الفهرس 
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Abstract
Samples of Avicennia marina (Forsk.) Vierh were collected from a location at Safaga Mangrove Stand, 17 km south Safaga, Red Sea shore, Egypt. Collection of these samples was achieved at different seasons; i.e., summer, autumn, winter, and spring. The collected plant samples were divided into leaves, lateral branches, bark and seeds (seeds were absent in spring and winter), ready for experimentation as mentioned in the methods. This was achieved in order to detect the appropriate harvesting time and plant organ, where highest amounts of respective plant components are attained. For this purpose, the contents of ash, lipids, cellulose, hemicellulose, pectin, low molecular weight carbohydrates (LMWC), crude proteins, and polysaccharides were determined. The most interesting results are summarized in the following:
1. Polysaccharides comprised the major constituents of Avicennia marina organs and hence these polymers were promising for further studies. In this instance, the second part of the present work was devoted to their isolation, chemical analysis, and biological evaluation of their various fractions under different conditions.
2. The extracted and isolated polysaccharides represented two fractions: PI including material of relatively high molecular weight and that with lower molecular weight designated as PII-product. In general, the PI-yield in different plant organs at different seasons was higher than that of corresponding PII-product. Maximum level of PI-product was recorded in the branches at summer, whereas highest yield of PII-product was shown in the autumn bark.
3. Analysis of the PI and PII-products showed inclusion of various proportions of D-galactose, D-glucose, L-arabinose, and D-xylose moieties. Some of the polysaccharide fractions also included D-glucuronic acid, D-mannose, and L-rhamnose units, as minor constituents.
4. Biological evaluation of the PI and PII-products was carried out through assaying their anticoagulation and fibrinolytic activities. Furthermore, another biological activity of the same products was also evaluated, in a separate part of this work, by determining their growth regulation activities, using the callus of Helianthus annus L. as a test object.
5. Mostly, the PI-products were characterized by relatively higher fibrinolytic and anticoagulant activities than the corresponding PII-products. The most important results showed that seven of the natural components in the PI- product and three in the PII-product exhibited fibrinolytic activities higher than that of the standard Hemoclar preparation, whereas three residues in each of the PI-and the PII-materials showed fibrinolytic activity similar to that of the standard Hemoclar.
6. A correlation was found between highest fibrinolytic activities (higher than Hemoclar) in the PI-product and higher ratios of the minor sugar components D-glucuronic acid and L-rhamnose, in addition to higher pentose portions. In the PII material, on the other hand, highest fibrinolytic activity was underlined by higher content of L-arabinose.
7. Further chemical modification has been tried to be carried out for getting better biological activity of the polysaccharide products of Avicennia marina. For this purpose a native polysaccharide (PS) material, including both PI-and PII-products, was isolated from the leaves collected in autumn, where highest availability of these organs was attained, with high fibrinolytic activity. Chemical analysis and fractionation of the PS extract was carried out as usual and the biological activity of each model was determined. Each of the two fractions F3 and F5, which exhibited the highest and the following biological activity also matched highest sulfate values, respectively. Thus, sulfating the polysaccharide fractions of Avicennia marina was promising, with respect to enhancing their biological activity. The higher sulfate contents (up to 61.8%), higher toluidine blue values, and lower carbohydrate contents of the polysaccharide fractions with highest activity indicated a nearly complete sulfation of their chains.
8. Assessing possible growth regulating activities of the polysaccharide fractions of Avicennia marina plant organs at different seasons was carried out, using callus tissue initiated from Helianthus annus L. seedlings. The six polysaccharide models exhibiting higher bioactivities were experimented, where each was added to the culture medium at a specific concentration (0.4 mg/L). Some of the tested fractions showed an influence on the morphogenetic response of the callus tissue. The most interesting result was the rooting- inductive effect of the PI-products originated from the autumn leaves and the winter bark