Comparative phytochemistry using UPLC-ESI-QTOF-MS phenolic compounds profile of the water and aqueous ethanol extracts of Tagetes minuta and their cytotoxicity

Abstract

The complexity of secondary metabolites in different medicinal plants, including Tagetes minuta, defines the general properties and uses of the plant. Tagetes minuta is reportedly a valuable medicinal plant that has long been used as a spice herb, medicine, a natural herbicide for weeds, and pest control in agriculture. In this study, the secondary metabolite profiles of the water and aqueous ethanol extracts of T. minuta were profiled through identification and quantification using colorimetric assays and a Waters Synapt G2 Quadrupole time-of-flight (QTOF) mass spectrometer (MS) connected to a Waters Acquity ultra-performance liquid chromatograph (UPLC). The antioxidant capacity of the extracts was evaluated with 2,2-Azino-di-3-ethylbenzthiazoline sulfonate and ferric reducing antioxidant power, as well as their toxicity on HepG2 (cancerous) and Vero (non-cancerous) cell lines. The major classes of secondary metabolites identified and quantified were phenolic acids (benzoic acids and hydroxycinnamic acids), flavonoids (chalcones, flavonols, flavanols, and flavones), fatty acids, coumarins and furanocoumarins. The bioavailability of these secondary metabolites is influenced by the polarity of the solvent of extraction. Extracts from aqueous ethanol showed higher secondary metabolites, corresponding to antioxidant content and activity as well as cytotoxicity in HepG2 and Vero cells, compared to the water extract. This study presents a comprehensive phytochemical knowledge of secondary metabolites, primarily phenolic compounds, identified in T. minuta, which can pave the way for future studies on the pharmacological importance and standardisation of the medicinal uses of the plant.