ISHS Acta Horticulturae 747: VIII International Symposium on Protected Cultivation in Mild Winter Climates: Advances in Soil and Soilless Cultivation under Protected Environment
INFLUENCE OF UV-LIGHT ON THE ANTIOXIDATIVE CAPACITY OF EXTRACTS FROM SPINACIA OLERACEA L. AND GYNURA BICOLOR (WILLD.) DC |
| Authors: | G. Schirrmacher, W.H. Schnitzler, J. Graßmann |
| Keywords: | UV-B, pholyphenols, carotenoids, spinach, xanthinoxidase, ABTS, Folin-Ciocalteu |
| Abstract:
When UV-light, especially UV-B, reaches the leaves of plants, this can lead to an augmentation of secondary plant metabolites (SPM). These compounds are, for example, pholyphenols (phenolic acids or flavonoids) or carotenoids (Stapleton, 1992; Bolink et al., 2001). Since these compounds are valuable for human nutrition (Kaur and Kapoor, 2001), we investigated (in the year 2003) if the antioxidative capacity (AC) is altering when plants (spinach and gynura) are grown under a controlled environment in a greenhouse and are radiated with UV-B. We examined the AC of polyphenolic and carotenoid extracts of the treated plants in two biochemical test systems: Xanthin/Xanthinoxidase- and ABTS-system. Collateral determination of Total Phenolics by means of Folin-Ciocalteu and HPLC-analyses helped to explain the results. We found that the content of SPM was altered by a treatment with UV-B. The treatment leads to an increase in total phenolics, whereas carotenoids reacted with a slight decrease. The AC of phenolic extracts from gynura was increased in both in vitro test systems. Spinach extracts only showed positive results in the ABTS-System. The AC of carotenoid extract of spinach was not affected by a light-treatment. For gynura a slight rise could be observed. HPLC-analyses confirmed that the composition of phenolic SPM was not changed randomly, but protected the plant from UV-B. | |
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