Impact of Temperature on Phenolic and Osmolyte Contents in In Vitro Cultures and Micropropagated Plants of Two Mediterranean Plant Species, Lavandula viridis and Thymus lotocephalus.

In this study, in vitro cultures and micropropagated plants of two Mediterranean aromatic plants, Lavandula viridis L'Hér and Thymus lotocephalus López and Morales, were exposed to different temperatures (15, 20, 25, and 30 °C). The effect of temperature on the levels of hydrogen peroxide (H2O2), lipid peroxidation, and osmoprotectants (proline, soluble sugars, and soluble proteins), as well as on the phenolic profile by HPLC-HRMS and intermediates of the secondary metabolism (phenylalanine ammonia lyase (PAL) activity and shikimic acid content), was investigated. Moreover, the antioxidant activity of the plant extracts was also analyzed. Overall, considering the lipid peroxidation and H2O2 content, the extreme temperatures (15 and 30 °C) caused the greatest damage to both species, but the osmoprotectant response was different depending on the species and plant material. In both species, phenolic compounds and related antioxidant activity increased with the rise in temperature in the micropropagated plants, while the opposite occurred in in vitro cultures. L. viridis cultures showed the highest biosynthesis of rosmarinic acid (92.6 g/kgDW) at 15 °C and seem to be a good alternative to produce this valuable compound. We conclude that contrasting temperatures greatly influence both species' primary and secondary metabolism, but the response is different depending on the plant micropropagation stage.

Impact of Metallic Nanoparticles on In Vitro Culture, Phenolic Profile and Biological Activity of Two Mediterranean Lamiaceae Species: Lavandula viridis L'Hér and Thymus lotocephalus G. López and R. Morales.

Nanoparticles (NPs) recently emerged as new chemical elicitors acting as signaling agents affecting several processes in plant metabolism. The aim of this work was to investigate the impact of the addition of copper oxide (CuO), zinc oxide (ZnO) and iron oxide (Fe3O4) NPs (<100 nm) at different concentrations (1, 5 and 10 mg/L) to the culture media on several morphological, physiological and -biochemical parameters of in vitro shoot cultures of Lavandula viridis L'Hér and Thymus lotocephalus G. López and R. Morales (Lamiaceae), as well as on phenolic profile and bioactivity (antioxidant and enzyme inhibition capacities). Although some decreases in shoot number and length were observed in response to NPs, biomass production was not affected or was improved in both species. Most NPs treatments decreased total chlorophyll and carotenoid contents and increased malondialdehyde levels, an indicator of lipid peroxidation, in both species. HPLC-HR-MS analysis led to the identification of thirteen and twelve phenolic compounds, respectively, in L. viridis and T. lotocephalus extracts, being rosmarinic acid the major compound found in all the extracts. ZnO and Fe3O4 NPs induced an increase in total phenolic and rosmarinic acid contents in T. lotocephalus extracts. Additionally, some NPs treatments also increased antioxidant activity in extracts from this species and the opposite was observed for L. viridis. The capacity of the extracts to inhibit tyrosinase, acetylcholinesterase and butyrylcholinesterase enzymes was not considerably affected. Overall, NPs had a significant impact on different parameters of L. viridis and T. lotocephalus in vitro shoot cultures, although the results varied with the species and NPs type.

Greener Is Better: First Approach for the Use of Natural Deep Eutectic Solvents (NADES) to Extract Antioxidants from the Medicinal Halophyte Polygonum maritimum L.

In this study, natural deep eutectic solvents (NADES) formed by choline chloride (ChCl), sucrose, fructose, glucose, and xylose, were used to extract antioxidants from the halophyte Polygonum maritimum L. (sea knotgrass) and compared with conventional solvents (ethanol and acetone). NADES and conventional extracts were made by an ultrasound-assisted procedure and evaluated for in vitro antioxidant properties by the radical scavenging activity (RSA) on the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, oxygen radical absorbance capacity (ORAC), and copper chelating activity (CCA). Samples were profiled by liquid chromatography (LC)-electrospray ionization (ESI)-QTOF-MS analysis. ChCl:fructose was more efficient in the DPPH assay, than the acetone extract. ChCl:sucrose and ChCl:fructose extracts had the highest ORAC when compared with the acetone extract. NADES extracts had higher CCA, than the acetone extract. The phenolic composition of the NADES extracts was less complex than the conventional extracts, but the proportions of major antioxidants, such as flavonols and flavan-3-ols, were similar in all the solvents. Myricitrin was the major flavonoid in all of the samples, while gallic acid was the main phenolic acid in the conventional extracts and present in a greater amount in ChCl:fructose. Results suggest that NADES containing ChCl and sucrose/fructose can replace conventional solvents, especially acetone, in the extraction of antioxidants from sea knotgrass.

Influence of elaboration process on chemical, biological, and sensory characteristics of European pennyroyal liqueurs.

BACKGROUND: Mentha pulegium is an aromatic and medicinal plant used in different Mediterranean herb-based liqueurs, whose phytochemical composition depends on the elaboration technique used. The aim of this work was to investigate differences in the sensory, chemical, and biological characteristics of pennyroyal liqueurs elaborated by hydro-alcoholic (HI) and aqueous (AI) infusions, percolation (P), maceration (M), and distillation (D) techniques, and by the mixture of spirit with pennyroyal essential oil (EO). The volatile composition determined by gas chromatography-mass spectrometry (GC-MS) and gas chromatography coupled to flame ionization detection (GC-FID), the total phenolic (TPC) and flavonoid (TFC) contents, the antioxidant (AC), and enzyme (α-glucosidase, tyrosinase, and acetylcholinesterase) inhibitory capacities, and the sensory analysis by napping, were evaluated in the liqueurs obtained. RESULTS: Monoterpenes and sesquiterpenes were the main volatiles present in liqueurs. The M, P, HI, and AI liqueurs showed the highest TPC, TFC, and AC values; and pulegone, the main hepatotoxic chemotype, was found in concentrations that gave rise to concern. The D and EO liqueurs stand out for their acceptable pulegone content and greater tyrosinase inhibition. Similar liqueur classifications were achieved by sensory analyses, and physico-chemical and biological analyses using multiple factor and principal component analyses, respectively. CONCLUSION: These results are an important contribution to the identification of the most appropriate elaboration conditions for herbal liqueurs with the healthiest chemical composition and functional properties. © 2020 Society of Chemical Industry.