|Authors: ||A.L. Thomas, P.L. Byers, C.E. Finn, Y.-C. Chen, G.E. Rottinghaus, A.M. Malone, W.L. Applequist|
|Keywords: ||Sambucus, phytochemical, medicinal, phenolic, quercetin|
The American elderberry (Sambucus nigra subsp. Canadensis) is being increasingly consumed as a nutraceutical.
In Europe, tea made from flowers of the elderberry subspecies nigra is a popular herbal treatment for respiratory infections such as colds and influenza, but little is known about the medicinal attributes of the subspecies Canadensis. Potentially-active compounds in elderberry include phenolics such as rutin, chlorogenic acid, and quercetin.
Genetic, environmental and seasonal influences on the concentration of such metabolites in the fruit and non-fruit tissues of American elderberry are unknown.
The objective of this study was to quantify the production of medicinal compounds in various non-fruit elderberry tissues in response to genotype, environment and season.
In 2003, an experiment was established at Mt.
Vernon and Mountain Grove, Missouri, and Corvallis, Oregon (USA) to evaluate the performance of 10 new elderberry selections compared with two older standard cultivars.
In 2005, tissue samples were collected from each site in early June (at peak anthesis) and late July (at initiation of fruit ripening). Representative samples of leaf, flower, new green stem, and year-old woody stem were collected from all plots.
Dried samples were analyzed by HPLC for the phenolic compounds chlorogenic acid and rutin.
Mean levels of chlorogenic acid were 3,367 mg kg-1 in leaf, 2,064 mg kg-1 in flower, 584 mg kg-1 in green stem, and 1,111 mg kg-1 in woody stem, whereas mean levels of rutin were 6,746 mg kg-1 in leaf, 5,546 mg kg-1 in flower, 187 mg kg-1 in green stem, and 44 mg kg-1 in woody stem.
Levels of chlorogenic acid and rutin generally varied among the 12 cultivars in leaf tissues only, with the cultivar ‘Johns’ showing very high levels of both compounds.
Significant, but somewhat inconclusive, differences in rutin and chlorogenic acid levels were detected among the three locations; the two Missouri sites tended to have higher levels of rutin.
In both leaf and green stem tissues, higher phytochemical levels were detected within tissues harvested earlier in the season.
Such genotypic, environmental, and seasonal variations in occurrence of these two representative compounds point to the possibility of focused agricultural production of specific phytochemicals.
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