Effects of phenolic acids on human phenolsulfotransferases in relation to their antioxidant activity

Sulfate conjugation by phenolsulfotransferase (PST) enzyme is an important process in the detoxification of xenobiotics and endogenous compounds. There are two forms of PST that are specific for the sulfation of small phenols (PST-P) and monoamines (PST-M). Phenoilc acids have been reported to have important biological and pharmacological properties and may have benefits to human health. In the present study, human platelets were used as a model to investigate the influence of 13 phenolic acids on human PST activity and to evaluate the relationship to their antioxidant activity. The results showed that chlorogenic acid, syringic acid, protocatechuic acid, vanillic acid, sinapic acid, and caffeic acid significantly (p < 0.05) inhibited the activities of both forms of PST by 21-30% at a concentration of 6.7 microM. The activity of PST-P was enhanced (p < 0.05) by p-hydroxybenzoic acid, gallic acid, gentisic acid, o-coumaric acid, p-coumaric acid, and m-coumaric acid at a concentration of 6.7 microM, whereas the activity of PST-M was enhanced by gentisic acid, gallic acid, p-hydroxybenzoic acid, and ferulic acid. The phenolic acids exhibited antioxidant activity as determined by the oxygen radical absorbance capacity (ORAC) assay and Trolox equivalent antioxidant capacity (TEAC) assay, especially gallic acid, p-hydroxybenzoic acid, gentisic acid, and coumaric acid, which had strong activity. The overall effect of phenolic acids tested on the activity of PST-P and PST-M was well correlated to their antioxidant activity of ORAC value (r = 0.71, p < 0.01; and r = 0.66, p < 0.01). These observations suggest that antioxidant phenolic acids might alter sulfate conjugation.     

Comparison of Swiss red wheat grain and fractions for their antioxidant properties

Swiss red wheat grain, bran, aleurone, and micronized aleurone were examined and compared for their free radical scavenging properties against 2,2-diphenyl-1-picrylhydrazyl radical (DPPH*), radical cation ABTS*+ and peroxide radical anion O(2)*-, oxygen radical absorbance capacity (ORAC), chelating capacity, total phenolic content (TPC), and phenolic acid composition. The results showed that micronized aleurone, aleurone, bran, and grain may significantly differ in their antioxidant properties, TPC, and phenolic acid composition. Micronized aleurone had the greatest antioxidant activities, TPC, and concentrations of all identified phenolic acids, suggesting the potential of postharvesting treatment on antioxidant activities and availability of TPC and phenolic acids. Ferulic acid was the predominant phenolic acid in Swiss red wheat and accounted for approximately 57-77% of total phenolic acids on a weight basis. Ferulic acid concentration was well correlated with scavenging activities against radical cation and superoxide anion, TPC, and other phenolic acid concentrations, suggesting the potential use of ferulic acid as a marker of wheat antioxidants. In addition, 50% acetone and ethanol were compared for their effects on wheat ORAC values. The ORAC value of 50% acetone extracts was 3-20-fold greater than that of the ethanol extracts, indicating that 50% acetone may be a better solvent system for monitoring antioxidant properties of wheat. These data suggest the possibility to improve the antioxidant release from wheat-based food ingredients through postharvesting treatment or processing.     

Effect of roasting on phenolic content and antioxidant activities of whole cashew nuts, kernels, and testa

The effect of roasting on the content of phenolic compounds and antioxidant properties of cashew nuts and testa was studied. Whole cashew nuts, subjected to low-temperature (LT) and high-temperature (HT) treatments, were used to determine the antioxidant activity of products. Antioxidant activities of cashew nut, kernel, and testa phenolics extracted increased as the roasting temperature increased. The highest activity, as determined by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity, oxygen radical absorbance capacity (ORAC), hydroxyl radical scavenging capacity, Trolox equivalent antioxidant activity (TEAC), and reducing power, was achieved when nuts were roasted at 130 °C for 33 min. Furthermore, roasting increased the total phenolic content (TPC) in both the soluble and bound extracts from whole nut, kernel, and testa but decreased that of the proanthocyanidins (PC) except for the soluble extract of cashew kernels. In addition, cashew testa afforded a higher extract yield, TPC, and PC in both soluble and bound fractions compared to that in whole nuts and kernels. Phenolic acids, namely, syringic (the predominant one), gallic, and p-coumaric acids, were identified. Flavonoids, namely, (+)-catechin, (-)-epicatechin, and epigallocatechin, were also identified, and their contents increased with increasing temperature. The results so obtained suggest that HT-short time (HTST) roasting effectively enhances the antioxidant activity of cashew nuts and testa.     

Phenolic compounds and antioxidant activity of kernels and shells of Mexican pecan (Carya illinoinensis)

The phenolic composition and antioxidant activity of pecan kernels and shells cultivated in three regions of the state of Chihuahua, Mexico, were analyzed. High concentrations of total extractable phenolics, flavonoids, and proanthocyanidins were found in kernels, and 5-20-fold higher concentrations were found in shells. Their concentrations were significantly affected by the growing region. Antioxidant activity was evaluated by ORAC, DPPH?, HO?, and ABTS?-- scavenging (TAC) methods. Antioxidant activity was strongly correlated with the concentrations of phenolic compounds. A strong correlation existed among the results obtained using these four methods. Five individual phenolic compounds were positively identified and quantified in kernels: ellagic, gallic, protocatechuic, and p-hydroxybenzoic acids and catechin. Only ellagic and gallic acids could be identified in shells. Seven phenolic compounds were tentatively identified in kernels by means of MS and UV spectral comparison, namely, protocatechuic aldehyde, (epi)gallocatechin, one gallic acid-glucose conjugate, three ellagic acid derivatives, and valoneic acid dilactone.     

Identification and quantification of antioxidant components of honeys from various floral sources

Little is known about the individual components of honey that are responsible for its antioxidant activity. The present study was carried out to characterize the phenolics and other antioxidants present in honeys from seven floral sources. Chromatograms of the phenolic nonpolar fraction of the honeys indicated that most honeys have similar but quantitatively different phenolic profiles. Many of the flavonoids and phenolic acids identified have been previously described as potent antioxidants. A linear correlation between phenolic content and ORAC activity was demonstrated (R(2) = 0.963, p < 0.0001). Honeys were separated by solid-phase extraction into four fractions for sugar removal and separation based on solubility to identify the relative contribution of each fraction to the antioxidant activity of honey. Antioxidant analysis of the different honey fractions suggested that the water-soluble fraction contained most of the antioxidant components. Specific water-soluble antioxidant components were quantified, including protein; gluconic acid; ascorbic acid; hydroxymethylfuraldehyde; and the combined activities of the enzymes glucose oxidase, catalase and peroxidase. Of these components, a significant correlation could be established only between protein content and ORAC activity (R(2) = 0.674, p = 0.024). In general, the antioxidant capacity of honey appeared to be a result of the combined activity of a wide range of compounds including phenolics, peptides, organic acids, enzymes, Maillard reaction products, and possibly other minor components. The phenolic compounds contributed significantly to the antioxidant capacity of honey but were not solely responsible for it.     

Characterization of phenolic substances and antioxidant properties of food soybeans grown in the North Dakota-Minnesota region

Phenolic profiles and antioxidant properties of a total of 30 soybean samples, including 27 grown in the North Dakota-Minnesota region and three soybeans from the other regions, were investigated. The total phenolic content (TPC), total flavonoids content (TFC), phenolic acids, flavonols, anthocyanins, and isoflavones were quantified. Antioxidant properties of soybean extracts were assessed using 2-diphenyl-1-picryhydrazyl free radical scavenging activity (DPPH), ferric reducing antioxidant power (FRAP), and oxygen radical absorbance capacity (ORAC) methods. Results showed that black soybean cultivars possessed significantly higher TPC, TFC, DPPH, FRAP, and ORAC values than all yellow soybean cultivars. However, black soybean cultivars did not exhibit significantly higher individual phenolic contents (except for anthocyanins), such as phenolic acids and isoflavones, than the yellow soybean cultivars. The isoflavone profiles of North Dakota soybean cultivars were similar to those of South Dakota, but average values of total isoflavone (TI) contents were higher than soybeans grown in the other states and Korea and Japan according to the U.S. Department of Agriculture-Iowa State University Database on the isoflavone contents of foods. Correlation assays showed that TPC, TI, total phenolic acids, daidzin, genistin, malonyldaidzin, daidzein, genistein, and trans-cinnamic acid significantly ( r = 0.73, 0.62, 0.49, 0.68, 0.59, 0.59, 0.56, 0.47, and 0.76, respectively, p < 0.0001) correlated with ORAC values of yellow soybeans. Both isoflavones and phenolic acids contributed to the ORAC values of yellow soybeans. These data suggest that some selected soybean cultivars may be used as high-quality food-grade soybeans for providing high phenolic phytochemicals and antioxidant activities.     

Total phenolics, phenolic acids, isoflavones, and anthocyanins and antioxidant properties of yellow and black soybeans as affected by thermal processing

The effects of boiling and steaming processes on the phenolic components and antioxidant activities of whole yellow (with yellow seed coat and yellow cotyledon) and black (with black seed coat and green cotyledon) soybeans were investigated. As compared to the raw soybeans, all processing methods caused significant (p < 0.05) decreases in total phenolic content (TPC), total flavonoid content (TFC), condensed tannin content (CTC), monomeric anthocyanin content (MAC), DPPH free radical scavenging activity (DPPH), ferric reducing antioxidant power (FRAP), and oxygen radical absorbing capacity (ORAC) in black soybeans. Pressure steaming caused significant (p < 0.05) increases in TPC, CTC, DPPH, FRAP, and ORAC in yellow soybeans. The steaming resulted in a greater retention of TPC, DPPH, FRAP, and ORAC values in both yellow and black soybeans as compared to the boiling treatments. To further investigate the effect of processing on phenolic compounds and elucidate the contribution of these compounds to changes of antioxidant activities, phenolic acids, isoflavones, and anthocyanins were quantitatively determined by HPLC. The pressure steaming treatments caused significant (p < 0.05) increases in gallic acid and 2,3,4-trihydroxybenzoic acid, whereas all treatments caused significant (p < 0.05) decreases in two predominant phenolic acids (chlorogenic acid and trans-cinnamic acid), and total phenolic acids for both yellow and black soybeans. All thermal processing caused significant (p < 0.05) increases in aglucones and beta-glucosides of isoflavones, but caused significant (p < 0.05) decreases in malonylglucosides of isoflavones for both yellow and black soybeans. All thermal processing caused significant (p < 0.05) decreases of cyanidin-3-glucoside and peonidin-3-glucoside in black soybeans. Significant correlations existed between selected phenolic compositions, isoflavone and anthocyanin contents, and antioxidant properties of cooked soybeans.     

Effects of roasting on the antioxidant status and phenolic profiles of commercial Turkish hazelnut varieties (Corylus avellana L.)

The effect of roasting on the antioxidant status and phenolic profiles of seven commercial Turkish hazelnut varieties (namely, ?ak?ldak, Fo?a, Karaf?nd?k, Mincane, Palaz, Sivri, and Tombul) was assessed. Samples were examined for their total phenolics, oxygen radical absorbance capacity (ORAC) values, condensed tannins, and phenolic acids (free and bound forms). Significant losses (p < 0.05) in total phenolics (~66.3%), ORAC values (~41.6%), condensed tannins (~75.2), and phenolic acids (~42.7) were noted when the hazelnuts were roasted. Some variations both between and within natural and roasted hazelnuts were observed (p < 0.05). Phenolic acids were mainly found in the bound form. Gallic, protocatechuic, p-coumaric, and ferulic + sinapic acids were present in all hazelnut varieties, albeit to different extents, and the first two were dominant. Mincane, in roasted form, had the highest total phenolics, ORAC values, condensed tannins, and phenolic acids. This was due to the presence of some skin in roasted Mincane. No skin was left in all other varieties upon roasting. The present work suggests that roasting results in a significant loss in the antioxidant status and phenolic profiles because of the removal of the skin, which is a rich source of phenolics. It is highly recommended to consume natural hazelnut instead of the roasted counterpart to take advantage of all of the functional benefits of this nut.     

Quantitative evaluation of antioxidant components in prunes (Prunus domestica L.)

Prunes are known to show high antioxidant activity on the basis of the oxygen radical absorbance capacity (ORAC), and their major antioxidant components are caffeoylquinic acid isomers. The aim of this study is to prove the contribution of caffeoylquinic acid isomers to the ORAC of prunes, and to investigate the existence of other antioxidant components. Caffeoylquinic acid isomers in ethanol (EtOH) extracts of prunes were quantified by HPLC analysis, and the degree of contribution of these isomers to the ORAC was found to be 28.4%; hence, it was speculated that the remaining ORAC is dependent on other antioxidant compounds. EtOH extract was partitioned between hexane and H(2)O. The H(2)O layer was further separated into H(2)O and 2-100% methanol (MeOH) eluates by Diaion HP-20 column chromatography. Both the H(2)O and 50% MeOH eluates showed high values of total phenolics and ORAC, although the contribution of caffeoylquinic acid isomers to the ORAC was low. Therefore, it was predicted that unknown antioxidants exist in these fractions, and several compounds were identified by HPLC analysis. Furthermore, hydrolysis of EtOH extract residue led to higher levels of total phenolics and ORAC, and these results suggested the existence of conjugated antioxidant components in prunes.     

Identification and antioxidant potential of flavonoids and low molecular weight phenols in olive cultivar chemlali growing in Tunisia

Increasing interest in phenolic compounds in olives is due to their antioxidant and health-enhancing properties. In this study the phenolics in fruits of the Tunisian olive cultivar Chemlali were extracted by methanol-water and fractionated using Sephadex LH-20 column chromatography. The identification of phenolic monomers and flavonoids was based on separation by high-performance liquid chromatography equipped with a diode array detector followed by liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry analysis. Oleuropein, a secoiridoid glycoside esterified with a phenolic acid, was the major compound. Eight phenolic monomers and 12 flavonoids were also identified in Chemlali olives. Five flavonoids were isolated and purified using Sephadex LH-20 column chromatography and preparative paper chromatography. The antioxidant activity of the extract and the purified compounds was evaluated by measuring the radical scavenging effect on 1,1-diphenyl-2-picrylhydrazyl and by using the beta-carotene-linoleate model assay. Acid hydrolysis of the extract enhanced its antioxidant activity. Hydroxytyrosol and quercetin showed antioxidant activities similar to that of 2,6-di-tert-butyl-4-methylphenol. A hydroxyl group at the ortho position at 3' on the B ring of the flavonoid nucleus could contribute to the antioxidant activity of the flavonoids.     

Investigation of the antioxidant behavior of air- and freeze-dried aromatic plant materials in relation to their phenolic content and vegetative cycle

The total phenolic and flavonoid content of the aerial parts of five aromatic plants harvested at different periods was estimated, and their antioxidant capacity was evaluated. Major phenolic compounds present in their extracts were determined by RP-HPLC. The results demonstrated different amounts of total phenolic compounds and various degrees of antioxidant activity depending on the plant species, the time of harvest, and the drying method employed. Extracts from air-dried Mentha viridis L., Origanum majorana L., and Rosmarinus officinalis L. demonstrated the greatest efficacy during the flowering stage, in which the identified flavonoids were found in significantly higher amounts, whereas phenolic acids were found in their lowest concentration. Extracts from air-dried Laurus nobilis L. and Foeniculum vulgare Mill were less efficient in terms of antioxidant activity, with the highest values being observed during the early fruiting stage. This stage was characterized by the lowest flavonoid content and high phenolic acid content, except for L. nobilis L. extracts. Overall, the amount of identified phenolic acids did not vary considerably within the investigated year. The total phenolic concentration in all plant extracts decreased significantly when freeze-dried rather than air-dried samples were used. The HPLC analysis further supported the above for most of the phenolic compounds present in the extracts, except for hydroxybenzoic acids, which were better retained during the freeze-drying process.     

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.     

Structure-antioxidant efficiency relationships of phenolic compounds and their contribution to the antioxidant activity of sea buckthorn juice

The phenolic composition of juice derived from fruits of sea buckthorn (Hippophae rhamnoides) was investigated by high-performance liquid chromatography (HPLC) with diode array and electrochemical detection. Flavonols were found to be the predominating polyphenols while phenolic acids and catechins represent minor components. Of the seven flavonols identified, isorhamnetin 3-O-glycosides were the most important representatives quantitatively. However, because of their structural properties, they were poor radical scavengers as shown by electron spin resonance spectroscopy. Phenolic compounds such as quercetin 3-O-glycosides, catechins, and hydroxybenzoic acids with a catechol structure exhibited good antioxidant capacities, but their concentration in sea buckthorn juice was small. These phenolic compounds, determined by HPLC, accounted for less than 5% of the total antioxidant activity of the filtered juice. Ascorbic acid was shown to be the major antioxidant in sea buckthorn juice. Because of its high concentration of 1.22 g/L, it contributes approximately 75% to total antioxidant activity. The remaining difference can be attributed to higher molecular weight flavan-3-ols (proanthocyanidins), which were determined photometrically after acid depolymerization to colored anthocyanidins.     

Targeted metabolite analysis and antioxidant potential of Rumex induratus

Targeted metabolite analysis of aqueous extract of Rumex induratus leaves, in terms of phenolic compounds and organic acids, and the study of its antioxidant activity against the DPPH(*) radical, a reactive oxygen species, hypochlorous acid, and a reactive nitrogen species, nitric oxide ((*)NO), were performed. The samples were collected in several locations, spontaneously occurring or from greenhouse culture, at different stages of development and seasons. The phenolic composition was achieved by high-performance liquid chromatography (HPLC)-diode array detection, and four hydroxycinnamic acid derivatives and 10 flavonoid glycosides (C- and O-heterosides) were determined. Organic acids composition was established by HPLC-UV, revealing five compounds. The total amount of phenolic compounds and organic acids were affected by growing conditions and developmental phase. The aqueous extract exhibited a dose-related activity against all tested reactive species.     

Chemical composition and antioxidant properties of extracts of fresh fruiting bodies of Pleurotus sajor-caju (Fr.) Singer

The chemical composition and in vitro antioxidant activity of aqueous butanol and ethyl acetate extracts of Pleurotus sajor-caju were investigated in this study. Twenty-two compounds comprising methyl esters, hydrocarbon fatty acids, ethyl esters, and sterols were identified in ethyl acetate extracts, while cinnamic acid, nicotinamide, benzeneacetamide, and 4-hydroxybenzaldyhde were identified in butanol extracts by gas chromatography-mass spectrometry and NMR analysis. The antioxidant activity was determined by a β-carotene bleaching method, ferric reducing antioxidant power, trolox equivalent antioxidant capacity, and lipid peroxidation assays, while the total phenolic content in P. sajor-caju was assessed by Folin-Ciocalteau's method. The aqueous and butanol extracts exhibited the highest antioxidant activity, corresponding to the total phenolic content. The subfractions from the ethyl acetate extract (EP1, EP2, EP3, and EP4), however, showed moderate antioxidant activity. The regular consumption of P. sajor-caju as a part of our diet may render nutritional and nutraceuticals benefits for good health.     

Chemical and cellular antioxidant activity of phytochemicals purified from olive mill waste waters

The isolation and identification of a phytocomplex from olive mill waste waters (OMWW) was achieved. The isolated phytocomplex is made up of the following three phenolic compounds: hydroxytyrosol (3,4-DHPEA), tyrosol (p-HPEA) and the dialdehydic form of decarboxymethyl elenolic acid, linked with (3,4-dihydroxyphenyl)ethanol (3,4-DHPEA-EDA). The purification of this phytocomplex was reached by partial dehydration of the OMWW, followed by liquid-liquid extraction with ethyl acetate and middle pressure liquid chromatography (MPLC) on a Sephadex LH-20 column. The phytocomplex accounted for 6% of the total phenolic content of the OMWW. The phytocomplex and individual compounds were tested for antioxidant capacity by the oxygen radical absorbance capacity (ORAC) method. The ORAC phytocomplex produced 10,000 ORAC units/g dry weight, whereas the cellular antioxidant activity, measured by the cellular antioxidant activity in red blood cell (CAA-RBC) method, demonstrated that the phytocomplex and all of the components are able to permeate the cell membrane thus exhibiting antioxidant activity inside the red blood cells. Our phytocomplex could be employed in the formulation of fortified foods and nutraceuticals, with the goal to obtain substantial health protective effects due to the suitable combination of the component molecules.     

Effect of heat treatment on the phenolic compounds and antioxidant capacity of citrus peel extract

This paper reports the effects of heat treatment on huyou (Citrus paradisi Changshanhuyou) peel in terms of phenolic compounds and antioxidant capacity. High-performance liquid chromatography (HPLC) coupled with a photodiode array (PDA) detector was used in this study for the analysis of phenolic acids (divided into four fractions: free, ester, glycoside, and ester-bound) and flavanone glycosides (FGs) in huyou peel (HP) before and after heat treatment. The results showed that after heat treatment, the free fraction of phenolic acids increased, whereas ester, glycoside, and ester-bound fractions decreased and the content of total FGs declined (P < 0.05). Furthermore, the antioxidant activity of methanol extract of HP increased (P < 0.05), which was evaluated by total phenolics contents (TPC) assay, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) (ABTS*+) method, and ferric reducing antioxidant power (FRAP) assay. The correlation coefficients among TPC, ABTS, FRAP assay, and total cinnamics and benzoics (TCB) in the free fraction were significantly high (P < 0.05), which meant that the increase of total antioxidant capacity (TAC) of HP extract was due at least in part to the increase of TCB in free fraction. In addition, FGs may be destroyed when heated at higher temperature for a long time (for example, 120 degrees C for 90 min or 150 degrees C for 30 min). Therefore, it is suggested that a proper and reasonable heat treatment could be used to enhance the antioxidant capacity of citrus peel.     

Antioxidant Activity and Characterization of Phenolic Compounds from Bacaba ( Oenocarpus bacaba Mart.) Fruit by HPLC-DAD-MS(n)

The phytochemicals in fruits have been shown to be major bioactive compounds with regard to health benefits. Bacaba ( Oenocarpus bacaba Mart.) is a native palm fruit from the Brazilian savannah and Amazon rainforest that plays an important role in the diet of rural communities and is also a source of income for poor people. This paper reports the characterization and analyses of phenolics from bacaba fruit extract. The total phenolic content of bacaba fruit amounted to 1759.27 ± 1.01 mg GAE/100 g, the flavonoid content was 1134.32 ± 0.03 mg CTE/100 g, and the anthocyanin content was 34.69 ± 0.00 mg cyn-3-glc/100 g. The antioxidant activity was evaluated through different assays [ORAC, FRAP, DPPH, TEAC, and cellular antioxidant assay (CAA) assays] and revealed a significant antioxidant capacity for bacaba in comparison to the data available in the literature. The assignment of the phenolic compounds using HPLC-DAD-MS(n) was based on the evaluation of their UV-vis absorption maxima (λ(max)) and mass spectral analyses, and 14 compounds were tentatively identified. The results suggest that bacaba fruits are a promising source of phenolics.     

Obtention and characterization of phenolic extracts from different cocoa sources

The aim of this study was to evaluate several cocoa sources to obtain a rich phenol extract for use as an ingredient in the food industry. Two types of phenolic extracts, complete and purified, from different cocoa sources (beans, nibs, liquor, and cocoa powder) were investigated. UPLC-MS/MS was used to identify and quantify the phenolic composition of the extracts, and the Folin-Ciocalteu and vanillin assays were used to determine the total phenolic and flavan-3-ol contents, respectively. The DPPH and ORAC assays were used to measure their antioxidant activity. The results of the analysis of the composition of the extracts revealed that the major fraction was procyanidins, followed by flavones and phenolic acids. From the obtained results, the nib could be considered the most interesting source for obtaining a rich phenolic cocoa extract because of its rich phenolic profile content and high antioxidant activity in comparison with the other cocoa sources.     

Assessment of antioxidant activity of cane brown sugars by ABTS and DPPH radical scavenging assays: determination of their polyphenolic and volatile constituents

Seven cane brown sugars (four from La Réunion, two from Mauritius, and one from France) were investigated for their polyphenol content and volatile composition in relation to their free radical scavenging capacity determined by ABTS and DPPH assays. The thin layer coated on the sugar crystal was extracted by Soxhlet extractor with dichloromethane. The volatile compounds of brown sugars were studied by GC-MS, and 43 compounds were identified. The total phenolic content of brown sugars was determined according to the Folin-Ciocalteu method. Phenolic compounds were quantified in the brown sugar extracts by LC-UV-ESI-MS. Brown sugar aqueous solutions exhibited weak free radical scavenging activity in the DPPH assay and higher antioxidant activity in the ABTS assay at relatively high concentration. The brown sugar extracts showed interesting free radical scavenging properties despite the low concentration of phenolic and volatile compounds. Sugar is a common foodstuff traditionally used for its sweetening properties, which might be accompanied by antioxidant properties arising from molecules (polyphenols, Maillard products) other than sucrose of the cane brown sugars.