الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Sunflower (Heilanthus annuus), Gazania (Gazania rigens), Gaillardia (Gaillardia Pulchella), Zinnia (Zinnia elegans) and chrysanthemum (Chrysanthemum morifollium) species are commonly used due to their medical and nutritional properties, despite the spread of these plants in Egypt and their high levels of medicinal substances, antioxidants, and nutrients, comprehensive research is needed to confirm their effectiveness and explore potential applications. Thus, the main purpose of this work is to identify novel and natural antioxidants in these plants. To achieve this purpose, the level and concentration of antioxidants in all selected plants were verified in two ways: biochemical and molecular analysis. Total phenolic contents (TPC) and the [2,2-diphenyl -1-picrylhydrazyl] (DPPH) Scavenging antioxidant activity test. These assays were successfully applied to determination of the antioxidant capacity of complex samples, so they were used with the five research samples as biochemical analysis. Additionally, the research concluded measuring the expression of some antioxidant genes by Quantitative Real-Time PCR (APX3*, CATA1, PAL and Actin as a housekeeping gene) as a molecular analysis. The research concluded the following results: TPC analysis showed that sunflower and chrysanthemum had the highest phenolic contents, 3.26±0.39 and 2.99±0.22, respectively. Furthermore, DPPH method, the extracts of sunflower, Gazania, Gaillardia, Zinnia, and chrysanthemum species showed no statistically significant difference in antioxidant activity. The antioxidant genes expression had a different expression in each sample; In Gazania, the floral parts had higher CATA1 expression. In the leaves of the same plant CATA1 expression was the lowest compared to Sunflower. CATA1 levels expression in the leaves of Gaillardia and chrysanthemum were higher when compared to Sunflower. On the other hand CATA1 expression in Gaillardia and chrysanthemum floral parts were lower compared to Sunflower. Hence, PAL expression rates showed some similarities and some differences between the leaves and the flowery parts. Interestingly, PAL expression was elevated in chrysanthemum floral parts. In the same plant leaves PAL expression showed the highest level compared to Sunflower. The expression of PAL in Gazania leaves was higher compared to Sunflower. In the same plant floral parts, the expression of PAL gene was the lowest in comparing to Sunflower. In Zinnia and Gaillardia, PAL expression of the floral parts was higher. Otherwise, PAL gene expression in the leaves of the pervious plant showed lower levels compared to Sunflower. The relative expression of the APX3 gene in Zinnia was down regulated in the leaves. Likewise in the flowers of Zinnia the APX3 expression was lower compared to Sunflower. In Gaillardia, the APX3 gene was high levels in leaves. In floral parts of the same plant APX3 gene expression showed the lowest level comparing to the Sunflower.