Rapid reversed-phase high performance liquid chromatographic method for the quantification of L-Dopa (L-3,4-dihydroxyphenylalanine), non-methylated and methylated tetrahydroisoquinoline compounds from Mucuna beans

A high-performance liquid chromatographic (HPLC) assay for the extraction and quantitative determination of L-Dopa, L-3-carboxy-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline and 1-methyl-3-carboxy-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline in Mucuna pruriens var. utilis seeds has been developed. All the three compounds, L-Dopa, CDTHIQ and MCDTHIQ in the white variety of whole (4.96 g 100 g−1, 130.3 and 116.8 mg 100 g−1) and dehulled (5.21 g 100 g−1, 138.3 and 125.9 mg 100 g−1) seeds have been found to be significantly (P<0.05) higher than the black variety, respectively. The method makes use of a reversed-phase system with a C18-bonded column and yields quantitative recovery of all the three compounds, L-Dopa (101.8%), CDTHIQ (98.2%) and MCDTHIQ (94.5%). This procedure is superior to other analytical techniques currently available because of its simplicity with regard to sample preparation, the sensitivity and rapidity of the method.