Distribution of reserpine in Rauvolfia species from India – HPTLC and LC–MS studies

Abstract

Rauvolfia species are important medicinal plants due to the presence of bioactive indole alkaloids, especially reserpine. Reserpine content in the roots of six Rauvolfia species (R. hookeri, R. micrantha, R. serpentina, R. tetraphylla, R. verticillata, and R. vomitoria), were detected by high performance liquid chromatography coupled with electrospray ionization quadrapole time of flight tandem mass spectrometry (HPLC–ESI-QToF-MS/MS) and estimated by validated high performance thin layer chromatography (HPTLC) method. Reserpine has positively been identified in the crude alkaloid extracts through HPLC–ESI-QToF-MS/MS method by exact mass, isotopic peak pattern, tandem mass fragmentation pattern, and with authentic standard match. Excellent separation of reserpine was achieved in HPTLC using the solvent system hexane:acetone:methanol (6:3.5:0.5, v/v). The HPTLC estimation method was validated in terms of linearity, specificity, detection limit, quantitation limit, precision, accuracy, and repeatability. Among the six Rauvolfia species, reserpine content was highest in the exotic species R. vomitoria (689.5μg/g, dry wt.), while among the five Indian species the highest reserpine content was for R. tetraphylla (450.7μg/g, dry wt.). In the most common Indian Rauvolfia species, R. serpentina, the reserpine content was comparatively low (254.8μg/g, dry wt.). The endemic species R. micrantha possesses significant quantity of reserpine (422.1μg/g, dry wt.), making it a potential candidate for developing as a source of reserpine, replacing R. serpentina and R. tetraphylla that are endangered due to over exploitation.