Identification, characterization and distribution of terpene indole alkaloids in ethanolic extracts of Catharanthus roseus using high-performance liquid chromatography/electrospray ionization quadrupole time-of-flight tandem mass spectrometry and the study of their geographical variation

Abstract

Rationale: Catharanthus roseus is a well-known dicotyledonous medicinal plant containing diverse classes of bioactive terpene indole alkaloids (TIAs), in particular the anticancer agents vinblastine and vincristine. In view of the commercial importance of these compounds there is an urgent need to develop an accurate and reliable method for the screening of TIAs from C. roseus.

Methods: A method for the separation and characterization of these compounds was developed using high-performance liquid chromatography coupled with positive electrospray ionization quadrupole time-of-flight tandem mass spectrometry (HPLC/ESI-QTOF-MS/MS). Chromatographic separation of TIAs was carried out using a Thermo Betasil C8 column (250 mm × 4.5 mm, 5 μm) at 25°C using 0.1% formic acid in water and acetonitrile.

Results: Diagnostic fragmentation pathways for vinpocetine, vindesine, catharanthine, vinblastine, vindoline and vincristine were established on the basis of their product ions. A total of 72 TIAs were detected of which 11 were unambiguously identified by comparison with their standards, and the remaining 61 were tentatively identified. The geographical distribution of the TIAs in ethanolic extracts of 30 samples of C. roseus collected from five states of India was studied using principal component analysis (PCA).

Conclusions: The developed analytical method together with diagnostic fragment patterns were used to rapidly and effectively identify targeted and untargeted TIAs in C. roseus. A PCA study of the results obtained was used to discriminate among the C. roseus samples.