الفهرس 
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Abstract
Soybean (Glycine max (L.) Merrill) is a crop of world economic importance. The objective of this work was to evaluate, eight soybean cultivars (Giza 21, Giza 22, Giza 35, Giza 111, Giza 82, Giza 83, Crawford, and Holliday). The chemical composition of eight soybean cultivars were estimated. On the other hand, methanolic extracts of the seeds of eight soybean cultivars were prepared, analyzed to determine their total phenolic compounds (TPC), total flavonoids content (TF), antioxidant activities (DPPH and FRAP- assay), and in vitro antiproliferative activities against HepG-2 and MCF-7. HPLC was used to detect and quantify syringic, quercetin, gallic acid, benzoic acid, genistein, daidezein, P. coumaric, glycitein, and Ferulic acid. The results of chemical composition revealed no significant differences among some cultivars and significant differences among others in constituents, which reflect the variations in genetic background and/or origin, Giza 21, Giza 111, and Crawford cultivars recorded higher than 40% crude protein. The analysis revealed TPC values in seed extracts ranging from 10.5 mg GAE/g extract in Giza 35 to 6.4 mg GAE/g extract in Giza 22. Total flavonoids (TFC) varied from 1.20 mg QE/g extract in Giza 111 to 0.55 mg QE/g extract in Crawford. An HPLC chromatogram shows the isoflavones compounds (genistein, daidezein and glycitein). Giza 35 exhibited the highest content of genistein and daidezein (30.00 %, 15.07 %, respectively) while Giza 111 was recorded the lowest genistein and daidezein amount (15.87 %, 1.87 %, respectively). Giza 35 exhibited the highest free radical scavenging activity (61.833 %) whereas Holliday had the lowest (47.928 %). The results of the MTT assay demonstrated that the soybean methanolic extracts inhibited the proliferation of HepG-2 and MCF-7 cells in dose-dependent manners. Giza 35 exhibited the highest cytotoxic activity. Protein electrophoretic banding patterns of SDS-PAGE and ISSR-PCR analyses were performed to establish molecular diversity pattern for eight soybean cultivars (Giza 21, Giza 22, Giza 35, Giza 111, Giza 82, Giza 83, Crawford, and Holliday) and to elucidate their genetic relationships. The results of protein banding pattern showed a low level of polymorphism, so cannot be used for complete discrimination among the eight cultivars under study. However, the results of protein profiles could be considered as indicators for general protein model pattern for the studied soybean cultivars. On the other hand, ISSR-PCR profiles revealed high levels of polymorphism among the five cultivars. Ten primers successfully generated reproducible polymorphic products. Both number and size of the amplified products varied considerably with different primers and a sum of 103 polymorphic and 20 monomorphic bands were generated in all cultivars that used. A total of 36 unique bands were also identified, 13 positive unique bands and 23 negative unique bands. Four of the primers were more successful in cultivar’s identification since they produced high polymorphism and unique bands that are characteristics of each cultivar under study. The combination of all polymorphic bands generated by the ten primers, were enough to discriminate between the examined soybean cultivars. To elucidate the genetic relationship, a dendrogram was constructed using both SDS-PAGE and ISSR profiles. The resulting dendrogram from ISSR profiles based on clustering analysis grouped the eight soybean cultivars into seven clusters, The first and the second and third and the Fourth and the Fifth and the Sixth groups included Crawford, Giza111, Giza 22, Giza35, Giza82 and holiday, respectively where each cultivar was in separate group. While the seven-group included two cultivars Giza21 and Giza83.On the other hand The cluster analysis that based on SDS-PAGE markers (plant seeds and subunits and total protein) classified the studied cultivars into four main groups The first groups included Giza 35, while the second group comprises Giza21, Giza22, Giza111 and Crawford, and the third group comprises Giza 82 while the Fourth group comprises holiday and Giza83. The second group has been subdivided into two subgroups; the first subgroup comprises two cultivar Crawford and Giza22 whereas the second subgroup includes the two cultivars Giza21and Giza111. In conclusion, Giza 35 cultivar recorded the highest TPC and TFC values and antioxidant and cytotoxic activities. Therefore, this cultivar can be used as a source to produce pharmaceutical and medicinal products rather than as a nutritional source of protein.