Send to

Choose Destination
J Agric Food Chem. 2007 Oct 3;55(20):8243-50. Epub 2007 Sep 6.

S-alk(en)yl-L-cysteine sulfoxides and relative pungency measurements of photosynthetic and nonphotosynthetic tissues of Allium porrum.

Author information

Department of Plant Agriculture, University of Guelph, 50 Stone Rd., Guelph, Ontario, Canada.


Three standard assays for pyruvate gave equivalent measurements of relative pungency for two leek cultivars ( 'Tadorna' and 'Ramona'). Background pyruvate levels varied depending on the assay used, ranging from 0.4 (lactate dehydrogenase) to 1.5 (high-performance liquid chromatography, HPLC) micromol g(-1) fresh weight (FW) on average. The relative pungencies of the two leek cultivars were also compared to total concentrations of the S-alk(en)yl-L-cysteine sulfoxides (RCSOs). The average ratio of EPy to total RCSOs was 10.9, indicating that standard pungency assays underestimate the levels of RCSOs in the tissue. A detailed analysis of 'Tadorna' leaves showed that total RCSO concentrations decreased acropetally. Profiles were composed of (-/+)-methyl-, (-/+)-ethyl-, (+)-propyl-, and (+)-1-propenyl-L-cysteine sulfoxide (MCSO, ECSO, PCSO, and 1-PeCSO, respectively). (+)-PCSO was the most prominent in green (2.4 mg g (-1) FW), yellow (5.5 mg g (-1) FW), and white (3.8 mg g (-1) FW) tissues. The prop(en)yl-L-cysteine sulfoxide derivatives were dominant in tissues that had photosynthetic capacity. The (+)-MCSO levels were high in the bulb (3.6 mg g (-1) FW). Interestingly, detectable levels of (-/+)-ECSO were measured in the leaves ( approximately 0.5 mg g (-1) FW). RCSO profiles of the different tissue regions were similar, but more (+)-PCSO and (+)-1-PeCSO were detected in the bulb. In general, mature upper leaf tissues had lower levels of total RCSOs. Overall, mild extraction methods and a low-temperature HPLC protocol (preferably with long retention times) achieved adequate compound separation and resolution of the diastereomers.

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for American Chemical Society
Loading ...
Support Center