Assessment of the antibacterial activity and the antidiarrheal function of flavonoids from bayberry fruit

Chinese bayberry fruits are used as a folk medicine to cure diarrhea. However, the active compounds have not yet been reported. We found that bayberry fruit extract showed significant antibacterial activity against Salmonella, Listeria, and Shigella, and the minimal inhibitory concentration (MIC) ranged from 2.07 to 8.28 mg/mL. Positive relationships were found between the antibacterial activity and the total polyphenol (r = 0.88) and flavonoid contents (r = 0.92) of samples using different extraction times. The active compounds showed green or blue fluorescence under UV light using the bioautography method and were purified using a polyamide column. The fraction F1 with the most activity was comprised of flavonoids, which included cyanidin-3-O-glucoside, myricetin deoxyhexoside, quercetin-3-O-glucoside, and quercetin deoxyhexoside, and it also possessed an antidiarrheal activity (p < 0.10) at 80 mg/kg in mice. These findings provide scientific evidence for the antidiarrheal function of bayberry.     

Tea enhances insulin activity

The most widely known health benefits of tea relate to the polyphenols as the principal active ingredients in protection against oxidative damage and in antibacterial, antiviral, anticarcinogenic, and antimutagenic activities, but polyphenols in tea may also increase insulin activity. The objective of this study was to determine the insulin-enhancing properties of tea and its components. Tea, as normally consumed, was shown to increase insulin activity >15-fold in vitro in an epididymal fat cell assay. Black, green, and oolong teas but not herbal teas, which are not teas in the traditional sense because they do not contain leaves of Camellia senensis, were all shown to increase insulin activity. High-performance liquid chromatography fractionation of tea extracts utilizing a Waters SymmetryPrep C18 column showed that the majority of the insulin-potentiating activity for green and oolong teas was due to epigallocatechin gallate. For black tea, the activity was present in several regions of the chromatogram corresponding to, in addition to epigallocatechin gallate, tannins, theaflavins, and other undefined compounds. Several known compounds found in tea were shown to enhance insulin with the greatest activity due to epigallocatechin gallate followed by epicatechin gallate, tannins, and theaflavins. Caffeine, catechin, and epicatechin displayed insignificant insulin-enhancing activities. Addition of lemon to the tea did not affect the insulin-potentiating activity. Addition of 5 g of 2% milk per cup decreased the insulin-potentiating activity one-third, and addition of 50 g of milk per cup decreased the insulin-potentiating activity approximately 90%. Nondairy creamers and soy milk also decreased the insulin-enhancing activity. These data demonstrate that tea contains in vitro insulin-enhancing activity and the predominant active ingredient is epigallocatechin gallate.     

Antioxidant and pro-oxidant activities of aqueous extracts and crude polyphenolic fractions of rooibos (Aspalathus linearis)

Unfermented rooibos tea is known to contain higher levels of total polyphenols and flavonoids than its fermented counterpart, making it the obvious choice for the preparation of flavonoid-enriched fractions. Evaluation of aqueous extracts and crude polyphenolic fractions of unfermented and fermented rooibos showed anti- and/or pro-oxidant activities, using a linoleic acid-Tween-buffer emulsion for lipid peroxidation and the deoxyribose degradation assay, based on a Fenton reaction model system containing FeCl3-EDTA and H2O2 for the generation of hydroxyl radicals. Except for the ethyl acetate fraction, with the highest total polyphenol (TP) content and offering the least protection presumably due to pro-oxidant activity, the inhibition of lipid peroxidation by the samples correlated moderately with their TP content in a linear relationship (r = 0.896, P < 0.01). Using the deoxyribose degradation assay, the pro-oxidant activity of the aqueous extracts and their crude polymeric fractions (0.1 mg/mL in the reaction mixture) was linear with respect to their dihydrochalcone (aspalathin and nothofagin) (r = 0.977, P = 0.023) and flavonoid (r = 0.971, P = 0.029) content. Pro-oxidant activity was demonstrated for pure aspalathin. Using the same assay, but with ascorbate added to regenerate Fe3+ to Fe2+, the aqueous extract and crude polymeric fraction of fermented rooibos displayed hydroxyl radical scavenging activity. Fermentation (i.e., oxidation) of rooibos decreased the pro-oxidant activity of aqueous extracts, which was contributed to a decrease in their dihydrochalcone content. The in vitro pro-oxidant activity displayed by flavonoid-enriched fractions of rooibos demonstrates that one must be aware of the potential adverse biological properties of potent antioxidant extracts utilized as dietary supplements.     

Extraction of rutin from buckwheat (Fagopyrum esculentumMoench) seeds and determination by capillary electrophoresis.

The content of the flavonoid rutin was determined in different milling fractions of buckwheat seeds and in buckwheat stems, leaves, and flowers. The extraction was performed by using a solvent containing 60% of ethanol and 5% of ammonia in water. The extracts were analyzed by capillary electrophoresis (running buffer of 50 mM borate (pH 9.3), 100 mM sodium dodecyl sulfate; determination at 380 nm). In bran fractions the concentration of rutin was 131-476 ppm, and in flour fractions 19-168 ppm. On average, about 300, 1000, and 46000 ppm of rutin were found in leaves, stems, and flowers, respectively. The results indicate that buckwheat could be an important nutritional source of flavonoids, especially in countries with a low mean daily flavonoid intake.     

Fermentation enhances the biological activity of Allium cepa bulb extracts

In this study, we compared the analytical fingerprint and bioactivity of three onion extracts, including an aqueous, a methanol, and a fermented aqueous extract. The extracts were characterized by HPLC-DAD, LC-MS, and GC-MS analyses. The antibacterial, antigenotoxic, and antiproliferative activity of these extracts was assessed by means of agar disk diffusion, bacterial growth kinetics, a comet assay, cell cycle distribution analysis, and cell viability testing. Both the aqueous and methanolic extracts showed a typical flavonol-fingerprint as assessed by HPLC measurements and showed little to no bioactivity. The fermented aqueous extract, which lacks the usual onion flavonoid profile, was found to be the most active in all of the assays. This finding indicates that metabolites of onion compounds, generated by lactic acid fermentation, may be more active than their precursor substances.     

Protection against nitric oxide toxicity by tea

It is found that green tea and black tea are able to protect against nitric oxide (NO(*)) toxicity in several ways. Both green tea and black tea scavenge NO(*) and peroxynitrite, inhibit the excessive production of NO(*) by the inducible form of nitric oxide synthase (iNOS), and suppress the LPS-mediated induction of iNOS. The NO(*) scavenging activity of tea was less than that of red wine. The high activity found in the polyphenol fraction of black tea (BTP) could not be explained by the mixed theaflavin fraction (MTF) or catechins [epicatechin, epigallocatechin, epicatechin gallate, epigallocatechin gallate (EGCG)], which were tested separately. Synergistic effects between the compounds, or the presence of a potent, unidentified NO(*) scavenger, may explain the high activity of BTP. The peroxynitrite scavenging of tea was comparable to that of red wine. The main activity was found in the polyphenol fraction. MTF and the catechins were found to be potent peroxynitrite scavengers. Tea and tea components were effective inhibitors of iNOS. Of the tea components tested, only MTF had an activity higher than that of the tea powders. The polyphenol fractions of tea were much more active than the tea powders in suppressing the induction of iNOS. On the basis of its abundance and activity, EGCG was the most active inhibitor. The protective effect of tea on NO(*) toxicity is discussed in relation to the beneficial effect of flavonoid intake on the occurrence of cardiovascular heart disease.     

Procyanidin fractions from pine (Pinus pinaster) bark: radical scavenging power in solution, antioxidant activity in emulsion, and antiproliferative effect in melanoma cells

Pine (Pinus pinaster) bark is a rich source of procyanidin oligomers. From a total polyphenolic extract, we have generated fractions of different procyanidin composition. The mixtures, devoid of gallate esters, were active as free radical scavengers against ABTS(*+), DPPH, and HNTTM. Pine bark fractions were tested for antioxidant activity in solution (hydrogen donation and electron transfer) and emulsion (inhibition of lipid peroxidation) and compared with their galloylated counterparts from grape origin. While galloylation clearly influenced the free radical scavenging efficiency in solution, it did not seem to play a determinant role in protection against lipid peroxidation in emulsion. The fractions were very mild inhibitors of cell proliferation. Because gallate esters appear to interfere with crucial cell functions, gallate free pine procyanidins may be the innocuous chemopreventative agents of choice for many applications in food and skin protection.     

Antioxidant activity and phenolic compositions of lentil (Lens culinaris var. Morton) extract and its fractions

Phenolic compounds were extracted from Morton lentils using acidified aqueous acetone. The crude Morton extract (CME) was applied onto a macroresin column and desorbed by aqueous methanol to obtain a semipurified Morton extract (SPME). The SPME was further fractionated over a Sephadex LH-20 column into five main fractions (I-V). The phytochemical contents such as total phenolic content (TPC), total flavonoid content (TFC), and condensed tannin content (CTC) of the CME, SPME, and its fractions were examined by colorimetric methods. Antioxidant activity of extracts and fractions were screened by DPPH scavenging activity, Trolox equivalent antioxidant capacity (TEAC), ferric reduced antioxidant power (FRAP), and oxygen radical absorbing capacity (ORAC) methods. In addition, the compositions of active fractions were determined by HPLC-DAD and HPLC-MS methods. Results showed that the fraction enriched in condensed tannins (fraction V) exhibited significantly higher values of TPC, CTC, and antioxidant activity as compared to the crude extract, SPME, and low molecular weight fractions (I-IV). Eighteen compounds existed in those fractions, and 17 were tentatively identified by UV and MS spectra. HPLC-MS analysis revealed fraction II contained mainly kaempferol glycoside, fractions III and IV mainly contained flavonoid glycosides, and fraction V was composed of condensed tannins. The results suggested that the extract of Morton lentils is a promising source of antioxidant phenolics and may be used as a dietary supplement for health promotion.     

Subcritical water extraction of antioxidant compounds from rosemary plants

Subcritical water extraction at several temperatures ranging from 25 to 200 degrees C has been studied to selectively extract antioxidant compounds from rosemary leaves. An exhaustive characterization of the fractions obtained using subcritical water at different temperatures has been carried out by LC-MS, and the antioxidant activities of the extracts have been measured by a free radical method (DPPH). Results indicate high selectivity of the subcritical water toward the most active compounds of rosemary such as carnosol, rosmanol, carnosic acid, methyl carnosate, and some flavonoids such as cirsimaritin and genkwanin. The antioxidant activity of the fractions obtained by extraction at different water temperatures was very high, with values around 11.3 microg/mL, comparable to those achieved by SFE of rosemary leaves. A study of the effect of the temperature on the extraction efficiency of the most typical rosemary antioxidant compounds has been performed.     

Assay-guided fractionation study of alpha-amylase inhibitors from Garcinia mangostana pericarp

Alpha-amylase inhibitor (alpha-AI) activity of Garcinia mangostana, commonly known as mangosteen, pericarp extracts was studied by assay guided fractionations from lipophilic to hydrophilic using combined solvent extraction and Amberlite XAD2 adsorption chromatography. Neither the lipophilic, xanthone containing fraction, nor the highly polar fraction, which has no affinity on Amberlite XAD2, showed any alpha-AI. The fraction that shows very high inhibitory activity contains primarily polyphenols and can be adsorbed on Amberlite XAD2. The IC50 of 5.4 microg/mL of this fraction is comparable to that of acarbose, a prescribed alpha-AI used in the control of type II diabetes, at 5.2 microg/mL. Total phenolic content (TPC) of each fraction was measured and the TPC has no correlation with the alpha-AI activity. The lipophilic fraction contains mainly xanthones as revealed by HPLC-MS analysis. Colorimetric analysis coupled with UV-vis and IR spectroscopic analysis demonstrated that the fractions with high alpha-AI activity are primarily oligomeric proanthocyanidins (OPCs) with little gallate moiety. There is also evidence to show that the alpha-AI by these OPCs is not purely by nonspecific protein complexation. Both tannic acid and G. mangostana OPCs precipitate BSA equally well but G. mangostana OPCs are 56 times more effective in inhibiting alpha-amylase.     

Flavonoid content of U.S. fruits, vegetables, and nuts

Analytical data are reported for 20 flavonoids (as aglycones) determined for more than 60 fresh fruits, vegetables, and nuts collected from four regions across the United States at two times of the year. Sample collection was designed and implemented by the Nutrient Data Laboratory (USDA). Analyses of eight flavan-3-ols (catechin, catechin gallate, epicatechin, epicatechin gallate, epigallocatechin, epigallocatechin gallate, gallocatechin, and gallocatechin gallate), six anthocyanins (cyanidin, delphinidin, malvidin, pelargonidin, peonidin, and petunidin), two flavanones (hesperetin and naringenin), two flavones (apigenin and luteolin), and two flavonols (myricetin and quercetin) were performed by the Food Composition Laboratory (USDA) using a hydrolysis method for the anthocyanidins, flavones, and flavonols and a direct extraction method for the flavan-3-ols and flavanones. Experimental results compare favorably (few statistically significant differences) to literature values in the flavonoid and proanthocyanidin database previously compiled by the Nutrient Data Laboratory. The results of this study showed a seasonal variation only for blueberries. This study also showed that the variation in the flavonoid content of foods, as purchased by the U.S. consumer, is very large. The relative standard deviation, averaged for each flavonoid in each food, was 168%.     

Evaluation of extracts from Gevuina avellana hulls as antioxidants

The antioxidant activity of the extracts from Gevuina avellana hulls was evaluated and compared with that of BHT (butylated hydroxytoluene) and BHA (butylated hydroxyanisole), using the beta-carotene bleaching assay, the accelerated oxidation of crude soybean oil, and the 2,2-diphenyl-beta-picrylhydrazyl (DPPH) radical scavenging method. Solvents of different polarity were used to obtain the extracts. Both the extraction yield and the antioxidant activity were strongly dependent on the solvent. The ethanol and diethyl ether soluble fractions were the most active with the beta-carotene assay. Ethanol and methanol extracts were the most active in hydrogen radical scavenging activity. Water and methanol inhibited more efficiently the oxidation of soybean oil at 70 and 80 degrees C, respectively. As a general trend, increased antioxidant activity was observed for increased extract concentration. Except the acetone extracts, all were stable after 6 months storage at 4 degrees C. The ethanol solubles from G. avellana hulls present antioxidant activity similar to that of synthetic antioxidants and to other reported residual agroindustrial materials.     

Characterization of the constituents and antioxidant activity of Brazilian green tea (Camellia sinensis var. assamica IAC-259 cultivar) extracts

Freeze-dried extracts from Camellia sinensis var. assamica IAC-259 cultivar named Brazilian green tea were prepared by hot water and ultrasound-assisted extractions using leaves harvested in spring and summer. Their caffeine and catechin contents were measured by high performance liquid chromatography-diode array detector. The antioxidant activity of the major green tea compounds and Brazilian green tea extracts was evaluated using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The levels of caffeine were higher in the summer samples (p < 0.05); otherwise, there were no significant variations related to the catechin contents between spring and summer samples. The sonication method using water/acetone as solvent had a high efficiency to extract not only epigallocatechin gallate but also epicatechin gallate (p < 0.05). Antioxidant activities of the Brazilian green tea extracts were not significantly different among seasons and extraction systems. The antioxidant data (IC50) of the Brazilian green tea extracts showed a significant correlation with their epigallocatechin gallate and epicatechin gallate contents (p < 0.05).     

Synergistic antioxidative effects of alkamides, caffeic acid derivatives, and polysaccharide fractions from Echinacea purpurea on in vitro oxidation of human low-density lipoproteins

Preparations of Echinacea are widely used as alternative remedies to prevent the common cold and infections in the upper respiratory tract. After extraction, fractionation, and isolation, the antioxidant activity of three extracts, one alkamide fraction, four polysaccharide-containing fractions, and three caffeic acid derivatives from Echinacea purpurea root was evaluated by measuring their inhibition of in vitro Cu(II)-catalyzed oxidation of human low-density lipoprotein (LDL). The antioxidant activities of the isolated caffeic acid derivatives were compared to those of echinacoside, caffeic acid, and rosmarinic acid for reference. The order of antioxidant activity of the tested substances was cichoric acid > echinacoside > or = derivative II > or = caffeic acid > or = rosmarinic acid > derivative I. Among the extracts the 80% aqueous ethanolic extract exhibited a 10 times longer lag phase prolongation (LPP) than the 50% ethanolic extract, which in turn exhibited a longer LPP than the water extract. Following ion-exchange chromatography of the water extract, the majority of its antioxidant activity was found in the latest eluted fraction (H2O-acidic 3). The antioxidant activity of the tested Echinacea extracts, fractions, and isolated compounds was dose dependent. Synergistic antioxidant effects of Echinacea constituents were found when cichoric acid (major caffeic acid derivative in E. purpurea) or echinacoside (major caffeic acid derivative in Echinacea pallida and Echinacea angustifolia) were combined with a natural mixture of alkamides and/or a water extract containing the high molecular weight compounds. This contributes to the hypothesis that the physiologically beneficial effects of Echinacea are exerted by the multitude of constituents present in the preparations.     

Identifying new lignin bioengineering targets: impact of epicatechin, quercetin glycoside, and gallate derivatives on the lignification and fermentation of maize cell walls

Apoplastic targeting of secondary metabolites compatible with monolignol polymerization may provide new avenues for designing lignins that are less inhibitory toward fiber fermentation. To identify suitable monolignol substitutes, primary maize cell walls were artificially lignified with normal monolignols plus various epicatechin, quercetin glycoside, and gallate derivatives added as 0 or 45% by weight of the precursor mixture. The flavonoids and gallates had variable effects on peroxidase activity, but all dropped lignification pH. Epigallocatechin gallate, epicatechin gallate, epicatechin vanillate, epigallocatechin, galloylhyperin, and pentagalloylglucose formed wall-bound lignin at moderate to high concentrations, and their incorporation increased 48 h in vitro ruminal fiber fermentability by 20-33% relative to lignified controls. By contrast, ethyl gallate and corilagin severely depressed lignification and increased 48 h fermentability by about 50%. The results suggest several flavonoid and gallate derivatives are promising lignin bioengineering targets for improving the inherent fermentability of nonpretreated cell walls.     

Isolation and partial characterization of rennet-like proteases from Australian cardoon (Cynara cardunculus L.)

The yield, protein content, proteolytic activity, and substrate specificity of crude and partially purified extracts from dried and fresh Australian cardoon (Cynara cardunculus L.) flowers were determined. Crude water extracts had high yield but low protein content and proteolytic activity, whereas citric acid extracts had low yield but high protein content and proteolytic activity. Fresh flower extracts gave higher yield and proteolytic activity but lower protein content in comparison with dried flower extracts. Purification with ammonium sulfate resulted in significantly increased proteolytic activity for water extracts from both fresh and dried cardoon flowers, whereas the proteolytic activity of citric acid extracts did not change significantly after purification. Irrespective of extraction method, all extracts had higher proteolytic activity against ovine whole and kappa-caseins compared to their bovine counterparts, showing optimal activity at 37 degrees C and pH 6.0. Separation of purified extracts by ion-exchange liquid chromatography yielded three active fractions, each of which when assayed with sodium dodecyl sulfate capillary electrophoresis revealed two subunits with molecular masses of 15.5 and 33.1 kDa, respectively.     

Antioxidant properties of various solvent extracts of total phenolic constituents from three different agroclimatic origins of drumstick tree (Moringa oleifera Lam.) leaves

Water, aqueous methanol, and aqueous ethanol extracts of freeze-dried leaves of Moringa oleifera Lam. from different agroclimatic regions were examined for radical scavenging capacities and antioxidant activities. All leaf extracts were capable of scavenging peroxyl and superoxyl radicals. Similar scavenging activities for different solvent extracts of each collection were found for the stable 1,1-diphenyl 2-picrylhydrazyl (DPPH(*)) radical. Among the three different moringa samples, both methanol and ethanol extracts of Indian origins showed the highest antioxidant activities, 65.1 and 66.8%, respectively, in the beta-carotene-linoleic acid system. Nonetheless, increasing concentration of all the extracts had significantly (P < 0.05) increased reducing power, which may in part be responsible for their antioxidant activity. The major bioactive compounds of phenolics were found to be flavonoid groups such as quercetin and kaempferol. On the basis of the results obtained, moringa leaves are found to be a potential source of natural antioxidants due to their marked antioxidant activity. This is the first report on the antioxidant properties of the extracts from freeze-dried moringa leaves. Overall, both methanol (80%) and ethanol (70%) were found to be the best solvents for the extraction of antioxidant compounds from moringa leaves.     

Effect of water: soil ratio on phosphate release: P, aluminium and fulvic acid associations in water extracts from Andisols and Andic soils

The influence of water: soil ratio (w: s) on phosphorus fractions was studied in Andisols and Andic soils. Phosphorus was fractionated in 0.45-μm filtered water extracts, and pH, monomeric Al and dissolved organic carbon (DOC) were determined. Speciation of dialysed extracts was also studied. Increasing w: s from 2.5 to 75 resulted in a release of dissolved reactive phosphorus (DRP), while DOC decreased significantly and pH increased moderately. For the 29 samples studied desorbed DRP =K (w: s)^β, where β represents a P buffering term and ranged from 1 to 1.26 for DRP (mg kg^?1). On dialysis, we observed a uniform partition between dialysable (DP) and non-dialysable P (NDP) which was explained by the corresponding difference in DOC; these results were consistent with the existence of soluble P-Al-fulvic complexes. Study of solubility diagrams for determining solid-phase controls on P activities in the extracts suggested that dissolution of Al-phosphates could explain most of P release to water as free orthophosphate. Both this mechanism and organic P partition between solid and solution soil phases may be considered to reflect the main sources of P in Andisols: Al-phosphate and organic-Al-P complexes.     

Metabolic profiling of strawberry grape ( Vitis × labruscana cv. 'Isabella') components by nuclear magnetic resonance (NMR) and evaluation of their antioxidant and antiproliferative properties

In the assessment of the antioxidant properties of edible plants, the widely consumed Vitis × labruscana cv. 'Isabella', known in Italy as "fragola" (strawberry) grape, was of interest. Phenol and flavonoid contents of the methanolic extracts of peel, pulp, seed, leaf, and stalk components of the plant were determined. The metabolic profile of the extracts was performed by 1D and 2D NMR. Quantitative analysis, obtained in the presence of 0.01% of internal standard trimethylsilyl propionate, evidenced the presence of catechins in both stalk and seed extracts, whereas caffeic acid and quercetin were the main metabolites of the leaf extract. Furthermore, the extracts were tested for their radical scavenging and reducing capacities by measuring their capacity to scavenge DPPH(?) and ABTS(?+) and to reduce Fe(III) and Mo(VI) salts. The antioxidant efficacy of the extracts in cell-free systems and their antiproliferative activity toward HepG2 and A549 cells were also evaluated. Seed and stalk components are able to reduce by 39.6 and 40.6%, respectively, the amount of the metabolically active HepG2 cells after only 24 h of exposure.     

Effects of wine phenolics and sorghum tannins on tyrosinase activity and growth of melanoma cells

In this study, three different phenolic (anthocyanin, other flavonoid, and phenolic acid) fractions from wine and a condensed tannin preparation from sorghum were tested for their effects on melanogenesis of normal cells and growth of human melanoma cells. The wine phenolic fractions decreased melanogenic activity (tyrosinase activity) at concentrations that resulted in a slight variation in melanocyte viability. Sorghum tannins, however, increased melanogenic activity, although no increase was found in total melanin at the concentrations that least affect melanocyte viability. Incubation of human melanoma cells with the wine fractions and sorghum tannins resulted in a decrease in colony formation, although the effect was not dose dependent in all cases. These results suggest that all of these phenolic fractions have potential as therapeutic agents in the treatments of human melanoma, although the mechanisms by which cellular toxicity is effected seem to be different among the fractions.