Isolation of Antimutagenic Compounds in Corn and Cottonseed.

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

Aflatoxin Contamination of Commercial Maize Products during an Outbreak of Acute Aflatoxicosis in Eastern and Central Kenya

In April 2004, one of the largest aflatoxicosis outbreaks occurred in rural Kenya, resulting in 317 cases and 125 deaths. Aflatoxin-contaminated homegrown maize was the source of the outbreak, but the extent of regional contamination and status of maize in commercial markets (market maize) were unknown. We conducted a cross-sectional survey to assess the extent of market maize contamination and evaluate the relationship between market maize aflatoxin and the aflatoxicosis outbreak. We surveyed 65 markets and 243 maize vendors and collected 350 maize products in the most affected districts. Fifty-five percent of maize products had aflatoxin levels greater than the Kenyan regulatory limit of 20 ppb, 35% had levels > 100 ppb, and 7% had levels > 1,000 ppb. Makueni, the district with the most aflatoxicosis case-patients, had significantly higher market maize aflatoxin than did Thika, the study district with fewest case-patients (geometric mean aflatoxin = 52.91 ppb vs. 7.52 ppb, p = 0.0004). Maize obtained from local farms in the affected area was significantly more likely to have aflatoxin levels > 20 ppb compared with maize bought from other regions of Kenya or other countries (odds ratio = 2.71; 95% confidence interval, 1.12–6.59). Contaminated homegrown maize bought from local farms in the affected area entered the distribution system, resulting in widespread aflatoxin contamination of market maize. Contaminated market maize, purchased by farmers after their homegrown supplies are exhausted, may represent a source of continued exposure to aflatoxin. Efforts to successfully interrupt exposure to aflatoxin during an outbreak must consider the potential role of the market system in sustaining exposure

Case–Control Study of an Acute Aflatoxicosis Outbreak, Kenya, 2004

Objectives: During January–June 2004, an aflatoxicosis outbreak in eastern Kenya resulted in 317 cases and 125 deaths. We conducted a case–control study to identify risk factors for contamination of implicated maize and, for the first time, quantitated biomarkers associated with acute aflatoxicosis. Design: We administered questionnaires regarding maize storage and consumption and obtained maize and blood samples from participants. Participants: We recruited 40 case-patients with aflatoxicosis and 80 randomly selected controls to participate in this study. Evaluations/Measurements: We analyzed maize for total aflatoxins and serum for aflatoxin B(1)–lysine albumin adducts and hepatitis B surface antigen. We used regression and survival analyses to explore the relationship between aflatoxins, maize consumption, hepatitis B surface antigen, and case status. Results: Homegrown (not commercial) maize kernels from case households had higher concentrations of aflatoxins than did kernels from control households [geometric mean (GM) = 354.53 ppb vs. 44.14 ppb; p = 0.04]. Serum adduct concentrations were associated with time from jaundice to death [adjusted hazard ratio = 1.3; 95% confidence interval (CI), 1.04–1.6]. Case patients had positive hepatitis B titers [odds ratio (OR) = 9.8; 95% CI, 1.5–63.1] more often than controls. Case patients stored wet maize (OR = 3.5; 95% CI, 1.2–10.3) inside their homes (OR = 12.0; 95% CI, 1.5–95.7) rather than in granaries more often than did controls. Conclusion: Aflatoxin concentrations in maize, serum aflatoxin B(1)–lysine adduct concentrations, and positive hepatitis B surface antigen titers were all associated with case status. Relevance: The novel methods and risk factors described may help health officials prevent future outbreaks of aflatoxicosis

Workgroup report: Public health strategies for reducing aflatoxin exposure in developing countries

10.1289/ehp.9302Environmental Health Perspectives114121898-190

Evaluation of immunochemical assays for on-site determination of aflatoxin in cottonseed

The performance of four immunochemical test kits in detecting aflatoxin contamination in cottonseed under non-laboratory conditions was evaluated. Naturally contaminated cottonseed was analyzed at cotton gins, ammoniation plants, cotton oil processing plants, a dairy farm and at the University of Arizona. Evaluation was based on the ability to determine aflatoxin concentrations as more or less than 20 ppb when analyzed on-site and in the laboratory using a common extract. Comparison of results from both locations showed excellent agreement (Afla-20 Cup 86 ± 6%, (n = 188); Agri-Screen I, 75 ± 9%, (n = 56); Agri-Screen II, 93 ± 5%, (n = 106); Agri-Chek, 93 ± 4%, (n = 156) and Aflatest-10, 90 ± 4%, (n = 178)). Overall agreement between on-site and laboratory results was 88%. Comparison of kit results to those of TLC demonstrated a low potential for obtaining false negative values. From these results the kits can reliably be used to screen cottonseed for aflatoxin contamination under non-laboratory conditions

Aflatoxigenic <i>Aspergillus</i> Modulates Aflatoxin-B1 Levels through an Antioxidative Mechanism

Aflatoxins (AFs) are considered to play important functions in species of Aspergillus section Flavi including an antioxidative role, as a deterrent against fungivorous insects, and in antibiosis. Atoxigenic Flavi are known to degrade AF-B1 (B1). To better understand the purpose of AF degradation, we investigated the degradation of B1 and AF-G1 (G1) in an antioxidative role in Flavi. Atoxigenic and toxigenic Flavi were treated with artificial B1 and G1 with or without the antioxidant selenium (Se), which is expected to affect levels of AF. After incubations, AF levels were measured by HPLC. To estimate which population would likely be favoured between toxigenic and atoxigenic Flavi under Se, we investigated the fitness, by spore count, of the Flavi as a result of exposure to 0, 0.40, and 0.86 µg/g Se in 3%-sucrose cornmeal agar (3gCMA). Results showed that levels B1 in medium without Se were reduced in all isolates, while G1 did not significantly change. When the medium was treated with Se, toxigenic Flavi significantly digested less B1, while levels of G1 significantly increased. Se did not affect the digestion of B1 in atoxigenic Flavi, and also did not alter levels of G1. Furthermore, atoxigenic strains were significantly fitter than toxigenic strains at Se 0.86 µg/g 3gCMA. Findings show that while atoxigenic Flavi degraded B1, toxigenic Flavi modulated its levels through an antioxidative mechanism to levels less than they produced. Furthermore, B1 was preferred in the antioxidative role compared to G1 in the toxigenic isolates. The higher fitness of atoxigenic over toxigenic counterparts at a plant non-lethal dose of 0.86 µg/g would be a useful attribute for integration in the broader biocontrol prospects of toxigenic Flavi