¹H-qNMR for direct quantification of stachydrine in Leonurus japonicus and L. cardiaca.

(1)H-qNMR-spectroscopy was successfully applied to quantify the pharmacologically active alkaloid stachydrine ((2S)-1,1-dimethylpyrrolidinium-2-carboxylic-acid) in aerial parts of Leonurus japonicus (Leonuri herba, yimucao; Chin.Ph.2010, DAB2012) which are used in TCM and Kampo for the treatment of various gynaecological and cardiovascular disorders. Pharmacological publications on this betaine describe cardiovascular, hypotensive, and tissue-protective effects. However, its pharmacopeial analytics poses severe difficulties as it does not contain any chromophore suitable for HPLC-UV-detection. Nine samples from three countries were prepared as decoctions and freeze-dried. (1)H-NMR-spectra were recorded in D2O. The direct-quantitative (1)H-qNMR-procedure was carried out using the N-CH3-singlet at δ 3.03 ppm in comparison to the δ 6.18 ppm singlet of the two vinylic protons of maleic-acid, which was identified as a most favourable internal standard. The quantification limit of stachydrine was 0.44 mg/g drug material. Neither reference-compounds for calibration-curves nor sample-pre-purification was necessary. This protocol revealed stachydrine contents in the range from 0.09 up to 1.01% (w/w) for the tested yimucao samples. Furthermore, between 0.18 and 0.21% of stachydrine was found in the L. japonicus fruit-drug (Leonuri fructus, chongweizi; Chin.Ph.2010) which was examined for this constituent for the first time. In four co-investigated samples of the closely related and similarly used European herb Leonurus cardiaca Ph.Eur., even higher contents up to 1.55% were attested. The presented quantitative (1)H-qNMR-method was shown to be precise with respect to concentration, and yielded highly reproducible data in a series of inter-day repetitions. Methodically, (1)H-qNMR may be a powerful tool for quality assurance of stachydrine containing plants and herbal drugs, especially for industrial routine protocols.

Anthraquinone Content in Noni (Morinda citrifolia L.).

Noni has been used in traditional medicine and as food for thousands of years. While the fruits serve as food and internal medicine, leaves were traditionally used only topically. In recent years, concern regarding the possible content of anthraquinones in noni has led to scrutiny by the European Food Safety Authority. Little research existed on the content of anthraquinones in different noni preparations, with no information about the potential effect of harvest and preparation methods. Our research focused on lucidin, alizarin, and rubiadin, the most important anthraquinones from a health perspective. We found that the production process (fermentation/juice production versus drying/lyophilization) has no effect on the anthraquinone content. The source product, however, does have implications: noni fruit puree from which seeds had been removed as well as consumer products produced from such puree had no detectable amounts of any anthraquinones. Products that did contain seed or leaf material in all cases did contain partly significant amounts of anthraquinones. To alleviate safety concerns, we suggest that noni products, whether fermented or unfermented juice or powder, should be derived only from fully ripe noni fruits, and that any seed material needs to be removed during the production process.