Chemical Composition and Seasonality of Aromatic Mediterranean Plant Species by NMR-Based Metabolomics

Effects of seasonal variation on phytochemicals contributing to the antimalarial and antitrypanosomal activities of Breonadia salicina using a metabolomic approach

This study involves the investigation of various plant parts of Breonadia salicina (Vahl) Hepper and J.R.I. Wood across multiple consecutive seasons. It aims to delve into the phytochemistry of these different plant parts and establish connections between the findings and their biological activities. This comprehensive approach employs metabolomics techniques, with the ultimate goal of exploring the potential for drug development. Samples were collected in Fondwe, a village in Limpopo (South Africa), based on local reports of the efficacy of this plant used by traditional healers in the area. The antimalarial and antitrypanosomal activities of samples collected over the seasons were determined with the parasite lactate dehydrogenase (pLDH) and specific Trypanosoma brucei assays, respectively. Consequently, a total of 24 compounds were tentatively identified through ultra-performance liquid chromatography with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS). Chemical profiles of the different plant parts of Breonadia salicina collected in different seasons produced contrasting metabolic profiles. Chemometric analysis of the UPLC-QTOF-MS data enabled us to determine the chemical variability of the crude stem bark, root and leaf extracts (n = 48) collected over four consecutive seasons by evaluating the metabolomics fingerprinting of the samples using an untargeted approach. Principal component analysis (PCA), hierarchical cluster analysis (HCA), and partial least squares discriminant analysis (PLS-DA) indicated the existence of two key clusters that are linked to the root, stem bark, and leaves. The stem and root chemistry differed from that of the leaves. Seasonal variations were noted in each plant part, with autumn and winter samples closely grouped compared to spring and summer samples in the methanol leaf extracts. Biochemometric analysis could not relate specific compounds to the antimalarial and antitrypanosomal activities of the active extracts, underscoring the intricate interactions among the secondary metabolites. This study further confirms the optimal plant parts to collect in each season for the most effective antimalarial and antitrypanosomal activities.

Metabolomics and chemometrics of seven aromatic plants: Carob, eucalyptus, laurel, mint, myrtle, rosemary and strawberry tree

INTRODUCTION

Arbutus unedo L. (strawberry tree), Ceratonia siliqua L. (carob), Eucalyptus camaldulensis Dehnh. (eucalyptus), Laurus nobilis L. (laurel), Mentha aquatica L. (water mint), Myrtus communis L. (common myrtle), and Rosmarinus officinalis L. (rosemary) are aromatic plants from the Mediterranean region whose parts and preparations are used for their nutritional properties and health benefits.

OBJECTIVES

To evaluate and compare the metabolites profile, total phenol content (TPC), and antioxidant activity of plant leaves for their future use. Gas chromatography-mass spectrometry (GC-MS) was used for metabolomics. Data comparison was performed by chemometrics.

METHODOLOGY

Polar and apolar extracts were analysed using untargeted GC-MS metabolomics followed by chemometrics (principal component analysis, heatmap correlation and dendrogram) to identify, quantify and compare the major organic compounds in the plants. Additionally, nuclear magnetic resonance (NMR) spectroscopy was used for the laurel polar extract to identify d-gluco-l-glycero-3-octulose whose presence was unclear from the GC-MS data. TPC and antioxidant assays were performed using classical methods (Folin-Ciocalteu, 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH)) and correlated to the phytochemical profiles.

RESULTS

Forty-three metabolites were identified including amino acids, organic acids, carbohydrates, phenols, polyols, fatty acids, and alkanes. Eight metabolites (d-fructose, d-glucose, d-mannose, gallic acid, quinic acid, myo-inositol, palmitic and stearic acids) were in common between all species. d-Gluco-l-glycero-3-octulose (37.29 ± 1.19%), d-pinitol (31.33 ± 5.12%), and arbutin (1.30 ± 0.44%,) were characteristic compounds of laurel, carob, and strawberry tree, respectively. Carob showed the highest values of TPC and antioxidant activity.

CONCLUSION

GC-MS metabolomics and chemometrics analyses are fast and useful methods to determine and compare the metabolomics profiling of aromatic plants of food and industrial interest.

Nontargeted 1 H NMR fingerprinting and multivariate statistical analysis for traceability of Greek PDO Vostizza currants

In this study, non-targeted ¹ H NMR fingerprinting was used in combination with multivariate statistical analyses for the classification of Greek currants based on their geographical origins (Aeghion, Nemea, Kalamata, Zante, and Amaliada). As classification techniques, Principal Component Analysis (PCA) and Partial Least Squares Discriminant Analysis (PLS-DA) were carried out. To elucidate different components according to PDO (Protected Designation of Origin), products from Aeghion (Vostizza) were statistically compared with each one of the four other regions. PLS-DA plots ensure that currants from Kalamata, Nemea, Zante, and Amaliada are well classified with respect to the PDO currants, according to differences observed in metabolites. Results suggest that composition differences in carbohydrates, amino, and organic acids of currants are sufficient to discriminate them in correlation to their geographical origin. In conclusion, currants metabolites which mostly contribute to classification performance of such discriminant analysis model present a suitable alternative technique for currants traceability. The study results contribute information to the currants' metabolite fingerprinting by NMR spectroscopy and their geographical origin. PRACTICAL APPLICATION: This study presents an analytical approach for a high nutritional value Greek PDO product, Vostizza currant. A further research and implementation of this method in food industry, can be the key to food fraud incidents. Thus, application of this work opens up posibilities to "farm to table" mission.

Metabolomic Analysis of Combretum lanceolatum Plants Interaction with Diaporthe phaseolorum and Trichoderma spirale Endophytic Fungi through 1 H-NMR

Endophytic fungi are an important class of microorganisms, able to interact with a host plant via a mutualistic mechanism without visible symptoms of the fungal colonization. The synergy between endophytic fungi and their host plant can promote morphological, physiological and biochemical changes through the expression of bioactive metabolites. This work aims to correlate metabolic changes in the Combretum lanceolatum plant metabolome with its endophytic fungi Diaporthe phaseolorum (Dp) and Trichoderma spirale (Ts), and to discover corresponding metabolite-biomarkers, with the principal focus being on its primary metabolism. The ¹ H-NMR metabolomic analysis of qualitative and quantitative changes was performed through multivariate statistical analysis and the identification of primary metabolites was achieved on the Madison Metabolomics Consortium Database. The presence of Dp significantly impacted the plant's metabolic pathways, improving the biosynthesis of primary metabolites such as threonine, malic acid and N-acetyl-mannosamine, which are precursors of special metabolites involved in plant self-defence. This work represents a valuable contribution to advanced studies on the metabolic profiles of the interaction of plants with endophytes.

NMR Profiling of Ononis diffusa Identifies Cytotoxic Compounds against Cetuximab-Resistant Colon Cancer Cell Lines

In the search of new natural products to be explored as possible anticancer drugs, two plant species, namely Ononis diffusa and Ononis variegata, were screened against colorectal cancer cell lines. The cytotoxic activity of the crude extracts was tested on a panel of colon cancer cell models including cetuximab-sensitive (Caco-2, GEO, SW48), intrinsic (HT-29 and HCT-116), and acquired (GEO-CR, SW48-CR) cetuximab-resistant cell lines. Ononis diffusa showed remarkable cytotoxic activity, especially on the cetuximab-resistant cell lines. The active extract composition was determined by NMR analysis. Given its complexity, a partial purification was then carried out. The fractions obtained were again tested for their biological activity and their metabolite content was determined by 1D and 2D NMR analysis. The study led to the identification of a fraction enriched in oxylipins that showed a 92% growth inhibition of the HT-29 cell line at a concentration of 50 µg/mL.

Revealing the 1H NMR metabolome of mirasol chili peppers (Capsicum annuum) infected by Candidatus Phytoplasma trifolii

The infection of Capsicum annuum cv. mirasol by Candidatus Phytoplasma trifolii (16SrVI) causes devastating crop losses in northern Mexico. This study addresses the metabolomics profiling of mirasol chili peppers (Capsicum annuum cv. mirasol) infected by Candidatus Phytoplasma trifolii. For this study, 25 diseased fruits and 25 healthy fruits were used. Principal component analysis (PCA) and orthogonal projections to latent structures discriminant analysis (OPLS-DA) revealed dramatic changes in the content of 42 metabolites which were identified in diseased and healthy mirasol chili peppers. The endogenous levels of fructose, glucose and formic acid were substantially decreased in the diseased chili peppers. In the same group of samples, high concentrations of alanine, asparagine, fumaric acid, sucrose and threonine were observed. The content of Choline didńt present a significant difference. This evidence supports the fact that Candidatus Phytoplasma trifolii infection reduces de CO₂ fixation into carbohydrates, decreases invertase activity, and inhibits glycolysis in the diseased plant tissues. The levels of ascorbic acid, capsaicin and dihydrocapsaicinin in diseased fruits were dramatically decreased, suggesting that Candidatus Phytoplasma trifolii can reduce the pungency and the nutraceutical value of mirasol chili peppers.

Compatible and Incompatible Pollen-Styles Interaction in Pyrus communis L. Show Different Transglutaminase Features, Polyamine Pattern and Metabolomics Profiles

Pollen-stigma interaction is a highly selective process, which leads to compatible or incompatible pollination, in the latter case, affecting quantitative and qualitative aspects of productivity in species of agronomic interest. While the genes and the corresponding protein partners involved in this highly specific pollen-stigma recognition have been studied, providing important insights into pollen-stigma recognition in self-incompatible (SI), many other factors involved in the SI response are not understood yet. This work concerns the study of transglutaminase (TGase), polyamines (PAs) pattern and metabolomic profiles following the pollination of Pyrus communis L. pistils with compatible and SI pollen in order to deepen their possible involvement in the reproduction of plants. Immunolocalization, abundance and activity of TGase as well as the content of free, soluble-conjugated and insoluble-bound PAs have been investigated. 1H NMR-profiling coupled with multivariate data treatment (PCA and PLS-DA) allowed to compare, for the first time, the metabolic patterns of not-pollinated and pollinated styles. Results clearly indicate that during the SI response TGase activity increases, resulting in the accumulation of PAs conjugated to hydroxycinnamic acids and other small molecules. Metabolomic analysis showed a remarkable differences between pollinated and not-pollinated styles, where, except for glucose, all the other metabolites where less concentrated. Moreover, styles pollinated with compatible pollen showed the highest amount of sucrose than SI pollinated ones, which, in turn, contained highest amount of all the other metabolites, including aromatic compounds, such as flavonoids and a cynnamoil derivative.

1H NMR-based metabolomic profiling for identification of metabolites in Capsicum annuum cv. mirasol infected by beet mild curly top virus (BMCTV)

Beet mild curly top virus (BMCTV) is associated with an outbreak of curly top in chili pepper, tomato and other Solanaceae species, which can cause severe crop losses. The aim of this work was to obtain the ¹H NMR metabolomic profiling of both healthy chili peppers (cv. mirasol) and infected chili peppers with BMCTV in order to find chemical markers associated to the infection process. Significant differences were found between the two groups, according to principal component analysis and orthogonal projections to latent structure discriminant analysis. Compared to the asymptomatic peppers, the symptomatic fruits had higher relative abundance of fructose, isoleucine, histidine, phenylalanine and tryptophan. Contrarily, the asymptomatic samples showed greater amounts of malonate and isobutyrate. These results suggest that in diseased chili peppers there are metabolic changes related to the viral acquisition of energy for replication and capsid assembly. This is the first study describing the chemical profiling of a polar extract obtained from Capsicum annuum infected by BMCTV under open field conditions.

2D-NMR investigation and in vitro evaluation of antioxidant, antigenotoxic and estrogenic/antiestrogenic activities of strawberry grape

Strawberry grape is considered beneficial due to its extensive phytochemical properties. To expand the knowledge about the chemical constituents and the biological activities of the whole plant, 2D-NMR investigation has been carried out on pulp, peel, seeds, stalks and leaves. Catechin and epicatechin were identified as the main constituents of the seed extract, quercetin and ferulic acid were detected in the leaves and malvidin and cyanidin glucopyranoside in the peels. The leaf, stalk and seed extracts were found to be very rich in phytochemicals and were tested for their ability to reduce the mutagenicity and genotoxicity of standard agents via Salmonella mutagenicity assay and SOS chromotest, respectively. Moreover, the estrogen/antiestrogen-like activity was evaluated on the MCF-7 estrogen-responsive cells. Seed and stalk extracts had an elevated antimutagenic/antigenotoxic activity. Stalk extracts highly reduced the proliferative effect of natural estrogen, 17β-estradiol.

Phenolic profile, antioxidant activity and enzyme inhibitory activities of extracts from aromatic plants used in Mediterranean diet

The antioxidant and enzyme inhibitory properties of methanolic extracts from four aromatic plants used in traditional medicine and food [Calamintha nepeta (L.) Savi subsp. nepeta, Helichrysum italicum subsp. picardii Franco, Mentha spicata L. and Origanum vulgare subsp. virens (Hoffmanns. & Link) Bonnier & Layens] were evaluated. The extract from O. vulgare exhibited the strongest DPPH (IC50 of 4.65 ± 0.12 µg/ml) and ABTS (1479.56 ± 12.29 µmolTE/gextract) scavenging capacities, as well as the largest ferric reducing ability (1746.76 ± 45.11 µmolAAE/gextract). This extract also showed the highest total phenolic content (1597.20 ± 24.10 µmolGAE/gextract) and although HPLC-DAD analysis revealed rosmarinic acid as the main compound of the extract, other compounds seem to be involved in the antioxidant activity. Furthermore, the extract from H. italicum, which was found to be rich in caffeoylquinic and dicaffeoylquinic acids and in pinocembrin, showed the highest inhibitory potential against acetylcholinesterase, tyrosinase and α-glucosidase. Overall, the results obtained validate the usefulness of the studied plants as valuable sources of natural agents beneficial for human health.

Food metabolomics: from farm to human

Metabolomics, one of the latest components in the suite of systems biology, has been used to understand the metabolism and physiology of living systems, including microorganisms, plants, animals and humans. Food metabolomics can be defined as the application of metabolomics in food systems, including food resources, food processing and diet for humans. The study of food metabolomics has increased gradually in the recent years, because food systems are directly related to nutrition and human health. This review describes the recent trends and applications of metabolomics to food systems, from farm to human, including food resource production, industrial food processing and food intake by humans.