OPTICAL-ROTATION OF QUINOLIZIDINE ALKALOIDS - AN IMPORTANT VARIABLE IN CHEMOSYSTEMATIC STUDIES OF FABACEAE

The anomalous distribution of (+)-lupanine and (-)-lupanine in Podalyr ia species provides circumstantial evidence that hydroxylation and sub sequent esterification of lupanine is only possible when (-)-sparteine and (+)-lupanine are the precursors. The optical rotation of lupanine and/or sparteine isolated from different genera, in combination with literature data, provide evidence of a separate biosynthetic pathway w hich leads to lupanine-type esters rather than alpha-pyridones. The oc currence of this pathway can be predicted from the optical rotation of sparteine and/or lupanine, even in the absence of end products. Enant iomers-specificity is thus an important variable for establishing homo logy in comparative studies.