Biomedical subjects

T D Phillips

Publications and source records attributed to T D Phillips.

At least 37 records · Page 2Linked to original sources

PubMed1999

Utilization of electrochemically generated ozone in the degradation and detoxication of benzo[a]pyrene.

The ability of electrochemically generated ozone (O3) to degrade and detoxify the polycyclic aromatic hydrocarbon (PAH) benzo[a]pyrene (BaP) was assessed utilizing the chick embryotoxicity screening test (CHEST) and Hydra attenuata bioassays. Aqueous solutions containing 10 microg/ml BaP and 0.5% (v/v) acetonitrile were subjected to ozonolysis for 0 to 30 min. Rapid degradation of BaP was evident by both gas chromatography/mass spectroscopy (GC/MS) and high-performance liquid chromatography (HPLC) analysis. HPLC fluorescence detection revealed no BaP shortly after 5 min of ozonolysis, while HPLC with PDA detection demonstrated continued reactions with ozone over the 30-min time course. As little as 2 min of O3 treatment afforded protection from BaP-induced mortality and toxicity (embryolethality and liver discoloration) in the chicken embryos. In the hydra bioassay, no toxicity was observed in the adult hydra until the ozonolysis products were reconstituted 100-fold from their initial post-ozonolysis concentrations. The results obtained from this study clearly demonstrate the potential application of electrochemically generated O3 for the detoxication and prevention of toxicity of BaP. Both CHEST and hydra assays predict that the ozonolysis products of BaP are less toxic than the parent compound.

Acetonitriles↗

PubMed1999

Assessment of the estrogenic effects of zearalenone after treatment with ozone utilizing the mouse uterine weight bioassay.

The ability of ozone gas (O3) to detoxify zearalenone (ZEN), a commonly occurring estrogenic mycotoxin, was assessed utilizing the mouse uterine weight bioassay. Solutions containing 12 ppm ZEN in water were ozonated for varying time periods (0, 0.5, and 5 min), then extracted with chloroform and evaporated to dryness. The residue was redissolved in acetonitrile and analyzed for ZEN. High-performance liquid chromatography (HPLC) analysis of aliquots indicated a rapid degradation and decline in parent ZEN level with increasing time of ozone treatment. The acetonitrile solution containing the degraded ZEN residue was added to a known volume of corn oil and evaporated under nitrogen to eliminate the acetonitrile in the oil. Eighteen-day-old prepubertal female mice (B6C3F1 strain) were gavaged daily with the test chemicals in 50 microl of corn oil between d 18 and 23. Initial dose-response studies showed that a concentration of 60 microg ZEN/mouse/d produced uterine weights that were significantly higher than the uterine weights of control animals (2.7 times higher than that of the solvent control). Treatment groups for the ozonation study included: DES, 0.1 microg (positive control), untreated ZEN (60 microg), extraction control for ZEN (60 microg), 0.5 min ozone-treated ZEN (60 microg), 5 min ozone-treated ZEN (60 microg), solvent control (50 microl), and absolute control. Results showed the uterine weights of animals receiving the ozone-treated ZEN were not significantly affected. These findings were in agreement with HPLC analyses and suggested that ozone can prevent the estrogenic effects of this important mycotoxin in mice. Importantly, ozone treatment of contaminated whole grains may enable the practical detoxification and control of ZEN. Also, the mouse uterine weight bioassay may be useful in assessing the efficacy of other detoxification strategies for estrogenic chemicals.

Animals↗

PubMed1999

Multi-bioassay approach for assessing the potency of complex mixtures of polycyclic aromatic hydrocarbons.

The chick embryotoxicity screening test (CHEST) and the Salmonella/microsome bioassay were used to evaluate embryotoxic and mutagenic endpoints from crude coal tar (CT) and its fractionated polycyclic aromatic hydrocarbon (PAH) mixtures (designated as A, B, C, D and E). In the CHEST assay, CT and PAH mixtures were injected into the egg yolk. A dose-dependent increase in embryo mortality was observed for all fractions. The E fraction resulted in 47% embryo mortality at a dose of 0.125 mg/kg and was more toxic than CT. At a dose of 1 mg/kg, 85-100% embryonic deaths occurred in fractions C and D and these two fractions were more potent than fractions A and B. The main visual toxic manifestations were liver lesions, discoloration of the liver, and edema. Both CT and fractionated PAH mixtures were also tested in the Salmonella/microsome plate incorporation assay with Salmonella typhimurium strain TA98 and were evaluated with and without metabolic activation at five dose levels. In the presence of S9, the CT and fractions C, D and E induced a dose-dependent positive response. Results from the Salmonella/microsome assay were in good agreement with findings from the CHEST assay suggesting that these two bioassays in combination may facilitate the rapid detection and ranking of complex PAH mixtures.

Animals↗

PubMed1999

Molecular characterization of high affinity, high capacity clays for the equilibrium sorption of ergotamine.

Ergot alkaloids (mycotoxins) produced by Claviceps and Neotyphodium species of fungi may contaminate animal feedstuffs and results in disease in livestock. In this study, diverse phyllosilicate clays and other adsorbent materials, differing in chemical and structural characteristics, were tested for their ability to sorb ergotamine, a prevalent ergot mycotoxin, from acidic solution. Results indicated minimal binding to those sorbents possessing low surface area, cation exchange capacity and inaccessible interlayer regions. Cetyl pyridinium-exchanged montmorillonite (organoclay) exhibited decreased propensity for ergotamine in acidic solution as compared with the unexchanged hydrophilic parent clay. The highest ergotamine sorption was observed with cation exchanged montmorillonite clays; whereas, when collapsed, these same clays sorbed very little ligand. Based on initial binding experiments, calcium and sodium montmorillonite clays were prioritized for further characterization, including: capacity, affinity, and heat (enthalpy) of adsorption. Computer models of energy-minimized ergotamine isomers and clay were used to illustrate possible mechanisms of ergot alkaloid sorption at interlayer sites. Additional studies are warranted to assess the stability of ergot alkaloid/clay complexes under alkaline conditions to further understand the mechanism of adsorption.

Adsorption↗

PubMed1999

Dietary clay in the chemoprevention of aflatoxin-induced disease.

Aflatoxins are harmful by-products of mold growth and, though invisible to the naked eye, are potentially fatal. The aflatoxin problem is long-standing and inextricable. Concerns about the aflatoxins originate from the strong implications of their involvement in disease and death in humans and animals, yet scientists and clinicians are still seeking ways to effectively deal with these dangerous and elusive chemicals. Safe, practical, and effective strategies for the detoxification of aflatoxin-contaminated food and feed are highly desirable. A simple and effective approach to the chemoprevention of aflatoxicosis has been to diminish or block exposure to aflatoxins via the inclusion of HSCAS clay in the diet. HSCAS clay acts as an aflatoxin enterosorbent that tightly and selectively binds these poisons in the gastrointestinal tract of animals, decreasing their bioavailability and associated toxicities. Further studies to delineate the molecular mechanisms of action have shown that the dicarbonyl system of aflatoxin is essential for tight binding by HSCAS. In these studies, adsorption data was fitted to multiple isotherm equations including the Langmuir, multi-Langmuir, general Freundlich, Langmuir-Freundlich, Toth and various transforms. Information derived included: the Gibbs standard free energy change of adsorption, enthalpy of adsorption, capacity, affinity, and heterogeneity coefficient. Computer modeling was also utilized to provide additional structural information and insight into the mechanism. Evidence suggests that aflatoxins may react at multiple sites on HSCAS particles, especially the interlayer region, but also at edges and basal surfaces. Since clay and zeolitic minerals comprise a broad family of functionally diverse chemicals, there may be significant hidden risks associated with their indiscriminate inclusion in the diet. All aflatoxin binding agents should be rigorously tested, paying particular attention to their effectiveness and safety in aflatoxin-sensitive animals and their potential for interactions with critical nutrients.

Aflatoxins↗

PubMed1998

Prevention of maternal and developmental toxicity in rats via dietary inclusion of common aflatoxin sorbents: potential for hidden risks.

In earlier work, we have reported that a phyllosilicate clay (HSCAS or NovaSil) can tightly and selectively bind the aflatoxins in vitro and in vivo. Since then, a variety of untested clay and zeolitic minerals have been added to poultry and livestock feeds as potential "aflatoxin binders." However, the efficacy and safety of these products have not been determined. A common zeolite that has been frequently added to animal feed is clinoptilolite. Our objectives in this study were twofold: (1) to utilize the pregnant rat as an in vivo model to compare the potential of HSCAS and clinoptilolite to prevent the developmental toxicity of aflatoxin B1 (AfB1), and (2) to determine the effect of these two sorbents on the metabolism and bioavailability of AfB1. Clay and zeolitic minerals (HSCAS or clinoptilolite) were added to the diet at a level of 0.5% (w/w) and fed to pregnant Sprague-Dawley rats throughout pregnancy (i.e., day 0 to 20). Treatment groups (HSCAS or clinoptilolite) alone and in combination with AfB1 were exposed to sorbents in the feed as well as by gavage. Untreated and AfB1 control animals were fed the basal diet without added sorbent. Between gestation days 6 and 13, animals maintained on diets containing sorbent were gavaged with corn oil in combination with an amount of the respective sorbent equivalent to 0.5% of the estimated maximum daily intake of feed. Animals receiving AfB1 were dosed orally (between days 6 and 13) with AfB1 (2 mg/kg body wt) either alone or concomitantly with a similar quantity of the respective sorbent. Evaluations of toxicity were performed on day 20. These included: maternal (mortality, body weights, feed intake, and litter weights), developmental (embryonic resorptions and fetal body weights), and histological (maternal livers and kidneys). Sorbents alone were not toxic; AfB1 alone and with clinoptilolite resulted in significant maternal and developmental toxicity. Animals treated with HSCAS (plus AfB1) were comparable to controls. Importantly, clinoptilolite (plus AfB1) resulted in severe maternal liver lesions (more severe than AfB1 alone), suggesting that this zeolite may interact with dietary components that modulate aflatoxicosis. In metabolism studies, adult male Sprague-Dawley rats, maintained on diets containing 0.5% (w/w) HSCAS or clinoptilolite, were dosed orally with 2.0 mg AfB1/kg body wt. The concentration of the major urinary metabolite (AfM1) was considerably decreased in the presence of HSCAS. These results suggest that the mechanism of protection of AfB1-induced maternal and developmental toxicities in the rat may involve adsorption and reduction of AfB1 bioavailability in vivo. Importantly, this study demonstrates the potential for significant hidden risks associated with the inclusion of nonselective aflatoxin binders in feeds. Aflatoxin sorbents should be rigorously tested individually and thoroughly characterized in vivo, paying particular attention to their effectiveness and safety in sensitive animal models and their potential for deleterious interactions.

Aflatoxin B1↗

PubMed1998

In vitro studies on the use of clay, clay minerals and charcoal to adsorb bovine rotavirus and bovine coronavirus.

Rotaviruses are the leading cause and coronaviruses are the major contributors of acute gastroenteritis in the young of various mammalian and avian species. Despite numerous trials and decades of research, vaccines have limited efficacy particularly for calves. As an alternative method of controlling infection, we have investigated broad spectrum antiviral agents that are not discriminatory among various viruses. This report involves testing a variety of adsorbent agents including charcoal, clay, and clay minerals to adsorb rotavirus and coronavirus in vitro. Results revealed that all the adsorbent agents had good to excellent capability of adsorbing rotavirus and excellent capability of adsorbing coronavirus. Percent adsorptions ranged from 78.74% to 99.89% for rotavirus and 99.99% for coronavirus; while sand (negative control) was < 0.01%. A high affinity binding was present as determined by a low percent desorption (0.06-3.09%). However, the adsorbent bound virus complex retained, and may have actually enhanced, infectivity.

Adsorption↗

PubMed1998

An in vitro study of theaflavins extracted from black tea to neutralize bovine rotavirus and bovine coronavirus infections.

Crude theaflavin was extracted from black tea and then fractionated by HPLC into five components (initial peaks (IP), TF1, TF2A, TF2B, and TF3). The crude extract and the various fractions of theaflavin were collected and tested, individually and in combination, for antirotaviral activity. The mean effective concentration (EC50) was calculated and compared. Activity varied from the most active being the uncharacterized theaflavin-like initial peaks (IP) with an EC50 of 0.125 microgram/ml to the least active being theaflavin-3 monogallate (TF2A) with an EC50 of 251.39 micrograms/ ml. The combination of TF1 + TF2A + TF2B + TF3 was more active than the sum of the activities of these four fractions individually, indicating synergism among the peaks. Only the crude extract was assayed for activity against coronavirus; the EC50 was 34.7 micrograms/ml.

Animals↗

PubMed1998

Aflatoxicosis in turkey poults is prevented by treatment of naturally contaminated corn with ozone generated by electrolysis.

Previous studies have demonstrated that a novel source of ozone gas (O3) maybe used to chemically degrade numerous mycotoxins, including aflatoxin (AF) B1. Subsequent in vitro analyses demonstrated detoxification of AFB1, suggesting a potential method of remediate AF-contaminated grain. The objective of this study was to evaluate the capability of electrochemically produced ozone to degrade AFB1 in naturally contaminated whole kernel corn and confirm detoxification in turkey poults. Corn was procured from the southern coastal areas of Texas and HPLC revealed 1,220 +/- 73.3 ppb AFB1. Control and contaminated corn were treated for 92 h with O3 at 200 mg/min in 30 kg batches; greater than 95% reduction of AFB1 in contaminated corn was achieved. One-day-old female turkey poults were fed 1) control corn, 2) control corn + O3, 3) AFB1 corn, or 4) AFB1 corn + O3 mixed in rations (46% by wt.) and consumed ad libitum for 3 wk. When compared with controls, turkeys fed AFB1 corn had reduced body weight gain and relative liver weight, whereas turkeys fed control corn + O3 or AFB1 corn + O3 did not differ from controls. Furthermore, alterations in the majority of relative organ weight, liver discoloration, serum enzyme activity, hematological parameters, and blood chemistry caused by AFB1 were eliminated (no difference from controls) by treatment with O3. These data demonstrate that treatment of contaminated corn with electrochemically produced O3 provided protection against AFB1 in young turkey poults. It is important to note that treatment of control corn with O3 did not alter the performance of the turkey poults.

Animal Feed↗

PubMed1997

Inhibition of 3,3',4,4',5-pentachlorobiphenyl-induced chicken embryotoxicity by 2,2',4,4',5,5'-hexachlorobiphenyl.

3,3',4,4',5-Pentachlorobiphenyl (pentaCB) caused a dose-dependent induction of chicken embryolethality, malformations, edema, and liver lesions at doses ranging from 0.5 to 12.0 microg/kg. In contrast, no embryotoxicity was observed after treatment with 10, 25, or 50 mg/kg 2,2',4,4',5,5'-hexaCB. In eggs cotreated with 2.0 microg/kg, 3,3',4,4',5-pentaCB plus 10, 25, or 50 mg/kg 2,2',4,4',5,5'-hexaCB, there was significant protection from 3,3',4,4',5-pentaCB-induced embryo malformations, edema, and liver lesions, whereas no inhibition of embryolethality was observed. These results further extend the response-specific nonadditive interactions of binary mixtures of polychlorinated biphenyls (PCBs) and should be considered in the development of approaches for hazard assessment of PCB mixtures and related compounds.

Abnormalities, Drug-Induced↗

PubMed1997

Oxidative degradation and detoxification of mycotoxins using a novel source of ozone.

Practical methods to degrade mycotoxins using ozone gas (O3) have been limited due to low O3 production capabilities of conventional systems and their associated costs. Recent advances in electrochemistry (i.e. proton-exchange membrane and electrolysis technologies) have made available a novel and continuous source of O3 gas up to 20% by weight. It is possible that the rapid delivery of high concentrations of O3 will result in mycotoxin degradation in contaminated grains--with minimal destruction of nutrients. The major objectives of this study were to investigate the degradation and detoxification of common mycotoxins in the presence of high concentrations of O3. In this study, aqueous equimolar (32 microM) solutions of aflatoxins B1 (AfB1), B2 (AfB2), G1 (AfG1), G2 (AfG2), cyclopiazonic acid (CPA), fumonisin B1 (FB1), ochratoxin A (OA), patulin, secalonic acid D (SAD) and zearalenone (ZEN) were treated with 2, 10 and/or 20 weight% O3 over a period of 5.0 min and analysed by HPLC. Results indicated that AfB1 and AfG1 were rapidly degraded using 2% O3, while AfB2 and AfG2 were more resistant to oxidation and required higher levels of O3 (20%) for rapid degradation. In other studies, patulin, CPA, OA, SAD and ZEN were degraded at 15 sec, with no by-products detectable by HPLC. Additionally, the toxicity of these compounds (measured by a mycotoxin-sensitive bioassay) was significantly decreased following treatment with O3 for 15 sec. In another study, FB1 (following reaction with O3) was rapidly degraded at 15 sec, with the formation of new products. One of these appeared to be a 3-keto derivative of FB1. Importantly, degradation of FB1 did not correlate with detoxification, since FB1 solutions treated with O3 were still positive in two bioassay systems.

Aflatoxins↗

PubMed1997

Individual and combined effects of fumonisin B1 present in Fusarium moniliforme culture material and diacetoxyscirpenol or ochratoxin A in turkey poults.

The individual and combined effects of feeding diets containing 300 mg fumonisin B1 (FB1), and 4 mg diacetoxyscirpenol (DAS) or 3 mg ochratoxin A (OA) were evaluated in two experiments using female turkey poults (Nicholas Large Whites) from day of hatch to 3 wk of age. When compared with controls, body weight gains were reduced 30% (Study 1) and 24% (Study 2) by FB1, 30% by DAS, 8% by OA, 46% by the FB1 and DAS combination, and 37% by the FB1 and OA combination. The efficiency of feed utilization was adversely affected by all treatments except FB1 in Experiment 2. Relative weights of the liver were significantly increased by all treatments except the DAS treatment. Serum concentrations of cholesterol were decreased and activities of aspartate aminotransferase and lactate dehydrogenase were increased and several hematological values were altered in poults fed FB1 alone and in combination with either DAS or OA. Results indicate additive or less than additive toxicity, but not toxic synergy, when poults are fed diets containing 300 mg FB1, and 4 mg DAS or 3 mg OA/kg of diet. The likelihood of encountering FB1, DAS, or OA at these concentrations in finished feed is small. However, under field conditions, other stress factors could alter the impact of these mycotoxins on the health and performance of poultry.

Animal Feed↗

PubMed1997

Effects of inorganic adsorbents and cyclopiazonic acid in broiler chickens.

Previous studies with cyclopiazonic acid (CPA) have indicated that this mycotoxin strongly adsorbs onto the surface of a naturally acidic phyllosilicate clay (AC). The objective of this study was to determine whether AC (and similar adsorbents) could protect against the toxicity of CPA in vivo. Acidic phyllosilicate clay, neutral phyllosilicate clay (NC, or hydrated sodium calcium aluminosilicate), and a common zeolite (CZ, or clinoptilolite) were evaluated. One-day-old broiler chicks consumed diets containing 0 or 45 mg/kg CPA alone or in combination with 1% AC, NC, or CZ ad libitum from Day 1 to 21. Body weight, feed consumption, feed:gain, hematology, serum biochemical values, and enzyme activities were evaluated. Compared to controls, CPA alone reduced body weight at Day 21 by a total of 26% and resulted in a significantly higher feed:gain ratio. Toxicity of CPA was also expressed through increased relative weights of kidney, proventriculus, and gizzard. Also, there were some alterations in hematology, serum biochemical values, and enzyme activities. Treatment with inorganic adsorbents did not effectively diminish the growth-inhibitory effects of CPA or the increased weights of organs, although there was some protection from hematological, serum biochemical, and enzymatic changes produced by CPA. The results of this study suggest that in vitro binding of CPA to clay does not accurately forecast its efficacy in vivo; the reasons for this discrepancy are not clear, but they may be related to differences in clay binding capacity and ligand selectivity for CPA in vitro vs in vivo. Predictions about the ability of inorganic adsorbents to protect chickens from the adverse effects of mycotoxins should be approached with caution and should be confirmed in vivo, paying particular attention to the potential for nutrient interactions.

Adsorption↗

PubMed1997

Individual and combined effects of fumonisin B1 present in Fusarium moniliforme culture material and T-2 toxin or deoxynivalenol in broiler chicks.

The individual and combined effects of feeding diets containing 300 mg fumonisin B1 (FB1), and 5 mg T-2 toxin (T-2)/kg of diet, or 15 mg/kg deoxynivalenol (DON, vomitoxin) from naturally contaminated wheat were evaluated in two studies in male broiler chicks from day of hatch to 19 or 21 d of age in Experiments 1 and 2, respectively. When compared with controls, body weight gains were reduced 18 to 20% by FB1, 18% by T-2, 2% by DON, 32% by the FB1 and T-2 combination, and 19% by the FB1 and DON combination. The efficiency of feed utilization was adversely affected by FB1 with or without T-2 or DON. Mortality ranged from none for the controls to 15% for the FB1 and T-2 combination. Relative weights of the liver and kidney were significantly increased by FB1 with or without T-2 or DON. Serum concentrations of cholesterol were increased in chicks fed FB1 with or without T-2 or DON. Activities of aspartate aminotransferase, lactate dehydrogenase, and gamma glutamyltransferase were increased in chicks fed FB1 at 300 mg/kg alone and in combination with T-2 or DON, indicating possible tissue damage and leakage of the enzymes into the blood. Results indicate additive toxicity when chicks were fed diets containing 300 mg FB1 and 5 mg T-2/kg of diet and less than additive toxicity when chicks were fed 300 mg FB1 and 15 mg DON/kg of diet. Of importance to the poultry industry is the fact that toxic synergy was not observed for either of these toxin combinations and the likelihood of encountering FB1 at this concentration in finished feed is small. However, under field conditions with additional stress factors, the toxicity of these mycotoxins could be altered to adversely affect the health and performance of poultry.

Animals↗

PubMed1996

Hydrated sodium calcium aluminosilicate (HSCAS), acidic HSCAS, and activated charcoal reduce urinary excretion of aflatoxin M1 in turkey poults. Lack of effect by activated charcoal on aflatoxicosis.

In one experiment, the effect of inorganic sorbents on the metabolic fate of aflatoxin B1 (AFB1) was studied in turkey poults. At 5 weeks of age, female poults were surgically colostomized and 9 days later orally dosed with 0.75 mg AFB1/kg BW. Hydrated sodium calcium aluminosilicate (HSCAS), acidic HSCAS, and activated charcoal (AC) were tested, by concomitant administration with AFB1. Urine was collected up to 48 h post-dosing and analyzed for aflatoxin M1 (AFM1) which was the major metabolite found in all treatment groups. Hydrated sodium calcium aluminosilicate, previously proven beneficial in alleviating aflatoxicosis in farm animals, reduced urinary AFM1 output when orally dosed simultaneous with AFB1. Also, acidic HSCAS and AC significantly decreased AFM1 excretion when administered concomitantly with AFB1. A second experiment was conducted to evaluate the ability of two types of AC to modify aflatoxicosis when added to aflatoxin (AF)-contaminated (from culture material) diets of turkey poults. Although AC was able to decrease AFM1 excretion in the first experiment, no protective effects from AF toxicity were observed in the feeding study.

Aflatoxin M1↗

PubMed1996

Alteration of oxytocin-induced calcium oscillations in clone 9 cells by toxin exposure.

A communication-competent rat liver cell line (Clone 9) was examined as a model system to investigate the action of toxins on [Ca2+]i induced by extracellular signals. Clone 9 cells exhibit an initial [Ca2+]i spike followed by Ca2+ oscillations for at least 30 min after exposure to oxytocin (10 to 1000 nM). Oscillations of mitochondrial membrane potential were also detected using the potentiometric fluorescent probe rhodamine 123. Fast Fourier Transform showed that complex patterns of oscillations in Clone 9 cells exhibit both amplitude- and frequency-encoded signals. The initial Ca2+ peak and oscillations were not altered by ryanodine pretreatment but were suppressed by nifedipine and blocked by thapsigargin. Brief exposure of cells to the food-borne toxins patulin or gossypol or the environmental toxicant 2,3,7,8-tetrachlorodibenzo-p-dioxin at doses which have no effect on cell viability within the duration of experiments was used to monitor any changes in Ca2+ oscillations. Toxin treatment either blocked or changed the amplitude and/or frequency of Ca2+ oscillations depending upon the toxin-specific mechanisms of cellular injury. These studies indicate that toxic agents may alter amplitude- and frequency-encoded information derived from cell signaling events which could result in altered cellular homeostasis at nonlethal doses of toxin.

Animals↗

PubMed1995

Selective chemisorption and detoxification of aflatoxins by phyllosilicate clay.

Practical and effective strategies for the detoxification of aflatoxins are critically needed. We have shown that a phyllosilicate clay (HSCAS): i) tightly binds aflatoxins in aqueous solutions, including milk; ii) markedly decreases the bioavailability of radiolabeled aflatoxins; iii) greatly diminishes aflatoxicosis in young animals, i.e., rats, chickens, turkeys, lambs, and pigs; and iv) reduces the level of aflatoxin M1 in the milk from lactating dairy cattle and goats. In further studies, ligands with one or more of the functional groups in common with aflatoxin were reacted with HSCAS in vitro in an attempt to elucidate the specificity and mechanism of tight binding (or chemisorption). A chemisorption index (C alpha) was developed, allowing for direct comparison of various clay and zeolitic minerals with HSCAS. Chemisorption indices were determined by HPLC analysis of extracts of the supernatants and sorbed pellets (exhaustively extracted with methanol and chloroform). The beta-dicarbonyl system of aflatoxin was found to be essential for tight binding by HSCAS. Comparison of the chemisorption indices from various classes of compounds with spectral data (DRIFTS) indicated that the molecular mechanism of aflatoxin binding may involve the chelation of metal ions in HSCAS with the beta-dicarbonyl moiety in aflatoxin. Computer modeling was utilized to provide additional information. Preliminary evidence suggests that aflatoxin B1 may react at surfaces and within the interlayers of HSCAS particles. With knowledge of the mechanism involved, it has been possible to further enhance the propensity of HSCAS for aflatoxins.

Aflatoxins↗

PubMed1995

Effects of phyllosilicate clay on the metabolic profile of aflatoxin B1 in Fischer-344 rats.

The phyllosilicate clay, hydrated sodium calcium aluminosilicate (HSCAS), has been shown to prevent aflatoxicosis in farm animals by reducing the bioavailability of aflatoxin. The present study was designed to determine the effects of HSCAS on the metabolism of aflatoxin B1 (AFB1) in an aflatoxin-sensitive species. Male Fischer-344 rats were orally dosed with 1.0, 0.5, 0.25 and 0.125 mg AFB1/kg body weight alone and in combination with 0.5% HSCAS. Urine samples were collected after 6, 24, 36, and 48 h. Aflatoxin M1 (AFM1) and aflatoxin P1 (AFP1) were detected in most urine samples, with or without HSCAS. AFM1 was found to be the major metabolite. Metabolite concentrations were significantly decreased in the presence of HSCAS, and more importantly, no additional metabolites were detected. Our results suggest that the AFB1-HSCAS complex was not significantly dissociated in vivo, and support earlier findings that HSCAS tightly binds aflatoxin.

Aflatoxin B1↗