fumonisin-b3 and safingol

Fumonisinmycotoxins are produced by Fusaria fungi that grow worldwide primarily on corn. Fumonisin B(1), the most predominant form in corn samples, is a renal carcinogen in male F344/N rats and a hepatocarcinogen in female B6C3F(1) mice when fed at concentrations higher than 50 ppm (70 micromol/kg) in the diet for 2 years. We sought to determine the relative toxicities of several naturally occurring fumonisin derivatives when included in the diet of female B6C3F(1) mice. Mice were fed diets containing fumonisin B(1), fumonisin B(2), fumonisin B(3), fumonisin P1, hydrolyzed-fumonisin B(1), N-(acetyl)fumonisin B(1), or N-(carboxymethyl)fumonisin B(1) (approximately 0, 14, 70, and 140 micromol/kg diet) for 28 days. None of the doses used caused a decrease in body weight gain over the 28 days. Serum levels of total bile acids, cholesterol, and alkaline phosphatase were increased only in mice receiving 72 and 143 micromol/kg fumonisin B(1), suggesting that only fumonisin B(1) was hepatotoxic in the mice. Corroborating this observation, the liver weight, relative to body weight, was decreased only in the mice that consumed 143 micromol/kg fumonisin B(1). Consistent with fumonisin B(1) inhibition of ceramide synthase, the liver sphinganine-to-sphingosine ratio was increased and the liver ceramide levels were decreased only in the mice receiving 72 and 143 micromol/kg fumonisin B(1). Increased hepatocellular apoptosis, hepatocellular hypertrophy, Kupffer cell hyperplasia, and macrophage pigmentation were detected in the mice consuming 72 and 143 micromol/kg fumonisin B(1). The other fumonisin derivatives did not alter serum analytes, organ weights, or hepatic structure. These results suggest that, of the naturally occurring fumonisins, fumonisin B(1) is the principal hepatotoxic derivative in the B6C3F(1) mouse.

Topics: Alkaline Phosphatase; Animals; Bile Acids and Salts; Blood Chemical Analysis; Body Weight; Carcinogens, Environmental; Ceramides; Cholesterol; Chromatography, High Pressure Liquid; Diet; Female; Fumonisins; Mice; Mice, Inbred Strains; Organ Size; Proteinuria; Sphingosine

Fumonisin B1 (FB1) is the predominant member of a family of toxic metabolites produced by several species of Fusarium and is commonly found on corn. FB1 is a potent competitive inhibitor of ceramide synthase, which catalyzes the conversion of sphinganine and sphingosine to ceramide. The resultant accumulation of free sphingoid bases and the disruption of sphingolipid metabolism is believed to be the mechanism of toxicity of the fumonisins. The objectives of this study were to determine the relative potency of analogs of FB1 to inhibit ceramide synthase and to determine whether the inhibition is specific to mycotoxins with fumonisin-like structures. Fumonisins B1, B2, B3, B4, C4, and TA toxin (a structurally similar mycotoxin produced by the tomato pathogen, Alternaria alternata f. sp. lycopersici) were approximately equipotent inhibitors. Hydrolyzed fumonisins B1, B2, and B3, which lack the tricarballylic side chains, were only 30-40% as potent as the parent toxins. N-acetylated FB1 (FA1) did not block ceramide synthase, suggesting that FA1 is nontoxic. Inhibition of ceramide synthase by fumonisin analogs did not appear to be related to the lipophilicity of the compounds, as determined by computer estimation of log P values. The ability of relatively high (10 and 100 microm) doses of other mycotoxins that bear no structural similarity to fumonisins, including aflatoxin B1, cyclopiazonic acid, beauvericin, T-2 toxin, sterigmatocystin, luteoskyrin, verrucarin A, scirpentriol, and zearalenone, to block ceramide synthase was also determined. All of the toxins tested were negative in the bioassay with the exception of fumonisins, indicating that disruption of sphingolipid metabolism is a specific cytotoxic response.

Topics: Acetylation; Alternaria; Amidohydrolases; Animals; Carboxylic Acids; Carcinogens, Environmental; Ceramidases; Fumonisins; Liver; Male; Mycotoxins; Rats; Rats, Sprague-Dawley; Solanum lycopersicum; Sphingolipids; Sphingosine; Structure-Activity Relationship

This study was conducted to investigate the effects of dietary Fusarium moniliforme culture material (M-1325) containing known concentrations of fumonisins B1, B2 and B3 on sphingolipids in urine and hair of mink (Mustela vison) for use as potential, non-invasive biomarkers of exposure to fumonisins in this species. Feeding mink diets containing 86, 22, and 7 ppm or 200, 42, and 12 ppm of fumonisins B1, B2 and B3, respectively, yielded marked increases in urinary free sphinganine (Sa) and free sphingosine (So) concentrations, and free Sa/free So ratios (2 to 11-fold) within 7 d, compared to controls. Free Sa and free So concentrations and Sa/So ratios in hair samples from mink fed the control or high dose fumonisin diets for 100 days were similar and were not apparently altered by exposure to these mycotoxins. These results suggest that Sa/So ratios in urine, but not in hair of mink can serve as an early indicator of exposure to fumonisins in this species.

Topics: Animals; Carboxylic Acids; Female; Fumonisins; Hair; Male; Mink; Sphingolipids; Sphingosine

Adult female mink (Mustela vison) were fed a diet that contained Fusarium moniliforme culture material that provided dietary concentrations of 89 ppm fumonisin B1, 21 ppm fumonisin B2, and 8 ppm fumonisin B3 for 87 days. During the trial, there was mild lethargy in the mink fed fumonisins, but no other clinical signs or differences in feed consumption (measured during the first two weeks), body weights, or survivability were observed between the fumonisin-treated and control mink. Several hematologic parameters (mean corpuscular hemoglobin concentration, plasma total solids, and lymphocyte concentration) and serum chemical concentrations (globulin, phosphorus, potassium, blood urea nitrogen, creatinine, bilirubin, and cholesterol) and activities (alkaline phosphatase, alanine aminotransferase, amylase, and aspartate aminotransferase) were greater in the mink fed fumonisins than in the controls. Serum albumin/globulin and sodium/potassium ratios and chloride concentrations were lower in the fumonisin-fed mink than in the controls. The concentrations of free sphinganine and the ratio of free sphinganine to free sphingosine in the liver and kidneys of the fumonisin-treated mink were greater than in the control mink. No histopathologic alterations were associated with fumonisin treatment. These results indicate that long-term dietary exposure to F. moniliforme culture material containing 118 ppm total fumonisins is not lethal to adult mink, but can produce adverse physiological effects in the animals.

Topics: Animals; Female; Food Contamination; Fumonisins; Kidney; Liver; Mink; Mycotoxins; Sphingosine