الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 231 |  |  |
| | | from | 231 | | |
Abstract
This work aimed to study the bioactivities of polysaccharides extracted from M. oleifera leaves and how to benefit from its characteristics in nanomaterial preparation. The study plan was as follow:
• Collecting and preparing of M. oleifera leaves in powder form.
• Preparation of different extracts from leaves by different solvents including methanol, 70% ethanol, ethyl acetate and hot dist.H2O.
• Extraction of crude polysaccharides from leaves by hot water extraction method.
• Studying antimicrobial, antibiofilm and antioxidant activities of both crude leaves extracts and crude polysaccharides.
• Results revealed that crude polysaccharides had higher antimicrobial, antibiofilm and antioxidant activity than crude leaves extracts.
• Crude polysaccharides were fractionized by fractional alcohol precipitation method. Three polysaccharide fractions MOLP-1, MOLP-2 and MOLP-3 were obtained.
• Polysaccharide fractions were investigated for their antimicrobial, antibiofilm and antioxidant activities.
• MOLP-1 represented the most effective polysaccharide fraction. So, it was characterized by colorimetric analysis, HPLC, FTIR and SEM.
• MOLP-1 was used as a reducing and bio-capping agent for the biosynthesis of polysaccharide nanocomposite with silver (MOLP-1-AgNPs)
• MOLP-1-AgNPs were characterized by UV-vis spectrophotometer, TEM, XRD, FTIR and DLS.
• Both MOLP-1 and MOLP-1-AgNPs were tested for their antimicrobial, antibiofilm, antioxidant, immunomodulatory, anticancer and antidiabetic activities.
Results revealed that :
• Crude polysaccharides had higher antibacterial activity against both Gram positive and Gram-negative bacteria than other crude extracts while had no antifungal activity against the tested strains.
• Hot water crude extract had high antioxidant activity followed by crude polysaccharides and other crude extracts.
• Crude polysaccharides had the highest biofilm inhibition activity compared to other crude extracts.
• Fractionation of crude polysaccharides resulted in three fractions MOLP-1, MOLP-2 and MOLP-3 with 41.90%, 21.15% and 2.20%, respectively.
• MOLP-1 exhibited the highest antimicrobial, antibiofilm and antioxidant compared to crude polysaccharides and other crude extracts.
• Characterization of MOLP-1 revealed that its carbohydrate content, protein content and uronic acid content were 54.74%, 0.16% and 1.086%, respectively. While monosaccharide composition was galactose, rhamnose, fructose, arabinose and glucose with molar ratio 2.02:1.86:1.56:1.38:1, respectively. FTIR exhibited characteristic peaks of polysaccharide at 3415, 2917, 1602, 1412, 1119 and 869 cm-1. The surface morphology of MOLP-1 by SEM looked like as it had a rough surface like clouds with characteristic large wrinkles.
• Polysaccharide nanocomposite with silver MOLP-1-AgNPs were prepared. Its characterization revealed strong absorption peak within the wavelength range of 390-420 nm that confirmed its formation. TEM images revealed that it was spherical in shape with no or little agglomeration having average size 9.5 nm. XRD analysis confirmed its crystalline nature as various peaks appeared at 2 of 37.9, 46.5, 64.3 and 74.7 corresponding to (111), (200), (220) and (311) planes of SAED of MOLP-1-AgNPs, respectively. Its particle size distribution was found to be 62.64 nm and zeta potential value was -36.8 mV which indicated that it was in dispersion with high stability.
Both MOLP-1 and MOLP-1-AgNPs were investigated for their bioactivities, the results revealed that:
• MOLP-1 and MOLP-1-AgNPs had antibacterial activity against Gram-positive and Gram-negative bacteria. MOLP-1 had MIC 200 µg/ml against S. aureus and B. subtilis and 300 µg/ml against E. coli and P. aeruginosa. While MOLP-1-AgNPs had MIC 100 µg/ml against S. aureus and B. subtilis and 200 µg/ml against E. coli and P. aeruginosa.
• Both MOLP-1 and MOLP-1-AgNPs had biofilm inhibitory activity under tested concentration (500 µg/ml) with no significant difference. Both inhibited E. coli and S. aureus biofilm in between (65.6-70.03%).
• MOLP-1-AgNPs had higher antioxidant activity than MOLP-1: IC50 of MOLP-1-AgNPs for DPPH scavenging, ABTS scavenging, H2O2 scavenging, ferrous ions chelating and NO radical scavenging was 97.57, 98.78, 98.05, 112.01 and 152.43 µg/ml, respectively. while it was 105.10, 191.59, 209.66, 218.60 and 356.83 µg/ml for MOLP-1, respectively.
• MOLP-1-AgNPs had higher immunostimulatory activity than MOLP-1 as viability increased within tested concentrations without any toxic effect and production of ROS, NO, IL-6 and TNF-α increased consequently.
• Both MOLP-1 and MOLP-1-AgNPs had anticancer activity against HCT 116 cell line with IC50 116.39 and 177.82 µg/ml, respectively, and anticancer activity against Hela cell line with IC50 115.03 and 109.21 µg/ml, respectively.
• MOLP-1-AgNPs had significant higher antidiabetic activity than MOLP-1 with IC50 =260.60 µg/ml.
• In conclusion, MOLP-1 has potent biological activities and can be used in the biosynthesis of silver particles MOLP-1-AgNPs, which could be used in medicine due to their potent biological activities, safety, and low cost.