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

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.

New cyclopeptide alkaloid and lignan glycoside from Justicia procumbens.

This study reported a new cyclopeptide alkaloid, justicianene A (1), and a new lignan glycoside, procumbenoside H (2), isolated from Justicia procumbens. The structures of the new compounds were elucidated by means of spectroscopic analysis, including extensive 2D NMR studies and mass spectrometry. Cyclopeptide alkaloids were first observed from the genus Justicia. Compound 2 was cytotoxic against human LoVo colon carcinoma cells with an IC50 value of 17.908 ± 1.949 µM.

A new cyclopeptide alkaloid from Clematis Florida.

One new 14-membered ring cyclopeptide alkaloid, plenane A (1), along with six known compounds (2-7), was isolated from the roots of Clematis florida. Their structures were elucidated by means of NMR spectroscopic analysis and mass spectrometry. In addition, their anti- inflammatory effects on lipopolysaccharide-induced RAW264.7 macrophages were evaluated in vitro. The compounds 1, 2 and 6 exhibited potent indirect inhibitory effects, with IC50 values of 40.92, 22.88 and 6.32 µM, respectively.