Lipophilic Extracts of Cynara cardunculus L. var. altilis (DC): A Source of Valuable Bioactive Terpenic Compounds

Lipophilic extracts of Cynara cardunculus L. var. altilis (DC) from the south of Portugal (Baixo Alentejo) were studied by gas chromatography–mass spectrometry. One sesquiterpene lactone, four pentacyclic triterpenes, and four sterols were reported for the first time as cultivated cardoon components, namely, deacylcynaropicrin, β- and α-amyrin, lupenyl and ψ-taraxasteryl acetates, stigmasterol, 24-methylenecholesterol, campesterol, and Δ⁵-avenasterol. In addition, other new compounds were identified: ten fatty acids, eight long-chain aliphatic alcohols, and six aromatic compounds. Four triterpenyl fatty acid esters were also detected. Sesquiterpene lactones and pentacyclic triterpenes were the major lipophilic families, representing respectively 2–46% and 10–89% of the detected compounds. Cynaropicrin was the most abundant sesquiterpene lactone, while taraxasteryl acetate was the main pentacyclic triterpene. Fatty acids and sterols, mainly hexadecanoic acid and β-sitosterol, were present at lower amounts (1–20% and 1–11% of the detected compounds). Long-chain aliphatic alcohols and aromatic compounds were detected at reduced abundances (1–6% of the detected compounds)

Enhanced Solubility of Lignin Monomeric Model Compounds and Technical Lignins in Aqueous Solutions of Deep Eutectic Solvents

The solubilities of lignin monomeric model compounds and technical lignins (organosolv and kraft) in aqueous solutions of several deep eutectic solvents (DES) were here investigated. The effects of DES components, temperature and concentration, were evaluated. The results show aqueous solutions of DES to be a new class of powerful solvents where both the hydrogen bond donor and the hydrogen bond acceptor synergistically contribute to increase the solubility of the lignin model compounds, being the dispersive interactions with lignin the driving force behind the good performance of DES. The solubility of the model compounds is shown to be a good guide for the selection of the best DES for technical lignins solubility, leading to identifying an aqueous solution of DES allowing a solubility enhancement of 1181.7 ± 29.2 and 228.5 ± 9.7 times for kraft and organosolv lignin, respectively. The results indicate that the solubility of the technical lignins and their monomers in DES aqueous solutions is driven by a hydrotropic mechanism, here confirmed by dynamic light scattering that is here observed for the first time with DES as hydrotropes

NMR Metabolomics Reveals Metabolism-Mediated Protective Effects in Liver (HepG2) Cells Exposed to Subtoxic Levels of Silver Nanoparticles

The expansion of biomedical and therapeutic applications of silver nanoparticles (AgNPs) raises the need to further understand their biological effects on human cells. In this work, NMR metabolomics has been applied to reveal the metabolic effects of AgNPs toward human hepatoma (HepG2) cells, which are relevant with respect to nanoparticle accumulation and detoxification. Cellular responses to widely disseminated citrate-coated AgNPs (Cit30) and to emergent biogenic AgNPs prepared using an aqueous plant extract as reducing and stabilizing agent (GS30) have been compared with a view to assess the influence of nanoparticle coating on the metabolic effects produced. Subtoxic concentrations (IC₅ and IC₂₀) of both nanoparticle types caused profound changes in the cellular metabolome, suggesting adaptations in energy production processes (glucose metabolism and the phosphocreatine system), antioxidant defenses, protein degradation and lipid metabolism. These signatures were proposed to reflect mainly metabolism-mediated protective mechanisms and were found to be largely common to Cit30 and GS30 AgNPs, although differences in the magnitude of response, not captured by conventional cytotoxicity assessment, were detected. Overall, this study highlights the value of NMR metabolomics for revealing subtoxic biological effects and helping to understand cell–nanomaterial interactions

Aqueous Solutions of Surface-Active Ionic Liquids: Remarkable Alternative Solvents To Improve the Solubility of Triterpenic Acids and Their Extraction from Biomass

Triterpenic acids (TTAs) are well-known for their relevant biological properties and have been facing an increasing interest for nutraceutical and pharmaceutical applications. To overcome the concerns associated with the commonly used volatile organic solvents for their extraction from biomass, here we investigate the potential of aqueous solutions of ionic liquids (ILs) as alternative solvents. The solubility of ursolic acid (UA) was first determined in several aqueous solutions of ILs (hydrotropes or surface-active) at 30 °C for evaluation of the dissolution phenomenon. Conventional surfactants were also investigated for comparison purposes. The collected data reveal a remarkable enhancement in the solubility of UA (8 orders of magnitude) in surface-active IL aqueous solutions when compared to that in pure water. Afterward, the potential of these IL aqueous solutions was confirmed by their use in the extraction of TTAs from apple peels. Total extraction yields of TTAs of 2.62 wt % were obtained using aqueous solutions of surface-active ILs at moderate conditions, overwhelming the extraction yields of 2.48 wt % obtained with chloroform and 1.37 wt % with acetone using similar conditions

Ex Situ Reconstitution of the Plant Biopolyester Suberin as a Film

Biopolymers often have unique properties of considerable interest as a basis for new materials. It is however not evident how to extract them from plants without destroying their chemical skeleton and inherent properties. Here we report the ex situ reconstitution of the biopolyester suberin as a new waterproof and antimicrobial material. In plant cell walls, suberin, a cross-linked network of aromatic and aliphatic monomers, builds up a hydrophobic protective and antimicrobial barrier. Recently we succeeded in extracting suberin from the plant cell wall using the ionic liquid cholinium hexanoate. During extraction the native three-dimensional structure of suberin was partially preserved. In this study, we demonstrate that this preservation is the key for its ex situ reconstitution. Without any chemical additives or purification, the suberin composing macromolecules undergo self-association on the casting surface forming a film. Suberin films obtained show barrier properties similar to those of the suberin barrier in plants, including a potentially broad bactericidal effect

Fluorescent Bioactive Corrole Grafted-Chitosan Films

Transparent corrole grafted-chitosan films were prepared by chemical modification of chitosan with a corrole macrocycle, namely, 5,10,15-tris­(pentafluorophenyl)­corrole (TPFC), followed by solvent casting. The obtained films were characterized in terms of absorption spectra (UV–vis), FLIM (fluorescence lifetime imaging microscopy), structure (FTIR, XPS), thermal stability (TGA), thermomechanical properties (DMA), and antibacterial activity. The results showed that the chemical grafting of chitosan with corrole units did not affect its film-forming ability and that the grafting yield increased with the reaction time. The obtained transparent films presented fluorescence which increases with the amount of grafted corrole units. Additionally, all films showed bacteriostatic effect against S. aureus, as well as good thermomechanical properties and thermal stability. Considering these features, promising applications may be envisaged for these corrole-chitosan films, such as biosensors, bioimaging agents, and bioactive optical devices

Nanostructured Bacterial Cellulose–Poly(4-styrene sulfonic acid) Composite Membranes with High Storage Modulus and Protonic Conductivity

The present study reports the development of a new generation of bio-based nanocomposite proton exchange membranes based on bacterial cellulose (BC) and poly­(4-styrene sulfonic acid) (PSSA), produced by <i>in situ</i> free radical polymerization of sodium 4-styrenesulfonate using poly­(ethylene glycol) diacrylate (PEGDA) as cross-linker, followed by conversion of the ensuing polymer into the acidic form. The BC nanofibrilar network endows the composite membranes with excellent mechanical properties at least up to 140 °C, a temperature where either pure PSSA or Nafion are soft, as shown by dynamic mechanical analysis. The large concentration of sulfonic acid groups in PSSA is responsible for the high ionic exchange capacity of the composite membranes, reaching 2.25 mmol g^–1 for a composite with 83 wt % PSSA/PEGDA. The through-plane protonic conductivity of the best membrane is in excess of 0.1 S cm^–1 at 94 °C and 98% relative humidity (RH), decreasing to 0.042 S cm^–1 at 60% RH. These values are comparable or even higher than those of ionomers such as Nafion or polyelectrolytes such as PSSA. This combination of electric and viscoelastic properties with low cost underlines the potential of these nanocomposites as a bio-based alternative to other polymer membranes for application in fuel cells, redox flow batteries, or other devices requiring functional proton conducting elements, such as sensors and actuators