الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 164 |  |  |
| | | from | 164 | | |
Abstract
The current study was aimed to synthesis and characterization of silver (AgNPs) & gold (AuNPs) nanoparticles using Callistemon citrinus (Family Myrtaceae) leaf extract, and to evaluate their in vitro antioxidant, antimicrobial, cytotoxic activities as well as their total phenolic content (TPC). Silver and gold were synthesized and characterized via UV-vis absorbance spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD) analyses. The antioxidant activity was evaluated using dot-blot and DPPH staining, and via phosphomolybdenum assays. Also, the in vitro antimicrobial activity was evaluated via disc agar plate method. The cytotoxic activity was evaluated via brine shrimp lethality test (BSLT), and TPC was estimated via Folin-Ciocalteu’s assay. The transmission electron microscopy (TEM) analysis showed that the sizes of the synthesized AgNps ranged from 8-14nm with maximum UV/vis absorbance at 450nm. Also, the synthesized AuNPs exhibited an average size of 5.8 to 8.84nm with maximum UV/vis absorbance at 535nm. Moreover, the results revealed that TPC of the tested extracts was ranged from 67.75 to 617.84 mg gallic acid equivalent (GAE)/g dry extract. The total antioxidant capacity (TAC) was ranged from 110.56 to 904.06 mg ascorbic acid equivalent/g dry extract. Furthermore, there is a promising antimicrobial activity against four strains with inhibition zones ranged from 7.5 to 18.5mm, Penicillin G was used as positive control at concentration of 100 μg/disc. In terms of LC50 the n-butanol extract (63.09 μg/ml) was the most potent cytotoxic against brine shrimp (Artemia salina L.), followed by EtOAc (100.0 μg/ml). In, conclusion the leaves of Callistemon citrinus showed a noticeable antioxidant,
antimicrobial & cytotoxic activities and the ability to produce AgNPs and AuNPs.
Also, the current study were to use the leaves of Syzygium jambos (syn. Eugenia jambos L.) (Family Myrtaceae) for the biosynthesis of silver (AgNPs) and gold (AuNPs) nanoparticles and to evaluate their in vitro antioxidant, antimicrobial, cytotoxic activities as well as their total phenolic content (TPC).The antioxidant activity was evaluated qualitatively using dot-blot and DPPH staining, and quantitatively via phosphomolybdenum assay. Also, the in vitro antimicrobial activity was evaluated via disc agar plate method against five pathogenic microbial strains including Gram +ve and Gram -ve bacteria, yeast & fungi. The preliminary cytotoxic activity was evaluated via brine shrimp lethality test (BSLT), and total phenolic content (TPC) was estimated via Folin-Ciocalteu’s assay. Silver (AgNPs) and gold (AuNPs) were synthesized and characterized via UV-vis absorbance spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD) analyses. The results indicated that AgNPs and AuNPs can be synthesized using Syzygium jambos leaf extract. The transmission electron microscopy (TEM) analysis showed that the sizes of the synthesized AgNps ranged from 6-23nm, and the synthesized AuNPs also exhibited an average size of 6-23nm. Moreover, the results revealed that TPC of the tested extracts was ranged from 548.85 to 123.30 mg gallic acid equivalent (GAE)/ g dry extract. The total antioxidant capacity (TAC) was ranged from 643.90 to 147.96mg ascorbic acid equivalent (AAE)/g dry extract. Furthermore, there is a promising antimicrobial activity against four strains viz., Pseudomonas aeruginosa with inhibition zones from 9 to 15.5mm; Staphylococcus aureus with inhibition zones from 9 to 14.5mm; Methicillin-resistant Staphylococcus aureus with inhibition zones from
8.5 to 14.5mm and Candida albicans with inhibition zones from 9.5 to 13.5mm; respectively for 85% MeOH, defatted 85% MeOH, pet. ether, CH2Cl2, EtOAc, n-BuOH, H2O, and 85% MeOH of flower part), while the cytotoxic results against brine shrimp (Artemia salina L.) showed LC50 values ranged from 50.11 to 446.68 μg/ ml.
Six compounds were isolated from the n-butanol extract of Callistemon citrinus plant, they were identified as; nepetolide )1), callislignan A (2),
6,8-dimethoxy-4,5-dimethyl-3-methyleneisochroman-1-one (3), 7-O-benzoyl-β-D-glucopyranoside (4), 5, 7, 3’, 5’-tetrahydroxy-6, 8-di-C-methyl flavanone (5), and (2R,3R,4S,5S)-2,4-bis(4-hydroxyphenyl)-3,5-dihydroxy-tetrahydropyran (6). These compounds (1-6) were evaluated as antioxidant and antimicrobial agents.
Eight compounds were isolated from the n-butanol extract of Syzygium jambos plant, they were identified as; quercetin-3-O-rutinoside (7),
prenylbenzoic acid 4-β-D-glucoside (8), morolic acid 3-O-caffeate (9), 5,4’-dihydroxy, 7-methoxy, 6-methyl-flavone (10), 3,4,5-trihydroxybenzoic (11), quercetin (12), isoetin-7-O-β-D-glucopyranoside (13), and (4’-hydroxy-3’-methoxyphenol-β-D-[6-O-(4”-hydroxy-3”, 5”-dimethoxylbenzoate)]-glucopyranoside) (14). These compounds (7-14) were evaluated as antioxidant and antimicrobial agents.
Also the GC/MS analysis of its leaves essential oil presented six identified compounds representing 91% of the total oil constituents, which were major and identified based on their retention times and mass spectral fragmentation patterns into; 3-methoxyphenol (15.06%), Isofraxidin (13.96%), Hydronaphthoquinone (10.84%), Methimazole (8.82%), Sinapic acid (6.93%), as the major constituents.
Moreover, five identified components representing 92% of its total oil composition, which were identified based on their retention times and mass spectral fragmentation patterns using GC/MS analysis into; δ-cadinene (10.85%), cumaldehyde (10.75%), β-himachalene (6.40%), isocaryophyllene (6.39%), and β-cedrene (5.63%) as the major components, most of them belonging to sesquiterpenes.