Pharmacognostic evaluation of three Apocynaceae plants that share the same West African local names

Abstract

Across West Africa, Tabernaemontana crassa Benth., Voacanga africana Stapf., and Rauvolfia vomitoria Azfel. (Apocynaceae) share the same local names, a situation that puts them at risk of unintended adulteration. The study aimed at setting macro- and micromorphological standards, phytochemical and physicochemical standards for the unequivocal differentiation of the three plants. Macro- and micro-morphological features, quantitative microscopy, soluble extractives, pH, ash values, fluorescence, phytochemical and thin layer chromatographic profiles of leaves, stem, and roots of the three plants were determined using standard methods. The whole leaves showed that all three plants possessed opposite petiolate leaves. The leaves of R. vomitoria and V. africana were elliptic in /shape, whereas T. crassa leaves were oblanceolate. Further differences in stomata arrangement, epidermal cells, histological features of their midribs, surface data determinations, phytochemical and physicochemical profiles of the leaves, stem bark and roots present useful data for clearly distinguishing between the three species. The determined parameters of the leaves, stems, and roots of T. crassa, V. africana, and R. vomitoria support the unequivocal identification of the individual plants. This is important for correct sourcing of these plants for herbal product manufacturers, regulators, and researchers.