Structure of a Dopa Glucoside from Vicia faba

Abstract

β-(3,4-Dihydroxyphenyl)-L-alanine (L-DOPA) has only been detected in a limited number of plants, and it appears to be confined mainly to leguminous species. Unlike most other phenols of low molecular weight, however, it exists in relatively high concentrations in the free state. This is particularly the case, for example, with the broad-bean, Vicia faba¹, but Nagasawa and his associates² have also isolated an O-β-D-glucoside of DOPA from the testa of the bean seed. The Japanese workers did not, however, determine whether it was a 3- or 4-O substituted derivative and in view of our interest in the formation and metabolism of DOPA in plants we have reinvestigated the structure and distribution of this compound.