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ARS Home » Pacific West Area » Logan, Utah » Poisonous Plant Research » Research » Publications at this Location » Publication #331657
Title: Could nitrile derivatives of turnip (Brassica rapa) glucosinolates be Hepato-and/or cholangiotoxic in cattle?

Author
item COLLETT, MARK - Massey University
item Stegelmeier, Bryan
item TAPPER, BRIAN - Hamilton University

Submitted to: International Symposium on Poisonous Plants
Publication Type: Proceedings
Publication Acceptance Date: 5/30/2015
Publication Date: 6/5/2015
Citation: Collett, M.G., Stegelmeier, B.L., Tapper, B.A. 2015. Could nitrile derivatives of turnip (Brassica rapa) glucosinolates be Hepato-and/or cholangiotoxic in cattle?. International Symposium on Poisonous Plants. 9:31-41.

Interpretive Summary: Turnip, rape and other brassica forage crops are generally regarded as “safe” feed for cattle during late summer and fall in New Zealand. However, they can be infected with fungus and when spore counts are high there are epidemics of sporidesmin induce photosensitivity or sun burn (facial eczema). In this study we have identified a second brassica associated photosensitivity. Sporadic severe cases photosensitization occurs in dairy cows that develop liver disease that mimic those seen in facial eczema. The two diseases can, however, be distinguished as they produce different types of liver disease. Of the hydrolysis products of the various potential toxins in turnip and rape, nitriles and epithionitriles can cause liver disease in rats. These toxins are ß-hydroxy-thiiranepropanenitrile and 3-hydroxy-4-pentenenitrile from progoitrin; thiiranepropanenitrile and 4-pentenenitrile from gluconapin; thiiranebutanenitrile and 5-hexenenitrile from glucobrassicanapin; phenyl-3-propanenitrile from gluconasturtiin; and indole-3-acetonitrile from glucobrassicin. This chapter discusses the possibility of the preferential formation of such derivatives, especially the epithionitriles, in acidic conditions in the bovine rumen, followed by absorption, hepatotoxicity, and secondary photosensitization.

Technical Abstract: Turnip (Brassica rapa ssp. rapa) and rape (Brassica napus ssp. biennis) and other brassica forage crops are generally regarded as “safe” feed for cattle during late summer and fall in New Zealand. However, when Pithomyces chartarum spore counts are high there are epidemics of sporidesmin toxicity (facial eczema). Sporadic acute severe cases of turnip photosensitization in dairy cows characteristically exhibit high '-glutamyl transferase and glutamate dehydrogenase serum enzyme activities that mimic those seen in facial eczema. The two diseases can, however, be distinguished by histopathology of the liver, where lesions, in particular those affecting small bile ducts, differ. To date, the hepato-/cholangiotoxic phytochemical causing liver damage in turnip photosensitization in cattle is unknown. Of the hydrolysis products of the various glucosinolate secondary compounds found in high concentrations in turnip and rape, work has shown that nitriles and epithionitriles can be hepatotoxic (and nephro- or pancreatotoxic) in rats. These derivatives include ß-hydroxy-thiiranepropanenitrile and 3-hydroxy-4-pentenenitrile from progoitrin; thiiranepropanenitrile and 4-pentenenitrile from gluconapin; thiiranebutanenitrile and 5-hexenenitrile from glucobrassicanapin; phenyl-3-propanenitrile from gluconasturtiin; and indole-3-acetonitrile from glucobrassicin. This perspective explores the possibility of the preferential formation of such derivatives, especially the epithionitriles, in acidic conditions in the bovine rumen, followed by absorption, hepatotoxicity, and secondary photosensitization.