5 research outputs found
Advances in structure elucidation of small molecules using mass spectrometry
The structural elucidation of small molecules using mass spectrometry plays an important role in modern life sciences and bioanalytical approaches. This review covers different soft and hard ionization techniques and figures of merit for modern mass spectrometers, such as mass resolving power, mass accuracy, isotopic abundance accuracy, accurate mass multiple-stage MS(n) capability, as well as hybrid mass spectrometric and orthogonal chromatographic approaches. The latter part discusses mass spectral data handling strategies, which includes background and noise subtraction, adduct formation and detection, charge state determination, accurate mass measurements, elemental composition determinations, and complex data-dependent setups with ion maps and ion trees. The importance of mass spectral library search algorithms for tandem mass spectra and multiple-stage MS(n) mass spectra as well as mass spectral tree libraries that combine multiple-stage mass spectra are outlined. The successive chapter discusses mass spectral fragmentation pathways, biotransformation reactions and drug metabolism studies, the mass spectral simulation and generation of in silico mass spectra, expert systems for mass spectral interpretation, and the use of computational chemistry to explain gas-phase phenomena. A single chapter discusses data handling for hyphenated approaches including mass spectral deconvolution for clean mass spectra, cheminformatics approaches and structure retention relationships, and retention index predictions for gas and liquid chromatography. The last section reviews the current state of electronic data sharing of mass spectra and discusses the importance of software development for the advancement of structure elucidation of small molecules
Double Bond Stereochemistry Influences the Susceptibility of Short‑Chain Isoprenoids and Polyprenols to Decomposition by Thermo‑Oxidation
Alcohols are common constituents of
living cells. They are usually assigned a role in the adaptation
of the cell to environmental stimuli, and this process
might give rise to their oxidation by reactive oxygen
species. Moreover, cellular isoprenoids may also undergo
various chemical modifications resulting from the physicochemical
treatment of the tissues, e.g., heating during food
processing. Susceptibility of isoprenoid alcohols to heat
treatment has not been studied in detail so far. In this study,
isoprenoid alcohols differing in the number of isoprene units
and geometry of the double bonds, β-citronellol, geraniol,
nerol, farnesol, solanesol and Pren-9, were subjected to
thermo-oxidation at 80 °C. Thermo-oxidation resulted in the
decomposition of the tested short-chain isoprenoids as well
as medium-chain polyprenols with simultaneous formation
of oxidized derivatives, such as hydroperoxides, monoepoxides,diepoxides and aldehydes, and possible formation of oligomeric derivatives. Oxidation products were monitored by GC-FID, GC-MS, ESI-MS and spectrophotometric methods. Interestingly, nerol, a short-chain isoprenoid with a double bond in the cis (Z) configuration, was more oxidatively stable than its trans (E) isomer, geraniol. However, the opposite effect was observed for medium-chain polyprenols, since Pren-9 (di-trans-poly-cis-prenol) was more susceptible to thermo-oxidation than its all-trans isomer, solanesol. Taken together, these results experimentally confirm that both short- and long-chain polyisoprenoid alcohols are prone to thermo-oxidation