Four different types of wheat bran were extracted and analyzed for phenolic acids using the Folin–Ciocalteu method and HPLC. The extracts and their hydrolysis products were also evaluated for their ...antioxidant activities. The total phenolic content of the red wheat bran was higher than that of the white wheat. We found that the majority of the phenolic acids existed in a bound form in wheat bran. These phenolic acids can be released by hydrolyzing the bran under alkaline or acidic conditions; however, the former was more efficient in the release of free phenolic acids than the latter. Ferulic, vanillic, and syringic acids were the major individual phenolic acids in the studied wheat bran. The main portion of the total ferulic acid was from alkaline hydrolysis. The alkaline hydrolysable fractions had greater antioxidant activities, while the acid hydrolysable fractions showed lower activities in both the red and white bran. The antioxidant activity of bran extract was stronger than that of free phenolic acids.
Antioxidant activities of 43 commonly consumed mushrooms in China were evaluated using ABTS free radical scavenging (ABTS) assay, DPPH free radical scavenging (DPPH) assay, ferric reducing ...antioxidant power (FRAP) assay, and metal chelating ability (MCA) assay. Phenolic profiles in total phenol content (TPC) and total flavonoid contents (TFC) of mushrooms were also determined by colorimetric methods. The contents of free phenolic acids in mushrooms were determined by HPLC. The mushroom samples exhibited diverse antioxidant activity in different assays. The highest antioxidant ability was found in porcino nero in DPPH value, mulberry yellow in FRAP value, stone ear in ABTS value, and maitake in MCA value. Total phenolic and flavonoid content determination showed that all mushrooms are rich in phenolics and flavonoids. Stone ear and pine-spike had the highest phenolic and flavonoid content. Mushrooms exhibited a positive linear correlation between TPC and ABTS antioxidant capacities at the level of 0.01. Mushrooms have different phenolic acid profiles. Gallic acids were detected with high quantity in most of the mushrooms. Other phenolic acids were detected with low content, and some of phenolic acids were not detected in mushrooms.
•Phenolic profiles of commonly consumed mushroom were investigated firstly.•43 mushrooms presented substantial antioxidant activities.•Maitake possess the strongest metal chelating ability.•Gallic acid were detected in most of mushrooms.•Current findings will guide consumers and manufactures to utilize mushrooms.
Diabetes is a global health challenge. Currently, an effective treatment for diabetes is to reduce the postprandial hyperglycaemia by inhibiting the carbohydrate hydrolysing enzymes in the digestive ...system. In this study, we investigated the in vitro α-glucosidase and α-amylase inhibitory effects of free and bound phenolic extracts, from the bran and kernel fractions of five sorghum grain genotypes. The results showed that the inhibitory effect of sorghum phenolic extracts depended on the phenolic concentration and composition. Sorghum with higher phenolic contents generally had higher inhibitory activity. Among the tested extracts, the brown sorghum (IS131C)-bran-free extract (BR-bran-free, half-maximal inhibitory concentration (IC50) = 18 ± 11 mg sorghum/mL) showed the strongest inhibition against α-glucosidase which was comparable to that of acarbose (IC50 = 1.39 ± 0.23 mg acarbose/mL). The red sorghum (Mr-Buster)-kernel-bound extract (RM-kernel-bound, IC50 = 160 ± 12 mg sorghum/mL) was the most potent in inhibiting α-amylase but was much weaker compared to acarbose (IC50 = 0.50 ± 0.03 mg acarbose/mL).
Sizeable scientific evidence indicates the health benefits related to phenolic compounds and dietary fiber. Various phenolic compounds‐rich foods or ingredients are also rich in dietary fiber, and ...these two health components may interrelate via noncovalent (reversible) and covalent (mostly irreversible) interactions. Notwithstanding, these interactions are responsible for the carrier effect ascribed to fiber toward the digestive system and can modulate the bioaccessibility of phenolics, thus shaping health‐promoting effects in vivo. On this basis, the present review focuses on the nature, occurrence, and implications of the interactions between phenolics and food components. Covalent and noncovalent interactions are presented, their occurrence discussed, and the effect of food processing introduced. Once reaching the large intestine, fiber‐bound phenolics undergo an intense transformation by the microbial community therein, encompassing reactions such as deglycosylation, dehydroxylation, α‐ and β‐oxidation, dehydrogenation, demethylation, decarboxylation, C‐ring fission, and cleavage to lower molecular weight phenolics. Comparatively less information is still available on the consequences on gut microbiota. So far, the very most of the information on the ability of bound phenolics to modulate gut microbiota relates to in vitro models and single strains in culture medium. Despite offering promising information, such models provide limited information about the effect on gut microbes, and future research is deemed in this field.
•Blue honeysuckle berries are a rich source of selected secondary metabolites.•Four studied cultivars differed in contents of some bioactive compounds.•All blue honeysuckle berry cultivars had low ...sugar contents.•Cultivar 'Aurora' had the biggest berries and the highest sugar content.•Cultivar 'Tundra' had the smallest berries, but the highest phenolics content.
Organically grown blue honeysuckle berries have become extremely popular in the last few years, mainly because of their taste and high ascorbic acid content. With the spectrophotometer and aid of high-performance liquid chromatography (HPLC) coupled with mass spectrophotometry (MS) we compare the content of organic and ascorbic acids, sugars, individual phenolics, total phenolics, saponins and tannins, of four blue honeysuckle berry cultivars. On average the cultivar 'Aurora' was the biggest in terms of weight and size, with the highest sugar (2585.45 mg/100 g) and the lowest organic acid (655.46 mg/100 g) contents. Conversely, the cultivar 'Honey Bee' was the smallest and had the highest ascorbic acid (25.77 mg/100 g) and saponin (640.79 mg/100 g), but the lowest sugar (1557.37 mg/100 g) contents. Cultivars 'Borgalis' and 'Tundra' had intermediate weight and size, with high and low contents of other identified compounds.
Agro-industrial wastes have gained great attention as a possible source of bioactive compounds, which may be utilized in various industries including pharmaceutics, cosmetics, and food. The food ...processing industry creates a vast amount of waste which contains valuable compounds such as phenolics. Polyphenols can be found in soluble (extractable or free), conjugated, and insoluble-bound forms in various plant-based foods including fruits, vegetables, grains, nuts, and legumes. A substantial portion of phenolic compounds in agro-industrial wastes is present in the insoluble-bound form attached to the cell wall structural components and conjugated form which is covalently bound to sugar moieties. These bound phenolic compounds can be released from wastes by hydrolysis of the cell wall and glycosides by microbial enzymes. In addition, they can be converted into unique metabolites by methylation, carboxylation, sulfate conjugation, hydroxylation, and oxidation ability of microorganisms during fermentation. Enhancement of concentration and antioxidant activity of phenolic compounds and production of new metabolites from food wastes by microbial fermentation might be a promising way for better utilization of natural resources. This review provides an overview of mechanisms and factors affecting release and bioconversion of phenolic compounds in agro-industrial wastes by microbial fermentation.
The phytochemical composition and antioxidant activity of fruits are associated with their health benefits. Longan is a traditional Chinese edible and medicinal fruit, but its varietal differences in ...phytochemical profiles and antioxidant activity were unknown. Twenty-four longan cultivars from southern China were investigated in this study. Their total phenolic and flavonoid contents in pulp were 22.09-132.47 mg gallic acid equivalents/100 g and 2.48-14.26 mg catechin equivalents/100 g, respectively. The mean contributions of free phenolics and flavonoids to the total were 82.5% and 94.0%, respectively. Among 10 individual phenolics detected by HPLC, the contents of epicatechin, 4-methylcatechol, chlorogenic, and vanillic acids were relatively higher. The cellular antioxidant activity (CAA) of longan pulp showed significant varietal discrepancies and positive correlation with phenolic and flavonoid contents. Phenolics in longan pulp of 24 cultivars showed lower CAA potential than many other fruits with the CAA qualities from 0.35 to 1.21 µmol quercetin equivalent/100 µmol total phenolics. Longan cultivars were classified into six groups by hierarchical clustering analysis. Six cultivars in group 4 and 6 had higher phytochemical contents and CAA activity.
•First comprehensive profiling of free, conjugated and bound phenolics in lentil hulls.•Catechin/proanthocyanins, hydroxycinnamates and hydroxybenzoic acids were the main phenolics.•First ...comprehensive profiling of carotenoids, tocochromanols and essential fatty acids in lentil hulls.•Lutein/zeaxanthin and δ-tocotrienol/γ-tocotrienol were the main carotenoids and tocochromanols.•All phenolics, carotenoids and tocochromanols contributed significantly to antioxidant activities in vitro.
A systemic approach was taken in profiling the hydrophilic and lipophilic antioxidants in lentil hulls using a combination of HPLC, LC-ESI-MS2 and GC techniques. A total of 37 phenolics were tentatively identified in the hydrophilic fractions, while four carotenoids and three tocopherols were found in the lipophilic fraction. Results showed that in addition to the high free extractable phenolics, phenolic compounds in conjugated and bound forms also exist in similar amounts. Information on conjugated and bound phenolics are particularly important as these forms of phenolics often go unnoticed by chromatographic profiling of extractables. All phenolic, carotenoid and tocopherol fractions contributed to antioxidant activities. Information about bioactives from lentil hulls, specifically conjugated and bound phenolics are reported here for the first time. The comprehensive profiling of these bioactives lays a good foundation for further assessment of the value-added uses of lentil hulls which are by-products of pulse processing.
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•A system containing Ni–W catalyst and dodecane was used for the HDO of phenolics.•The Ni0 and WOx species derived from NiWO4 precursors were key to HDO.•10Ni–15WOx/NiAl2O4 was ...effective for HDO reaction at 250 °C, 4 MPa, and 4 h.•The formation of cyclohexane was promoted successfully using a dodecane solvent.•Cycloalkanes with a high content of 44.3% were obtained by the HDO of bio-oil.
Hydrodeoxygenation (HDO) of lignin-derived bio-oil offers a promising route for the production of advanced biofuels. However, the conventional HDO of lignin-derived bio-oil faces serious problems, such as low hydrocarbon yield and easy deactivation of catalysts. Herein, a novel reaction system consisting of a highly stable bifunctional catalyst (i.e., Ni−WOx/NiAl2O4) and a dodecane solvent was developed for the HDO of lignin-derived phenolics. The Ni0 species, derived from NiWO4 precursors on the NiAl2O4, were of small crystallite size and high dispersion, together with the strong oxophilicity of W, thereby exhibiting high activity. The use of a highly stable NiAl2O4 spinel support and the replacement of common solid acid with more stable WOx for the cleavage of CO bond accounted for excellent stability. The optimized 10Ni−15WOx/NiAl2O4 exhibited a high guaiacol conversion of 97.8% with a high cycloalkane yield of 83.8% under the optimum conditions (250 °C, 5 MPa H2, and 4 h). Cycloalkanes with a high yield over 90% were also obtained by the HDO of other complex lignin-derived compounds. More importantly, the catalyst always retained its initial activity for the HDO of guaiacol in five runs, with negligible coke formation. Subsequently, the HDO behavior of the bio-oil obtained from walnut shell pyrolysis was also studied. The relative content of cycloalkanes in the products reached 44.3% after the reaction. This study highlights the prospect of a highly stable catalyst consisting of hydrogenation metal and oxophilic promoter, and dodecane solvent to enable efficient production of cycloalkanes from the HDO of lignin-derived phenolics.
•The majority phenolics in walnut kernel were free phenolics.•Acetone was better to extract soluble phenolics, and methanol for insoluble bound phenolics.•Jeuglone, kaempferol, ...quercetin-7-o-β-D-glucoside and dihydroquercetin were only found in free phenolics.•There was positive linear correlation between antioxidant activities and total phenolic contents.
The free, esterified and bound forms of 37 phenolic compounds (including hydroxybenzoic acid, hydroxycinnamic acids, flavanols, flavonols and flavones) from walnut kernel (Juglans regia L.) were investigated in this study. Results showed that the majority of walnut phenolics were presented in the free form (51.1%–68.1%), followed by bound (21.0%–38.0%) and esterified forms (9.7%–18.7%). Ellagic acid, gallic acid, ferulic acid, sinapic acid and caffeic acid were widely distributed in three forms. Differently, jeuglone, kaempferol, quercetin-7-o-β-d-glucoside and dihydroquercetin were only found in free phenolics. Among the three forms, free phenolics had the highest radical scavenging activity (IC50: DPPH, 15.5 µg/ml; ABTS, 13.6 µg/ml). The correlation coefficients between the antioxidant activities of phenolics and their corresponding contents were 0.82–0.92. More soluble phenolics (free and esterified forms) could be extracted by acetone, while methanol was better at extracting insoluble bound phenolics.
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