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

Abstract

Uncaria is a multi-source herb and its species identification has become a bottleneck in quality control. To study the identification method of different Uncaria species herbs through HPLC-MS coupled with rDNA Internal Transcribed Spacer (rDNA ITS) sequence, both plant morphological traits and molecular identification were used to determine the species of every collected Uncaria herb. The genetic analysis of different Uncaria species was performed using their rDNA ITS sequence as a molecular marker. Meanwhile, the phylogenetic relationships of 22 samples from six Uncaria species were divided and classified clearly. By optimizing the chromatographic conditions, a practical HPLC method to differentiate various varieties of Uncaria herbs was set up based on a set of characteristic components across each species. A high-performance liquid chromatography-photodiode array detector tandem ion trap and time of flight mass spectrometry technique combined with reference substances was utilized to derive 21 characteristic compounds containing six groups of six Uncaria species in China. Thus, this study provides a feasible method to solve the current problem of confusion in Uncaria species, and makes a significant step forward in the appropriate clinical use, in-depth research and further utilization of different Uncaria species.

Phylogenetic analysis of Uncaria species based on internal transcribed spacer (ITS) region and ITS2 secondary structure

“…Nucleotide comparison of consensus sequences is a reliable method that may be considered to identify closely-related, adulterated or misidentified Uncaria species, and be used to confirm morphological and chemical identification (Zhao et al. 2018 ). For example, when a query sequence was aligned to a consensus sequence of Uncaria rhynchophylloides F.C.How, a match of six sites (118 bp-C, 152 bp-G, 247 bp-A, 447 bp-T, 493 bp-T and 580 bp-C) identified the query sequence as U. sinensis .…”

“…Zhao et al. ( 2018 ) demonstrated that the liquid chromatography–mass spectrometry tandem ion trap-time of flight mass spectrometry (LCMS-IT-TOF) was a feasible method to solve the confusion in Uncaria species. Tang et al.…”

Quality standard of traditional Chinese medicines: comparison between European Pharmacopoeia and Chinese Pharmacopoeia and recent advances

“…Another example is Uncariae Ramulus cum Uncis, EP states that its botanical source is Uncaria rhynchophylla , but there are five botanical sources in ChP: Uncaria rhynchophylla , Uncaria macrophylla , Uncaria hirsute , Uncaria sinensis and Uncaria sessilifructus . The genetic analysis based on rDNA ITS sequences showed that Uncaria rhynchophylla , Uncaria sinensis and Uncaria hirsute were closely related to each other but were far away from Uncaria macrophylla and Uncaria sessilifructus [ 14 ]. The chromatographic fingerprint showed that significant difference could be observed among the five Uncaria species, yet there were also some similarities between each other [ 14 , 15 ].…”

“…The genetic analysis based on rDNA ITS sequences showed that Uncaria rhynchophylla , Uncaria sinensis and Uncaria hirsute were closely related to each other but were far away from Uncaria macrophylla and Uncaria sessilifructus [ 14 ]. The chromatographic fingerprint showed that significant difference could be observed among the five Uncaria species, yet there were also some similarities between each other [ 14 , 15 ]. As mentioned above, there are reasons to include several species and subspecies for one TCM in the monographs, but it brings more difficulty and challenges for the quality control and pharmacological study.…”

UFLC-PDA-MS/MS Profiling of Seven Uncaria Species Integrated with Melatonin/5-Hydroxytryptamine Receptors Agonistic Assay

“…Flavonoids display characteristic UV absorptions at 220-280 (band II) and 300-400 (band I) nm, by which they can be easily characterized [33]. Peaks 4 and 8 with UV maximum absorption at 280 nm were designated with the molecular formula of C 30 indicating flavonoids dimers.…”