Phenolic constituents in the fruits of Cinnamomum zeylanicum and their antioxidant activity

Defatted cinnamon fruit powder was successively extracted with benzene ethyl acetate, acetone, MeOH, and water. The concentrated water extract contained the maximum amount of phenolics and showed the highest antioxidant activities. Hence, it was fractionated by Diaion HP-20SS, Diaion HP-20, and Sephadex LH-20 column chromatographies. It gave five purified compounds, the purities of which were analyzed by HPLC. Compounds 1-5 were identified as 3,4-dihydroxybenzoic acid (protocatechuic acid), epicatechin-(2beta-->O-7,4beta-->8)-epicatechin-(4beta-->8)-epicatechin (cinnamtannin B-1), 4-[2,3-dihydro-3-(hydroxymethyl)-5-(3-hydroxypropyl)-7-(methoxy)benzofuranyl]-2-methoxyphenyl beta-d-glucopyranoside (urolignoside), quercetin-3-O-(6-O-alpha-l-rhamnopyranosyl)-beta-d-glucopyranoside (rutin), and quercetin-3-O-alpha-l-rhamnopyranoside by using extensive spectral studies. The antioxidant activities of purified compounds were screened for their antioxidative potential using beta-carotene-linoleate and 1,1-diphenyl-2-picrylhydrazyl model systems. All of the compounds showed antioxidant and radical scavenging activities. This is the first report of the isolation and identification of nonvolatile constituents and as well as antioxidant activities from cinnamon fruits.     

Phenolic constituents and antioxidant properties of Xanthosoma violaceum leaves

An extract of Xanthosoma violaceum leaves was subjected to a polyphenol profile determination, including total polyphenols, and antioxidant activity evaluation. Analysis of the extract resulted in the isolation of a new flavone C-glycoside, apigenin 6-C-beta-D-glucopyranosyl-8-C-beta-D-apiofuranoside (1), as well as known flavone C-glycosides, including vitexin (2), isovitexin (3), isovitexin 4'-O-rhamnopyranoside (4), apigenin 6-C-[beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside] (5), and apigenin 6,8-diC-beta-D-glucopyranoside (6). The antioxidant activity of the extract was assessed by means of two different in vitro tests: bleaching of the stable 1,1-diphenyl-2-picrylhydrazyl radical (DPPH test) and peroxidation induced by the water-soluble radical initiator 2,2'-azobis(2-amidinopropane) hydrochloride, on mixed dipalmitoylphosphatidylcholine/linoleic acid unilamellar vesicles (LP-LUV test). In both tests used, the extract and a fraction II showed a significant antioxidant/free-radical scavenging effect (fraction II, EC(50) = 11.6 microg/mL) in comparison to alpha-tocopherol (EC(50) = 10.1 microg/mL).     

Phenolic content and antioxidant capacity of muscadine grapes

Fruits of 10 cultivars of muscadine grapes (five bronze skin and five purple skin) grown in southern Georgia were separated into skin, seed, and pulp. Each fruit part and the leaves from the corresponding varieties were extracted for HPLC analysis of major phenolics. Total phenolics were determined colorimetrically using Folin-Ciocalteu reagent. Total anthocyanins were determined according to a pH-differential method, using a UV-visible spectrophotometer. Antioxidant capacity was determined by the Trolox equivalent antioxidant capacity (TEAC) assay. Gallic acid, (+)-catechin, and epicatechin were the major phenolics in seeds, with average values of 6.9, 558.4, and 1299.4 mg/100 g of fresh weight (FW), respectively. In the skins, ellagic acid, myricetin, quercetin, kaempferol, and trans-resveratrol were the major phenolics, with respective average values of 16.5, 8.4, 1.8, 0.6, and 0.1 mg/100 g of FW. Contrary to previous results, ellagic acid and not resveratrol was the major phenolic in muscadine grapes. The HPLC solvent system used coupled with fluorescence detection allowed separation of ellagic acid from resveratrol and detection of resveratrol. Reported here for the first time are the phenolic content and antioxidant capacity of muscadine leaves. Major phenolics in muscadine leaves were myricetin, ellagic acid, kaempferol, quercetin, and gallic acid, with average concentrations of 157.6, 66.7, 8.9, 9.8, and 8.6, respectively. Average total phenolics were 2178.8, 374.6, 23.8, and 351.6 mg/g gallic acid equivalent in seed, skin, pulp, and leaves, respectively. Total anthocyanin contents were 2.1 and 132.1 mg/100 g of FW in the skins of bronze and purple grapes, respectively, and 4.3 and 4.6 mg/100 g of FW in seeds and pulps, in that order. Antioxidant capacity values were, on average, 2.4, 12.8, 281.3, and 236.1 microM TEAC/g of FW for pulps, skins, seeds, and leaves, respectively.     

Phenolic compounds and antioxidant capacity of Georgia-grown blueberries and blackberries

Blueberries and blackberries grown at various locations in Georgia were collected and analyzed for flavonoids, total anthocyanins, total polyphenols, and Trolox-equivalent antioxidant capacity (TEAC). Each sample was analyzed for phenolic acids (gallic acid, p-hydroxybenzoic acid, caffeic acid, ferulic acid, and ellagic acid) and flavonoids (catechin, epicatechin, myricetin, quercetin, and kaempferol). A high-performance liquid chromatographic (HPLC) method with photodiode array detection was used for analysis. Compounds were analyzed as aglycons after acid hydrolysis with 1.2 M HCl. Identification of each compound was based on retention time and UV spectra by comparison with pure commercial standards. Phenolic acids ranged from 0.19 to 258.90 mg/100 g fresh weight (FW), and flavonoids ranged from 2.50 to 387.48 mg/100 g FW. Total polyphenols ranged from 261.95 to 929.62 mg/100 g FW, and total anthocyanins ranged from 12.70 to 197.34 mg/100 g FW. TEAC values varied from 8.11 to a maximum of 38.29 microM/g FW. A linear relationship was observed between TEAC values and total polyphenols or total anthocyanins. The data indicate that blueberries and blackberries are rich sources of antioxidants.     

Evolution of antioxidant capacity during storage of selected fruits and vegetables

Interest in the consumption of fresh fruits and vegetables is, to a large extent, due to its content of bioactive nutrients and their importance as dietary antioxidants. Among all of the selected fruits and vegetables, strawberries and black grapes have relatively high antioxidant capacities associated with high contents of total phenolic compounds, ascorbic acid, and flavonols. More interesting, the results of this study indicated that in most fruits and vegetables storage did not affect negatively the antioxidant capacity. Better, in some cases, an increase of the antioxidant capacity was observed in the days following their purchase, accompanied by an increase in phenolic compounds. In general, fruits and vegetables visually spoil before any significant antioxidant capacity loss occurs except in banana and broccoli. When ascorbic acid or flavonoids (aglycons of flavonols and anthocyanins) were concerned, the conclusions were similar. Their content was generally stable during storage.     

Phenolic constituents, furans, and total antioxidant status of distilled spirits.

The concentrations of 11 phenols and 5 furans were measured in 12 categories of distilled spirits by HPLC methodology, together with the total antioxidant status (TAS) of the same beverages. Ellagic acid was the phenol present in highest concentration in all beverages. Moderate amounts of syringaldehyde, syringic acid, and gallic acid, as well as lesser amounts of vanillin and vanillic acid, were measurable in most samples of whiskey, brandy, and rum but were largely undetectable in gin, vodka, liqueurs, and miscellaneous spirits. 5-(Hydroxymethyl)furfural was the predominant furan in the former three beverages, notably cognac, with 2-furaldehyde the next highest, but these were undetectable in most of the latter beverages. Highest TAS values were given by armagnac, cognac, and bourbon whiskey, all three of which tended toward the highest concentrations of phenols. Negative TAS values were exhibited by rum, vodka, gin, and miscellaneous spirits in line with the low or undetectable phenol concentrations in these beverages. Wood aging is the most likely source of phenols and furans in distilled spirits. Those beverages exposed to this treatment contain significant antioxidant activity, which is between the ranges for white and red wines, with the potential to augment the antiatherosclerotic functions attributable to the ethanol that they contain.     

Phenolic profile and hydrophilic antioxidant capacity as chemotaxonomic markers of tomato varieties

Tomatoes (Solanum lycopersicum L.), the second most important vegetable crop worldwide, are a key component in the so-called "Mediterranean diet", which is strongly associated with a reduced risk of chronic degenerative diseases. In this work, we evaluate the differences in the total and individual polyphenol content and hydrophilic antioxidant capacity of seven varieties of tomato cultivated in Vegas Bajas del Guadiana, Badajoz (Spain), which were collected from two consecutive harvests (2008-2009). Hydrophilic antioxidant capacity was evaluated using the TEAC assay, while the Folin-Ciocalteau assay with a previous cleanup was used to establish total polyphenol content. The method was optimized and validated. Individual polyphenols were quantified using liquid chromatography/electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) on a triple quadrupole. All compounds were found to be significantly different when analysis of variance was performed. Results from the principal component analysis show that phenolic compounds and hydrophilic antioxidant capacity were responsible for the differences among tomato samples according to variety.     

Cyclooxygenase inhibitory and antioxidant compounds from crabapple fruits

Crabapple trees belong to the Malus genus (Rosaceae) and bear fruits that are sparingly consumed and used in the preparation of fruit beverages. Cyclooxygenase (COX) enzyme inhibitory and antioxidant bioassay-guided fractionation of the aqueous and methanol extracts of Malus x kornicensis and Malus x Indian Summer yielded (+)-catechin (1), (-)-epicatechin (2), cyanidin-3-O-beta-galactopyranoside (3), and amygdalin (4). Pure compounds 1-4 were obtained by HPLC, identified by LC-ES/MS, CD, and NMR spectroscopic methods and evaluated for their COX enzyme inhibitory and antioxidant activities. In COX-1 and -2 enzyme inhibitory assays, compounds 1-3 (all at 80 microM) showed activities of 20.4, 46.3%; 57.6, 47.9%; and 8.2, 13.7%, respectively, compared to naproxen (54.3, 41.3%; 10 microM), ibuprofen (47.5, 39.8%; 10 microM), Celebrex (46.2, 66.3%; 1.67 ppm), and Vioxx (23.8, 88.1%, 1.67 ppm). In the antioxidant assay, the catechins (1-2) and anthocyanin (3) (all at 40 microM) showed activities of 61.3, 62.5, and 60.1%, respectively. The synthetic antioxidants, tert-butylhydroquinone (TBHQ), butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), and vitamin E (all tested at 10 microM), gave 75.2, 80.1, 70.0, and 10.2% activities, respectively. The cyanogenic glycoside, amygdalin (4), and its hydrolysis products, mandelonitrile (5) and benzaldehyde (6), were not active in the antioxidant or COX enzyme inhibitory assays at 80 microM concentrations.     

Phenolic compounds in NaOH extracts of UK soils and their contribution to antioxidant capacity

Antioxidants are released during the NaOH extraction of soils, and this also releases phenolic compounds from plant and soil material. We hypothesized that phenolics would be important contributors to the antioxidant capacity (AOC) of soils. The concentrations of 12 phenolic compounds and the AOCs in 4 m ‐NaOH extracts of a range of UK soil types were measured. Samples of both surface and subsurface horizons were taken from 24 sites representing the major soil types (brown soils, gleys, podzols, peats and lithomorphic soils). The land use/vegetation varied from deciduous woodland through heather moorland to agricultural crops. The internal standards method was used to quantify the phenolics, which were detected by gas chromatography. The AOCs of the extracts and of standards of the individual phenolic compounds were measured using the TEAC (Trolox Equivalent Antioxidant Capacity) method. There were differences in the phenolic distributions extracted from soils with different land uses/plant inputs, as well as differences between surface and subsurface samples. A statistically significant linear relationship was found between the AOCs of the extracts and the sum of the phenolic compounds, as both these variables were positively correlated with the organic matter content of the soils. The AOCs of the individual phenols were used to calculate their contribution to the overall AOC of the extracts, and this was found to be small (approximately 1% of the total AOC). We concluded that the measured phenolic compounds were not important contributors to the AOCs of the soil extracts, and therefore that other unidentified antioxidant compounds were probably present.     

Characterization and antioxidant potential of Brazilian fruits from the Myrtaceae family

The objective of this study is to evaluating the Brazilian biodiversity through physicochemical characterization and determination of antioxidant potential of three species from the Myrtaceae family, namely yellow guava (Psidium cattleyanum Sabine), guabiroba (Campomanesia xanthocarpa O. Berg), and uvaia ( Eugenia pyriformis Cambess). Guabiroba had the greater quantity of phenolic compounds (9033 mg chlorogenic acid/100 g) and vitamin C (30.58 mg/g) and showed the best TSS/TTA (total soluble solid/total titratable acid) ratio (45.12). For the ABTS (2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic) method, the guabiroba (507.49 μM Trolox/g) presented the highest antioxidant potential; however, in the DPPH (2,2-diphenyl-1-picrylhydrazyl) method, uvaia (170.26 g/g DPPH) and guabiroba (161.29 g/g DPPH) were not statistically different. The uvaia outranked the other fruits with respect to its high carotenoid (909.33 μg/g) and vitamin A (37.83 μg/g) contents, and the yellow guava, although showing a lower bioactive compound content and antioxidant activity, nevertheless presented much higher values than many traditionally consumed fruits.     

Lignans and other constituents of the fruits of Euterpe oleracea (Acai) with antioxidant and cytoprotective activities

Using a hydroxyl radical scavenging assay, bioactivity-guided fractionation of a methanol-soluble extract of the fruits of Euterpe oleracea (acai) led to the isolation of 22 compounds of previously known structure. Altogether, 14 of these isolates were found to be active in an in vitro hydroxyl radical scavenging assay and seven of these isolates in a 1,1-diphenyl-2-picrylhydrazyl radical scavenging assay. Dihydroconiferyl alcohol, (+)-lariciresinol, (+)-pinoresinol, (+)-syringaresinol, and protocatechuic acid methyl ester exhibited cytoprotective activity in cultured MCF-7 cells stressed by H2O2. Lignans have not been previously reported as constituents of this species and were found to be representative of the aryltetrahydronaphthalene, dihydrobenzofuran, furofuran, 8-O-4'-neolignan, and tetrahydrofuran structural types.     

Unsaponifiable lipid constituents of some underutilized tropical seed oils

Sterols, triterpene alcohols, and hydrocarbons present in the unsaponifiable fraction of some underutilized tropical seed oils have been examined.The seeds include Telfairia occidentalis (TLO), Andenopus breviflorus (ADB), Cucumeropsis edulis (CME), Antiaris africana (ATF), and Monodora tenuifolia (MNT). The oil content of the seeds was high (34.7-68.8%), whereas triacylglycerols comprised the dominant lipid group in the oils (65.4-73.9%). The percentage of unsaponifiables ranged from 1.1 to 7.9%. Ten sterols were identified in the fractions. In the Cucurbitaceae oils (TLO, CME, and ADB), Delta(7)-sterols constituted the dominant sterols. These include 24-ethylcholesta-7,22E,25-trienol (7), 24-ethylcholesta-7,25-dienol (9), 24Z-ethylidenecholes-7-enol (10), and 24-ethylcholesta-7, 24-dienol (11). However Delta(5)-sterols (1-5) occurred at the highest concentration in the other two samples (ATF and MNT). Fifteeen triterpene alcohols were detected in the fractions. Olean-12-enol (16), isomultiflorenol (8), and lupeol (23) were the dominant alcohols in the Cucurbitaceae family, whereas alpha-amyrin (urs-12-enol) (20) was the dominant triterpene alcohol in ATF and MNT. A mixture of C(18)-C(34) n-alkanes, squalene, and some monoterpenes was detected in the hydrocarbon fraction.     

Phenolic constituents and antioxidant activity of Wendita calysina leaves (Burrito), a folk Paraguayan tea

Burrito tea originates from the leaves of Wendita calysina, an indigenous Paraguayan plant, which is commonly consumed in South America and in Western countries. Phytochemical investigation of this species has led to the isolation of 14 constituents, among them 2 new flavanonols, dihydroquercetagetin (1) and 3,5,6,7,4'-pentahydroxyflavanonol (2), in addition to several known methoxyflavones, methoxyflavonols, phenylethanoid glycosides, and benzoic acid derivatives (4-14). All structures were elucidated by ESI-MS and NMR spectroscopic methods. Quantitative determination of phenolic constituents from burrito water infusions has been performed by HPLC-UV-DAD. The total antioxidant activity of the tea was measured by the ABTS(*)(+) radical cation decolorization and chemiluminescence (CL) assays and compared with the values of other commonly used herbal teas (green and black teas, mate, and rooibos).     

Anthocyanin composition of wild Colombian fruits and antioxidant capacity measurement by electron paramagnetic resonance spectroscopy

The qualitative and quantitative anthocyanin composition of four wild tropical fruits from Colombia was studied. Compounds of "mora peque?a" ( Rubus megalococcus Focke.), "uva de árbol" ( Myrciaria aff. cauliflora O. Berg), coral, and motilón ( Hyeronima macrocarpa Mull. Arg.) fruits were separately extracted with methanol-acetic acid (95:5, v/v). The anthocyanin-rich extracts (AREs) were obtained by selective adsorption on Amberlite XAD-7. Each extract was analyzed by HPLC-PDA and HPLC-HRESI-MS(n) with LCMS-IT-TOF equipment in order to characterize the anthocyanin pigments and the coinjection in HPLC using standards allowed identifying the major constituents in each extract. The antioxidant activity was measured by electron paramagnetic resonance (EPR) and UV-vis spectroscopy, using ABTS and DPPH free radicals. The ARE of motilón ( H. macrocarpa Müll. Arg) exhibited the highest radical scavenging activity in comparison to the other extracts. A second-order kinetic model was followed in all of the cases. These results suggested that the studied fruits are promising not only as source of natural pigments but also as antioxidant materials for food industry.     

Phenolic compound profiles and antioxidant capacity of Persea americana Mill. peels and seeds of two varieties

Avocado processing by the food and cosmetic industries yields a considerable amount of phenolic-rich byproduct such as peels and seeds. Utilization of these byproducts would be favorable from an economic point of view. Methanolic (80%) extracts obtained from lyophilized ground peels and seeds of avocado (Persea americana Mill.) of the Hass and Shepard varieties were characterized for their phenolic compound profiles using the HPLC-PAD technique. The structures of the identified compounds were subsequently unambiguously confirmed by ESI-MS. Compositional analysis revealed that the extracts contained four polyphenolic classes: flavanol monomers, proanthocyanidins, hydroxycinnamic acids, and flavonol glycosides. The presence of 3-O-caffeoylquinic acid, 3-O-p-coumaroylquinic acid, and procyanidin A trimers was identified in seeds of both varieties. Intervarietal differences were apparent in the phenolic compound profiles of peels. Peels of the Shepard variety were devoid of (+)-catechin and procyanidin dimers, which were present in the peels of the Hass variety. Peels of both varieties contained 5-O-caffeoylquinic acid and quercetin derivatives. The differences in the phenolic profiles between varietals were also apparent in the different antioxidant activity of the extracts. The peel extracts had a higher total phenolic compound content and antioxidant activity when compared to the seed extracts. The highest TEAC and ORAC values were apparent in peels of the Haas variety in which they amounted to 0.16 and 0.47 mmol Trolox/g DW, respectively. No significant (p > 0.05) differences were apparent between the TEAC values of seeds of the two varieties but the ORAC values differed significantly (p < 0.05). Overall these findings indicate that both the seeds and peel of avocado can be utilized as a functional food ingredient or as an antioxidant additive.     

Phenolic acids in berries, fruits, and beverages

The contents of soluble and total phenolic acids were analyzed in samples of 29 berries and berry products, 24 fruits and fruit peels, and 12 beverages. Variation of phenolic acids in berries was also studied. Soluble phenolic acids were extracted with methanolic acetic acid, and a tentative quantification was performed by high-performance liquid chromatography (HPLC). The total phenolic acid content was determined by HPLC after alkaline and acid hydrolyses. The content of total phenolic acids as aglycones in the above samples varied from 0 (pear cider) to 103 mg/100 g fresh weight (rowanberry). Besides rowanberry, the best phenolic acid sources among berries were chokeberry (96 mg/100 g), blueberry (85 mg/100 g), sweet rowanberry (75 mg/100 g), and saskatoon berry (59 mg/100 g). Among fruits, the highest contents (28 mg/100 g) were determined in dark plum, cherry, and one apple variety (Valkea Kuulas). Coffee (97 mg/100 g) as well as green and black teas (30-36 mg/100 g) were the best sources among beverages. Caffeic acid dominated in all of these samples except in tea brews. Variation in the phenolic acid contents of the berries was either small or moderate.     

Phenolic compound concentration and antioxidant activities of edible and medicinal mushrooms from Korea

A study was conducted to determine the content of phenolic compounds and the antioxidative activity of five edible and five medicinal mushrooms commonly cultivated in Korea. Phenolic compounds were analyzed using high performance liquid chromatography, and antioxidant activity was evaluated by 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity and superoxide dismutase activity. A total of 28 phenolic compounds were detected in the mushrooms studied. The average total concentration of phenolic compounds was 326 microg/g, the average being of 174 microg/g in edible mushrooms and 477 microg/g in medicinal mushrooms. The average total flavonoids concentration was 49 microg/g, with averages of 22 and 76 microg/g in edible and medicinal mushrooms, respectively. The DPPH radical scavenging activities ranged between 15 (Pleurotus eryngii) and 70% (Ganoderma lucidum) when reaction time was for 1 min. When reaction time was 30 min, the values ranged between 5 (Pleurotus eryngii) and 78% (Agaricus bisporus). The SOD activity averaged 28% among the 10 mushroom species, averages for edible and medicinal mushrooms being comparable. DPPH activities was significantly correlated (p < 0.01) with total content of phenolic compounds in edible mushrooms, while in medicinal mushrooms there was a significant correlation (p < 0.01) between SOD activity and total concentration of phenolic compounds. Numerous significant positive correlations were observed between phenolic compounds detected and antioxidative potential.     

Cellular antioxidant activity of common fruits

Measurement of antioxidant activity using biologically relevant assays is important in the screening of fruits for potential health benefits. The cellular antioxidant activity (CAA) assay quantifies antioxidant activity in cell culture and was developed to meet the need for a more biologically representative method than the popular chemistry antioxidant capacity measures. The objective of the study was to determine the cellular antioxidant activity, total phenolic contents, and oxygen radical absorbance capacity (ORAC) values of 25 fruits commonly consumed in the United States. Pomegranate and berries (wild blueberry, blackberry, raspberry, and blueberry) had the highest CAA values, whereas banana and melons had the lowest. Apples were found to be the largest contributors of fruit phenolics to the American diet, and apple and strawberries were the biggest suppliers of cellular antioxidant activity. Increasing fruit consumption is a logical strategy to increase antioxidant intake and decrease oxidative stress and may lead to reduced risk of cancer.     

Studies on the constituents of Cyclanthera pedata fruits: isolation and structure elucidation of new flavonoid glycosides and their antioxidant activity.

The isolation of six flavon glycosides (1-6), among them four new natural compounds (1-4), from the CHCl(3)/MeOH extract of the fruits of Cyclanthera pedata is reported. All of the structures were elucidated by spectroscopic methods, including the concerted application of one-dimensional ((1)H, (1)H TOCSY, (13)C, and (13)C DEPT-NMR) and two-dimensional NMR techniques (DQF-COSY, HSQC, and HMBC). For all of the isolated compounds the antioxidant activity was determined by measuring the free radical scavenging activity, using the Trolox equivalent antioxidant capacity (TEAC) method, and the coupled oxidation of beta-carotene and linoleic acid.     

Correlation of selected constituents with the total antioxidant capacity of coffee beverages: influence of the brewing procedure

Relationships between volatile and nonvolatile compounds and the antioxidant capacity of coffee brews prepared from commercial conventional and torrefacto roasted coffees, employing commonly used doses and prepared by four brewing procedures (filter, plunger, mocha, and espresso machine) were assessed. Significant correlations between volatile Maillard reaction products and antioxidant capacity (measured by both 2,2-diphenyl-1-picrylhydrazyl radical and redox potential methods) were not observed. Highly positive correlations between browned compounds and caffeine with both antioxidant capacity parameters were reported. Principal component analysis allowed coffee brews separation according to coffee roasting processes (PC1) and brewing procedures (PC2), showing that in all cases coffee brews from torrefacto roasted coffee were more antioxidant that those extracted from conventional ones; also, coffee brews extracted by an espresso machine were more antioxidant than those extracted by mocha, plunger, and filter machines.