Untargeted metabolomic and molecular network approaches to reveal tomato root secondary metabolites.

INTRODUCTION: The tomato plant, Solanum lycopersicum L. (Solanaceae), is one of the most widely consumed vegetables in the world and plays an important role in human diet. Tomato cultivars are hosts for diverse types of pests, implying diverse chemical defence strategies. Glycoalkaloids are the main specialised metabolites produced by tomato leaves and fruits to protect against pests. However, the roots have received little attention, leading to limited knowledge about their phytochemical content. OBJECTIVE: The main goal of the current study was the development of an untargeted ultra-high-performance liquid chromatography high-resolution mass spectrometry (UHPLC-HRMS) based metabolomic approach to study phytochemical variations in tomato roots at two different development stages (i.e. 34th and 62nd day after sowing). METHODS: UHPLC-HRMS was used to establish the fingerprint of 24 batches of tomato roots. Statistical analyses were performed to highlight the compounds that discriminated between young and mature tomato roots. A dereplication strategy using molecular networking and HRMS/MS data was set up to identify the metabolites regulated during early root development. KEY FINDINGS: The main biomarkers were guanidine and adenosine derivatives associated with tryptophan. Secondary metabolites such as glycoalkaloids and steroidal alkaloids were also characterised. Most of the metabolites were up-regulated in young tomato roots (34 days old) while tryptophan was up-regulated in the older roots (62 days old). CONCLUSION: The metabolic changes observed in this work contribute to a deeper understanding of early-stage root development and may help our understanding of the complex processes involved in the tomato root defence arsenal.

UPLC-HRMS Analysis Revealed the Differential Accumulation of Antioxidant and Anti-Aging Lignans and Neolignans in In Vitro Cultures of Linum usitatissimum L.

Over the last few decades, methods relating to plant tissue culture have become prevalent within the cosmetic industry. Forecasts predict the cosmetic industry to grow to an annual turnover of around a few hundred billion US dollars. Here we focused on Linum usitatissimum L., a plant that is well-known for its potent cosmetic properties. Following the a) establishment of cell cultures from three distinct initial explant origins (root, hypocotyl, and cotyledon) and b) selection of optimal hormonal concentrations, two in vitro systems (callus vs cell suspensions) were subjected to different light conditions. Phytochemical analysis by UPLC-HRMS not only confirmed high (neo)lignan accumulation capacity of this species with high concentrations of seven newly described (neo)lignans. Evaluation over 30 days revealed strong variations between the two different in vitro systems cultivated under light or dark, in terms of their growth kinetics and phytochemical composition. Additionally, antioxidant (i.e. four different in vitro assays based on hydrogen-atom transfer or electron transfer mechanism) and anti-aging (i.e. four in vitro inhibition potential of the skin remodeling enzymes: elastase, hyaluronidase, collagenase and tyrosinase) properties were evaluated for the two different in vitro systems cultivated under light or dark. A prominent hydrogen-atom transfer antioxidant mechanism was illustrated by the DPPH and ABTS assays. Potent tyrosinase and elastase inhibitory activities were also observed, which was strongly influenced by the in vitro system and light conditions. Statistical treatments of the data showed relationship of some (neo)lignans with these biological activities. These results confirmed the accumulation of flax (neo)lignans in different in vitro systems that were subjected to distinct light conditions. Furthermore, we showed the importance of optimizing these parameters for specific applications within the cosmetic industry.

Combination of molecular network and centrifugal partition chromatography fractionation for targeting and identifying Artemisia annua L. antioxidant compounds.

Artemisia annua L. is an annual weedy herb belonging to the Asteraceae family. As a traditional Chinese herb, Artemisia annua is a major source of artemisinin, an antimalarial drug. In addition to artemisinin, this plant contains several other molecular families presenting a wide range of biological properties. To facilitate the screening and the identification of active compounds, the present study describes their targeting by combining the dereplication information obtained by means of Molecular Networks and a crude extract fractionation by Centrifugal Partition Chromatography to obtain and test simplified fractions. This simple and fast approach was developed focused on the antioxidant activity of Artemisia annua with the aim of screening and identifying the antioxidant molecules for further cosmetic uses. Firstly, the aerial parts of Artemisia annua were extracted and their antioxidant activity was evaluated by DPPH, ABTS, CUPRAC, FRAP and iron (II) chelating assays. Extract with a positive response was subjected to UHPLC-HRMS with autoMS/MS experiments in order to build a Molecular Network using the GNPS (Global Natural Products Social Molecular Networking) platform. Secondly, the crude extract was fractionated using CPC with an adapted Arizona solvent system. The fractions obtained were evaluated for antioxidant activity to focus on active compounds, which were located on the Molecular Network and identified thanks to their MS/MS spectra. Using this approach, the major phenolic compound contributing to the antioxidant activity of Artemisia annua extract was identified.