Changes in composition of phenolic compounds and antioxidant properties of <Emphasis Type="Italic">Vitis amurensis</Emphasis> seeds germinated under osmotic stress |
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Authors: | Stanisław Weidner Magdalena Karamać Ryszard Amarowicz Ewa Szypulska Aleksandra Gołgowska |
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Institution: | (1) Department of Biochemistry, Faculty of Biology, University of Warmia and Mazury in Olsztyn, M. Oczapowskiego St. 1A, 10-957 Olsztyn-Kortowo, Poland;(2) Division of Food Science, Institute of Animal Reproduction and Food Research of Polish Academy of Sciences, Tuwima St. 10, Box 55, 10-718 Olsztyn 5, Poland |
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Abstract: | The research focused on the changes of phenolic compounds as well as their antiradical activity and reducing power isolated
from Amur grape (Vitis amurensis) seeds during germination under optimal conditions and under osmotic stress. The seeds were found to contain tannins, (+)
catechin, (−) epicatechin, and gallic acid (in free, ester- and glycoside-bound forms). Extracts from the seeds were also
shown to contain two other phenolic acids: caffeic and p-coumaric acids, in very low levels. During a 3-day seed germination test under osmotic stress (−0.5 MPa), the content of
total phenolics, tannins and phenolic acids declined as compared to the control. However, seed germination under stress conditions
led to a significant increase in the amount of catechins. Because catechin is the one of the units in condensed tannins, its
dynamic increase during seed germination may be involved in metabolism of tannins under osmotic stress. It is also likely
that the synthesis of catechins is greater under stress conditions and these compounds may be engaged in the process of acclimatization
of grapevines to stress conditions. The content of total phenolic compounds in seed extracts is positively correlated with
their antioxidant properties. The extracts from seeds germinated under optimal conditions exhibited strong antiradical properties
against the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical as well as reducing power. As regards the extracts from grape seeds
germinated under osmotic stress, this capability was much weaker. The research demonstrated that antioxidants could interfere
with the oxidation process induced by various stresses by acting as oxygen scavengers, therefore the tolerance to drought
stress might be correlated with an increase in the antioxidant potential. |
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Keywords: | Vitis amurensis Grape seeds Germination Osmotic stress Phenolic acids Tannins Catechins |
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