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Title: Antioxidant properties of seeds and sprouts of amaranth and quinoa, and their influence on selected parameters of antioxidative status in in vitro and in vivo study

Abstract:

Cereals and cereal-based foods have been recognized as one of the major constituents of a healthy diet. Their significance in human nutrition is best reflected in the position they occupy (especially unrefined products) at the bottom of the food pyramid. Pseudocereals, such as amaranth and quinoa that I examined, are poorly known in Poland. Research in amaranth (Amaranthus cruentus) and quinoa (Chenopodium quinoa), in Poland and worldwide, is rather scarce and mostly conducted by researchers from South America. It is due to the fact that these cereals have been the staple foods for the people of the continent for thousands of years, and thus, they have been of key importance to its successive civilizations. Neither amaranth nor quinoa is classified as true cereal in taxonomy, since they belong to the class of dicotyledons, unlike true cereals which are classified as monocotyledons. In accordance with the available data, seeds of amaranth and quinoa have high nutritional values, which are attributed to higher contents of proteins (including essential amino acids) than those of wheat, rye, and oat seeds, and some unsuturated fatty acids. In-vitro tests in pseudocereals were aimed at assessing the antioxidant potential of their seeds and very little known sprouts as an example of the so called new vegetables. In-vitro tests were carried out by three methods: FRAP, ABTS and DPPH and made it possible to measure the antioxidative activity in seeds and sprouts of amaranth and quinoa. In-vitro testing also led to significant improvement in the methods of sprouts cultivation and allowed for finding the optimal tillage conditions (depending on the amount of light) and its length so that sprouts with the highest antioxidant contents can be cultivated. Comparision of the antioxidative activity suggests that antioxidants in quinoa and amaranth differ both in quality and quantity. Quinoa seeds were higher in fast-acting antioxidants (much better results by DPPH were observed for quinoa than amaranth) such as e.g. polyphenols, whose total contents in quinoa were higher than in other seeds. It has also been confirmed by the positive correlation between the total contents of polyphenols in investigated seeds and their antioxidative activity. Contrary to seeds, amaranth sprouts had higher antioxidative activity than quinoa sprouts – a result confirmed by all analytical methods employed. Tests by DPPH showed the greatest differences, which may indicate that amaranth sprouts contained new, fast-acting antioxidative substances other than polyphenols, as their total content was still higher in amaranth sprouts. In amaranth sprouts, especially in amaranth v. Aztek, the level of anthocyanins increased significantly. The synthesis of antioxidants in sprouts (such as e.g. ascorbic acid and tocopheroles which were not investigated in this study) could have been significantly enhanced by light. In vitro testing allowed to determine which chemical substances contribute to antioxidative activity of these foods. Spectrophotometric methods were employed to measure the total contents of anthocyanins and polyphenols. Qualitative and quantitative analysis of flavonoids and phenolic acids was carried out by the HPLC/DAD method. Total contents of investigated phenolic acids in seeds and sprouts of quinoa were higher than in amaranth. The main phenolic acid fund in seeds and sprouts of all plant materials was gallic acid, with higher concentrations in seeds and sprouts of amaranth than in quinoa. Moreover, the following acids were found in the seed materials: p-hydroksybenzoic acid, vanillic acid, p-coumaric acid, caffeic acid, and cinnamic acid; whereas, p-coumaric acid, ferulic acid and syringic acid were found in sprouts. Quinoa seeds were several times higher in flavonoids than amaranth seeds. Seeds of quinoa contained: rutin, orientin, vitexin, morin and traces of hesperidin and neohesperidin. No flavonoids were detected in the seeds of amaranth v. ; Aztek, whereas v. Rawa contained only vitexin and isovitexin. The main flavonoid found in sprouts was rutin. Its contents were four times higher in quinoa sprouts than in amaranth. It was the only investigated flavonoid detected in amaranth sprouts, whereas quinoa sprouts also contained vitexin, isovitexin and morin. Sprouting conditions (daylight vs. darkness) did not have any influence on the gallic acid content, whereas light caused an increase in the level of rutin and darkness – an increase in the levels of vitexin and isovitexin. The above mentioned results suggest that seeds and sprouts of the investigated pseudocereals have relatively high antioxidative activity which can be attributed to the presence of polyphenols, the investigated phenolic acids, flavonoids and anthocyanins. In-vivo tests on rats were carried out to determine whether oxidative stress induced by the administration of 31% fructose could be reduced by co-administration of amaranth or quinoa seeds. The findings demonstrate that in fructose-administered control groups, fructose-induced damage to plasma and other tissues can be partly reduced by co-administration of amaranth and quinoa seeds. Changes in malondialdehyde concentration in plasma of the control group evidence that fructose administration induced oxidative stress. Significant increase in its concentration clearly indicated intensification of lipid peroxidation processes. My studies on the effect of amaranth administration on the antioxidant status of rats’ plasma confirmed that lower doses of amaranth seeds did not protect plasma against fructose-induced lipid peroxidation. Administration of higher doses of amaranth and quinoa seeds provided a protective mechanism, since the concentration of malondialdehyde in plasma decreased significantly, as compared to the control group. Amaranth-enriched fodder, especially in a higher dose, caused a significant increase in catalase and glutathione peroxidase activities in heart tissue of the investigated animals, as compared to the control group. Supplementation with fructose-enriched fodder did not lead to a decrease in glutathione peroxidase activity in this group. It can be concluded that the level of antioxidants present in heart tissue was raised through supplementation with amaranth seeds. These results confirm earlier findings on the advantageous effect of amaranth seeds on the cardiovascular system. Interesting results could be observed in rats supplemented with quinoa. In comparison with groups fed on different fodder, this group had significantly lower activity of enzymes in heart tissue. However, in response to fructose induced stress, a significant increase in glutathione peroxidase was observed, which is indicative of the protective response of cardiomyocytes against free radicals. Therefore, diet therapy can be successfully employed to restore the right concentration of antioxidants, both as a preventive measure, and on a short-term basis to protect againstdamage caused by free-radical processes. According to research, liver exhibits high resistance to moderate oxidative stress, and its enzymatic activity is not easily influenced by diet therapy (glutathione peroxidase and catalase). Increase in enzymatic activity in spleen tissue points to advantageous effect of pseudocereals on its antioxidative status. Results of my study demonstrate that fructose administration did not affect the concentration of total cholesterol in plasma. Additionally, the applied doses of seeds did not have a protective effect on the level of triglicerides which was significantly raised by fructose. However, the seeds changed the level of LDL, which decreased in all investigated groups of animals. It was also observed that the seeds of pseudocereals protected against a decrease in HDL concentration after fructose administration. In the face of the advantageous effects of amaranth and quinoa demonstrated in this study, and no significant side effects observed, pseudo

Level of degree:

2 - studia doktoranckie

Degree discipline:

farmacja

Degree grantor:

Wydział Farmacji

Promoter:

Zofia Zachwiejowa

Date issued:

2009

Format:

application/pdf

Identifier:

oai:dl.cm-uj.krakow.pl:900

Call number:

ZB-110210

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tylko w bibliotece

Location of original object:

Biblioteka Medyczna Uniwersytetu Jagiellońskiego - Collegium Medicum

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Last modified:

Sep 11, 2019

In our library since:

Nov 21, 2012

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