Fabrication and characterization of polylactic acid coaxial antibacterial nanofibers embedded with cinnamaldehyde/tea polyphenol with food packaging potential.

Polylactic acid (PLA) is a promising food packaging material with biocompatible, nontoxic and biodegradable. In order to reduce the deterioration of aquatic products caused by microorganisms, PLA coaxial nanofiber films with cinnamaldehyde (CMA), tea polyphenol (TP) and its composite as core materials were prepared by using coaxial electrospinning technology. Its microscopic morphology and structure were characterized separately, and its thermal stability, wettability and mechanical properties were determined. The antibacterial activity and antibacterial mechanism of nanofiber films were studied with Shewanella putrefaciens (S. putrefaciens) which is the dominant spoilage of aquatic products as the target of action. The results show that the CMA/TP (m/m = 2:5)-PLA coaxial nanofibers have small diameter, uniform distribution, smooth surface, no pores and fracture. At the same time, the film has strong hydrophobicity, good thermal stability and mechanical properties. Its antibacterial performance is better than that of single-core nanofiber films, which effectively destroys the cell membrane of S. putrefaciens, increases the permeability of cell membrane, and interferes with the synthesis and expression of its protein. The coaxial nanofiber films with CMA, TP and its composite as core material can be used as a fresh-keeping material with antibacterial properties, and has potential application value in the field of food preservation.

Production Mechanisms of Black Tea Polyphenols.

Black tea accounts for 70-80% of world tea production, and the polyphenols therein are produced by enzymatic oxidation of four tea catechins during tea fermentation. However, only limited groups of dimeric oxidation products, such as theaflavins, theasinensins, and theacitrins, have been isolated from black tea and chemically characterized. This is largely because of the complexity and heterogeneity of the oxidation products. To determine structures and production mechanisms of uncharacterized black tea polyphenols, in vitro model fermentation experiments using pure catechins and polyphenol oxidase have been applied, and basic oxidation mechanisms have been established. Contemporary methods, such as LC-MS, are also effective to identify catechin oxidation products in black tea. Despite ongoing efforts, almost 60% of the solids in black tea infusion remain uncharacterized. These compounds include the so-called thearubigins, which are a heterogeneous mixture of uncharacterized catechin oxidation products with oligomeric structures. This review summarizes the current knowledge of the production mechanisms of representative black tea polyphenols and presents recent progress in characterization of thearubigins.

Synthesis of bio-oil from waste Trichosanthes cucumerina seeds: a substitute for conventional fuel.

The present study explores the methodology for the synthesis of bio-oil from waste trichosanthes cucumerina seeds by the solvent extraction method. It investigates the yield percentage, concentration of free fatty acids and acid contents in the extracted bio-oil. Effects of size of the crushed seeds, moisture content, extraction time, solvent to seed ratio and extraction temperatures were examined. The non-polar hexane solvent resulted in a higher percentage of oil yield (28.4 ± 0.4%) for the crushed seed size of 0.21 mm, 6% moisture content, 270 min extraction time, 68 °C temperature and 6:1(ml/g) of solvent to seed ratio. The synthesized bio-oil was characterized using Fourier Transform Infra-Red spectrum and Gas Chromatography-Mass Spectroscopy analysis. The properties of the bio-oil and biodiesel were assessed according to the American Society for Testing and Materials and the Association of Official Analytical Chemists standards. The obtained methyl-ester by trans-esterification process results in the fuel properties closer to the conventional fuel. Thus, Trichosanthes cucumerina bio-diesel can be used as a potential substitute.

Synthesis and Comparative Structure-Activity Study of Carbohydrate-Based Phenolic Compounds as α-Glucosidase Inhibitors and Antioxidants.

Twenty-one natural and unnatural phenolic compounds containing a carbohydrate moiety were synthesized and their structure-activity relationship (SAR) was evaluated for α-glucosidase inhibition and antioxidative activity. Varying the position of the galloyl unit on the 1,5-anhydro-d-glucitol (1,5-AG) core resulted in changes in the α-glucosidase inhibitory activity and notably, particularly strong activity was demonstrated when the galloyl unit was present at the C-2 position. Furthermore, increasing the number of the galloyl units significantly affected the α-glucosidase inhibition, and 2,3,4,6-tetra-galloyl-1,5-AG (54) and 2,3,4,6-tetra-galloyl-d-glucopyranose (61) exhibited excellent activities, which were more than 13-fold higher than the α-glucosidase inhibitory activity of acertannin (37). Moreover, a comparative structure-activity study suggested that a hemiacetal hydroxyl functionality in the carbohydrate core and a biaryl bond of the 4,6-O-hexahydroxydiphenoyl (HHDP) group, which are components of ellagitannins including tellimagrandin I, are not necessary for the α-glucosidase inhibitory activity. Lastly, the antioxidant activity increased proportionally with the number of galloyl units.

Styryl-cinnamate hybrid inhibits glioma by alleviating translation, bioenergetics and other key cellular responses leading to apoptosis.

Gliomas are lethal and aggressive form of brain tumors with resistance to conventional radiation and cytotoxic chemotherapies; inviting continuous efforts for drug discovery and drug delivery. Interestingly, small molecule hybrids are one such pharmacophore that continues to capture interest owing to their pluripotent medicinal effects. Accordingly, we earlier reported synthesis of potent Styryl-cinnamate hybrids (analogues of Salvianolic acid F) along with its plausible mode of action (MOA). We explored iTRAQ-LC/MS-MS technique to deduce differentially expressed landscape of native & phospho-proteins in treated glioma cells. Based on this, Protein-Protein Interactome (PPI) was looked into by employing computational tools and further validated in vitro. We hereby report that the Styryl-cinnamate hybrid, an analogue of natural Salvianolic acid F, alters key regulatory proteins involved in translation, cytoskeleton development, bioenergetics, DNA repair, angiogenesis and ubiquitination. Cell cycle analysis dictates arrest at G0/G1 stage along with reduced levels of cyclin D; involved in G1 progression. We discovered that Styryl-cinnamate hybrid targets glioma by intrinsically triggering metabolite-mediated stress. Various oncological circuits alleviated by the potential drug candidate strongly supports the role of such pharmacophores as anticancer drugs. Although, further analysis of SC hybrid in treating xenografts or solid tumors is yet to be explored but their candidature has gained huge impetus through this study. This study equips us better in understanding the shift in proteomic landscape after treating glioma cells with SC hybrid. It also allows us to elicit molecular targets of this potential drug before progressing to preclinical studies.

Challenges and complexity of functionality evaluation of flavan-3-ol derivatives.

Flavan-3-ol derivatives are common plant-derived bioactive compounds. In particular, (-)-epigallocatechin-3-O-gallate shows various moderate biological activities without severe toxicity, and its health-promoting effects have been widely studied because it is a main ingredient in green tea and is commercially available at low cost. Although various biologically active flavan-3-ol derivatives are present as minor constituents in plants as well as in green tea, their biological activities have yet to be revealed, mainly due to their relative unavailability. Here, I outline the major factors contributing to the complexity of functionality studies of flavan-3-ol derivatives, including proanthocyanidins and oligomeric flavan-3-ols. I emphasize the importance of conducting structure-activity relationship studies using synthesized flavan-3-ol derivatives that are difficult to obtain from plant extracts in pure form to overcome this challenge. Further discovery of these minor constituents showing strong biological activities is expected to produce useful information for the development of functional health foods.

Synthesis of Effective Food Constituents toward the Development of Chemical Biology Investigations.

This article describes the development of various probes and immunogens for chemical-biological investigations of food flavonoids. We accomplished a large (gram)-scale asymmetric synthesis of a key intermediate, 5-aminopentyl deoxy epigallocatechin-3-gallate (APDOEGCg; 3), an analogue of green tea polyphenol EGCg, in which the key step was cationic cyclization utilizing neighboring group participation of the gallate carbonyl group. The synthetic APDOEGCg (3) was efficiently converted to a fluorescent probe 18 and an immunogen 19 by utilizing the high reactivity of the amine functional group. We confirmed the usefulness of these probes for imaging studies and the generation of antibodies, respectively. We also describe the efficient synthesis of a positron emission tomography (PET) probe [11C]20 by incorporation of 11C into EGCg (1), for which synthetic 4″-Me-EGCg (20) was utilized as an authentic sample. Our synthetic strategy was also applied for the practical synthesis of nobiletin (21), a polymethoxylated flavone from citrus. Synthetic nobiletin was readily converted to various probes by selective demethylation and incorporation of fluorescein, biotin or 11C. These probes should be useful for a range of biological applications. Detailed examination of the mechanisms and further applications are in progress.

Synthesis of a Functionalized Benzofuran as a Synthon for Salvianolic Acid C Analogues as Potential LDL Antioxidants.

A palladium mediated synthesis of a common synthon for the syntheses of antioxidant analogues of naturally occurring salvianolic acids is presented. The synthetic route may be used to obtain analogues with a balanced lipophilicity/hydrophilicity which may result in potentially interesting LDL antioxidants for the prevention of cardiovascular diseases.

Synthesis of oolongtheanins and their inhibitory activity on micellar cholesterol solubility in vitro.

The synthesis of oolongtheanins (1a-d) was accomplished from EGC and/or EGCg in three steps. Oolongtheanin-3'-O-gallate (1b) showed more potent inhibitory activity on micellar cholesterol solubility than did EGCg.

A novel voltammetric sensor for ascorbic acid based on molecularly imprinted poly(o-phenylenediamine-co-o-aminophenol).

A molecularly imprinted copolymer, poly(o-phenylenediamine-co-o-aminophenol) (PoPDoAP), was prepared as a new ascorbic acid (AA) sensor. The copolymer was synthesized by incorporation of AA as template molecules during the electrochemical copolymerization of o-phenylenediamine and o-aminophenol, and complementary sites were formed after the copolymer was electrochemically reduced in ammonium aqueous solution. The molecularly imprinted copolymer sensor exhibited a high sensitivity and selectivity toward AA. Differential pulse voltammograms (DPVs) showed a linear concentration range of AA from 0.1 to 10 mM, and the detection limit was calculated to be 36.4 µM. Compared to conventional polyaniline-based AA sensors, the analytical performance of the imprinted copolymer sensor was improved due to the broadened usable pH range of PoPDoAP (from pH 1.0 to pH 8.0). The sensor also exhibited a good reproducibility and stability. And it has been successfully applied in the determination of AA in real samples, including vitamin C tablet and orange juices, with satisfactory results.

Factors influencing the antifolate activity of synthetic tea-derived catechins.

Novel tea catechin derivatives have been synthesized, and a structure-activity study, related to the capacity of these and other polyphenols to bind dihydrofolate reductase (DHFR), has been performed. The data showed an effective binding between all molecules and the free enzyme, and the dissociation constants of the synthetic compounds and of the natural analogues were on the same order. Polyphenols with a catechin configuration were better DHFR inhibitors than those with an epicatechin configuration. Antiproliferative activity was also studied in cultured tumour cells, and the data showed that the activity of the novel derivatives was higher in catechin isomers. Derivatives with a hydroxyl group para on the ester-bonded gallate moiety presented a high in vitro binding to DHFR, but exhibited transport problems in cell culture due to ionization at physiologic pHs. The impact of the binding of catechins to serum albumin on their biological activity was also evaluated. The information provided in this study could be important for the design of novel medicinal active compounds derived from tea catechins. The data suggest that changes in their structure to avoid serum albumin interactions and to facilitate plasmatic membrane transport are essential for the intracellular functions of catechins.

Resveratrol: distribución, propiedades y perspectivas / Resveratrol: distribution, properties and perspectives

El resveratrol es un polifenol natural presente en numerosas plantas y frutos como cacahuetes, moras, arándanos y, sobre todo, en la uva y el vino tinto. Su síntesis está condicionada por la presencia de factores estresantes, tales como la contaminación fúngica o la radiación ultravioleta. En las plantas actúa como fitoalexina, es decir, posee la capacidad de inhibir el progreso de ciertas infecciones. La medicina antigua ha utilizado extractos de plantas que contienen resveratrol desde hace más de 2.000 años y hace más de 30 años que se aisló y se comenzaron a estudiar sus propiedades con métodos científicos. Sus propiedades in vitro han sido ampliamente estudiadas y contrastadas, entre ellas cabe destacar su actividad como anticancerígeno, antiagregante plaquetario, antiinflamatorio, antialérgico, etc. En cuanto a sus propiedades in vivo su actividad no está tan clara; existen numerosos estudios que encuentran beneficios sobre el sistema cardiovascular, enfermedades como la diabetes y sobre la longevidad; sin embargo, otros autores no encuentran una equivalencia de los estudios in vitro a in vivo. Esta discrepancia es debida a la biodisponibilidad que tiene el resveratrol. Tras un consumo oral se ha comprobado que la absorción es muy buena, pero las vías metabólicas dejan solo una pequeña fracción de resveratrol libre en sangre, por lo que la disponibilidad en los tejidos diana es muy baja y no se llegan a las concentraciones empleadas en los estudios in vitro. Así pues, aunque los estudios in vitro indican que se trata de una molécula biológicamente activa con propiedades saludables, los estudios realizados in vivo hasta el momento no pueden confirmar parte de estos resultados, lo cual puede atribuirse a su baja biodisponibilidad(AU)

Resveratrol is a natural polyphenol which can be found in many plants and fruits, such as peanuts, mulberries, blueberries and, above all, in grapes and red wine. Its synthesis is regulated by the presence of stressful factors, such as fungal contamination and ultra-violet radiation. In plants, it plays a role as a phytoalexin, showing a capacity to inhibit the development of certain infections. Plant extracts which contain resveratrol have been employed by traditional medicine for more than 2000 years. Resveratrol was first isolated, and its properties were initially studied with scientific methods, thirty years ago. Its in vitro properties have been extensively studied and demonstrated. It is worth highlighting its activity as an anti-cancer agent, platelet anti-aggregation agent, anti-inflammatory, antiallergenic, etc. The activity of its in vivo properties are not so clear. There are many studies that report benefits on the cardiovascular system, illnesses such as diabetes, and in longevity. However, other authors did not find any agreement between in vitro and in vivo studies. This discrepancy is due to the bioavailability of resveratrol. After an oral dose, it has been demonstrated that the absorption is very high, but the metabolic pathways leave just a little free resveratrol in blood, therefore the bioavailability in the target tissues is very low and the concentrations used in in vitro studies are not found in these tissues. Thus, resveratrol is a very active molecule for maintaining health, but due to the low bioavailability not all the in vitro effects can be translated to in vivo. This opens a new potential approach, seeking derivatives of resveratrol that can be measured in the desired tissues(AU)

Chemical synthesis of tea polyphenols and related compounds.

Tea polyphenol "catechin", which is a major constituent of green tea extract, has received special attention for its important bioactivities. In this article, we review the recent various syntheses of catechins by classifying the mode of of flavan ring-construction. Additionally, we also take notice of the application of the modified catechins that were created to uncover the mechanism of bioactivities and discover new activities.

Total synthesis of (+)-pentamethylsalvianolic acid C.

The total synthesis of a methylated analogue of (+)-Salvianolic acid C has been achieved. Key aspects of the synthetic route include an economical Cu(I) acetylide coupling, unique carboxyl activation conditions via microwave irradiation and a novel lipase catalysed kinetic resolution of a racemic mixture of secondary alcohol Danshensu. The preparation of this methylated analogue will not only improve the bioavailability, but also enable access to new and wider bioactivity applications for (+)-Salvianolic acid C.

Biocompatible, functional spheres based on oxidative coupling assembly of green tea polyphenols.

Green luminescent, monodisperse, smooth, porous and hollow spheres were simply prepared by Cu(2+) and temperature mediated oxidative coupling assembly of green tea polyphenols in water. These polymeric tea polyphenol spheres are GSH responsive, acid resistant but alkali-responsive, ideally used as platform for controlled delivery of functional guests.

Fabrication of biopolymeric complex coacervation core micelles for efficient tea polyphenol delivery via a green process.

Nanoencapsulation is a promising method to improve the bioavailability of tea polyphenol (TPP). In this work, we adopted a green process to develop a new kind of complex coacervation core micelles (C3Ms) based on biopolymers for efficient tea polyphenol delivery. First, gelatin-dextran conjugate was synthesized using Maillard reaction. Then the C3Ms were produced by mixing gelatin-dextran conjugate with TPP. Variable factors on the self-assembly of the C3Ms were investigated. Under optimal conditions, the obtained C3Ms are of nanosize (average 86 nm in diameter) with narrow distribution. The formation of the C3Ms is attributed to hydrophobic interaction and hydrogen bonding instead of electrostatic interaction. Transmission electron microscope (TEM) and scanning electron microscope (SEM) results showed that C3Ms have a spherical shape with core-shell structure. ζ-Potential measurement suggested that the core is composed of gelatin with TPP, whereas the shell is composed of dextran segments. The encapsulation efficiency of the C3Ms is pH-independent, but the loading capacity is controllable and as high as 360 wt % (weight/weight of protein). In addition, the C3Ms show sustained release of TPP in vitro. MTT assay revealed that the C3Ms have comparable or even stronger cytotoxicity against MCF-7 cells than free TPP.

Biomimetic one-pot preparation of a black tea polyphenol theasinensin A from epigallocatechin gallate by treatment with copper(II) chloride and ascorbic acid.

Chromatographic separation of black tea polyphenols is too difficult to supply sufficient quantities of pure compounds for biological experiments. Thus, facile methods to prepare black tea constituents were desired. Treatment of epigallocatechin gallate with copper(II) chloride efficiently afforded an unstable quinone dimer, dehydrotheasinensin A, and subsequent treatment with ascorbic acid stereoselectively yielded theasinensin A. The latter is a dimer with an R-biphenyl bond, one of the major polyphenols found in black tea. The method is simpler and more effective than enzymatic preparation.