Simultaneous Determination of L-dopa and Its Derivates in Seeds of Mucuna Pruriens Var. Utilis by HPLC

OBJECTIVE To establish a method for simultaneous determination of both L-dopa( 2 ) and its derivates in seeds of Mucuna pruriens var. utilis Burck by HPLC. METHODS Three ingredients, 3-carboxy-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline( 1 ), 1-methyl-3-carboxy-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline( 3 ) and 1,1-dimethyl-3-carboxy- 6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline( 4 ) were isolated from the herb. Chromatographic separation was performed on a Cosmosil C₁₈-PAQ analytical column (4.6 mm×250 mm, 5 mm) with 1% acetic acid as the mobile phase at 30 ℃. The detection wavelength was 280 nm and the flow rate was 0.5 mL·min^-1. RESULTS The 4 components were separated with satisfaction. Their linearity ranges were between 0.298 4-5.968 mg ( 1 ), 6.554-131.1 mg ( 2 , L-dopa), 0.262 6-5.252 mg ( 3 ) and 0.256 8-5.136 mg ( 4 ), respectively with their correlation coefficients all >0.999. Their average recovery rates were 97.7%, 99.1%, 98.7% and 97.9%. CONCLUSION The method is accurate and selective for simultaneous determination of 4 ingredients in seeds of Mucuna pruriens, which could be applied for the quality control of this herb.