Dehydropyrrolizidine alkaloid (DHPA) producing plants commonly poison livestock, wildlife and humans. Poisoning occurs when DHPAs are ingested as feed or food, or when they contaminate medicinal or herbal products. Direct toxicologic comparison of individual DHPAs is essential to estimate their actual health risks. This has been problematic due to varying models and difficulties in DHPA isolation or synthesis. In contrast, the macrocyclic DHPA riddelliine is readily isolated and it has been used as a benchmark to characterize different models of toxicity and carcinogenicity. Following earlier work with immortalized cell lines, the objective of this study was to characterize the effect of riddelliine on primary mouse, rat and chick hepatocyte cultures with the aim of developing a suitable, sensitive model for assessing DHPA-related cytotoxicity. After establishing viable cultures, the hepatocytes were exposed for 24 hours to riddelliine (from 0.1µM to 1.2mM) and cytotoxicity (CT50) was estimated using a mitochondrial function assay (MTT). Despite a biphasic response, possibly attributable to a sub-population of resistant chick hepatocytes, chick hepatocyte cultures were highly sensitive (CT50 0.9 µM) to riddelliine cytotoxicity relative to rat (CT50 289 µM) and mouse (CT50 627 µM) hepatocytes. Chick, mouse and rat hepatocyte cytochrome P450 3A4 activities did not correlate with riddelliine-induced cytotoxicity. With further development to utilize the highly sensitive primary chick hepatocytes, this model may be useful to directly compare panels of DHPAs, including rare or difficult to isolate alkaloids.
Stegelmeier, Bryan L.; Resager, William S.; and Colegate, Steven M.
"The comparative cytotoxicity of riddelliine in primary mouse, rat and chick hepatocytes,"
Poisonous Plant Research (PPR): Vol. 3, p. 43-57.
Available at: https://digitalcommons.usu.edu/poisonousplantresearch/vol3/iss1/4