Qualitative and Quantitative Analyses of Alkaloids in <i>Uncaria</i> Species by UPLC-ESI-Q-TOF/MS

Abstract

An ultra performance liquid chromatography (UPLC) coupled with quadrupole time-of-flight mass spectrometry (Q-TOF/MS) method has been optimized and established for the rapid analysis of the alkaloids in 22 samples originating from five Uncaria (U.) species. The accurate mass measurement of all the protonated molecules and subsequent fragment ions offers higher quality structural information for the interpretation of fragmentation pathways of the various groups of alkaloids. A total of 19 oxindole alkaloids, 16 indole alkaloids and 1 flavone were identified by co-chromatography of the sample extract with authentic standards, comparison of the retention time, characteristic molecular ions and fragment ions, or were tentatively identified by MS/MS determination. Moreover, the method was validated for the simultaneous quantification of the 24 components within 10.5 min. The potential chemical markers were identified for classification of the U. species samples by principal component analysis (PCA) and orthogonal partial least squared discriminant analysis (OPLS-DA). The results demonstrate the similarity and differences in alkaloids among the five U. species, which is helpful for the standardization and quality control of the medical materials of the U. Ramulus Cum Unics (URCU). Furthermore, with multivariate statistical analysis, the determined markers are more definite and useful for chemotaxonomy of the U. genus.

Metabolic Profile of Isocorynoxeine in Rats Obtained by Ultra-High Performance Liquid Chromatography/Quadrupole Time-of-Flight Mass Spectrometry

“…Furthermore, two fragment ions at m/z 201.10 and 187.08 were clearly detected in the Q-TOFMS spectra of IC, but poorly or less detected in those of C. The similar fragmentation and related diagnostic ions were also found in those of DCA and DCAB in the present study. Thus, the two ions could be used as diagnostic fragmentation ions for identification of tetracyclic oxindole alkaloids possessing a 7S configuration, which was well reported in our previous study [24]. Due to the lack of related reference standards, the diagnostic fragment ions for identification of 5-oxo-IC metabolites at 7S or 7R configuration have not been studied in the present research.…”

“…Thus, M 9 was tentatively identified as isocorynoxeinic acid [25], and M 17 was tentatively identified as 20-isomer of DCAB. 24 were speculated to be isocorynoxeinic acid, corynoxeinic acid and 16,17-dihydro isocorynoxeine-17-O-b-D-glucuronide, respectively, from their polarity, fragmentation patterns, etc. Only the metabolic pathways of other metabolites were identified, while their structures could not be confirmed in the present study.…”

An integrated strategy for the systematic characterization and discovery of new indole alkaloids from Uncaria rhynchophylla by UHPLC/DAD/LTQ-Orbitrap-MS

“…In addition, the retention capacities of A13 and A16 were much weaker than those of A43 and A47, which backs up this assumption. Thus, A13 and A16 were separately identified as 18,19-dehydrocorynoxinic acid and 18,19-dehydrocorynoxinic acid B, two known tMOA alkaloids that were previously isolated from UR [33]. Another pair of isomeric alkaloids, A3 (t R 0.99 min) and A4 (t R 1.36 min), followed similar fragmentation pathways to A13 and A16.…”

“…Common fragmentations such as the predominant elimination of H 2 O, H 2 O+CH 3 OH, the C-15 side chain (−102 Da), and a product ion indicative of an indole ring skeleton at m/z 160.08 were observed during their ESI-MS n fragmentations. The product ion obtained by elimination of the C-15 side chain and the easy elimination of H 2 O suggested the presence of a COOH group relating to the C-15 side chain (1-methoxy acrylic acid) [33]. In addition, the retention capacities of A13 and A16 were much weaker than those of A43 and A47, which backs up this assumption.…”

Characteristic component profiling and identification of different Uncaria species based on high‐performance liquid chromatography–photodiode array detection tandem ion trap and time of flight mass spectrometry coupled with rDNA ITS sequence

“…DC. (UTT) (Pan et al, ; Wang, Qi, Zhang, & Yuan, ; Xie et al, ). LCMS‐IT‐TOF successfully combines the MS n capability of IT with high resolution and the TOF with high accuracy mass measurement capability, which is available for the structure identification and characterization of the complex system, especially for Traditional Chinese Medicine.…”