|CHANG, CHENG-WEI TOM|
Submitted to: Journal of Natural Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/2/2004
Publication Date: 4/14/2005
Citation: Lee, S.T., Molyneux, R.J., Panter, K.E., Chang, C., Gardner, D.R., Pfister, J.A., Garrossian, M. 2005. Structure-activity relationships of ammodendrine and n-methyl ammodendrine enantiomers: isolation, optical rotation, and toxicity. Journal of Natural Products.
Interpretive Summary: Ingestion of Lupinus formosus by pregnant cows at specific gestational periods can result in calves with cleft palate and front limb contractures, commonly known as “crooked calf disease”. Ammodendrine, a piperidine alkaloid, found in L. formosus is a reported teratogen. L. formosus was collected at different sites in California. Ammodendrine was a major alkaloid in both plant collections. Ammodendrine has a chiral center indicating that it could be present in enantiomeric mixture in the plants. By reacting the ammodendrine isolated from these plant collections with a pure L-alanine based enantiomer we obtained alanine-ammodendrine based diasteriomers which were separated and isolated by HPLC. Pure D- and L-ammodendrine enantiomers were obtained by an Edman degradation procedure. D- and L-N-Methyl ammodendrine were synthesized. The optical rotation of the values of D- and L-ammodendrine and D- and L-N-methyl ammodendrine were established. A mouse bioassay was used to determine the difference in toxicity between D and L ammodendrine and D and L N-methyl ammodendrine
Technical Abstract: Ammodendrine (1) was found to occur as a mixture of enantiomers in two different collections of plants identified as Lupinus formosus. The ammodendrine fraction was reacted in a peptide coupling reaction with Fmoc-L-Ala-OH to give diastereomers which were separated by preparative HPLC. The pure D and L ammodendrine enantiomers were then obtained by Edman degradation. Optical rotation measurements revealed that the D and L enantiomers had optical rotations of [']24D +5.4° and -5.7º, respectively, D and L N-methylammodendrine enantiomers were synthesized from the corresponding ammodendrine enantiomers, and their optical rotations established as ['] 23D +62.4º and - 59.0º, respectively. A mouse bioassay was used to determine the difference in toxicity between these two pairs of naturally occurring enantiomers. The LD50 of (+)-D-ammodendrine in mice as determined to be 94.1± 6.8 mg/kg and that of (-)-L-ammodendrine as 115.0± 7.0 mg/kg. The LD50 of (+)-D-N-methyl ammodendrine in mice was estimated to be 56.3 mg/kg while that of (-)-L-N-methyl ammodendrine was determined to be 63.4± 4.7 mg/kg. These results establish the rotation values for pure ammodeendrine and N-methyl ammodendrine and indicate that there is little difference in acute toxicity between the respective enantiomers.