Date of Award

1999

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

School of Nutrition and Food Sciences

First Advisor

Douglas L. Park

Abstract

Food, which ensures the sustenance of life, has also been implicated in the development or prevention of numerous diseases including cancer. Cancer may be a result of hereditary factors or genomic instability induced by DNA damage, from the intrinsic chemistry of cells or extrinsic factors like aflatoxin B1. Aflatoxin B1, produced by Aspergillus flavus and Aspergillus parasiticus, is a common contaminant of corn and cottonseed and a proven mutagen and animal carcinogen. Increased scientific knowledge and establishment of regulation have reduced but not eliminated exposure to aflatoxin B1. Complete elimination may be uneconomical for producers and may deprive consumers of sources of nourishment. Consumption of substances that offset the deleterious effects of aflatoxin, particularly those intrinsic to a commonly consumed foodstuff, may circumvent the problem. This study set out to isolate, substances that possess antimutagenic activity from corn and cottonseed. A bioassay directed fractionation using the Ames Salmonella/microsomal assay (tester strains TA100 and TA98) and thin layer chromatography, was employed to determine occurrence and isolate constituents with a potential to inhibit the mutagenicity of aflatoxin B1. Dichloromethane or acidified methanol extracts of corn meal were sequentially purified by TLC while simultaneously being tested for antimutagenic activity against aflatoxin B1. Cottonseed meal aqueous acetone extracts were either directly fractionated or precipitated with lead acetate prior to fractionation. Semi-purified TLC isolates were analyzed by GC/MS and or HPLC and UV spectrophotometry. Some fractions of corn and cottonseed inhibited aflatoxin mutagenicity to varying degrees. Mass ratio and fragmentation comparisons using the Wiley data base, and ultra violet spectra tentatively identified linoleic, chlorogenic, and ferulic acids from corn. And gossypol, and quercetin and/or kaempferol in cottonseed. Several other active isolates from both corn and cottonseed could not be identified. The presence of antimutagenic compounds in corn and cottonseed has been confirmed. Further studies on efficient extraction techniques, chemical, physical and functional characterization, and variety and geographical distribution of active compounds are recommended. Selective breeding for high antimutagenic content in these commodities would greatly benefit consumers and increase their utilization and market value.

ISBN

9780599548732

Pages

186

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