Pharmacognostic Study and Phytochemical Profilling of Dichloromethane Extracts of the Leaf and Stem of Vernonia conferta Benth and Vernonia colorata Drake Asteraceae

Abstract

Aims: The study determines various taxonomic, pharmacognostic and phytochemical standards helpful to ensure the identity, purity, safety and efficacy of Vernonia colorata and Vernonia conferta. Study Design: To study these two species of Vernonia for their epidermal cell shapes, stomatal types and distribution, trichome types, chemomicroscopic and fluorescence characters, flow properties, ash values, extractive solvents and phytoconstituents of dichlormethane fractions using GC-MS. Place and Duration: This study was conducted at the Department of Pharmacognosy and Natural Medicine, Faculty of Pharmacy, University of Uyo, Uyo from June 2023 to December 2023. Methodology: The pharmacognostic characterization was determined following the guidelines given by the World Health Organization (WHO). Parameters determined included microscopy, powder microscopy, chemomicroscopy, micromeritic properties, ash values, extractive values, fluorescence analysis while phytochemical analysis was done using Gas Chromatography coupled to Mass Spectrometer. Results: Epidermal cell shapes were both irregular with undulate and sinuous anticlinal wall pattern for both V. colorata and C. conferta respectively. Stomatal distribution was hypostomatic with paracytic stomata on the abaxial surface for C. conferta while amphistomatic with anomocytic stomata in V. colorata. Stomatal index was highest in V. conferta with 27.31% and least in V. colorata 21.52%. Unicellular trichomes were observed in V. colorata and V. conferta epidermal surfaces. The chemomicroscopic study revealed the presence of lignin, starch, cellulose, oils, calcium oxalate crystals, mucilage and protein for both leaf and stem respectively. The fluorescence characteristics showed the presence of different colours supporting the presence of various phytoconstituents for both leaf and stem. The quantitative epidermal studies, chemomicroscopic and fluorescence characteristics revealed characteristic features for the drug. The flow properties for both leaf and stem were poor.  The total ash values for both leaf and stem ranges between (2.40 – 9.30 and 10.60 – 11.06), acid-insoluble ash values were low, moisture contents were between 8 - 14%w/w, water and methanol extracted more constituents. In total, 12 chemical constituents each were recorded for the leaves of V. colorata and V. conferta, respectively, while 10 and 12 were also recorded for the dichloromethane stem extracts of V. colorata and V. conferta, respectively. Conclusion: This study is useful in pharmacognostic standardization of Vernonia colorata and Vernonia conferta.