Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.687407
Title: Characterization of aflatoxin contamination of foods and identification of food components that protect against aflatoxin-mediated toxicity and mutagenicity
Author: Ruadrew, Sayan
ISNI:       0000 0004 5923 6405
Awarding Body: Glasgow Caledonian University
Current Institution: Glasgow Caledonian University
Date of Award: 2015
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Abstract:
Aflatoxins (AFs) are a group of mycotoxins produced by moulds of Aspergillus genus which contaminate food commodities of tropical and sub-tropical countries. The aims of this study are to assess the extent of AF contamination of foods in the UK that originated in Asia and to identify components of Thai foods that may protect against the toxicity of AFs. Examination of 12 commercial, dried Asian foods showed that long grain rice, fragrant rice, peanuts, black beans and black pepper contained Aspergillus spp. which were identified as A. parasiticus (afiatoxigenic), A. versicolor, A. ustus, A.niger and A. ochraceus. These commodities contained undetectable AFs. Jasmine brown rice and crushed chilli contained 14.7 and 11.4 IJglkg of AFs, respectively, in the absence of Aspergillus. AFBl, the most toxigenic AFs was detected in crushed chilli (lO.7IJglkg) so Aspergillus was present at some stage of food production, particularly pre-harvest stage. Cross contamination during food processing is one of possible cause of AFs contamination in these commodities. These results indicate direct and indirect risks of exposure to AFs from these products since AFs fOlmation is possible in Aspergillus-contaminated crops and AFs can be carried throughout the food chain. Hence an alternative strategy to mitigate toxicity of ingested AFs is required. One possibility is by using food components to modulate the harm from ingested AFs by altering AF metabolism and mutagenesis. In this study, the effectiveness of the compounds in Thai culinary herb, fingerroot (Boesenbergia rotunda) were investigated. A crude methanol extract (ME) of fingerroot was analysed and found to contain ~ 15 putative flavonoids as major components of which pinocembrin, pinocembrin chalcone, cardamonin, pinostrobin, 4-hydroxypanduratin A and panduratin A were identified by HPLC and LC-MS. The ME significantly inhibited fonnation of mutagenic/carcinogenic metabolite of AFBl (AFB1-epoxide, AFBO) in a cell-free metabolic system (Model 1) and also suppressed mutagenicity of AFBl in Salmonella/microsomal assay (Model 2). These inhibitory properties of the ME might be related to its indigenous flavonoids which could modulate activities of AFB1 -metabolising enzymes (CYPIA2, 3A4). Purified flavonoids (cardamonin, apigenin, pinostrobin) were found to affect AFB 1 toxicity to some extent in both models, but their potencies were much lower than the ME particularly in the Salmonella model and evidence is provided that suggests that Reactive Oxygen Species rather than AFBO are the mutagenic entities in this assay. This also suggests that fingerroot contains effective metabolic modulators that were not identified. Consumption of fmgerroot could provide a combination of potential phytochemicals that protect against aflatoxin-mediated toxicity by altering AF metabolism at the initial stages of enzymatic activation.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.687407  DOI: Not available
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