Date of Award
Doctor of Philosophy (PhD)
Joe P. Foley
The foliage of thirteen genetic clones of the nitrogen-fixing trees Erythrina berteroana, E. poeppigiana and E. costarricensis growing under similar environmental conditions in the Latin American Nitrogen Fixing Tree Arboretum, CATIE, Turrialba, Costa Rica, was evaluated by gas chromatography/mass spectrometry for toxic alkaloid content. The major alkaloid identified was $\beta$-erythroidine, a naturally derived drug used in the 1950s and 1960s as a neuromuscular blocking agent in surgery and electroshock treatments. Other alkaloids identified were $\alpha$-erythroidine, erybidine, erythraline, erysodine, oxo-$\beta$-erythroidine and several previously undescribed compounds. There was a difference of more than two orders of magnitude in the $\beta$-erythroidine concentration between the clones with the highest and the lowest content. Although all clones tested contained some amount of $\beta$-erythroidine, at least one clone of each species was notably low in this drug. The results indicate that the expression of Erythrina alkaloids is at least partially under genetic control. A feeding study was performed utilizing goats on three experimental diets: control, 40% E. berteroana foliage and 40% E. poeppigiana foliage. The $\beta$-erythroidine present in the foliage of Erythrina species was hydrogenated in the rumen and $\beta$-erythroidine, dihydroerythroidines and tetrahydroerythroidines were detected in the milk of goats in the Erythrina foliage treatment groups, however, these compounds were not detected in the milk of the control group. Synthetic experiments demonstrated that the dihydroerythroidine isomers present in the milk and rumen samples were not the same isomers produced by catalytic hydrogenation. During catalytic hydrogenation, the conjugated diene in $\beta$-erythroidine is reduced to a single double bond at the 1-6 position. Mass spectral data indicate that the conjugated diene is conserved during hydrogenation of $\beta$-erythroidine in the rumen and that the double bond in the lactone ring may be hydrogenated. Synthetically derived dihydroerythroidine is ten times more potent than the parent drug, $\beta$-erythroidine, therefore there is a possibility that the presence of biologically hydrogenated dihydroerythroidines in the milk of goats which consume Erythrina foliage may pose a health hazard to individuals consuming the contaminated milk. Further studies designed to investigate the toxicology of biologically hydrogenated dihydroerythroidines are recommended.
Payne, Lori Denise, "The Alkaloids of Erythrina: Clonal Evaluation and Metabolic Fate." (1991). LSU Historical Dissertations and Theses. 5268.