Phytochemical characterization of an underutilized green leafy vegetable, Sonchus oleraceus with the aid of liquid chromatographyion trap - time of flight - mass spectrometry (LCIT- TOF-MS)

Abstract: Historically, plants have been used as nutraceuticals owing to the presence of a vast array of bioactive compounds (metabolites/natural products). These bioactive molecules are reported to exhibit a variety of beneficial biological activities and with potentials to be used in various applications including medicine, drug design, agrochemicals and biopesticides. Recently, there has been a growing interest in the therapeutic value of underutilized herbal plants which are normally considered as wild plants or weeds. These plants have been reported to possess biologically active metabolites such as phenolic compounds. However, there is a lack of scientific studies to substantiate these beneficial claims, and to contribute in comprehensive phytochemical descriptions of these plants. It is to be noted that the differential distribution of metabolite patterns in different parts of the plant is highly regulated and, as such, comprehensive studies aimed at analyses of total metabolite composition in all these parts are thus imperative. Furthermore, the understanding of the metabolic compositions of these plants does not only contribute towards the nutraceutical attributes but can be further exploited for their other purposes such as chemotaxonomy. Thus, in the current study, a comprehensive phytochemical characterization of an underutilised plant, Sonchus oleraceus was investigated using the liquid chromatography mass spectrometry (LC-MS) based metabolomics approach. The studied metabolite composition namely, chicoric acid of S. oleraceus was from leaf, stem and roots. Furthermore, a comparative LC-MS-based metabolomics approach was applied to establish the chemotaxonomic correlation of S. oleraceus to other selected underutilised green leafy vegetable plants from the Asteraceae plants (Bidens pilosa and Vernonia fastigiata). Based on the chemotaxonomy results, chicoric acid found in S. oleraceus and B. pilosa were found to have a different elution profile and thus different bioactivity. Therefore, the discrimination of stereoisomers of chicoric acid found in S. oleraceus and B. pilosa leaves was also undertaken using ultraviolet (UV) irradiation, LC-MS, density functional theory (DFT) models and molecular docking. The results obtained revealed that S. oleraceus has a myriad spectrum of secondary metabolites including flavonoids, hydroxycinnamic acids and sesquiterpenes...M.Tech. (Biotechnology