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.</p

Metabolomic analysis and antioxidant activity of wild type and mutant Chia (Salvia hispanica L.) stem and flower grown under different irrigation regimes

BACKGROUND: Chia (Salvia hispanica L.) is a functional food from Central America. Interest in it is growing rapidly due to the many health benefits from the seed. However, when chia is grown at high latitudes, seed yield may be low whereas a high stem biomass and immature inflorescences are produced. Little is known about the chemical composition and the properties of stems and flowers. In this work, the metabolite profile, the antioxidant activity, and the total polyphenol content of stems and inflorescences were evaluated in a factorial experiment with different chia populations (commercial black chia and long-day flowering mutants G3, G8, and G17) and irrigation (100% and 50% of evapotranspiration).RESULTS: The results show the influence of irrigation and seed source on the antioxidant activity and total polyphenol content of chia flower and stem. Inflorescences exhibit higher antioxidant activity, suggesting their potential use as natural antioxidant. The mutants G3 and G8, at 50% irrigation, contained the highest amounts of compounds with nutraceutical value, especially within the flower. The mutant G17 showed lower antioxidant activity and polyphenol content compared to other seed sources but exhibited high omega 3 content in flowers but low in stems. This indicates that chia varieties should be chosen according to the objective of cultivation.CONCLUSION: These findings, indicating a close relation of metabolite content with irrigation and seed source, may provide the basis for the use of chia flower and stem for their nutraceutical value in the food, feed, and supplement industries.</p

Spectroscopic and multivariate data-based method to assess the metabolomic fingerprint of Mediterranean plants

Introduction: Most secondary metabolites from plants have a prominent defensive role and repellency against predators and microbial pathogens. These properties largely vary among plant species and offer potential applications as biologically active compounds in medicine as well in agriculture. Objectives: We propose a new procedure that combine different spectroscopic techniques and multivariate data analysis to determine the chemical composition and the relative amounts of each metabolites and/or each class of organic compounds. The approach was used for a rapid identification of secondary metabolites from leaf and root of eight Mediterranean plants species. Methodology: The polar and the apolar extracts of two leaves and roots of each plant were analysed by proton nuclear magnetic resonance (1H-NMR) and gas chromatography coupled to mass spectrometry (GC–MS), respectively. Multivariate data analysis was used for a faster interpretation of data. Results: The metabolic fingerprint of the Mediterranean plants, Acanthus mollis, Dittrichia viscosa, Festuca drymeja, Fraxinus ornus, Fagus sylvatica, Hedera helix, Quercus ilex, and Typha latifolia, showed a complex chemical composition, being specific for each species and plant tissue. Two alditols, mannitol and quercitol, were found in manna ash (Fraxinus ornus) and holm oak (Q. ilex) polar leaf extracts, respectively. The highest levels of aromatic compounds were found in D. viscosa and T. latifolia. Fatty acids were the predominant class of compounds in all apolar extracts under investigation. Triterpene were almost exclusively found in roots, except for holm oak, where they constitute 58% of total extract. Steroids were widespread in leaf extracts. Conclusion: The major advantages of the proposed approach are versatility and rapidity, thus making it suitable for a fast comparison among species and plant tissue types.</p

Pyrenosetin D, a New Pentacyclic Decalinoyltetramic Acid Derivative from the Algicolous Fungus Pyrenochaetopsis sp. FVE-087

The fungal genus Pyrenochaetopsis is commonly found in soil, terrestrial, and marine environments, however, has received little attention as a source of bioactive secondary metabolites so far. In a recent work, we reported the isolation and characterization of three new anticancer decalinoyltetramic acid derivatives, pyrenosetins A-C, from the Baltic Fucus vesiculosus-derived endophytic fungus Pyrenochaetopsis sp. FVE-001. Herein we report a new pentacyclic decalinoylspirotetramic acid derivative, pyrenosetin D (1), along with two known decalin derivatives wakodecalines A (2) and B (3) from another endophytic strain Pyrenochaetopsis FVE-087 isolated from the same seaweed and showed anticancer activity in initial screenings. The chemical structures of the purified compounds were elucidated by comprehensive analysis of HR-ESIMS, FT-IR, [a]D, 1D and 2D NMR data coupled with DFT calculations of NMR parameters and optical rotation. Compounds 1-3 were evaluated for their anticancer and toxic potentials against the human malignant melanoma cell line (A-375) and the non-cancerous keratinocyte cell line (HaCaT). Pyrenosetin D (1) showed toxicity towards both A-375 and HaCaT cells with IC50 values of 77.5 and 39.3 μM, respectively, while 2 and 3 were inactive. This is the third chemical study performed on the fungal genus Pyrenochaetopsis and the first report of a pentacyclic decalin ring system from the fungal genus Pyrenochaetopsis

Molecular networking-based analysis of cytotoxic saponins from sea cucumber holothuria atra

The saponin composition of a specimen of black sea cucumber, Holothuria atra collected in the Persian Gulf was studied by a combined approach including LC-MS/MS, Molecular Networking,pure compound isolation, and NMR spectroscopy. The saponin composition of Holothuria atra turned out to be more complex than previously reported. The most abundant saponins in the extract (1–4) were isolated and characterized by 1D- and 2D-NMR experiments. Compound 1 was identified as a new triterpene glycoside saponin, holothurin A5. The side chain of the new saponin 1, unprecedented among triterpene glycosides, is characterized by an electrophilic enone function, which can undergo slow water or methanol addition under neutral conditions. The cytotoxic activity of compounds 1–4, evaluated on the human cervix carcinoma HeLa cell line, was remarkable, with IC50 values ranging from 1.2 to 2.5 ug/mL

Application of Feature-Based Molecular Networking for Comparative Metabolomics and Targeted Isolation of Stereoisomers from Algicolous Fungi

Seaweed endophytic (algicolous) fungi are talented producers of bioactive natural products. We have previously isolated two strains of the endophytic fungus, Pyrenochaetopsis sp. FVE-001 and FVE-087, from the thalli of the brown alga Fucus vesiculosus. Initial chemical studies yielded four new decalinoylspirotetramic acid derivatives with antimelanoma activity, namely pyrenosetins A–C (1–3) from Pyrenochaetopsis sp. strain FVE-001, and pyrenosetin D (4) from strain FVE-087. In this study, we applied a comparative metabolomics study employing HRMS/MS based feature-based molecular networking (FB MN) on both Pyrenochaetopsis strains. A higher chemical capacity in production of decalin derivatives was observed in Pyrenochaetopsis sp. FVE-087. Notably, several decalins showed different retention times despite the same MS data and MS/MS fragmentation pattern with the previously isolated pyrenosetins, indicating they may be their stereoisomers. FB MN-based targeted isolation studies coupled with antimelanoma activity testing on the strain FVE-087 afforded two new stereoisomers, pyrenosetins E (5) and F (6). Extensive NMR spectroscopy including DFT computational studies, HR-ESIMS, and Mosher’s ester method were used in the structure elucidation of compounds 5 and 6. The 3′R,5′R stereochemistry determined for compound 6 was identical to that previously reported for pyrenosetin C (3), whose stereochemistry was revised as 3′S,5′R in this study. Pyrenosetin E (5) inhibited the growth of human malignant melanoma cells (A-375) with an IC50 value of 40.9 μM, while 6 was inactive. This study points out significant variations in the chemical repertoire of two closely related fungal strains and the versatility of FB MN in identification and targeted isolation of stereoisomers. It also confirms that the little-known fungal genus Pyrenochaetopsis is a prolific source of complex decalinoylspirotetramic acid derivatives

Fishing for Targets of Alien Metabolites: A Novel Peroxisome Proliferator-Activated Receptor (PPAR) Agonist from a Marine Pest

Although the chemical warfare between invasive and native species has become a central problem in invasion biology, the molecular mechanisms by which bioactive metabolites from invasive pests influence local communities remain poorly characterized. This study demonstrates that the alkaloid caulerpin (CAU)—a bioactive component of the green alga Caulerpa cylindracea that has invaded the entire Mediterranean basin—is an agonist of peroxisome proliferator-activated receptors (PPARs). Our interdisciplinary study started with the in silico prediction of the ligand-protein interaction, which was then validated by in vivo, ex vivo and in vitro assays. On the basis of these results, we candidate CAU as a causal factor of the metabolic and behavioural disorders observed in Diplodus sargus, a native edible fish of high ecological and commercial relevance, feeding on C. cylindracea. Moreover, given the considerable interest in PPAR activators for the treatment of relevant human diseases, our findings are also discussed in terms of a possible nutraceutical/pharmacological valorisation of the invasive algal biomasses, supporting an innovative strategy for conserving biodiversity as an alternative to unrealistic campaigns for the eradication of invasive pest