Identification of structurally diverse alkaloids in Talguenea quinquinervia (gill. Et hook) by liquid chromatography/electrospray ionisation tandem mass spectroscopy and insecticidal activity

• Published in: Phytochemical analysis Vol. 30; no. 6; pp. 635 - 643
• Main Authors: Quiroz‐Carreño, Soledad, Céspedes‐Acuña, Carlos L., Seigler, David S., Alarcón‐Enos, Julio
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01-11-2019
• Subjects: Alkaloids; Alkaloids - chemistry; Alkaloids - pharmacology; Animals; benzylisoquinoline alkaloid; Biological properties; Chemical composition; Chromatography; Chromatography, High Pressure Liquid - methods; Constituents; cyclopeptide alkaloid; Diagnostic systems; Drosophila melanogaster - growth & development; Electrospraying; Elution; HPLC‐MS analysis; Information processing; insecticidal activity; Insecticides - pharmacology; Ionization; Ions; Larva - drug effects; Liquid chromatography; Mass spectra; Mass spectrometry; Mass spectroscopy; Organic chemistry; pH effects; Plant Roots - chemistry; Quadrupoles; Scientific imaging; Spectrometry, Mass, Electrospray Ionization - methods; Spectroscopy; Talguenea quinquinervia; Tandem Mass Spectrometry - methods; Triterpenes; Wool; Talguenea quinquinervia; benzylisoquinoline alkaloid; HPLC-MS analysis; cyclopeptide alkaloid; insecticidal activity
• ISSN: 0958-0344; 1099-1565
• DOI: 10.1002/pca.2836

Introduction
Talguenea quinquinervia has been used in folk medicine and to dye wool, and the main constituents are alkaloids and triterpenes. Identification of these type of compounds in this specie is a necessary step to understand the biological properties.
Objective
To evaluate the relationship between the chemical composition of root from T. quinquinervia and its insecticidal properties using liquid chromatography electrospray ionisation tandem mass spectrometry (LC‐ESI‐MS/MS).
Methods
Alkaloids were extracted using Soxhlet extraction with methanol. Total extract was partitioned at pH 2 and 12 to enrich alkaloid constituents and to remove interferences. The separation of alkaloids in the Talguenea extract was performed on a C18 column using gradient elution and their tandem mass spectra were obtained by quadrupole time‐of‐flight tandem mass spectrometry (QTOF‐MS/MS) to perform accurate mass measurements of fragment ions for the alkaloid constituents.
Results
Several types of alkaloids were separated and identified by LC‐ESI‐MS/MS. The structural assignment of individual alkaloids was performed based on convergence of MS/MS spectral data, pH partitioning behaviour, LC retention behaviour, and accurate mass measurements. The pH partition of the extract provided structural information about unknown alkaloids extracted from T. quinquinervia. A total of 20 compounds were identified and tentatively characterised, and of these 15 alkaloids were reported for the first time in the investigated T. quinquinervia.
Conclusion
The chemical profiling of alkaloids in T. quinquinervia with different origins was performed for the first time and provided diagnostic ions for diverse alkaloids in T. quinquinervia. Insecticidal activity observed can be explain by the presence of alkaloid and pentacyclic triterpenes on the fractions assayed.
This work describes the isolation and identification for the first time of cyclopeptide and benzylisoquinoline alkaloids in T. quinquenervia roots (Rhamnaceae)