Biosynthesis of 15N-labeled cylindrospermopsin and its application as internal standard in stable isotope dilution analysis.

Abstract

Cylindrospermopsin (CYN) is a cyanobacterial toxin associated with human and animal poisonings. Due to its toxicity in combination with its widespread occurrence, the development of reliable methods for selective, sensitive detection and accurate quantification is mandatory. Liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis using stable isotope dilution analysis (SIDA) represents an ideal tool for this purpose. U-[(15)N5]-CYN was synthesized by culturing Aphanizomenon flos-aquae in Na(15)NO3-containing cyanobacteria growth medium followed by a cleanup using graphitized carbon black columns and mass spectrometric characterization. Subsequently, a SIDA-LC-MS/MS method for the quantification of CYN in freshwater and Brassica matrices was developed showing satisfactory performance data. The recovery ranged between 98 and 103 %; the limit of quantification was 15 ng/L in freshwater and 50 μg/kg dry weight in Brassica samples. The novel SIDA was applied for CYN determination in real freshwater samples as well as in kale and in vegetable mustard exposed to toxin-containing irrigation water. Two of the freshwater samples taken from German lakes were found to be CYN-contaminated above limit of quantification (17.9 and 60.8 ng/L). CYN is systemically available to the examined vegetable species after exposure of the rootstock leading to CYN mass fractions in kale and vegetable mustard leaves of 15.0 μg/kg fresh weight and 23.9 μg/kg fresh weight, respectively. CYN measurements in both matrices are exemplary for the versatile applicability of the developed method in environmental analysis.

• Authors: Katrin Kittler, Holger Hoffmann, Franziska Lindemann, Matthias Koch, Sascha Rohn, Ronald Maul
• Journal: Analytical and bioanalytical chemistry (Anal Bioanal Chem) Vol. 406 Issue 24 Pg. 5765-74 (Sep 2014) ISSN: 1618-2650 [Electronic] Germany
• PMID: 25064600 (Publication Type: Evaluation Study, Journal Article)

Chemical References

• Alkaloids
• Bacterial Toxins
• Cyanobacteria Toxins
• Marine Toxins
• Microcystins
• Nitrogen Isotopes
• cylindrospermopsin
• Uracil

Topics

• Alkaloids
• Bacterial Toxins (chemical synthesis, chemistry, metabolism)
• Brassica (chemistry, microbiology)
• Cyanobacteria (metabolism)
• Cyanobacteria Toxins
• Fresh Water (analysis, microbiology)
• Indicator Dilution Techniques (standards)
• Isotope Labeling
• Marine Toxins (chemical synthesis, chemistry, metabolism)
• Microcystins (chemical synthesis, chemistry, metabolism)
• Nitrogen Isotopes (chemistry)
• Reference Standards
• Tandem Mass Spectrometry (instrumentation, methods, standards)
• Uracil (analogs & derivatives, chemical synthesis, chemistry, metabolism)