Deep chemical identification of phytoecdysteroids in Achyranthes bidentata Blume by UHPLC coupled with linear ion trap-Orbitrap mass spectrometry and targeted isolation / 中国天然药物

Achyranthes bidentata Blume is widely used as a traditional Chinese medicine with the effects of nourishing the liver and kidneys and strengthening muscles and bones. In this work, a rapid and simple strategy was developed for characterizing phytoecdysteroids by ultra-high-performance liquid chromatography coupled with liner ion trap-Orbitrap mass spectrometry using electrospray ionization in the negative mode. As a result, 47 phytoecdysteroids were unambiguously or tentatively characterized. Among them, seven known compounds were identified according to the reference standards along with molecular formula, retention time and fragmentation patterns, while others were mostly potential new compounds. Through targeted isolation, the structures of three new compounds were determined by NMR spectra, which were consistent with LC-MS characterization. The present study provides an efficient method to deeply characterize phytoecdysteroids.

Mass spectrometry guided strategy based on feature fragment ions for guided-separation on quinoline alkaloids from root barks of Dictamnus dasycarpus / 中国中药杂志

The root bark of Dictamnus dasycarpus is one of common traditional Chinese medicines (TCMs). Quinoline alkaloids are one of the main active substances in this TCM and possess many biological activities including anti-titumor, anti-inflammation, anti-bacteria, anti-oxidation, and anti-platelet aggregation activities. In this study, eight quinoline alkaloids 1-8 were firstly separated from the root barks of D. dasycarpus. It was difficult to isolate more quinoline alkaloids from the remaining fraction 8 in D. dasycarpus by this conventional chemical separation, so the target analysis method combined LC-MS guided-separation of quinoline alkaloids from fraction 8 was established. MS/MS fragmentation patterns of eight quinoline alkaloids reference standard compounds 1-8 were studied by ultra-performance liquid chromatography-electrospary ionization-mass spectrometry (UPLC-ESI-MS/MS). Based on the feature fragment ion 200, the parent ion scan mode was established for the target analysis of quinoline alkaloids in fraction 8. Finally, 8-methoxyflindersine (9) and N-metilatanina (10) were discovered and isolated quickly from fraction 8 guided by LC-MS, and their structures were identified by NMR and MS. Among them, compound 10 was isolated from the genus Dictamnus for the first time. These results indicated that this method is not only quick and sensitive for analyzing the quinoline alkaloids, but also to effectively guided-separate this kind of alkaloids in the root barks of D. dasycarpus.

Chemical constituents from root barks of Dictamnus dasycarpus and their cytotoxic activities / 中国中药杂志

Nineteen compounds, including kihadanin D (1), obacunone (2), kihadanin A (3), kihadanin B (4), kihadanin C (5), limonin (6), evodol (7), fraxinellone (8), furo[2,3-b]quinolin-4-ol (9), preskimmianine (10), ifflaiamine (11), dictamnol (12), naringenin (13), diosmetin (14), wogonin (15), scopoletin (16), cleomiscosin A (17), apocynin (18), and methyl pyroglutamate (19), were isolated from the methanol extract of the root barks of Dictamnus dasycarpus by using various column chromatographies. Their chemical structures were extensively determined on basis of UV, IR, NMR, MS, and CD spectroscopic data analyses. Among them, 1 is a new limonoid, 9 was isolated from plant kingdom for the first time, 11, 13-14 and 17-19 were obtained from the genus Dictamnnus for the first time. Cytotoxicities of compounds 1-18 were tested, and the results indicated that 1 exhibited cytotoxicities against three human cancer cell lines MDA-MB-231, A549 and HT29 with IC₅₈ values of 16.22, 21.72 and 31.06 μmol·L⁻¹, respectively.