Comparative Chemical Profiling and Monacolins Quantification in Red Yeast Rice Dietary Supplements by <sup>1</sup>H-NMR and UHPLC-DAD-MS
Rabab Hachem,
Gaëtan Assemat,
Stéphane Balayssac,
Nathalie Martins-Froment,
Véronique Gilard,
Robert Martino,
Myriam Malet-Martino
Affiliations
Rabab Hachem
Biomedical NMR Group, Laboratoire SPCMIB, UMR CNRS 5068, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse CEDEX 9, France
Gaëtan Assemat
Biomedical NMR Group, Laboratoire SPCMIB, UMR CNRS 5068, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse CEDEX 9, France
Stéphane Balayssac
Biomedical NMR Group, Laboratoire SPCMIB, UMR CNRS 5068, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse CEDEX 9, France
Nathalie Martins-Froment
Service commun de spectrométrie de masse, Institut de Chimie de Toulouse, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse CEDEX 9, France
Véronique Gilard
Biomedical NMR Group, Laboratoire SPCMIB, UMR CNRS 5068, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse CEDEX 9, France
Robert Martino
Biomedical NMR Group, Laboratoire SPCMIB, UMR CNRS 5068, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse CEDEX 9, France
Myriam Malet-Martino
Biomedical NMR Group, Laboratoire SPCMIB, UMR CNRS 5068, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse CEDEX 9, France
Red yeast rice dietary supplements (RYR DS) are largely sold in Western countries for their cholesterol-lowering/regulating effect due to monacolins, mainly monacolin K (MK), which is, in fact, lovastatin, the first statin drug on the market. 1H-NMR was used as an easy, rapid and accurate method to establish the chemical profiles of 31 RYR DS and to quantify their monacolin contents. Among all the 1H resonances of the monacolins found in RYR, only those of the ethylenic protons of the hexahydronaphthalenic ring at 5.84 and 5.56 ppm are suitable for quantification because they show no overlap with the matrix signals. The total content in monacolins per capsule or tablet determined in 28 DS (the content in 3 DS being below the limit of quantification of the method, ≈ 0.25 mg per unit dose) was close to that measured by UHPLC, as shown by the good linear correlation between the two sets of values (slope 1.00, y-intercept 0.113, r2 0.986). Thirteen of the 31 RYR DS analyzed (i.e., 42%) did not provide label information on the concentration of monacolins and only nine of the 18 formulations with an indication (i.e., 50%) actually contained the declared amount of monacolins.
