Integrating morphological and phytochemical studies on some selected taxa of Lamiaceae Lindl. and Verbenaceae Juss.

Abstract

Abstract Background Lamiaceae and Verbenaceae are taxonomically sister families, belong to the order Lamiales. They are well known for their phytochemical constituents with bio-active properties, but considerable taxonomic difficulties in discriminating between the two families have been reported. The present study aims to explore the morpho-anatomical characters (stem and lamina) of 11 selected species bearing essential oils (EOs) by using the light microscope (LM), and to identify EO constituents in their aerial parts using gas chromatography–mass spectrometry (GC-MS), for taxonomic delimitation among these species. The essential oils of the species with the highest EO yield were tested in-vitro against a human hepatocellular carcinoma (HepG 2) cell line. Results The macro- and micromorphological characters of the stem and lamina were recorded. From these characters trichomes, ground system, and vascular bundles were diagnostic at the species level. GC-MS analysis detected the existence of 160 constituents prevailed by monoterpenes and sesquiterpenes classes in all species under investigation except in Citharexylum spinosum L. A, monoterpenes (2.19%) and sesquiterpenes (0.3%). In-vitro bioassay of EO against HepG 2 revealed a significant effect, as evidenced by the IC50 values being 58.9, 48.3, 36.7 and 34.5 µg/mL for Mentha spicata L., Salvia microphylla Kunth., Lantana camara L. and Ocimum labiatum (N.E.Br.) A.J. Paton respectively. Conclusions This work revealed that Lamiaceae and Verbenaceae families are closely related, showing fluctuation in the mutual morpho-anatomical characteristics of the studied species, however, EO analysis showed variation among these species.