Simultaneous quantitation of nucleosides, nucleobases, amino acids, and alkaloids in mulberry leaf by ultra high performance liquid chromatography with triple quadrupole tandem mass spectrometry.

An ultra high performance liquid chromatography coupled with a triple quadrupole mass detection and electrospray ionization mass spectrometry method has been established for the simultaneous determination of the 14 nucleosides and nucleobases, 24 amino acids and two main alkaloids in mulberry leaf. In this method, a complicated mobile phase, the flow rate of which was 0.4 mL/min, was applied to the gradient elution, which provided a satisfied separation of the 40 compounds. The present method was validated, and sufficient reproducibility and accuracy were obtained for the quantitative measurement of the 40 compounds. The method was subsequently applied to ten mulberry leaves and the results showed that almost all of these samples were rich in nucleosides, nucleobases, amino acids, and alkaloids. The proposed method, which is convenient and economical, could serve as a prerequisite for the quality control of mulberry leaf herbs and be applied analogously to other Chinese medicines.

[Dynamic analysis of alkaloids and flavonoids in Genus Morus L. in China during different harvesting time].

To investigate the optimum harvesting time and utilization of mulberry leaves during different growth periods based on the content of alkaloids and flavonoids, 88 samples of 11 species of mulberry leaves were collected and analyzed. UPLC-TQ/MS method was applied and the results showed that the ingredients of alkaloids and flavonoids in mulberry leaves are quite different in different growth periods and different species. There was a sharp decline of the average content of alkaloids in all samples from October, while the content of flavonoids dropped either from October but with less volatile. The content of flavonoids in M. atropurpurea was much higher than alkaloids, while M. australis was opposite completely. There was a sharp decline of alkaloids in M. cathayana and M. mongolica from Tuly to August, however, the content of alkaloids and flavonoids in M. alba is neither too high nor too low. In summary, it is more suitable to harvest tender mulberry leaves harvested from the end of September to beginning of October that provide a scientific evidence for rational harvest and comprehensive utilization of mulberry leaves.