m/z 271 ion. This is far from compelling evidence. Compelling evidence would be achieved if the MS/MS of this m/z 271 ion yields a spectrum which is similar to the MS/MS spectrum of apiginin. This hypothesis is tested via the MS4 experime nt of the m/z 271 ion. The spectrum (Figure 6) is an exact match of the spectrum generated by the MS/MS experiment of apiginin (Figure 7). Compound X is a flavonoid! In fact, it is the flavonoid rhoifolin (apiginin 7-0-neohesperidoside).


Figure 7. Comparison of full-scan MS/MS (271) spectrum of apiginin with the full-scan MS4 (579>433>271>) mass spectrum of Compound X.

Conclusions

Electrospray ionization of an unknown compound provides a soft ionization technique allowing the generation of an intact pseudomolecular ion at m/z 579. The MS2 experiment yielded two major ions which were indicative of the loss of a deoxyhexose sugar (m/z 433) and a product mass which was the same as a base component of flavonoids (m/z 271). MS3 of the m/z 433 ion proved that the m/z 271 ion was a product of the m/z 433 ion and also indicated the loss of a hexose sugar. The MS4 experiment on the m/z 271 ion resulted in a fragmentation spectrum which was a direct match with the fragment spectrum of apiginin. The direct match indicates that the unknown compound belongs to the flavonoid class.





'"/>

Source:


Page: All 1 2 3 4

Related biology technology :

1. Structural Analysis of Glycosylated Peptides in Complex Mixtures with Ion Trap MSn
2. Continuous-Elution Electrophoresis for Purification of the Baculovirus-Expressed Coronavirus Structural Proteins, Rev A
3. Total Cellular Protein Determination Using the DC Protein Assay
4. Simultaneous Determination of Residues of Approximately 100 Pesticides and Metabolites in Fruit and Vegetables by LC/MS/MS
5. Determination of Polar Organophosphorus Pesticides in Aqueous Samples by Direct Injection Using HPLC/MS/MS
6. Determination of N-nitrosamines in Baby Bottle Rubber Teats by Liquid Chromatography-Atmospheric Pressure Chemical Ionization Mass Spectrometry
7. Determination of the Chloramphenicol residues in milk and milk products using LC/MS/MS
8. A Microtiter-based Assay for the Determination of ID50s of b-lactamase Inhibitors Employing Reporter Substrates Detected at UV or Visible Wavelengths (MaxLine Application Note #20)
9. Determination of Acepromazine and its Major Metabolite in Equine Serum by LC-MS/MS using the Finnigan LCQ Deca XP Plus Ion Trap Mass Spectrometer
10. Low Abundance cDNA Cloned Using Stratagenes Human Universal cDNA Library
11. Oil-Free PCR Using the Hot Top Assembly
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:2/11/2016)... 11, 2016   BioInformant announces the February ... Research Products, Opportunities, Tools, and Technologies – Market Size, ... The first and ... cell industry, BioInformant has more than a decade of ... market, by stem cell type. This powerful 175 page ...
(Date:2/11/2016)... ... February 11, 2016 , ... Global ... treatment clinic in Quito, Ecuador. The new facility will provide advanced protocols and ... from around the world. , The new GSCG clinic is headed by ...
(Date:2/10/2016)... -- The Maryland House of Delegates and House Speaker ... Maryland School of Medicine Dean E. Albert Reece ... System President and CEO Robert Chrencik , MBA, ... given to the public by the leader of the ... and Mr. Chrencik for their contributions to our statewide ...
(Date:2/10/2016)... New York (PRWEB) , ... ... ... Inc. (NASDAQ: REGN) today announced that it has joined the Human Vaccines ... immunotherapies for infectious diseases and cancer. , The Human Vaccines Project ...
Breaking Biology Technology:
(Date:1/28/2016)... Synaptics (NASDAQ: SYNA ), a leading developer of human interface ... 31, 2015. --> --> ... percent compared to the comparable quarter last year to $470.5 million. ... million, or $0.93 per diluted share. --> ... of fiscal 2016 grew 9 percent over the prior year period ...
(Date:1/25/2016)... BELL, Pa. , Jan. 25, 2016   Unisys Corporation ... recognition system at John F. Kennedy (JFK) International Airport, ... Border Protection (CBP) identify imposters attempting to enter ... do not belong to them. pilot testing of ... out initially at three terminals at JFK during January 2016. ...
(Date:1/22/2016)... January 22, 2016 ... addition of the  "Global Behavioral Biometric ... --> http://www.researchandmarkets.com/research/4lmf2s/global_behavioral ) has ... Behavioral Biometric Market 2016-2020"  report to ... and Markets ( http://www.researchandmarkets.com/research/4lmf2s/global_behavioral ) has announced ...
Breaking Biology News(10 mins):