Development of a microchip-pulsed electrochemical method for rapid determination of L-DOPA and tyrosine inMucuna pruriens

Abstract

L-3,4-dihydroxyphenylalanine (L-DOPA) is a well-recognized therapeutic compound to Parkinson's disease. Tyrosine is a precursor for the biosynthesis of L-DOPA, both of which are widely found in traditional medicinal material, Mucuna pruriens. In this paper, we described a validated novel analytical method based on microchip capillary electrophoresis with pulsed electrochemical detection for the simultaneous measurement of L-DOPA and tyrosine in M. pruriens. This protocol adopted end-channel amperometric detection using platinum disk electrode on a homemade glass/polydimethylsiloxane electrophoresis microchip. The background buffer consisted of 10 mM borate (pH 9.5) and 0.02 mM cetyltrimethylammonium bromide, which can produce an effective resolution for the two analytes. In the optimal condition, sufficient electrophoretic separation and sensitive detection for the target analytes can be realized within 60 s. Both tyrosine and L-DOPA yielded linear response in the concentration range of 5.0-400 μM (R(2) > 0.99), and the LOD were 0.79 and 1.1 μM, respectively. The accuracy and precision of the established method were favorable. The present method shows several merits such as facile apparatus, high speed, low cost and minimal pollution, and provides a means for the pharmacologically active ingredients assay in M. pruriens.

Simultaneous determination of 4-hydroxyphenyl lactic acid, 4-hydroxyphenyl acetic acid, and 3,4-hydroxyphenyl propionic acid in human urine by ultra-high performance liquid chromatography with fluorescence detection

“…Amino acids play an important role in the process of human metabolism, so they are important substances which are related to human health . Studies have shown that amino acid metabolism diseases and malignant tumors had certain relevance to some tyrosine metabolite . At present, the studies of tyrosine metabolites mainly focus on the serum samples , and the analysis of tyrosine metabolites in urine samples were less reported.…”

“…Amino acids play an important role in the process of human metabolism, so they are important substances which are related to human health [1][2][3][4]. Studies have shown that amino acid metabolism diseases and malignant tumors had certain relevance to some tyrosine metabolite [5][6][7][8][9]. At present, the Abbreviations: FLD, fluorescence detection; PHPA, 3,4-hydroxyphenyl propionic acid; PHPAA, 4-hydroxyphenyl acetic acid; PHPLA, 4-hydroxyphenyl lactic acid Conflict of interest: The authors have declared no conflict of interest.…”

Separation of natural antioxidants using PDMS electrophoresis microchips coupled with amperometric detection and reverse polarity

“…At the same time, electrochemical detection (ED) is an interesting detection mode to be coupled with ME and has been successfully used for the determination of many biologically important compounds . Electrochemical methods are particularly attractive for the determination of antioxidants due to their high sensitivity and specificity for compounds undergoing redox reactions . ED allows the analysis of antioxidants in samples without the need of derivatization.…”

“…Among the ED modes, amperometry is the most commonly used approach for use with ME. It is the method that provides the best LODs, and many innovative improvements have been reported on recent years, such as new arrangements for integrating ME with ED .…”

Quantitative NMR analysis of L‐Dopa in seeds from two varieties of Mucuna pruriens

“…8 Several methods have been described in the literature for the quantitative determination of L-Dopa in various biological samples and pharmaceutical preparations, such as spectrofluorometry, gas chromatography, high-performance liquid chromatography (HPLC), high-performance thin-layer chromatography (HPTLC) chemiluminescence, and electrochemical determination. [9][10][11][12][13][14][15] In comparison with these techniques, NMR spectroscopy in quantitative analysis has the advantage that the determination can be made by adding an internal standard without performing a calibration curve. This is because, when a quantitative NMR (qNMR) method is used, the area of each signal is proportional to the molar concentration of the compounds analyzed.…”