Antioxidant activity of papaya seed extracts

The antioxidant activities of the ethanol, petroleum ether, ethyl acetate, n-butanol and water extract fractions from the seeds of papaya were evaluated in this study. The ethyl acetate fraction showed the strongest DPPH and hydroxyl free radical-scavenging activities, and its activities were stronger than those of ascorbic acid and sodium benzoate, respectively. The n-butanol fraction demonstrated the greatest ABTS? radicals scavenging activity. The ethyl acetate fraction and the n-butanol fraction not only showed higher antioxidant activities than the petroleum ether fraction, water fraction and ethanol fraction, but also showed higher superoxide anion and hydrogen peroxide radicals scavenging activities than those of the other extract fractions. The high amount of total phenolics and total flavonoids in the ethyl acetate and n-butanol fractions contributed to their antioxidant activities. The ethyl acetate fraction was subjected to column chromatography, to yield two phenolic compounds, p-hydroxybenzoic acid and vanillic acid, which possessed significant antioxidant activities. Therefore, the seeds of papaya and these compounds might be used as natural antioxidants.     

Antioxidant activity of extracts from Euryale ferox seed

Euryale ferox has been widely used in traditional oriental medicine to treat a variety of illness. However, very little is known about the cellular actions by which this plant mediates its therapeutic effects. Various aspects of antioxidant activity were evaluated in total extracts and fractions derived from Euryale ferox. Total extracts (IC50 5.6 microg/ml) showed relatively high level radical scavenging activity toward 1, 1-diphenyl-2-picrylhydrazyl (DPPH) and also enhanced viability of Chinese hamster lung fibroblast (V79-4) cells under exposure to oxidative agents. Upon further fractionation, the highest levels of DPPH radical scavenging and lipid peroxidation inhibitory activities were found in the ethyl acetate and butanol fractions. The ethyl acetate fractions, the butanol fractions, and total extracts of Euryale ferox also dose-dependently enhanced the activities of superoxide dismutase, catalase and glutathione peroxidase in V79-4 cells. Of these three antioxidant enzymes, glutathione peroxidase activity was most strongly induced. Taken together, our findings show that Euryale ferox contains a significant antioxidant activity and that specific components in the ethyl acetate and butanol fractions may play an important role in mediating these antioxidant properties.     

Antioxidant activity of hydroxystilbene derivatives in homogeneous solution

The antioxidant activity of the cis and trans isomers of several analogues of resveratrol and pterostilbene has been investigated, especially with regard to the effect of the stereochemistry about the olefinic double bond. The antioxidant power of these compounds was estimated by measuring the rate constants for their reactions with peroxyl radicals and, with two of them, the bond dissociation enthalpy (BDE) of the phenolic O-H bond which is cleaved in the inhibition reaction. The present data show that in homogeneous solution the various hydroxystilbenes investigated behave as mild antioxidants with the notable exceptions of the trans isomer of 4 and 6, whose activities are only slightly lower than that of alpha-tocopherol (vitamin E). The rate constants of the inhibition reaction show that the antioxidant activity of the cis-hydroxystilbene is in all the examined cases worse, by a factor ranging between 2 and 6, than that of the corresponding trans isomers. This lower reactivity depends on enthalpy factors as it can be inferred by the experimental values of the O-H bond dissociation enthalpy in the two geometric isomers of 3',5'-di-tert-butyl-4'-hydroxy-3,5-dimethoxystilbene showing that the strength of the O-H bond in the cis isomer is larger by 1.8 kcal/mol. DFT calculations provide a rationalization of this result, indicating that, although the cis geometry implies a destabilization with respect to the trans species of both phenoxyl radical and parent hydroxystilbene, the destabilization of the radical is larger because the folding of the structure strongly reduces the delocalization of the unpaired electron on the styryl group. A comparison of these results with previously reported data on the proapoptotic activity of these stilbenoids suggests that these two properties are not correlated.     

Studies on the solution behaviour of self-assembling polymeric systems

Functional groups were attached to styrene-butadiene copolymers with different polymeric architectures and a low molecular weight compound. These polar stickers form binary, chelate-like contacts or extended juntion zones depending on their chemical nature. The solution properties of these amphiphilic species in toluene were studied by static light scattering.     

Antioxidant and prooxidant activity of spent coffee extracts by isothermal calorimetry

Journal of Thermal Analysis and Calorimetry - This work aims to determine the antioxidant and prooxidant activity of spent coffee extracts obtained with (1) a low-pressure (LP) extraction with...     

Liquid chromatographic-mass spectrometric analysis of supercritical-fluid extracts of rosemary plants

A two-step supercritical fluid extraction process of rosemary leaves, on a pilot plant scale, is proposed to divide the oleoresin into two fractions with different antioxidant activities and essential oil composition. Rosemary leaves were extracted by using different conditions of pressure and temperature as well as different conditions for fractionation of the extracts. Conditions can be tuned to selectively extract one antioxidant fraction with almost no residual aroma. In the present investigation, the antioxidant fraction was exhaustively studied in terms of antioxidant activity measurements as well as of chemical composition. An LC–MS method was adapted to perform the analysis and identification of the compounds responsible for the antioxidant activity of the extracts. Different extraction and fractionation conditions were studied in order to correlate the process conditions with the antioxidant activities obtained.     

Antioxidant activity and total phenols in different extracts of four Staphylea L. Species

Staphylea L. is a deciduous ornamental shrub that possesses significant cytotoxic and antibacterial activity, although the chemical composition of its extracts and the identity of the structures responsible for these biological activities are not yet known. In this study we have determined the total phenolic content in chloroform and ethyl acetate extracts of four Staphylea species: Staphylea colchica Stev., S. elegans Zab., S. holocarpa Hemsl. and S. pinnata L.. The antioxidant potential (DPPH radical and peroxynitrite scavenging activity) of these extracts was also determined and a correlation between the phenolic content and antioxidant activities of the ethyl acetate extracts has been found. Ethyl acetate extracts were more active and one of them, obtained from S. colchica Stev., possessed the highest activity.     

Dynamics of polymeric systems

Using dielectric and mechanical relaxation data of polymeric systems, an alternative formula is examined. The formula describes the experimental data with a high degree of accuracy, not received by the other model functions (Arrhenius and non-Arrhenius type) under investigation. The proposed formula gives the answer on questions concerning a supermolecular structure and the nature of the structural relaxation. New definition of the glass-transition temperature is proposed. It is shown how we should combine the results of different experimental methods to conduct an unambiguous analysis of polymeric systems.     

Pressurized liquid extraction-capillary electrophoresis-mass spectrometry for the analysis of polar antioxidants in rosemary extracts

A method based on capillary electrophoresis-electrospray-mass spectrometry (CE-ESI-MS) was developed to qualitatively characterize natural antioxidants from rosemary (Rosmarinus officinalis L.) in different fractions obtained by pressurized liquid extraction (PLE) using subcritical water. The parameters of CE-ESI-MS were adjusted allowing the separation and characterization of different compounds from rosemary in the PLE fractions. These parameters for CE are kind, pH and concentration of the separation buffer, parameters for ESI-MS are dry gas temperature and flow, nebulizing gas pressure, and make-up flow. The following analytical conditions were found most favorable: aqueous CE buffer (40 mM ammonium acetate/ammonium hydroxide, pH 9); sheath liquid containing 2-propanol-water (60:40, v/v) and 0.1% (v/v) triethylamine at a flow rate of 0.24 mL/h; drying gas flow rate equal to 7 L/min at 350 degrees C, nebulizing gas pressure of 13.8 kPa (2 psi), using a compound stability of 50%. Different antioxidant compounds (e.g., rosmarinic acid and carnosic acid) could be detected in the rosemary extracts by CE-ESI-MS without any additional treatment, enabling the determination of variations in the extract composition caused by the different PLE conditions (i.e., 60 and 100 degrees C). The results provide complementary information to HPLC analysis.     

Antioxidant and antifungal activity of different extracts obtained from aerial parts of Inula crithmoides L.

The total phenolic content, antioxidant and antifungal activities of three Inula crithmoides extracts (n-hexane, methylene chloride and MeOH) were investigated. The methanolic extract showed the highest total phenolic content. In the DPPH assay, the methanolic and hexane extracts exhibited the highest DPPH-radical scavenging activity; in the 5-lipoxygenase assay, the hexane extract showed greater inhibitory effect with an IC₅₀ similar to that of Trolox and ascorbic acid. The antifungal activity of the methanolic extract revealed a higher activity against Phytophtora cryptogea and Alternaria solani.     

Concentrated solution viscosities of polymeric associates

Reasons have been advanced why in some cases concentrated-polymer-solution viscosity measurements are not a suitable method for determining the degree of association of groups attached to polymer chains. These are based on the finite lifetimes of associates compared with the finite lifetimes of the entanglements, which are the major contributors to concentrated-polymer-solution viscosities. The validity of these reasons has been checked in a system where the degree of association of polymer chains can be measured spectroscopically. It was found that the viscosity of these solutions was considerably less than that calculated by the concentrated-solution viscosity equation for solutions of polymers of the average molecular weight expected from the spectroscopically found degree of association.     

Single-walled carbon nanotubes embedded in oriented polymeric nanofibers by electrospinning

The electrospinning process was used successfully to embed single-walled carbon nanotubes (SWCNTs) in a poly(ethylene oxide) (PEO) matrix, forming composite nanofibers. Initial dispersion of SWCNTs in water was achieved by the use of an amphiphilic alternating copolymer of styrene and sodium maleate. The resulting dispersions were stable, having a dark, smooth, ink-like appearance. For electrospinning, the dispersions were mixed with PEO solution in an ethanol/water mixture. The distribution and conformation of the nanotubes in the nanofibers were studied by transmission electron microscopy (TEM). Oxygen plasma etching was used to expose the nanotubes within the nanofibers to facilitate direct observation. Nanotube alignment within the nanofibers was shown to depend strongly on the quality of the initial dispersions. Well-dispersed and separated nanotubes were embedded in a straight and aligned form, while entangled nonseparated nanotubes were incorporated as dense aggregates. X-ray diffraction demonstrated a high degree of orientation of the PEO crystals in the electrospun nanofibers with embedded SWCNTs. This result is in pronounced distinction to the detrimental effect of incorporation of multiwalled carbon nanotubes on polymer orientation in electrospun nanofibers, as reported previously.     

Antioxidant activity determination in Sencha and Gun Powder green tea extracts with the application of voltammetry and UV-VIS spectrophotometry

This article presents the electrochemical analysis of the oxidation of rutin and green tea extract solutions and the antioxidative properties of these substances. Flavonoids and other polyphenols contained in green tea have antioxidative properties due to the presence of various numbers of hydroxyl groups in different arrangements. The investigation of the oxidation of green tea extracts was performed to identify the most effective antioxidant. The cyclic and pulse voltammograms show that the extract of Gun Powder (GP) green tea contained rutin and other polyphenols, while the extract of Sencha (S) tea contained other antioxidants that are oxidised at a more positive potential. The GP extract showed slightly better antioxidative properties than did the S extract. The UV-VIS spectra show that, in addition to flavonoids extracts contain chlorophyll. The results obtained demonstrate that the tested tea extracts show very good antioxidative properties and therefore may be considered as potential stabilising agents that are able to reduce the rate of undesirable oxidation processes.     

Antioxidant activity of organic and aqueous leaf extracts of Cassia occidentalis L. in relation to their phenolic content

In this study, the antioxidant potency of sequential organic and aqueous leaf extracts of Cassia occidentalis was investigated, employing various established in vitro systems such as nitric oxide scavenging (NOS) activity, β-carotene-linoleic acid model system, hydroxyl radical scavenging (HRS) activity, reducing power, metal chelating activity (MCA) and superoxide radical scavenging (SRS) activity. The aqueous extract of the leaves of C. occidentalis was found to be most effective against free radicals, followed by the methanolic, chloroform, petroleum ether and benzene extracts, respectively. A preliminary study of qualitative and quantitative estimations of phenolics was performed, and the results were correlated with different antioxidant tests. A positive and significant (p?相似文献   

Antioxidant activity and total phenolic content of aqueous and methanolic extracts of Jordanian plants: an ICBG project

As part of an International Cooperative Biodiversity Groups (ICBG) program to study Jordan's biodiversity, the relative levels of antioxidant activity and the total phenolic content of aqueous and methanolic extracts of a total of 95 plant species, all of Jordanian origin and those collected at random, have been measured. The total phenolic content of aqueous and methanolic extracts of the investigated plant species ranged from 4.4 to 78.3 mg and from 2.1 to 52.8 mg gallic acid equivalents g(-1) dry weight, respectively, while the total antioxidant capacity ranged from 20.0 to 916.7 and from 15.1 to 915.6 micromol Trolox equivalents g(-1) dry weight, respectively. Based on this collection, approximately 5% of assayed plants showed high levels of antioxidant activity. There was a significant linear correlation between antioxidant activity and total phenolic content for aqueous and methanolic extracts, suggesting that phenolic compounds were the predominant antioxidant components in the investigated plant species. Interestingly, a few of the collected plants had high-antioxidant activity yet "low" phenolic content includes Ceratonia siliqua and Viscum cruciatum. These plants may serve as sources of antioxidants with new chemotypes.     

Spatial displacement correlations in polymeric systems

The spatial correlations of the monomer displacements are studied via molecular-dynamics simulations of a melt of fully flexible, unentangled polymer chains with different length, interacting potential, density, and temperature. Both the scalar and the vector characters of the correlations are considered and their extension quantified in terms of suitable dynamical correlation lengths. Displacements performed at both short, i.e., vibrational, and long times, i.e., comparable to the structural relaxation time, are investigated. On both time scales the spatial correlations are modulated according to the radial distribution function g(r) to an extent which is determined by the character of the correlations, the time scale of the displacements and the structural slowing down. The spatial correlations of the short-time displacements have clear directional character. The modulus correlations of the long-time displacements are more marked, especially for sluggish states. Analogous findings are found by experiments on colloids. By inspecting the dynamical heterogeneities of states with slowed-down dynamics, it is observed that fast monomers exhibit correlations which are stronger and more differing from the bulk than the slow ones. It is shown that states with identical average vibrational monomer displacement exhibit identical spatial correlations of the monomer displacements pertaining to the subsets of the fast and the slow monomers characterizing both the short-time and the long-time dynamical heterogeneities.     

Antioxidant and chemical properties of Inula helenium root extracts

The objective of the paper was to investigate the chemical composition of Inula helenium roots extracts and to evaluate the antioxidant potential conferred by the chemical constituents. GC/MS and HPLC/MS techniques were used to characterize two extracts separated from Inula helenium roots by extraction with chloroform and ethyl acetate, respectively. Volatile compounds have been identified by GC from their mass spectra and retention time values, while HPLC identification of phenolic compounds was realized by comparing their retention times, UV and MS spectra with those of standards or literature data. Measurements of antioxidant activity of Inula helenium root extracts showed a variation between them, which can be correlated with the flavonoid and total phenolic contents. Both Inula helenium root extracts contain phenolic acids (caffeic, chlorogenic, dicaffeoyl quinic, hydroxibenzoic), terpenes (alantolactone) and different flavonoids (epicatechin, catechin gallate, ferulic acid-4-O-glucoside, dihydroquercetin pentosyl rutinoside, kaempherol-7-O-dipentoside, quercetin-3-O-β-glucopyranoside). In addition, the study provides preliminary data on the anti-inflammatory activity of Inula helenium root extracts, this being evaluated using the fresh egg albumin as phlogistic agent, and aspirin as reference compound. Root extracts of I. helenium did not exert any significant anti-inflammatory effect on egg albumin-induced rat paw edema.      

Antioxidant activity of crude extracts and essential oils from flower buds and leaves of Cistus creticus and Cistus salviifolius

Volatile oils from flowers and leaves of C. creticus L. and C. salviifolius L. were extracted by two extraction methods; namely, hydrodistillation and solid-phase micro-extraction (SPME). The chemical composition of essential oils was analyzed by GC and GC–MS. The volatile extracted from leaves and flowers of C. criticus using SPME was dominated by monoterpenes and sesquiterpenes hydrocarbon with α-pinene, camphene and α-cubebene as major components. In hydrodistillation, the oil extracted from leaves was dominated by oxygenated diterpenes and diterpenes hydrocarbon with manoyl oxide and sclarene as major components, whereas, the oil extracted from flowers was dominated by oxygenated diterpenes and diterpenes hydrocarbon with manoyl oxide and abietatriene as major components. The volatile from flowers and leaves of C. salviifolius obtained by SPME were dominated by monoterpenes and sesquiterpenes with δ-3-carene, α-pinene, β-pinene, and E-caryophyllene as major constituents. On the other hand, the oils from flowers and leaves of C. salviifolius obtained by hydrodistillation were dominated by oxygenated diterpenes, diterpenes hydrocarbon and esters with dehydro abietol, abietol, manoyl oxide and methyl octadecenoate as major components. In the leaves, the major components of the oil were manoyl oxide, E-ethyl cinnamate, and Z-ethyl cinnamate. These oils showed weak antioxidant activity when compared to the positive controls α-tocopherol, ascorbic acid, and EDTA, while the crude extracts aq. MeOH, butanol, and water showed good antioxidant activity. Discriminating between the studied plants based on the extraction method was also possible upon applying Principle component analysis (PCA) to the obtained GC–MS data.     

Antioxidant capacity,radical scavenger activity,lipid oxidation protection analysis and antimicrobial activity of red grape extracts from different varieties cultivated in Portugal

The aim of this study was to investigate the antioxidant capacity, radical scavenger activity, lipid oxidation protection and antimicrobial activity of grape extracts from 12 different red grape varieties cultivated in Portugal. The mean values of total phenolic content quantified in grape extracts varied from 833.7 to 2005.6 mg/L gallic acid. Antioxidant capacity results showed different values for each grape variety ranging from 3.96 to 32.96 mm/L Fe(II). The scavenger activity values ranged from 15.99% to 54.82% for the superoxide radical and from 11.79% to 29.67% for the hydroxyl radical. The grape extracts with the highest antioxidant capacity had a positive effect on the lipid oxidation protection and induced low peroxide values in butter samples. Finally, concerning antimicrobial activity, grape extracts from Touriga Nacional and Tinta Roriz grape varieties had significant antimicrobial activity, especially notable for total mesophilic aerobics.     

Temperature dependent ultrasonic and conductivity studies in aqueous polymeric solution

Sound velocities, viscosity and density of aqueous solution of PEG of average molecular weight of 4000 g/mole have been measured as a function of temperature in the range 308–338 K at different frequencies. Isentropic compressibility, ultrasonic attenuation and acoustic impedance have been derived from the data. From velocity measurements it has been found that velocity changes near melting temperature due to change in the lattice of polymer. Changes in polymer lattice can also be monitored by complex impedance spectroscopy hence, real and imaginary part of the impedance of mixture of PEG with water were measured in the frequency range 40 Hz to 100 kHz in the same temperature range. From these data bulk electrical conductivity has been calculated. The results have been discussed in terms of molecular interaction occuring in the solution.