Alkaloid variation during germination in different lupin species

Quinolizidine alkaloids, occurring in lupins, are the largest single group of legume alkaloids with clear ecological functions in the defence of the plant. During germination, some degree of transformation of alkaloids to other more bioactive compounds, such as esters, occurs. The aim of this work was to investigate the transformations of alkaloids during germination, in Lupinus albus, L. angustifolius and L. campestris. Total quinolizidine alkaloid contents in raw seeds were 1.51 g/100 g (L. angustifolius), 2.36 g/100 g (L. albus) and 2.45 g/100 g (L. campestris). During germination in L. albus, lupanine increased and albine and 13-hydroxylupanine decreased substantially. In L. angustifolius, 13-hydroxylupanine also decreased. In L. campestris, hydroxyaphylline and hydroxyaphyllidine increased while epihydroxyaphylline and dehydroepihydroxyaphylline decreased. The ester 13-tigloyloxylupanine increased progressively during the germination of L. angustifolius (from 0 to 0.044 g/100 g) and L. albus (from 0.001 to 0.022 g/100 g). Germination of lupin seeds for 3 days, maximum, could be desirable in order to minimize the presence of alkaloids, as well as to avoid the formation of the quinolizidine alkaloid esters.