heliotrine and lasiocarpine

Pyrrolizidine alkaloids (PA) are secondary plant metabolites that occur as food and feed contaminants. Acute and subacute PA poisoning can lead to severe liver damage in humans and animals, comprising liver pain, hepatomegaly and the development of ascites due to occlusion of the hepatic sinusoids (veno-occlusive disease). Chronic exposure to low levels of PA can induce liver cirrhosis and liver cancer. However, it is not well understood which transcriptional changes are induced by PA and whether all hepatotoxic PA, regardless of their structure, induce similar responses. Therefore, a 28-day subacute rat feeding study was performed with six structurally different PA heliotrine, echimidine, lasiocarpine, senecionine, senkirkine, and platyphylline, administered at not acutely toxic doses from 0.1 to 3.3 mg/kg body weight. This dose range is relevant for humans, since consumption of contaminated tea may result in doses of ~ 8 µg/kg in adults and cases of PA ingestion by contaminated food was reported for infants with doses up to 3 mg/kg body weight. ALT and AST were not increased in all treatment groups. Whole-genome microarray analyses revealed pronounced effects on gene expression in the high-dose treatment groups resulting in a set of 36 commonly regulated genes. However, platyphylline, the only 1,2-saturated and, therefore, presumably non-hepatotoxic PA, did not induce significant expression changes. Biological functions identified to be affected by high-dose treatments (3.3 mg/kg body weight) comprise cell-cycle regulation associated with DNA damage response. These functions were found to be affected by all analyzed 1,2-unsaturated PA.In conclusion, 1,2-unsaturated hepatotoxic PA induced cell cycle regulation processes associated with DNA damage response. Similar effects were observed for all hepatotoxic PA. Effects were observed in a dose range inducing no histopathological alterations and no increase in liver enzymes. Therefore, transcriptomics studies identified changes in expression of genes known to be involved in response to genotoxic compounds at PA doses relevant to humans under worst case exposure scenarios.

Topics: Animals; DNA Damage; Gene Expression; Humans; Liver; Liver Neoplasms; Plants; Pyrrolizidine Alkaloids; Rats; Structure-Activity Relationship

Plants producing dehydropyrrolizidine alkaloids (DHPAs) are found throughout the world and they are dangerous to human and animal health. Several DHPAs are carcinogenic but only riddelliine has been classified as a potential human carcinogen by the National Toxicology Program. As DHPA-related carcinogenicity is probably linked to cytotoxicity, a model of CRL-2118 chicken hepatocyte cytotoxicity was developed to compare equimolar DHPA exposures between 19 and 300 μM. Alkaloid-related cytotoxicity was estimated using cytomorphology, cell viability reflected by mitochondrial function and cellular degeneration reflected by media lactate dehydrogenase activity. Lasiocarpine induced cytotoxicity and decreased cell viability in a concentration dependent manner at 24 h. At similar concentrations and exposures of 48 and 72 h, seneciphylline, senecionine, monocrotaline and riddelliine were cytotoxic. None of the DHPA-N-oxides were significantly cytotoxic at these concentrations. Using graphic analyses the median cytotoxic concentration (DHPA concentration that produced ½ the maximum response) were estimated. The estimated descending order of cytotoxicity was lasiocarpine, seneciphylline, senecionine, heliotrine, riddelliine, monocrotaline, riddelliine-N-oxide, lycopsamine, intermedine, lasiocarpine-N-oxide and senecionine-N-oxide. This comparison identifies DHPAs that were more cytotoxic than carcinogenic riddelliine. Additional studies to better characterize the carcinogenic potential of these alkaloids are essential to better determine the risk they each may pose for human and animal health.

Topics: Animals; Cattle; Cell Line, Tumor; Cell Survival; Chickens; Cyclic N-Oxides; Cytotoxins; HEK293 Cells; Hep G2 Cells; Humans; In Vitro Techniques; Molecular Structure; Monocrotaline; Pilot Projects; Pyrrolizidine Alkaloids; Tetrazolium Salts; Thiazoles

Experimental pyrrolizidine alkaloid intoxication was produced in inbred Swiss mice. Animals were fed diets containing 0, 1, 3, 5, or 10% Heliotropium dolosum seed for 24 w. The seeds contained 0.13% total alkaloid concentration composed of 4 specific components: lasiocarpine (78.79%), heliosupine (11.96%), echimidine (5.43%), and heliotrine (3.82%). Deaths occurred in all dosed groups and increased with dietary seed concentration. Massive to submassive liver necrosis together with sinusoidal congestion, and hemorrhage or multifocal hepatocytic necrosis was limited to animals which survived < 5 w and were fed on 10% seed. Moderate to severe hepatomegalocytosis, scattered single cell necrosis, and mild subcapsuler fibrosis were seen in all test group animals that survived > 5 w. Intranuclear eosinophilic inclusions in hepatocytes and bile duct and ductular cell hyperplasia were the most noticeable lesions in the 1, 3, and 5% groups. There was mild to moderate renal tubular megalocytosis in the 3, 5, and 10% groups. It seems likely that H dolosum seed, at least to a limited extent, constitutes a health hazard for certain animal species.

Topics: Animals; Cell Nucleus; Chemical and Drug Induced Liver Injury; Diet; Dose-Response Relationship, Drug; Gas Chromatography-Mass Spectrometry; Hepatocytes; Kidney; Liver; Longevity; Male; Mice; Necrosis; Plant Poisoning; Plants, Toxic; Pyrrolizidine Alkaloids; Seeds

Topics: Alkaloids; Animals; Benzaldehydes; Benzodioxoles; Liver; Oxides; Pyrrolizidine Alkaloids; Rats

Topics: Alkaloids; Animals; Benzaldehydes; Benzodioxoles; Oxides; Pyrrolizidine Alkaloids; Rats