الفهرس 
INTRODUCTION AND AIM OF WORK
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Abstract
Mycotoxins are toxic compounds produced by fungi that contaminate foodstuff and have detrimental effects on the health of humans and animals. Currently, more than 400 mycotoxins are identified in the world including aflatoxins. Aflatoxins are usually found as a mixture of AFB1, AFB2, AFG1 and AFG2 with a preponderance of AFB1, which is the most toxic. AFB1 is thermostable and possess very powerful mutagenic and carcinogenic effects. In general, aflatoxin exposure is most likely to occur in the developing countries due to lack of regulations that protect the exposed populations, prevailing hot humid weather and the poor storage conditions. Herbal contamination with AFB1 is a worldwide concern because of the increased consumption of herbal products and increased interest in organic products.
This study was divided into two parts; analytical part and experimental part. The analytical part aimed to screen the prevalence of AFB1 in traditional herbal products available in Assiut city markets in both forms; non-packaged products (RM) and packaged products (EP) by TLC and HPLC. Fifty five samples of herbal preparations were collected and grouped into 43 (RM) and 12 (EP). All samples were processed into powdered form and were inoculated into PDA plates after serial dilution. After 7 days, the fungal colonies on the inoculated plates, were recognized by macroscopic and microscopic analysis. All isolates of Aspergillus were screened for the ability to produce AFB1 qualitatively by TLC, and confirmed quantitatively by HPLC.
The fungal recovery was observed only in non-packaged products (RM). from 43 RM samples examined, 18 (41.80%) samples yielded isolates of Asp. flavus, 6 (13.95 %) samples yielded isolates of Asp. parasiticus, and 2 (4.65%) samples yielded isolates of Asp. Niger. Six chloroform extracts out of the 26 samples screened by TLC gave a bluish spot similar to that of AFB1 standard. Chloroform extracts that were positive for the presence of AFB1 by TLC investigated further by HPLC. AFB1 contamination was detected in samples of Phoenix Sylvestris (761.7 µg/kg), Linum Usitatissimum (69.83 µg / kg), Carum Carvi (46.55 µg/kg) and Zingiber Officinale (18.0 µg/kg), The 4 samples represent 9.3 % of the 43 non- packaged herbal products that were screened in this study.
The Experimental part of the study aimed to demonstrate the histopathological and biochemical changes in organs of rats after AFB1 administration and to identify the potential protective role of curcumin and melatonin against AFB1 toxicity. One hundred male adult rats weighing from 150 to 200 grams were maintained under optimal laboratory conditions. The animals were divided into 3 main groups and received the tested compounds by oral intubation in 7% DMSO daily for 90 days.
• The first group used as the control (C):
C1: 10 rats received nothing except laboratory diet (blank group/ negative control)
C2: 10 rats received the vehicle (DMSO).
C3: 10 rats received melatonin at a dose of 5 mg/Kg/day.
C4: 10 rats received curcumin at a dose of 200 mg/kg/day.
• The second group A:
A1: 10 rats received AFB1 at a dose of 25 µg /kg/day.
A2: 10 rats received 25 µg /kg/day of AFB1 along with melatonin (5 mg/Kg/day).
A3: 10 rats received 25 µg /kg/day of AFB1 along with curcumin (200 mg/kg/day).
• The third group B:
B1: 10 rats received AFB1 at a dose of 50 µg /kg/day.
B2: 10 rats received 50 µg /kg/day of AFB1 along with melatonin (5 mg/Kg/day).
B3: 10 rats received 50 µg /kg/day of AFB1 along with curcumin (200 mg/kg/day).
All Animals were followed until the end of study, animals were sacrificed, a thorough necropsy was performed and sections of livers, kidneys, lungs, testes and brains were taken for histopathological study. Parts of livers, kidneys and testes of all groups were homogenized and the homogenates were used for assay of MDA and NO as indices of oxidative stress.
The results of histopathological examination of organs of all animal groups suggested that AFB1 has a dose dependent deleterious effects on the histological structure of the liver, kidney, testis, and some degenerative effects on lung and cerebral cortex. The data obtained from the biochemical results of this study showed that AFB1 induced a significant increase in LPO in liver, kidney and testis tissues indicated by the increase in (MDA) and (NO) production.
Organs of rat administered melatonin in combination with AFB1 showed marked amelioration of the degenerative changes that were observed in organs of rats administered AFB1 alone. These results were confirmed by the biochemical results, which confirmed that melatonin decreases oxidative damage in the tissues as indicated by decreasing the MDA and NO values to levels not significantly different from that of the control group.
Organs of rats administered curcumin in combination with AFB1 showed less amelioration of the degenerative changes that were observed in organs of rats administered AFB1 alone. These results were confirmed by the biochemical results, curcumin administration in combination with AFB1 resulted in MDA and NO values that were significantly lower than AFB1 alone groups but significantly higher than the control groups and groups administered melatonin in combination with AFB1.
In conclusion, AFB1 could cause histopathological and biochemical changes in organs. These changes may occur due to inflicting oxidative injury to cellular components. Administration of melatonin or curcumin to rats concurrently with AFB1 resulted in a significant improvement in histopathological and biochemical changes. In the light of these results, melatonin was found to induce more potent protective action than curcumin.