Rapid structural determination of alkaloids in a crude extract of Stemona saxorum by high‐performance liquid chromatography/electrospray ionization coupled with tandem mass spectrometry

Abstract

The electrospray ionization (ESI) mass spectrometric behavior of five Stemona alkaloids, stemokerrin, oxystemokerrin, oxystemokerrilactone, oxystemokerrin N-oxide and stemokerrin N-oxide, was studied using an ESI tandem mass technique (MS(n)). These compounds, isolated from Stemona saxorum endemic in Vietnam, represent a class of alkaloids containing a pyrido[1,2-a]azepine A,B-ring core with a 1-hydroxypropyl side chain attached to C-4. Their fragmentation pathways were elucidated by ESI-MS(n) results and the elemental composition of the major product ions was confirmed by accurate mass measurement. In order to rationalize some fragmentation pathways, the relative Gibbs free energies of some product ions were estimated using the B3LYP/6-31+G(d) method. Based on the ESI-MS(n) results of five reference compounds, a reversed-phase high-performance liquid chromatography with tandem mass spectrometry (RP-HPLC/MS(n)) method was developed for the characterization of Stemona alkaloids with a pyrido[1,2-a]azepine A,B-ring core from the extract of S. saxorum. A total of 41 components were rapidly identified or tentatively characterized, of which 12 compounds were identified as Stemona alkaloids with a pyrido[1,2-a]azepine A,B-ring core, including four new compounds. This method is convenient and sensitive, especially for minor components in complex natural product extracts.

Isolation and structural elucidation of indole alkaloids from Geissospermum vellosii by mass spectrometry

“…Multiple tandem mass spectrometry (MS n ) is needed to obtain considerable structural information, which has been successfully used for the structure elucidation of alkaloids from Rhizoma coptidis [19] and Stemona saxorum [16]. To validate the structure of the alkaloids by ESI-MS, and to demonstrate the power of MS n to characterize the structure of alkaloids, isolated compounds from G. vellosii bark were first analyzed by NMR.…”

“…However, it is usually a challenge to identify minor active components with a traditional method like NMR. High-performance liquid chromatography with tandem mass spectrometry (LC-MS n ) is a selective and proficient method for qualitative characterization of known compounds as well as the identification of unknown compounds [14][15][16]. Due to its high sensitivity and specificity, LC-MS n has been proven to be a prevailing analytical tool for the identification of drug metabolites in biological matrices [17][18][19].…”

A target‐group‐change couple with mass defect filtering strategy to identify the metabolites of “Dogel ebs” in rats plasma, urine and bile

“…Although there are many studies on the chemical constituents of “Dogel ebs” , at present, it is essential to obtain its pharmacokinetic parameters and metabolism information to fully understand the pharmacological effects and mechanism of “Dogel ebs.” Unfortunately, the identification of metabolites and illustration of its metabolic patterns have not yet been studied, except the pharmacokinetics investigations on matrine , which restricted the therapeutic applications and development of “Dogel ebs.” In order to clarify the metabolic mechanism of “Dogel ebs,” a target‐group‐change couple with mass defect filtering strategy was proposed based on high performance liquid chromatography–quadrupole exactive Orbitrap mass spectrometry (HPLC‐Q‐Exactive/MS) and Compound Discoverer software. As previously reported , Compound Discoverer software could provide elemental composition assignment, exact mass measurement, and fragmentation information in Traditional Chinese medicines and their metabolites in biological matrices .…”

“…Although there are many studies on the chemical constituents of "Dogel ebs" [12][13][14][15][16][17][18][19][20], at present, it is essential to obtain its pharmacokinetic parameters and metabolism information to fully understand the pharmacological effects and mechanism of "Dogel ebs." Unfortunately, the identification of metabolites and illustration of its metabolic patterns have not yet been studied, except the pharmacokinetics investigations on matrine [21], which restricted the therapeutic applications and development of "Dogel ebs."…”

HPLC Quantitative Analysis of Insecticidal Didehydrostemofoline and Stemofoline in Stemona collinsiae Root Extracts

“…In order to standardise S. collinsiae root extracts for high quality raw materials in the development of insecticidal products, a quality assurance test using a validated analytical method is needed. Several HPLC methods (Zhou et al , ; Li et al , ; Pureesatien et al , ; Peng et al , ; Jiang et al , ) and an alternative capillary electrophoresis method (Sturm et al , ) have been studied in various Stemona plants. However, there has been no HPLC‐related report on the quantitative analysis and validation method of S. collinsiae .…”