الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Egypt has many wild plants such as Sonchus oleraceus, Cichorium
pumilum and Portulacaoleraceae which are one of prefect sources of natural
effective compounds including alkaloids, flavonoids, tannins, terpenes,
steroids, and phenols. In addition, the presence of weeds with the cultivated
crop plants reduces the amount of the crop produced. Also, it is considered as
an undesired weed infecting fields of many crops. In recent years,
nanomaterials have received an intense concentration of researchers due to
their physical and chemical properties, which prompted many researchers to
use a lot of metal, such as, silver, gold and others for the synthesis of them at
the nanoscale level. Several methods have been applied for the synthesis of
nanoparticles namely, chemical, physical and biological methods, but the biosynthesis of nanoparticles by the microorganisms and plant extracts were the favorite method because it had advantages like simplicity, lower cost and environmental-friendly. So, it is called a green chemistry. Therefore, in this study we described the green synthesis of silver nanoparticles from plant
extracts and their capacity as antifungal agents against fungal pathogens and their mycotoxins that can cause various diseases.The most important mycotoxins are AFB1 it is highly toxic, mutagenicand carcinogenic and classified by the International Agency of Research on<Cancer as Group1 human carcinogen. On the other hand, ochratoxin A are>mycotoxins produced by A. ochraceus , it is nephrotoxic that target the kidneys and urinary system in humans and animals also, it is a major cause of kidney failure in many countries. The International Agency for Research on<Cancer classified OTA as possibly a carcinogen (group 2B).from the above there are several strategies were developed to prevent fungal contamination and mycotoxins production which are evaluated and<>Summary And Conclusion123studied from time to time to improve them or to obtain more efficient,
effective and safe methods. So that this study aimed to use aqueous extracts
from Egyptian wild plant Sonchus oleraceus, Cichorium pumilum and
Portulacaoleraceae to synthesize AgNPs, then study their antifungal activity
and the inhibitory impact on the production of aflatoxin B1 (AFB1) produced
by A.aflatoxiformans and ochratoxinA produced by A.ochraceous .
Therefore, results could be summarized in the following points:
1- Qualitative Phytochemical screening for plant leaves extracts
The phytochemical screening for Sonchus oleraceus, Cichorium
pumilum and Portulaca oleracea extracted with water, 70% ethanol,
methanol and acetone. the results suggested that the aqueous extract for the
three plants was a better solvent for the extraction process that give the
highest yield (25.4%), (15.2%) and (14.2%) with P.oleracea ,S. oleraceus
and C. pumilum respectively followed by ethanol and methanol extracts
while the acetone had the lowest yield. Also, the results revealed that the
presence of carbohydrate, protein, steroid, Tannins, phenolic, Terpenoid,
Flavonoids, Alkaloid and Saponins. Also, The obtained results showed that
the highest levels of phenolics, flavonoids, alkaloids, and terpenoids were
observed in aqueous and ethanolic followed by methanolic and finally
acetone extracts.
2- Quantitative secondary phytochemical estimation
The results showed that the extract of P. oleracea has a greater total
phenolic (TPC) and flavonoids (TFC) that were 212.32and 36.83 mg/mL,
respectively, followed by S. oleraceus (192.07and 31.57mg/mL) and finally
C. pumilum (188.1 and 27.6 mg/mL). On the other hand, DPPH free radical
scavenging activity were (65.6, 63.8 and 57.3) % with three plants extract P.
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oleracea, S. oleraceus and C. pumilum respectively. In addition to the results
indicated that the alkaloid was found in all the plant examined with the
highest quantities obtained in S. oleraceus (78.6%) then P. oleracea (66.4%),
while C. pumilum have 41.8%. While the results reflect that total terpenoid
and saponin were the highest percentage with Portulaca oleracea (61.6%)
and (35.3%) respectively. On the other hand, the results showed that the rates
of saponins in plants were (35.8%, 25.4% and24.9%) with P. oleracea, C.
pumilum and S. oleraceus respectively.
3- Detection and characterization of Phyto Silver Nanoparticles
Here we use aqueous extracts from Egyptian wild plants as Sonchus
oleraceus and Cichorium pumilum to synthesize AgNPs. The reduction
of Ag+ can be showed as visual by changing the color from colorless
to yellowish-brown color. AgNPs were characterized by UV-Visible
Spectrophotometer, Dynamic Light Scattering (DLS), FTIR and
Transmission Electron Microscope (TEM).
AgNPs characterized using UV- Visible spectroscopy.
In this study it was observed that the absorption peaks occur at 430nm,
460nm and 416 nm indicating that AgNPs were produced by extracts
from S. oleraceous, C. pumilum and p. oleracea respectively.
Transmitted Electron Microscope (TEM) for AgNPs
The TEM micrograph images showed roughly spherical shapes with
variable sizes The size distribution of AgNPs in colloidal solution
which was found to be from (6 : 21, 7: 30 and 45:90 nm) with
P.oleracea ,S.oleraceus and C. pumilum, respectively .While the
average zeta potential were (-8.85, 12.33 and -1.07 mv) with
P. oleracea.L, S.oleraceous and C. pumilum.
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125
The FTIR of AgNPs synthesis by the extract of P. oleracea.L.,
S. oleraceous and C. pumilum indicated that many functional groups
appeared such as alcohols, phenols, alkanes, carboxylic acids, aldehydes, and
alkenes revealed that the absorption peaks at 3427.85, 2916.81, 1632.45,
1389.46 and 1026.91cm-1. Also, by comparing the FTIR spectrum of the
plant extract before and after the addition of silver nitrate and the formation
of AgNPs there are displacement of the peaks observed which indicates the
role of functional groups especially phenolic and aliphatic compounds in
stabilizing AgNPs. Also, the functional groups play acritical role in reducing
silver ions into AgNPs.
4- Assessment the antifungal activity for AgNPs synthesized by plant
extracts.
In this study the biogenic AgNPs were tested for their antifungal effects
against A. aflatoxiformans and A. ochraceus. The two fungal strains were
further identified based on the sequence of ITS regions. The amplified ITS
4/5 rDNA region for the two fungal isolates, the obtained ITS sequences of
these isolates were BLAST searched with non-redundant sequences on the
NCBI database giving A. Aflatoxiformans and A. ochraceus deposited on
Gene bank with accession # MN093924.1and MN093933.1, respectively.
And at Assiut University Mycological Centre (AUMC), with deposition
numbers AUMC14073and AUMC14074 respectively.
When studying the ability of AgNPs to inhibit fungal growth the results
showed that In case of A. aflatoxiformans strain the highest inhibition zones
were (33.3±7.6 , 32.3±2.5 and 30.7±5.13) mm with AgNPs from extract
S. oleraceus, P.oleracea and C. pumilum respectively at the concentration
400 ppm of AgNPs. While, with A. ochraceus the inhibition zone of AgNPs
synthesized by extract of C. pumilum ranged between 19.7±1.5 to
Summary And Conclusion
126
37.0±4.3mm, however the inhibition zone was 18.0±2.0 to 35.0±5.0 mm with
AgNPs synthesized by extract of S. oleraceus. On the other hand, data
indicated that higher inhibition level with AgNPs synthesized by extract of
P. oleracea was 25.0±5.0 to 43.3±2.8mm at concentration 50 and 400ppm,
respectively. In addition the strain of A.ochraceus is more affected by the
AgNPs than A. aflatoxiformans. .
In addition, the results showed that AgNPs influenced the mycelium dry
weight (biomass) of A. aflatoxiformans and A. ochraceus. AgNPs synthesized
from extract of Portulaca oleracea reduced biomass to 70% and 88.6% for
A. aflatoxiformans and A. ochraceous, respectively at the concentration 400
ppm. While Sonchus oleraceus caused reduction of mycelium weight to
69.18% and 80.4% for A. aflatoxiformans and A. ochraceus, respectively. On
the other hand, AgNPs synthesized from extract of Cichorium pumilum
caused reduction of mycelium weight to 58% and 75.9% for A.
aflatoxiformans and A. ochraceous, respectively at the same concentration.
5- Impact of AgNPs on the production of AFB1 and OTA
This is the first study that examined the effect of AgNPs on the ability
of A. aflatoxiformans to produce toxin. When studying the ability of
AgNPs to prevent the production of AFs and OTA in the YES media.
We used a gradually concentrations ranged 50 to 400 ppm. The results
indicated that the AgNPs synthesized by P. oleracea, S. oleraceus and
C. pumilum and reduced AFB1 to 88.4%, 74.2% and 70 % respectively
at 50ppm, while increased to 91% when treated liquid media by 400
ppm from AgNPs. According to these preliminary results, it is clear
that AgNPs have a high ability to inhibit the production of the AFB1
produced by that strain .
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Also, the results showed that at 50ppm from AgNPs synthesized by
extracts of P. oleracae, S. oleraceus, C.pumilum inhibit the production
of OTA to 92.3% , 86.6% and 84.9%, respectively. While at the high
concentrate from AgNPs (400 ppm) increased the percentages of
inhibition of OTA to 97%, 96.8%&94% respectively.
6- Effect of AgNPs on the expression of aflatoxin and ochratoxins genes
For evaluating the effects of AgNPs on expression genes encoding
proteins involved in aflatoxin and ochratoxin biosynthesis,
A. aflatoxiformans& A. ochraceus were cultured on YES broth amended with
AgNPs (100, 200 and 300) ppm then, the fungal mycelia were separated by
filtration, total RNA was extracted, and the expression levels of( nor-1and
omt A) genes in A. aflatoxiformans the results showed that the transcription
of the two genes was down-regulated to varying degrees after AgNPs
exposure However, the expression of none of these genes was completely
inhibited and the most strongly down-regulated gene was AflD (nor-1) , in
which at concentration of 300 ppm of AgNPs, the gene expression was
reduced by 99% and 63.4%with nor-1and omt A respectively, also the data
showed that the transcription level of nor-1 gene had the highest
downregulation. While the expression levels of PKS, NRPS genes in
A. ochraceus the results showed that the two genes were downregulated by
AgNPs, the transcription level of NRBS gene had the highest downregulation
85.4% while PKS reduced to 66.2% at same concentrations of AgNPs. Also,
the downregulation effect of AgNPs proportionally increased with the
concentrations.