Subcellular mapping of living cells via synchrotron microFTIR and ZnS hemispheres.

FTIR imaging is a label-free, non-destructive method valuably exploited in the study of the biological process in living cells. However, the long wavelength/low spatial resolution and the strong absorbance of water are still key constrains in the application of IR microscopy ex vivo. In this work, a new retrofit approach based on the use of ZnS hemispheres is introduced to significantly improve the spatial resolution on live cell FTIR imaging. By means of two high refractive index domes sandwiching the sample, a lateral resolution close to 2.2 µm at 6 µm wavelength has been achieved, i.e. below the theoretical diffraction limit in air and more than twice the improvement (to ~λ/2.7) from our previous attempt using CaF2 lenses. The ZnS domes also allowed an extended spectral range to 950 cm-1, in contrast to the cut-off at 1050 cm-1 using CaF2. In combination with synchrotron radiation source, microFTIR provides an improved signal-to-noise ratio through the circa 12 µm thin layer of medium, thus allowing detailed distribution of lipids, protein and nucleic acid in the surround of the nucleus of single living cells. Endoplasmic reticula were clearly shown based on the lipid ν(CH) and ν(C=O) bands, while the DNA was imaged based on the ν(PO2-) band highlighting the nucleus region. This work has also included a demonstration of drug (doxorubicin) in cell measurement to highlight the potential of this approach. Graphical abstract.

In situ Fourier transform infrared analysis of live cells' response to doxorubicin.

The study of the response of cancer cells to chemotherapy drugs is of high importance due to the specificity of some drugs to certain types of cancer and the resistance of some specific cancer types to chemotherapy drugs. Our aim was to develop and apply the label-free and non-destructive Fourier transform infrared (FTIR) method to determine the sensitivity of three different cancer cell-lines to a common anti-cancer drug doxorubicin at different concentrations and to demonstrate that information about the mechanism of resistance to the chemotherapy drug can be extracted from spectral data. HeLa, PC3, and Caco-2 cells were seeded and grown on an attenuated total reflection (ATR) crystal, doxorubicin was applied at the clinically significant concentration of 0.1-20 µM, and spectra of the cells were collected hourly over 20 h. Analysis of the amide bands was correlated with cell viability, which had been cross validated with MTT assays, allowing to determine that the three cell lines had significantly different resistance to doxorubicin. The difference spectra and principal component analysis (PCA) highlighted the subtle chemical changes in the living cells under treatment. Spectral regions assigned to nucleic acids (mainly 1085 cm(-1)) and carbohydrates (mainly 1024 cm(-1)) showed changes that could be related to the mode of action of the drug and the mechanism of resistance of the cell lines to doxorubicin. This is a cost-effective method that does not require bioassay reagents but allows label-free, non-destructive and in situ analysis of chemical changes in live cells, using standard FTIR equipment adapted to ATR measurements.

Label-free in situ quantification of drug in living cells at micromolar levels using infrared spectroscopy.

Quantifying the rate and the amount of drug entering live cells is an essential part of the medicine development process. Infrared spectroscopy is a label-free, chemically selective tool for analyzing the composition of live cells in culture that has the potential to quantify, in situ, the amount of drug entering living cells in a nondestructive manner, although its sensitivity is currently limited. This paper is the first to demonstrate in situ quantification of the cancer drug, fluorouracil, in live cells at a therapeutically relevant concentration using Fourier transform infrared spectroscopy. To achieve the required improvement in detection and quantitation limits of the IR measurement, two strategies were exploited. First, a sampling method called multibounce attenuated total reflection was used to optimize the signal while second, a long pass filter in combination with a mercury cadmium telluride detector was used to reduce the instrument noise. Using these novel adaptations, it was possible to quantify 20 µM of fluorouracil in cell culture medium using a standard FTIR instrument, while it was possible to quantify and measure the flux of fluorouracil in situ in living cells treated with an 80 µM drug.

Bifunctional phenolic-choline conjugates as anti-oxidants and acetylcholinesterase inhibitors.

Because of the complex cascade of molecular events that can occur in the brain of an Alzheimer's disease (AD) patient, the therapy of this neurodegenerative disease seems more likely to be achieved by multifunctional drugs. Herein, a new series of dual-targeting ligands have been developed and in vitro bioevaluated. Their architecture is based on conjugating the acetylcholinesterase inhibition and anti-oxidant properties in one molecular entity. Specifically, a series of naturally occurring phenolic acids with recognized anti-oxidant properties (derivatives of caffeic acid, rosmarinic acid, and trolox) have been conjugated with choline to account for the recognition by acetylcholinesterase (AChE). The synthesized hybrid compounds evidenced AChE inhibitory capacity of micromolar range (rationalized by molecular modeling studies) and good antioxidant properties. Their effects on human neuroblastoma cells, previously treated with beta-amyloid peptides and 1-methyl-4-phenylpyridinium ion neurotoxins (to simulate AD and Parkinson's disease, respectively), also demonstrated a considerable capacity for protection against the cytotoxicity of these stressors.

Phytochemical analysis and in vitro and in vivo evaluation of biological activities of artichoke (Cynara scolymus L.) floral stems: Towards the valorization of food by-products.

Artichoke floral stems (AFS) food waste by-products were examined for their phytochemical constituents and their in vitro and in vivo biological activities. Although that the highest total phenol content and total flavonoid content were found in ethyl acetate extract, methanol extract possessed the strongest DPPH and ABTS radical scavenging activity, and showed the highest reducing ferric antioxidant power (FRAP). The anti-acetylcholinesterase activity was higher in butanol extract, whereas the ethyl acetate extract had the highest inhibitory effect on heat-induced protein denaturation. In alloxan-induced diabetic mice, the AFS methanol extract (AFSE) rich in caffeoylquinic acids and flavones reduced blood glucose, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase, creatinine, and improved liver, and renal antioxidative status. Administration of AFSE to diabetic mice reduced total cholesterol, triglycerides, LDL-cholesterol, and the atherogenic index of plasma (AIP) suggesting its hypolipidemic action. Overall, AFS could be considered as attractive source of health-promoting ingredients.

Action of euptox A from Ageratina adenophora juice on human cell lines: A top-down study using FTIR spectroscopy and protein profiling.

Euptox A, from Ageratina adenophora juice, is a toxin associated with the plant's resistance to infections, invasiveness and traditional use in cancer treatment. We used FTIR spectroscopy and protein profiling of cell lines to study the impact of euptox A on human cells, to clarify its mechanism of action in a top-down approach. Euptox A was extracted from the juice of A. adenophora. Its stability in the gastrointestinal tract was evaluated, as the compound/juice is generally taken orally. Cytotoxicity was determined in HeLa, Caco-2 and MCF7 cells, and the mechanism of action analyzed by protein and metabolite profiles using electrophoresis and FTIR spectroscopy. Euptox A resisted gastrointestinal digestion and was the most cytotoxic component of the extract for all cell lines tests. Euptox A-treated HeLa cells showed changes in protein profile, especially on 40S ribosomal protein S8 (RP), generally associated with cancer cells. FTIR profiles of treated cells diverged in the same metabolites as cells treated with cisplatin, both in metabolite directed analysis and in multivariate analysis (principal component analysis). In conclusion, euptox A in this top-down study showed a cellular impact that suggests a strong potential against cancer, acting on cancer targeted cellular characteristics.

Bioactivities of decoctions from Plectranthus species related to their traditional use on the treatment of digestive problems and alcohol intoxication.

ETHNOPHARMACOLOGICAL RELEVANCE: Decoctions of Plectranthus species are traditionally ingested after large meals for treatment of food digestion and alcohol abuse. AIM OF THE STUDY: This study aims at associating the digestion-related ethno-uses of Plectranthus species decoctions to molecular mechanism that might explain them: easing digestion (AChE inhibition) and treating hangover (ADH inhibition) MATERIAL AND METHODS: Decoctions from Plectranthus species were analysed for their alcohol dehydrogenase (ADH) inhibition and acetylcholinesterase (AChE) inhibition, related with alcohol metabolism and intestinal motility, respectively. Identification of the active components was carried out by LC-MS/MS and the docking studies were performed with AChE and the bioactive molecules detected. RESULTS: All decoctions inhibited ADH activity. This inhibition was correlated with their rosmarinic acid (RA) content, which showed an IC50 value of 19 µg/mL, similar to the reference inhibitor CuCl2. The presence of RA also leads to most decoctions showing AChE inhibiting capacity. P. zuluensis decoction with an IC50 of 80 µg/mL presented also medioresinol, an even better inhibitor of AChE, as indicated by molecular docking studies. Furthermore, all decoctions tested showed no toxicity towards two human cell lines, and a high capacity to quench free radicals (DPPH), which also play a helpful in the digestive process, related with their RA content. CONCLUSIONS: All activities presented by the RA-rich Plectranthus decoctions support their use in treating digestion disorders and P. barbatus could explain its use also for alleviating hangover symptoms. Medioresinol, which is present in P. zuluensis, exhibited a significant AChE inhibition and may provide, in the future, a new lead for bioactive compounds.

Digestibility and Bioavailability of the Active Components of Erica australis L. Aqueous Extracts and Their Therapeutic Potential as Acetylcholinesterase Inhibitors.

Erica australis L. (Ericaceae) is used in traditional medicine to treat many free-radical related ailments. In the present work, the stability and biological activity of the plant aqueous extracts submitted to an in vitro digestive process were investigated. Chemical stability was monitored by HPLC-DAD and LC-MS/MS, while the bioactivities were evaluated through the inhibition of acetylcholinesterase (AChE) and DPPH radical scavenging activity. Both extracts, whose main components were flavonol glycosides, inhibited AChE, showing IC50 values of 257.9 ± 6.2 µg/mL and 296.8 ± 8.8 µg/mL for the decoction and for the infusion, respectively. Significant radical scavenging activities were also revealed by both extracts, as denoted by the IC50 values for the decoction, 6.7 ± 0.1 µg/mL, and for the infusion, 10.5 ± 0.3 µg/mL. After submission to gastric and pancreatic juices, no remarkable alterations in the composition or in the bioactivities were observed, suggesting that the extracts may pass through the gastrointestinal tract, keeping their composition and therefore their biological properties. Moreover, the bioavailability of the components of both extracts, as studied in a Caco-2 cell model, showed that compounds can permeate the membrane, which is a condition to exert their biological activities. Our results add further support to the potential of E. australis for its antioxidant and neuroprotective properties.

New In Vitro Studies on the Bioprofile of Genista tenera Antihyperglycemic Extract.

The inhibition of α-glucosidase and glucose-6-phosphatase, two enzymes involved in the carbohydrate metabolism, is an important target to control glycaemia on individuals with type 2 diabetes. In this work we report for the first time the inhibition of both enzymes by the antihyperglycemic n-butanol extract from Genista tenera (Fabaceae). This extract decreased α-glucosidase and glucose-6-phosphatase activities to 0.97 and 80.25 %, respectively, being more effective than acarbose, and phlorizin, the positive controls, which reduced enzymes activities only to 17.39 and 96.06 %. Once inflammation and oxidative stress are related to diabetic impairments, the anti-inflammatory activity of the extract was also evaluated, through its inhibitory activity over COX-1 enzyme (47.5 % inhibition). Moreover, after induction of oxidative stress by UV radiation, the viability of irradiated rat liver hepatoma cells exposed to the extract was significantly higher (67.82 %) than that promoted by ascorbic acid, the positive control (45.05 %). In addition, the stability of the extract under gastrointestinal conditions was evaluated by HPLC-DAD-ESI-MS/MS. Flavonoid diglycosides were identified as the main constituents of the extract, and no alterations in the chemical composition nor in the antioxidant activity were observed after in vitro digestion with artificial gastric and pancreatic juices.

Effect of luteolin and apigenin on rosmarinic acid bioavailability in Caco-2 cell monolayers.

Herbal teas are usually complex mixtures of therapeutically active compounds. The present study is focused on the interference of flavonoids on the bioavailability of rosmarinic acid, as these types of compounds are often present together in decoctions of medicinal plants, namely Lamiaceae species. The bioavailability of rosmarinic acid was analysed in the decoction of P. barbatus and in mixtures with apigenin and luteolin. Rosmarinic acid in the herbal tea showed a 43% bioavailability through the Caco-2 cells when luteolin and apigenin were approximately 30 µM each. In the artificial mixtures the bioavailability could be increased to 90% when the concentration of flavonoids was increased to 90 µM. The co-administration of substrates of known intestinal transport systems, Pgp, Oatp and MCT, showed that the extract components not only modulated the activity of these transporters but also their own bioavailability was dependent on them. Our results demonstrate that plant extracts with a high diversity of polyphenol compounds may have higher bioavailability than that predicted by the isolated compounds.

Evaluation of cholesterol absorption and biosynthesis by decoctions of Annona cherimola leaves.

ETHNOPHARMACOLOGICAL RELEVANCE: Decoctions of the leaves of Annona cherimola Mill. are traditionally used in Azores to treat hypercholesterolemia. Although they are sold and consumed by people in order to improve their health, these are products that cannot be sold with claims for health benefits as they have never been studied scientifically. MATERIALS AND METHODS: The activities of decoctions from Annona cherimola leaves were analysed for the two therapeutic approaches currently used to reduce plasma cholesterol: inhibition of dietary cholesterol uptake and inhibition of HMG-CoA reductase activity. Furthermore, the composition of the decoction was elucidated by LC-MS and the permeability of the active components was analysed using Caco-2 cell monolayers as a model of the intestinal barrier (dietary cholesterol uptake). RESULTS: The chemical composition of the Annona cherimola leaves' extract revealed that rutin was its main component. The in vitro gastrointestinal digestion did not modify the chemical composition of the extract. This extract was able to originate a slight reduction in cholesterol absorption through Caco-2 cells lines and to reduce the HMG-CoA reductase activity in 50% when using 137.3 µg of the extract/mL. Rutin, when used in the same concentration as that found in the extract, was able to reduce cholesterol absorption through Caco-2 cells monolayer in approximately 47%. This flavonoid had an IC50 of 17.85 µM relatively to the HMG-CoA reductase activity. CONCLUSIONS: The traditional use of decoctions from the leaves of Annona cherimola may be justified, at least by the inhibition of HMG-CoA reductase activity.

Interaction between Plectranthus barbatus herbal tea components and acetylcholinesterase: binding and activity studies.

Plectranthus barbatus water extracts, have been used as herbal teas, for the treatment of various diseases. In a previous study it was demonstrated that antioxidant and anti-acetylcholinesterase active extract constituents and their metabolites were found in the plasma of rats after P. barbatus tea intraperitoneal administration. Consequently, a decrease in brain acetylcholinesterase activity occurred. The aim of the present research is to elucidate how P. barbatus extract components interact with acetylcholinesterase. The estimated thermodynamic parameters suggest that the main intermolecular interaction is hydrophobic association, although hydrogen bonds between flavonoids and the active gorge of the acetylcholinesterase molecule seem to occur and have a great impact on acetylcholinesterase inhibition. The hydroxyl positions in flavonoids seem to be of utmost importance for enzyme inhibition, as they interact with specific amino acid residues in the active gorge. FTIR analysis showed that the plant extract components do not interfere with the secondary structure of the enzyme, but decreases the rate of hydrogen-deuterium exchange, possibly by decreasing solvent accessibility in the acetylcholinesterase active gorge. The spectroscopic data complements docking studies of acetylcholinesterase inhibition by plant phenolic compounds, clarifying the dominant interactions between enzyme and inhibitor and the most important structural features of the inhibitor molecules.

Function of Plectranthus barbatus herbal tea as neuronal acetylcholinesterase inhibitor.

This study aims to determine the function of Plectranthus barbatus (Lamiaceae) herbal tea as inhibitor of the brain acetylcholinesterase (AChE) activity. To accomplish this objective the herbal tea as well as its main component, rosmarinic acid were administered to laboratory animals (rats) and the effect on the brain AChE activity was evaluated. The study of the herbal tea metabolites in the plasma and also in the brain was undertaken. The herbal water extract was administered intragastrically and also intraperitoneally. When the plant extract was intragastrically administered, vestigial amounts of metabolites from P. barbatus extract compounds were present in rat plasma, but none were found in brain, although inhibition of brain acetylcholinesterase activity was detected. However, when P. barbatus extract was administered intraperitoneally, all its compounds were found in plasma, and rosmarinic acid was found in brain. The highest concentrations of compounds/metabolites were found 30 min after administration. An inhibition of 29.0 ± 2.3% and 24.9 ± 3.7% in brain acetylcholinesterase activity was observed 30 and 60 min after intraperitoneal administration, respectively. These values were higher than those expected, taking into account the quantity of rosmarinic acid detected in the brain, which suggests that other active extract compounds or metabolites may be present in non-detectable amounts. These results prove that the administration of P. barbatus aqueous extract can reach the brain and act as AChE inhibitor.

Inhibition of HMG-CoA reductase activity and cholesterol permeation through Caco-2 cells by caffeoylquinic acids from Vernonia condensata leaves

ABSTRACT The aim of this study was to provide scientific knowledge to support the use of Vernonia condensata Baker, Asteraceae, beverages for their alleged hypocholesterolemic properties by testing their action as HMG-CoA reductase inhibitors and their capacity to lower dietary cholesterol permeation. Chlorogenic acid, and other caffeoylquinic acids derivatives were identified as the main components of these beverages by LC–MS/MS. No changes in the composition were notice after the in vitro gastrointestinal digestion and no toxicity against Caco-2 and HepG2 cell lines was detected. Cholesterol permeation through Caco-2 monolayers was reduced in 37% in the presence of these herbal teas, and the caffeoylquinic acids permeated the monolayers in 30–40% of their initial amount in 6 h. HMG-CoA reductase activity was reduced with these beverages, showing an IC50 of 217 µg ml−1. It was concluded that caffeoylquinic acids, the major components, justified 98% of the enzyme inhibition measured.

Preparation and physicochemical characterization of Ag nanoparticles biosynthesized by Lippia citriodora (Lemon Verbena).

The purpose of this study was to develop a simple biological method for the synthesis of Ag nanoparticles (AgNPs) using Lippia citriodora leaves aqueous extract as reducing agent. Transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDX), X-ray diffraction (XRD), and visible absorption spectroscopy (UV-vis) confirmed the reduction of silver ions to AgNPs. Stable, spherical crystalline AgNPs with well defined dimensions (average size of 15-30 nm) were obtained, on treating aqueous silver nitrate with the plant leaf aqueous extract. The kinetic of particles formation was proportional to the effect of reducing agent concentration and was enhanced by the increase of temperature from 25 degrees C to 95 degrees C. Time, temperature and extract concentration did not influence significantly the shape and size of nanoparticles. In order to identify the compounds responsible for the bioreduction of silver ions and stabilization of the AgNPs formed, we investigated the constituents of L. citriodora aqueous extract by high performance liquid chromatography (HPLC) and mass spectrometry (MS). The main compounds found were verbascoside, isoverbascoside, chrysoeriol-7-O-diglucoronide and luteonin-7-O-diglucoronide. The data obtained suggests that the isoverbascoside compound is responsible for Ag(+) ions reduction and act as capping agents of the nanoparticles afterwards.