Self‐organization of liquid crystalline 3,4,5‐tris[(11‐methacryloyl‐undecyl‐1‐oxy)‐4‐benzyloxy]benzoates in low‐shrinkage methacrylate mixtures

Crystallization and supramolecular aggregation of 3,4,5‐tris[(11‐methacryloyl‐undecyl‐1‐oxy)‐4‐benzyloxy]benzoate (1), 2‐methyl‐(1,4,7,10,13‐pentaoxabenzocyclopentadecane)‐3,4,5‐tris[(11‐methacryloyl‐undecyl‐1‐oxy)‐4‐benzoxyloxy]benzoate (2) and its 1 : 1 sodium triflate complex (2a) are described in solutions of methacrylate monomers. Formation of gels and subsequent polymerization yielded “supramolecular interpenetrating networks” consisting of an isotropic polymethacrylate resin, percolated by supramolecular aggregates of the solute, which are covalently connected to the resin phase. Compound 1 formed whisker‐type crystals, while 2 self‐organizes in networks of elongated supramolecular fibrils with diameters corresponding to the twofold length of one molecule. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 631–640, 2000     

HRMS Characterization,Antioxidant and Cytotoxic Activities of Polyphenols in Malus domestica Cultivars from Costa Rica

There is increasing interest in research into fruits as sources of secondary metabolites because of their potential bioactivities. In this study, the phenolic profiles of Malus domestica Anna and Jonagold cultivars from Costa Rica were determined by Ultra Performance Liquid Chromatography coupled with High Resolution Mass Spectrometry (HRMS) using a quadrupole-time-of-flight analyzer (UPLC-QTOF-ESI MS), on enriched-phenolic extracts from skins and flesh, obtained through Pressurized Liquid Extraction (PLE). In total, 48 different phenolic compounds were identified in the skin and flesh extracts, comprising 17 flavan-3-ols, 12 flavonoids, 4 chalcones, 1 glycosylated isoprenoid and 14 hydroxycinnamic acids and derivatives. Among extracts, the flesh of Jonagold exhibits a larger number of polyphenols and is especially rich in procyanidin trimers, tetramers and pentamers. Evaluating total phenolic content (TPC) and antioxidant activities using ORAC and DPPH procedures yields higher values for this extract (608.8 mg GAE/g extract; 14.80 mmol TE/g extract and IC₅₀ = 3.96 µg/mL, respectively). In addition, cytotoxicity evaluated against SW620 colon cancer cell lines and AGS gastric cancer cell lines also delivered better effects for Jonagold flesh (IC₅₀ = 62.4 and 60.0 µg/mL, respectively). In addition, a significant negative correlation (p < 0.05) was found between TPC and cytotoxicity values against SW620 and AGS adenocarcinoma (r = −0.908, and −0.902, respectively). Furthermore, a significant negative correlation (p < 0.05) was also found between the number of procyanidins and both antioxidant activities and cytotoxicity towards SW620 (r = −0.978) and AGS (r = −0.894) cell lines. These results align with Jonagold flesh exhibiting the highest abundance in procyanidin oligomers and yielding better cytotoxic and antioxidant results. In sum, our findings suggest the need for further studies on these Costa Rican apple extracts—and particularly on the extracts from Jonagold flesh—to increase the knowledge on their potential benefits for health.     

Nanoprecipitation of Biocompatible Poly(malic acid) Derivative,Its Ability to Encapsulate a Molecular Photothermal Agent and Photothermal Properties of the Resulting Nanoparticles

Biocompatible nanoparticles (NPs) of hydrophobic poly(benzyl malate) (PMLABe) were prepared by nanoprecipitation. The influence of nanoprecipitation parameters (initial PMLABe, addition rate, organic solvent/water ratio and stirring speed) were studied to optimize the resulting formulations in terms of hydrodynamic diameter (Dh) and dispersity (PDI). PMLABe NPs with a Dh of 160 nm and a PDI of 0.11 were isolated using the optimized nanoprecipitation conditions. A hydrophobic near infra-red (NIR) photothermally active nickel-bis(dithiolene) complex (Ni8C12) was then encapsulated into PMLABe NPs using the optimized nanoprecipitation conditions. The size and encapsulation efficiency of the NPs were measured, revealing that up to 50 weight percent (wt%) of Ni8C12 complex can efficiently be encapsulated with a slight increase in Dh of the corresponding Ni8C12-loaded NPs. Moreover, we have shown that NP encapsulating Ni8C12 were stable under storage conditions (4 °C) for at least 10 days. Finally, the photothermal properties of Ni8C12-loaded NPs were evaluated and a high photothermal efficiency (62.7 ± 6.0%) waswas measured with NPs incorporating 10 wt% of the Ni8C12 complex.     

Docetaxel Loaded in Copaiba Oil-Nanostructured Lipid Carriers as a Promising DDS for Breast Cancer Treatment

Breast cancer is the neoplasia of highest incidence in women worldwide. Docetaxel (DTX), a taxoid used to treat breast cancer, is a BCS-class-IV compound (low oral bioavailability, solubility and intestinal permeability). Nanotechnological strategies can improve chemotherapy effectiveness by promoting sustained release and reducing systemic toxicity. Nanostructured lipid carriers (NLC) encapsulate hydrophobic drugs in their blend-of-lipids matrix, and imperfections prevent drug expulsion during storage. This work describes the preparation, by design of experiments (2³ factorial design) of a novel NLC formulation containing copaiba oil (CO) as a functional excipient. The optimized formulation (NLC_DTX) showed approximately 100% DTX encapsulation efficiency and was characterized by different techniques (DLS, NTA, TEM/FE-SEM, DSC and XRD) and was stable for 12 months of storage, at 25 °C. Incorporation into the NLC prolonged drug release for 54 h, compared to commercial DTX (10 h). In vitro cytotoxicity tests revealed the antiproliferative effect of CO and NLC_DTX, by reducing the cell viability of breast cancer (4T1/MCF-7) and healthy (NIH-3T3) cells more than commercial DTX. NLC_DTX thus emerges as a promising drug delivery system of remarkable anticancer effect, (strengthened by CO) and sustained release that, in clinics, may decrease systemic toxicity at lower DTX doses.     

Exploration of Cytotoxic Potential of Longifolene/Junipene Isolated from Chrysopogon zizanioides

Since ancient times, Chrysopogon zizanioides has been utilized as a traditional medicinal plant for the treatment of numerous ailments, but neither its plant extract form nor its phytoconstituents have been fully explored. With this in mind, the present research was designed to isolate and structurally characterize one of its chemical constituents and evaluate its cytotoxic potential. Therefore, an ethanolic extract of roots was prepared and subjected to column chromatography using solvents of varying polarities. The obtained pure compound was characterized using various chromatographic and spectroscopic techniques such as high-performance liquid chromatography (HPLC), carbon and proton nuclear magnetic resonance (NMR), and liquid chromatography–mass spectroscopy (LC-MS) and identified as longifolene. This compound was evaluated for its cytotoxic potential using an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay on the prostate (DU-145), oral (SCC-29B) cancer cell line and normal kidney cell line (Vero cells), taking doxorubicin as a standard drug. The obtained outcomes revealed that longifolene possesses cytotoxic potential against both prostate (IC₅₀ = 78.64 µg/mL) as well as oral (IC₅₀ = 88.92 µg/mL) cancer cell lines with the least toxicity in healthy Vero cells (IC₅₀ = 246.3 µg/mL) when compared to doxorubicin. Hence, this primary exploratory study of longifolene exhibited its cytotoxic potency along with wide safety margins in healthy cell lines, giving an idea that the compounds possess some ability to differentiate between cancerous cells and healthy cells.     

Inhibitory Effect of GRAS Essential Oils and Plant Extracts on the Growth of Aspergillus westerdijkiae and Aspergillus carbonarius Strains

The effect of essential oils (obtained using hydrodistillation) and plant extracts (ethanolic, aqueous, and hexanic extractions) of 10 different plants cultivated in Brazil were tested using the diffusion agar method, with the objective of evaluating the inhibitory effect of the oils and extracts on the mycelial growth of Aspergillus westerdijkiae NRRL 3174 and A. carbonarius RC 2054 (UNRC). Of the 40 essential oils and plant extracts analyzed, oregano essential oil and plant extract, rosemary essential oil, and the clove ethanolic extract were the best choice to obtain the growth parameters (radial growth rates (mm day⁻¹) and lag phase (h)) due the good results presented and the volume of oil/extract obtained. Comparing all the essential oils and plant extracts that were tested for growth parameters, the best results were obtained for the clove ethanolic extract for both strains assayed. These results demonstrated an outstanding potential use of some of these products in prevention of fungal contamination in food. However, further studies need to be conducted to determine the ability of these oils and extracts to inhibit or reduce ochratoxin A production.     

Brazilian Agroindustrial Wastes as a Potential Resource of Bioative Compounds and Their Antimicrobial and Antioxidant Activities

The study of the recovery of bioactive compounds from natural resources and its implications in several areas is very significant for the scientific community. This work aimed to study Brazilian agroindustrial wastes’ antioxidant and antimicrobial activities using green extraction. Olive leaves, jaboticaba peel, araçá peel, and pecan nut shells were evaluated under four conditions: (1) convective-drying and aqueous extraction, (2) convective-drying and ethanolic extraction, (3) freeze-drying and aqueous extraction, and (4) freeze-drying and ethanolic extraction. The results demonstrated that all samples showed high antioxidant potential, and the highest antioxidant activity was obtained for the extract of pecan nut shell. As for the quantification of compounds by HPLC, the olive leaf presented the highest content of phenolic compounds in the extract, mainly oleuropein. Finally, the antimicrobial activity analysis revealed the extracts’ bactericidal potential against Staphylococcus aureus and Escherichia coli. The present study shows that green extraction can extract bioactive compounds with antioxidant and antimicrobial properties, highlighting the importance of choosing the drying method and solvent for future uses of these natural resources by the industry.     

Fatty-Acid-Rich Agave angustifolia Fraction Shows Antiarthritic and Immunomodulatory Effect

Agave angustifolia is a xerophytic species widely used in Mexico as an ingredient in sweet food and fermented beverages; it is also used in traditional medicine to treat wound pain and rheumatic damage, and as a remedy for psoriasis. Among the various A. angustifolia extracts and extract fractions that have been evaluated for their anti-inflammatory effects, the acetonic extract (AaAc) and its acetonic (F-Ac) and methanolic (F-MeOH) fractions were the most active in a xylene-induced ear edema model in mice, when orally administered. Four fractions resulting from chemically resolving F-Ac (F1–F4) were locally applied to mice with phorbol 12-myristate 13-acetate (TPA)-induced ear inflammation; F1 inhibited inflammation by 70% and was further evaluated in a carrageenan-induced mono-arthritis model. When administered at doses of 12.5, 25, and 50 mg/kg, F1 reduced articular edema and the spleen index. In addition, it modulated spleen and joint cytokine levels and decreased pain. According to a GC–MS analysis, the main components of F1 are fatty-acid derivatives: palmitic acid methyl ester, palmitic acid ethyl ester, octadecenoic acid methyl ester, linoleic acid ethyl ester, and oleic acid ethyl ester.     

Capture of activated dioxygen intermediates at the copper-active site of a lytic polysaccharide monooxygenase

Metalloproteins perform a diverse array of redox-related reactions facilitated by the increased chemical functionality afforded by their metallocofactors. Lytic polysaccharide monooxygenases (LPMOs) are a class of copper-dependent enzymes that are responsible for the breakdown of recalcitrant polysaccharides via oxidative cleavage at the glycosidic bond. The activated copper-oxygen intermediates and their mechanism of formation remains to be established. Neutron protein crystallography which permits direct visualization of protonation states was used to investigate the initial steps of oxygen activation directly following active site copper reduction in Neurospora crassa LPMO9D. Herein, we cryo-trap an activated dioxygen intermediate in a mixture of superoxo and hydroperoxo states, and we identify the conserved second coordination shell residue His157 as the proton donor. Density functional theory calculations indicate that both superoxo and hydroperoxo active site states are stable. The hydroperoxo formed is potentially an early LPMO catalytic reaction intermediate or the first step in the mechanism of hydrogen peroxide formation in the absence of substrate. We observe that the N-terminal amino group of the copper coordinating His1 remains doubly protonated directly following molecular oxygen reduction by copper. Aided by molecular dynamics and mining minima free energy calculations we establish that the conserved second-shell His161 in MtPMO3* displays conformational flexibility in solution and that this flexibility is also observed, though to a lesser extent, in His157 of NcLPMO9D. The imidazolate form of His157 observed in our structure following oxygen intermediate protonation can be attributed to abolished His157 flexibility due steric hindrance in the crystal as well as the solvent-occluded active site environment due to crystal packing. A neutron crystal structure of NcLPMO9D at low pH further supports occlusion of the active site since His157 remains singly protonated even at acidic conditions.

Superoxo and hydroperoxo intermediates were cryotrapped at the copper active site of lytic polysaccharide monooxygenase using neutron protein crystallography.     

Isothiouronium salts as useful and odorless intermediates for the synthesis of thiaalkylimidazolium ionic liquids

A simple and odorless route for the synthesis of monocationic and dicationic thiaalkylimidazolium ionic liquids (ILs) is reported. Our approach starts with the selective monoalkylation of dihalogenated substrates by methylimidazole derivatives, followed by the synthesis of odorless isothiouronium salts via reaction with thiourea. The target ILs are obtained after sequential hydrolysis-alkylation of the isothiouronium salts followed by anion metathesis in water. After extraction, the novel thiaalkylimidazolium ILs are obtained with high purity, without the requirement of additional purification steps. In order to demonstrate their applicability, two of these task-specific ILs were employed as ligands in Ullmann and Suzuki couplings and also as charged probes to detect copper intermediates via ESI(+)-MS.