Simultaneous determination of glicine max L. and lupulus humulus L. active principles in dietary supplement

Introduction Soy isoflavones and hop prenylflavonoids are the most effective natural substances against menopausal symptomatology and are used in herbal supplements [1]. Nowadays the easy recourse to supplements is of immediate concern for overdoses and side effects, moreover, these products are more exposed than drugs to the risk of adulteration. Novel analytical approaches for quality control are necessary. Methods Methanolic extracts of hop and soy supplements were evaporated and dissolved in DMSOd6. NMR analysis was carried out with a Bruker Avance III HD600 MHz spectrometer equipped with CryoProbe BBO H&F 5mm. The most resolved peaks in the aromatic area were assigned to the main compounds using 2D sequences. Daidzein, genistein, glicitein and xanthohumol were determined by Bruker-ERETIC2 technique. Results High quality spectra were obtained with signal to noise ratio largely over the limit required for the quantification of the main compounds of interest. 7 out of the 8 analysed samples actually presented content of active principles which differ from the declared value more than 10%. In particular, 5 samples presented lower amounts while the remaining 2 showed higher quantities with respect to the value reported on the label. In the former case the therapeutic dose will not be reached when the product is administered. In the latter instead, the greater risk is to exceed the maximum recommended dose. Conclusions qNMR in the ambit of complex mixtures analysis has proved to be promising and advantageous, allowing the simultaneous determination in a single experiment, of many molecules also structurally different from one another and avoiding time consuming sample purification steps also reducing the production of artefacts.