ISHS Acta Horticulturae 440: International Symposium on Plant Production in Closed Ecosystems
QUANTITATIVE DIFFERENCES IN BIOLOGICALLY ACTIVE COMPONENTS AMONG HYDROPONICALLY CULTURED LETTUCE AND ENDIVE CULTIVARS |
| Authors: | K. Amimoto, H. Fukui |
| Keywords: | biologically active component, electrical conductivity, endive, hydroponics, lettuce |
| Abstract:
Biologically active components (chlorogenic acid, caffeic acid, chicoric acid and 3,5-dicaffeoylquinic acid) in lettuce (Lactuca sativa L.) and endive (Cichorium endivia L.) were determined by high-performance liquid chromatography (HPLC) in order to evaluate the chemical differences among cultivars cultured at various levels of electrical conductivity (EC) of the hydroponic solution. Five cultivars of lettuce composed of three types (leaf lettuce, stem lettuce and cos lettuce) and one cultivar of endive were cultured using hydroponics (NFT) in a greenhouse at three different times in August through October, 1995. EC was adjusted to 2.4, 3.6 and 4.8 mS · cm-1 with the same relative ratios of nutrients. Plant samples of the edible parts were soaked in methanol, and the extracts were analyzed by HPLC. Chlorogenic acid, chicoric acid and 3,5-dicaffeoylquinic acid were identified by MS and NMR, and caffeic acid by comparison of its HPLC retention time with that of a standard. Chlorogenic acid and chicoric acid were the main components and the same HPLC retention times were observed in all the cultivars, indicating that there were no qualitative differences among the cultivars examined. However, the peak areas of the above four components varied with the cultivars and with culture conditions, indicating a variation in their contents. Cultivars cultured at EC 3.6 mS · cm-1 contained larger concentrations of chlorogenic acid and 3,5-dicaffeoylquinic acid than those cultured at EC 2.4 mS · cm-1, whereas the concentrations of caffeic acid and chicoric acid were lower in leaf lettuce cultured at EC 3.6 mS · cm-1. Among the five cultivars, quantitative differences in the chemical components were also significant at the P< 0.01 level. In addition, significant quantitative differences (P< 0.01 level) in chlorogenic acid and 3,5-dicaffeoylquinic acid were found among the cultivars cultured at various EC levels. These results indicate that the contents and composition of secondary metabolites in these vegetables vary among cultivars and can also be controlled by altering the culture conditions such as the EC level of the culture solution. | |
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