Clever use of high-resolution mass spectrometry allows rapid cataloging of sulfur-containing compounds in plant extracts

April 26, 2013
Rapid cataloging of sulfur-containing compounds in extracts from plants such as onions has been demonstrated using a FT-ICR mass spectrometer (pictured). Credit: 2013 American Chemical Society; 2013 iStockphoto/Thinkstock (foreground)

Plants are a rich resource of bioactive compounds, many of which have inspired therapeutic drugs. Yet countless plant compounds, potentially with medical uses, still remain to be identified. Kazuki Saito, Ryo Nakabayashi and colleagues from the RIKEN Plant Science Center have now developed a technique for rapidly cataloging subsets of compounds in plant extracts based on mass spectrometry data as a first step toward a fully automated system for cataloging novel plant compounds.

Mass spectrometry is an analytical technique that captures the mass spectrum of molecules in a sample, making it a powerful tool for identifying unknown compounds. Those compounds that contain certain 'heteroatoms' such as oxygen, nitrogen and sulfur produce a spectral 'fingerprint' that can be resolved in high-resolution mass spectra. Saito and his team hypothesized that this characteristic could be exploited to quickly catalog compounds in .

To test their approach, the researchers profiled sulfur-containing compounds in onion extracts. Sulfur-containing compounds produce a pair of adjacent peaks in the mass spectrum—one 20 times stronger than the other—associated with the ratio of the two most common naturally occurring isotopes of the .

Using an ultrahigh-resolution, highly mass-accurate instrument called a Fourier transform (FT-ICR) , Saito and his colleagues were able to identify 67 sulfur-containing ions in the onion extract. Then, using isotope chemistry, they were able to establish the number of in each structure.

The researchers analyzed extracts from two sets of onions: one grown under a normal atmosphere, and another grown under an atmosphere in which the carbon in CO2 was replaced with the heavier carbon isotope, carbon-13. By measuring how much heavier a plant compound was when formed from carbon-13, the researchers could calculate its carbon count and so determine its complete atomic make-up. In a final step, the team established the full chemical structure of some of the sulfur-containing compounds by comparing their data with that of known compounds.

"We are now planning to develop an automated structural assignment system," says Nakabayashi. The researchers hope to automate this time-consuming process by incorporating an additional analysis technique called nuclear magnetic resonance (NMR), developing a database of high-quality mass spectrometry and NMR reference data, and establishing a computational algorithm for checking each compound against this database to establish its chemical structure. The researchers also plan to extend their existing technique to compounds containing other heteroatoms, such as oxygen, nitrogen, bromine and chlorine.

Explore further: Researchers provide new information about mass spectrometry

More information: Nakabayashi, R., et al. Combination of liquid chromatography−Fourier transform ion cyclotron resonance-mass spectrometry with 13C‑labeling for chemical assignment of sulfur-containing metabolites in onion bulbs. Analytical Chemistry 85, 1310–1315 (2013). dx.doi.org/10.1021/ac302733c

Related Stories

Researchers provide new information about mass spectrometry

October 15, 2007

Fresh data on mass spectrometry are presented in the report ‘Low-energy collision-induced fragmentation of negative ions derived from ortho-, meta-, and para-hydroxyphenyl carbaldehydes, ketones, and related compounds,’ ...

Identifying Molecules from the Deep Sea (w/ Video)

August 2, 2010

In a pioneering research project, for the first time, scientists at IBM and the University of Aberdeen have collaborated to "see" the structure of a marine compound from the deepest place on the Earth using an atomic force ...

Spot the chemical difference

June 27, 2012

(Phys.org) -- Scientists at Kew have devised a method to distinguish similar flavonoids when chemically profiling plant extracts.

Recommended for you

Hitching a ride: Misfiring drugs hit the wrong targets

August 25, 2016

It probably isn't surprising to read that pharmaceutical drugs don't always do what they're supposed to. Adverse side effects are a well-known phenomenon and something many of us will have experienced when taking medicines.

New method developed for producing some metals

August 25, 2016

The MIT researchers were trying to develop a new battery, but it didn't work out that way. Instead, thanks to an unexpected finding in their lab tests, what they discovered was a whole new way of producing the metal antimony—and ...

Using light to control genome editing

August 25, 2016

The genome-editing system known as CRISPR allows scientists to delete or replace any target gene in a living cell. MIT researchers have now added an extra layer of control over when and where this gene editing occurs, by ...

New electrical energy storage material shows its power

August 24, 2016

A powerful new material developed by Northwestern University chemist William Dichtel and his research team could one day speed up the charging process of electric cars and help increase their driving range.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.