Phytochemical Profiling and Cytotoxicity Evaluation of Wrightia tinctoria Extracts on Vero Cell Lines: A Comparative Analysis and Insight into the Bioactive Compounds

Abstract

Introduction: The utilisation of plant-based medicine is a continuing practice that remains prevalent even with modern times. Some therapeutic modalities have a long history, while others are quite recent. The lack of sufficient reporting on the utilisation of medicinal plants has resulted in an ongoing deficit in the understanding of their therapeutic benefits, as well as, their potential short-term and long-term side-effects. The Sweet Indrajao, commonly known as Pala Indigo Plant or Dyer’s Oleander, and scientifically identified as Wrightia tinctoria R. Br, is a member of the Apocynaceae family. It is known as the “Cure for jaundice tree” in southern India. Wrightia is a plant commonly found in India and Burma. The Wrightia tinctoria plant has been chosen for this study due to its long-standing medicinal usage and the variety of pharmacologically active compounds it contains. Despite of the fact, it is been widely used for medicinal uses, the information concerning its safety mentioned in the literature is scarce, particularly its cytotoxic effects on normal cellular systems, which this research aims to address. Aim: The study was aimed to analyse the therapeutic potential of Wrightia tinctoria plant extracts by evaluating the phytochemical composition and to assess the effect of the Wrightia tinctoria plant extracts on Vero cell lines, for a clearer understanding of its medicinal application and its safety profile. Materials and Methods: This in-vitro study was conducted at SRM Institute of Science and Technology, Chennai and the duration of the study was eight months (Jan to August 2023). For the phytochemical analysis of Wrightia tinctoria, dried plant material (leaves) was collected shade dried and extracted using Soxhlet solvent extraction methods followed by fractionation using techniques like column chromatography. Ethanol, ethyl acetate and aqueous solvents were used for the in-vitro study. The various standard protocols were employed to identify phytoconstituents. The cytotoxicity analysis on Vero cell line (Kidney epithelial cells of African green Monkey) was performed using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) assay, where vero cells were cultured and seeded into 96-well microtitre plates. Different concentrations of Wrightia tinctoria extract were added to the wells, followed by incubation. After incubation, MTT solution was added, and formazan crystals formed by viable cells were solubilised using a suitable solvent. Absorbance was measured at a specific wavelength using a microplate reader to assess cell viability and cytotoxic effects. Results: Phytochemical analysis revealed the presence of phenols, steroids, terpenoids, alkaloids, flavonoids, and glycosides. Of the three solvents used in the study, ethanolic extract yielded maximum amount of phytochemicals when compared with the other solvents (aqueous and ethyl acetate) that were investigated. MTT assay was used to determine the cytotoxicity and the Wrightia tinctoria ethanolic extract demonstrated Half maximal Inhibitory concentration (IC50) >100, ensuring the safety profile of the extract on normal cells. Conclusion: Wrightia tinctoria was a significant plant with highly potent phytochemicals with therapeutic properties. Moreover the extract was also safe against the normal cell line (vero cell line).

Keywords

• mtt assay
• phytochemical analysis
• sweet indrajao