Isolation and identification of an antioxidant flavonoid compound from citrus-processing by-product

BACKGROUND: Large amounts of citrus by‐products are released from juice‐processing plants every year. Most bioactive compounds are found in the peel and inner white pulp. Flavonoids are a widely distributed group of bioactive compounds. The methanolic extract of citrus peel powder has been shown to possess strong antioxidant activity. Therefore the aim of this study was to isolate the major antioxidant flavonoid compound from Citrus unshiu (satsuma) peel as citrus by‐product and evaluate its antioxidant activity. RESULTS: The major flavonoid isolated from C. unshiu peel was identified as quercetagetin. The structure of the compound was determined by tandem mass spectrometry and ultraviolet spectroscopy. Its antioxidant activity was assessed by assays of 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical, hydroxyl radical and intracellular reactive oxygen species (ROS) scavenging and DNA damage inhibition. Quercetagetin showed strong DPPH radical‐scavenging activity (IC₅₀7.89 µmol L^?1) but much lower hydroxyl radical‐scavenging activity (IC₅₀203.82 µmol L^?1). Furthermore, it significantly reduced ROS in Vero cells and showed a strong protective effect against hydrogen peroxide‐induced DNA damage. CONCLUSION: The results of this study suggest that quercetagetin could be used in the functional food, cosmetic and pharmaceutical industries. Copyright © 2011 Society of Chemical Industry     

Evaluation of Citrus aurantifolia peel and leaves extracts for their chemical composition,antioxidant and anti‐cholinesterase activities

BACKGROUND: The replacement of synthetic antioxidants by safe natural antioxidants fosters research on the screening of vegetables and food as sources of new antioxidants. Moreover, oxidative degeneration of cells is associated with neurodegenerative diseases such as Alzheimer's disease. On the basis of these considerations this work aimed to investigate the antioxidant properties [by using the diphenyl picryl hydrazyl, 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) and ferric reducing ability of plasma assays, and the β‐carotene bleaching test] and the anti‐cholinesterase activity of Citrus aurantifolia peel and leaves from different areas of growth. RESULTS: Methanol extracts of the peel and leaves demonstrated the strongest radical scavenging activity. A similar trend was observed with the reducing ability, with values from 112.1 to 146.0 µmol L^?1 Fe(II) g^?1. The relationship between phenol and flavonoid contents and antioxidant activity was statistically investigated. Based on analysis by high‐performance liquid chromatography, the most abundant flavonoids found in C. aurantifolia extracts were apigenin, rutin, quercetin, kaempferol and nobiletin. n‐Hexane fractions of both peel and leaves showed a good acetylcholinesterase inhibitory activity with IC₅₀ values in the range 91.4‐107.4 µg mL^?1. Gas chromatography‐mass spectrometry analysis revealed the presence of monoterpenes and sesquiterpenes as most common components. CONCLUSION: The findings of this study suggest a potential use of C. aurantifolia peel and leaves for supplements for human health. Copyright © 2012 Society of Chemical Industry     

Antioxidant and melanogenesis‐inhibitory activities of collagen peptide from jellyfish (Rhopilema esculentum)

BACKGROUND: Jellyfish collagen was hydrolysed with trypsin and properase E, and jellyfish collagen peptide (JCP) was purified from the enzymatic hydrolysate using ion exchange chromatography and gel filtration. The antioxidant activity of JCP in a linoleic acid emulsion system, its superoxide anion‐ and hydroxyl radical‐scavenging activities and its copper‐chelating ability were evaluated in vitro. Initial investigations of JCP's ability to inhibit melanogenesis were carried out using cultured B16 melanoma cells. RESULTS: The molecular weight distribution of JCP was from 400 to 1200 Da. Amino acid analysis showed that JCP was rich in Gly, Pro, Ser, Ala, Glu and Asp and had a total hydrophobic amino acid content of 384.2 g kg^?1. JCP showed high antioxidant activity (IC₅₀147.8 µg mL^?1), superoxide anion‐scavenging activity (IC₅₀21.9 µg mL^?1), hydroxyl radical‐scavenging activity (IC₅₀16.7 µg mL^?1) and copper‐chelating ability (IC₅₀88.7 µg mL^?1) in vitro. It also significantly inhibited intracellular tyrosinase activity, decreased melanin content and enhanced glutathione synthesis (P < 0.05). Furthermore, JCP decreased intracellular cAMP levels and suppressed tyrosinase mRNA expression. CONCLUSION: Based on the results of this study, JCP exerts anti‐melanogenic actions via its antioxidant properties and copper‐chelating ability. JCP could be used as a natural skin‐lightening agent in the medicine and food industries. Copyright © 2009 Society of Chemical Industry     

Juice components and antioxidant capacity of four Tunisian Citrus varieties

BACKGROUND: Juices from four Citrus species of Tunisia were investigated mainly for quality parameters and antioxidant capacity. RESULTS: Citrus reticulata (mandarin) juice had the highest content of total flavonoids (85.33 mg CE L^?1). The latter also occurred in high quantity (82.01 mg CE L^?1) in Citrus lemon (lemon) juice which was also marked by its richness in total aroma (70.16 µg mL^?1) and in total fatty acids (48.10 µg mL^?1). Mandarin and lemon juices had the highest antioxidant activity, as determined b the β‐carotene bleaching assay (26.67% and 22.67%, respectively). Citrus aurantium (bitter orange) juice was characterised by the highest content of total polyphenols (784.67 mg GAE L^?1) and by the greatest inhibition of DPPH (96.10%). Citrus sinensis (blood orange) juice was only marked by the high quantity of ascorbic acid (36.90 mg mL^?1). GC/MS analysis of juice aroma showed the predominance of limonene (48.85–69.59%) in mandarin and in bitter and blood oranges, but of camphene (89.05%) in lemon. GC analysis of juice fatty acids revealed their richness in oleic acid (23.13–39.52%). HPLC analysis of juice phenolics indicated the predominance of phenolic acids (73.13–86.40%). CONCLUSION: The Citrus species used in this study were considered valuable varieties from the point of view of antioxidant capacity and nutrition. Copyright © 2010 Society of Chemical Industry     

Isolation and characterisation of a novel angiotensin I‐converting enzyme‐inhibitory peptide derived from douchi,a traditional Chinese fermented soybean food

BACKGROUND: Douchi, a traditional fermented soybean food, has recently attracted a great deal of attention owing to its superior physiological activity. In the present study the angiotensin I‐converting enzyme (ACE)‐inhibitory activity of typical douchi procured from various regions of China was analysed. An ACE‐inhibitory peptide derived from the most potent douchi was also isolated and characterised. The pattern of ACE inhibition and resistance to hydrolysis by gastrointestinal proteases of this peptide are described. RESULTS: ACE‐inhibitory activities were detected in all douchi samples, with IC₅₀ values ranging from 0.204 to 2.011 mg mL^?1. Among the douchi samples, a Mucor‐type douchi exhibited the most potent ACE‐inhibitory activity (IC₅₀ = 0.204 mg mL^?1). A novel ACE‐inhibitory peptide was then isolated from this Mucor‐type douchi using ultrafiltration followed by Sephadex G‐25 column chromatography and reverse phase high‐performance liquid chromatography. The amino acid sequence of the purified peptide was identified by Edman degradation as His‐Leu‐Pro (IC₅₀ = 2.37 µmol L^?1). The peptide is a competitive inhibitor and maintained its inhibitory activity even after incubation with some gastrointestinal proteases. CONCLUSION: The present study shows that peptides derived from soybean fermentation during douchi processing could be the main contributor to the ACE‐inhibitory activity observed. Copyright © 2009 Society of Chemical Industry     

Identification of α‐glucosidase inhibitors from a new fermented tea obtained by tea‐rolling processing of loquat (Eriobotrya japonica) and green tea leaves

BACKGROUND: A new fermented tea produced by tea‐rolling processing of loquat (Eriobotrya japonica) leaf with green tea leaf (denoted as LG tea) showed a potent antihyperglycaemic effect in maltose‐loaded rats. The aim of this study, therefore, was to identify α‐glucosidase inhibitors in the antihyperglycaemic tea product. RESULTS: LG tea had a threefold higher maltase‐inhibitory activity (IC₅₀ 0.065 mg dried extract mL^?1) than either the constituent loquat leaf or green tea alone. In addition, LG tea favourably inhibited maltase action rather than sucrase action. As a result of bio‐guided high‐performance liquid chromatography separations of LG tea, theasinensin A, theasinensin B, strictinin and 1,6‐digalloylglucose were newly identified as maltase inhibitors with IC₅₀ values of 142, 225, 398 and 337 µmol L^?1 respectively, along with previously identified catechins and theaflavins. CONCLUSION: Judging from the magnitude of the α‐glucosidase‐inhibitory contribution of each isolated compound to the overall inhibition of LG tea, catechins were the main candidates responsible for α‐glucosidase or maltase inhibition in LG tea, followed by theaflavins, theasinensins, strictinin and 1,6‐digalloylglucose. Copyright © 2010 Society of Chemical Industry     

Antioxidant and semicarbazide‐sensitive amine oxidase inhibitory activities of alginic acid hydroxamates

The commercial polysaccharides of alginic acid (medium (3500 cps, 2% solution) and low (250 cps, 2% solution) viscosities) were esterified with acidic methanol (1 mmol L^?1 HCl) at 4 °C with gentle stirring for 5 days to obtain methyl esters of medium‐viscosity alginic acid (ME‐MVA) and low‐viscosity alginic acid (ME‐LVA). These ME‐MVA and ME‐LVA were reacted with alkaline hydroxylamine to obtain medium‐viscosity alginic acid hydroxamates (MVA‐NHOH) and LVA‐NHOH. The percentages of hydroxamic acid content in MVA‐NHOH and LVA‐NHOH were calculated as 25% and 20%, respectively. The hydroxamate derivatives of alginic acid were used to test the antioxidant and semicarbazide‐sensitive amine oxidase (SSAO) inhibitory activities in comparison with original materials (MVA and LVA). The half‐inhibition concentrations, IC₅₀, of scavenging activity against 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) were 24.5 and 29.8 µg mL^?1 for MVA‐NHOH and LVA‐NHOH, respectively. However, few scavenging activities of the MVA and LVA were found at the same concentrations. The IC₅₀ of the positive control of butylated hydroxytoluene was 5 µg mL^?1. The scavenging activity of DPPH radical was pH‐dependent, and the optimal pH for both of MVA‐NHOH and LVA‐NHOH was the Tris‐HCl buffer (pH 7.9). Using electron spin resonance (ESR) to detect the activity of scavenging hydroxyl radicals, both alginic acid hydroxamates showed dose‐dependent scavenging activities, and the IC₅₀ was 90 and 92 µg mL^?1, respectively, for MVA‐NHOH and LVA‐NHOH. Both alginic acid hydroxamates also exhibited protection against hydroxyl radical‐mediated DNA damage. Both MVA‐NHOH and LVA‐NHOH showed dose‐dependent inhibitory activities against bovine SSAO (2.53 units); the IC₅₀ was 0.16 and 0.09 µg mL^?1, respectively, for MVA‐NHOH and LVA‐NHOH, compared with 3.81 µg mL^?1 of semicarbazide (positive controls). Amine oxidase activity staining also revealed that both MVA‐NHOH and LVA‐NHOH exhibited SSAO inhibitory activities. Both MVA‐NHOH and LVA‐NHOH showed mixed non‐competitive inhibition against bovine SSAO. It was found that the V′_max value was reduced and the K′_m value was either increased (added MVA‐NHOH, 0.05 µg mL^?1) or reduced (added LVA‐NHOH, 0.11 µg mL^?1) in the presence of alginic acid hydroxamate. Copyright © 2006 Society of Chemical Industry     

Antiproliferative effects of prenylflavonoids from hops on human colon cancer cell lines

In recent years, interest in hop‐derived constituents, especially for prenylflavonoids has grown, as they have a wide range of biological properties including antioxidant, anticarcinogenic and antimicrobial activities. Two main hop prenylflavonoids, xanthohumol and isoxanthohumol, and hop extract enriched in prenylflavonoids, were tested for their antiproliferative activities on colon cancer cell lines, HT‐29 and SW620, and a noncancerous cell line, IEC‐6. It was confirmed that both xanthohumol and isoxanthohumol inhibited cell proliferation, even at micromolar concentrations. For cell line HT‐29, the IC₅₀ was 1.2 ± 0.9 and 16.9 ± 0.9 µmol dm^?3 for xanthohumol and isoxanthohumol, respectively. Similar values were obtained for SW620 cells (2.5 ± 0.2 and 37.3 ± 3.2 µmol dm^–3). None of the pure prenylflavonoids that were tested affected the proliferation of the noncancerous cell line, IEC‐6. The effect of the hop extract containing xanthohumol was also tested for antiproliferative activities on the cancer cell lines, HT‐29 (IC₅₀ = 3.1 ± 0.2 µmol dm^–3) and SW620 (IC₅₀ = 1 ± 0.2 µmol dm^?3), and on the cell line, IEC‐6 (IC₅₀ = 65.5 ± 11.3 µmol dm^?3). The results showed a similar trend to that for pure compounds, suggesting a possible future application of hop extracts in the pharmaceutical industry. Copyright © 2014 The Institute of Brewing & Distilling     

Purification of citrus limonoids and their differential inhibitory effects on human cytochrome P450 enzymes

Recent studies demonstrated that citrus limonoids and flavonoids possess numerous health promoting properties. In the present study, glucosides of limonoids and flavonoids were purified from citrus molasses and limonoid aglycones from citrus seeds. Glucosides were separated on styrene (divinylbenzene), Q‐sepharose resins with increasing concentration of sodium chloride. A pH‐dependent cold precipitation was carried out for the isolation of naringin in large quantity. Major aglycones such as limonin and nomilin were isolated from seeds by direct crystallization and minor limonoids were purified by vacuum liquid chromatography. The structures of the isolated compounds were confirmed by NMR spectra. Individual limonoids were tested for O‐dealkylase and hydroxylase activities of human cytochrome P450 (CYP) isoenzymes such as CYP1A2, CYP1B1, CYP3A4 and CYP19, using ethoxyresorufin, methoxyresorufin and dibenzylfluorescein as substrates. Partial to high inhibition of CYPs was observed in dose‐dependent assays. Significant (P < 0.001) reductions in enzyme activities were observed with purified compounds above 2 µmol. Kinetic analyses indicated that limonin glucoside inhibited CYP19 competitively (IC₅₀, 7.1 µ mol L^?1), whereas Nomilinic acid glucoside inhibited it noncompetitively (IC₅₀, 9.4 µ mol^?1). Nomilinic acid glucoside was the most potent limonoid, with an overall IC₅₀ of < 10 µ mol, for all the enzymes tested. The differential inhibition of CYPs can be ascribed to structural variations of the limonoid nucleus. Limonoid inhibition of key CYPs involved in carcinogenesis supports growing evidence that citrus limonoids act as anticancer agents. Copyright © 2007 Society of Chemical Industry     

Assessment of in vitro antioxidant, antibacterial and immune activation potentials of aqueous and ethanol extracts of Phyllanthus niruri

BACKGROUND: Recently much attention has been paid to biologically active plants because of their low production cost and fewer adverse effects compared with chemical drugs. In the present investigation the bioactivity of Phyllanthus niruri ethanol and aqueous extracts was evaluated in vitro. RESULTS: The ethanol extract of P. niruri showed a high level of flavonoid content (123.9 ± 0.002 mg g^?1), while the aqueous extract showed the highest 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH; IC₅₀6.85 ± 1.80 µmol L^?1) and 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS; 46.44 ± 0.53 µmol L^?1) free radical scavenging activities with high phenol content (376 ± 0.02 mg g^?1) and elevated levels of ferric reducing antioxidant power (FRAP; 23 883 ± 0.019 mmol g^?1) with excellent antibacterial activity against Staphylococcus aureus (20 mm inhibition zone) and Streptococcus agalactiae (12 mm inhibition zone), respectively, in addition to the best immune activation potential of human peripheral blood mononuclear cells (450.5%). CONCLUSIONS: It is clear from our results that both extracts of P. niruri has excellent bioactivity roles via elevated levels of antibacterial, antioxidant and percentage of peripheral blood mononuclear cell proliferation, which could lead to the development of medications for clinical use. Copyright © 2012 Society of Chemical Industry     

Scirpusin A,a hydroxystilbene dimer from Xinjiang wine grape,acts as an effective singlet oxygen quencher and DNA damage protector

BACKGROUND: Grapes and red wines are rich sources of phenolic compounds such as anthocyanins, catechins, flavonols and stilbenes, most of which are potent antioxidants showing cardioprotective properties. We first isolated scirpusin A, a hydroxystilbene dimer, from a wine grape of Xinjiang, and studied its antioxidant activity. RESULTS: Reactive oxygen species scavenging effects and the protection against reactive singlet oxygen‐induced DNA damage of scirpusin A have been investigated in our experiments. The concentration of scirpusin A required to inhibit 50% of ¹O₂ generation was 17 µmol L^?1, while addition of scirpusin A at 140 µmol L^?1 caused complete inhibition. Further kinetic study revealed that the reaction of Scirpusin A with singlet oxygen has an extremely high rate constant (k_a = 4.68 × 10⁹ L mol^?1 s^?1). Scirpusin A (140 µmol L^?1) exhibited significant inhibition effects on pBR322 DNA breakage. However, scavenging effects of scirpusin A on superoxide anion O₂^?? and hydroxyl radical ·OH were not potent as the inhibitor rates at a concentration of 1400 µmol L^?1 were 28.83% and 19.5%, respectively. CONCLUSION: The present study shows that scirpusin A is a selective quencher of singlet oxygen and a protector against reactive singlet oxygen‐induced pBR322 DNA damage at very low concentrations. Copyright © 2010 Society of Chemical Industry     

Effect of rosehip (Rosa canina L.) phytochemicals on stable free radicals and human cancer cells

BACKGROUND: The commercial development of plants as sources of antioxidants that can be used to enhance the properties of foods, for nutritional purposes and preservation as well as for prevention of oxidation‐related diseases, is currently of major interest. Rosehip (Rosa canina L.) is a rich source of vitamin C and polyphenols. RESULTS: Phytochemicals in rosehip tea were separated into three fractions: Fr1 (vitamin C, 39.17 mg kg^?1), Fr2 (flavonoids, 451.05 µg kg^?1) and Fr3 (phenolic acids, 504.69 µg kg^?1). Quercetin and ellagic acid were the most abundant polyphenolic compounds. Rosehip fractions, primarily rosehip flavonoids (EC₅₀ = 49 mg L^?1), showed high antioxidant activity towards 2,2‐diphenyl‐1‐picrylhydrazyl radicals (DPPH^?). Cell growth effects of rosehip fractions were assessed in HeLa, MCF7 and HT‐29 cell lines, with the lowest IC₅₀ values being determined for rosehip flavonoids, (80.63, 248.03 and 363.95 mg L^?1 respectively). However, the vitamin C fraction did not inhibit the growth of tested tumour cells. CONCLUSION: The results of this study confirm that vitamin C and flavonoids are responsible for the antioxidant activity of rosehip tea, while only polyphenols contribute to its antiproliferative activity. Copyright © 2011 Society of Chemical Industry     

α-Glucosidase- and α-amylase-inhibitory activities of phlorotannins from Eisenia bicyclis

BACKGROUND: In an effort to develop alternative therapeutic agents, strong inhibitory activity against α‐glucosidase and α‐amylase was detected in Eisenia bicyclis methanolic extract. RESULTS: In this study, two phlorotannins were isolated from E. bicyclis and characterised by chromatography and nuclear magnetic resonance. The active substances were identified as fucofuroeckol A (FF) and dioxinodehydroeckol (DD). To the authors' knowledge, this is the first report of the identification of these substances in E. bicyclis. However, to date, no antidiabetic activity of FF and DD has been reported. Both phlorotannins demonstrated significant inhibitory activity against α‐glucosidase and α‐amylase. FF showed potent antidiabetic activity, with IC₅₀ values of 131.34 nmol L^?1 against α‐glucosidase and 42.91 µmol L^?1 against α‐amylase. The corresponding IC₅₀ values of DD were 93.33 nmol L^?1 and 472.7 µmol L^?1. Furthermore, kinetic analysis revealed that FF and DD exhibited non‐competitive inhibitory activity against α‐glucosidase. CONCLUSION: These results suggest that FF and DD may be candidates for the development of an antidiabetic pharmaceutical agent or food additive. Copyright © 2012 Society of Chemical Industry     

Fate of aflatoxin B(1) in contaminated corn gluten during acid hydrolysis

BACKGROUND: Aflatoxins are a group of mycotoxins that cause serious chronic disease outbreaks and contaminate several food products such as corn and its by‐product, corn gluten. The aim of the current study was to evaluate the effect of hydrochloric acid (HCl) on aflatoxin B₁ (AFB₁) degradation in contaminated corn gluten under different HCl concentrations, hydrolysis temperatures and hydrolysis times. RESULTS: During the wet milling process the highest AFB₁ level (45.68 µg kg^?1) (37.86%) was found in corn gluten fraction. Treatment with 1 mol L^?1 HCL at 110 °C resulted in degradation of AFB₁ by 27.6% (33.07 µg kg^?1) after 4 h and reached 42.5% (26.26 µg kg^?1) after 8 h. Increasing HCl concentration from 1 to 3 mol L^?1 HCl resulted in increased degradation of AFB₁, while complete degradation occurred in the presence of 5 mol L^?1 HCl after 4 h at 110 °C. Meanwhile, half‐life time of AFB₁ was recorded after 2 h at 100 °C and was < 2 h at 110 °C in the presence of 3 mol L^?1 HCl. CONCLUSION: It could be demonstrated that the manufacture of hydrolyzed vegetable protein is a suitable method for decontamination of aflatoxin in highly contaminated grains, especially gluten fractions. The hydrolysis reaction could be considered in terms of first‐order reaction kinetics of AFB₁ degradation. Copyright © 2010 Society of Chemical Industry     

In vitro inhibitory effects of cranberry bean (Phaseolus vulgaris L.) extracts on aldose reductase, α‐glucosidase and α‐amylase

The in vitro inhibitory activities of different seed extracts prepared from cranberry bean mutant SA‐05 and its wild‐type variety Hwachia against aldose reductase, α‐glucosidase and α‐amylase were examined. The results indicated that the polyphenolics‐rich extracts obtained using 800 g kg^?1 methanol and 500 g kg^?1 ethanol demonstrated inhibitory activities against aldose reductase (IC₅₀ of 0.36–0.46 mg mL^?1) and α‐glucosidase (IC₅₀ of 1.32–1.94 mg mL^?1). The 500 g kg^?1 ethanol extracts also showed α‐amylase inhibitory activities (IC₅₀ of 70.11–80.22 μg mL^?1). Subsequent extracts, prepared further with NaCl and H₂O from precipitates of 800 g kg^?1 methanol or 500 g kg^?1 ethanol extracts, exhibited potent α‐amylase inhibitory activities (IC₅₀ of 17.68–38.68 μg mL^?1). A combination of 500 g kg^?1 ethanol extraction plus a subsequent H₂O extraction produced highest polyphenolics and α‐amylase inhibitors. The SA‐05 α‐amylase inhibitor extracts showed greater inhibitory activities than that of Hwachia. Thus, cranberry bean mutant SA‐05 is an advantageous choice for producing anti‐hyperglycaemic compounds.     

α‐Glucosidase and α‐amylase inhibitory activities of phloroglucinal derivatives from edible marine brown alga,Ecklonia cava

BACKGROUND: Diabetes mellitus (DM) is a chronic metabolic disorder characterized by defects in insulin secretion and action, which can lead to damaged blood vessels and nerves. With respect to effective therapeutic approaches to treatment of DM, much effort has being made to investigate potential inhibitors against α‐glucosidase and α‐amylase from natural products. The edible marine brown alga Ecklonia cava has been reported to possess various interesting bioactivities, which are studied here. RESULTS: In this study, five phloroglucinal derivatives were isolated from Ecklonia cava: fucodiphloroethol G ( 1 ), dieckol ( 2 ), 6,6′‐bieckol ( 3 ), 7‐phloroeckol ( 4 ) and phlorofucofuroeckol A ( 5 ); compounds 1, 3 and 4 were obtained from this genus for the first time and with higher yield. The structural elucidation of these derivatives was completely assigned by comprehensive analysis of nuclear magnetic spectral data. The anti‐diabetic activities of these derivatives were also assessed using an enzymatic inhibitory assay against rat intestinal α‐glucosidase and porcine pancreatic α‐amylase. Most of these phlorotannins showed significant inhibitory activities in a dose‐dependent manner, responding to both enzymes, especially compound 2 , with the lowest IC₅₀ values at 10.8 µmol L^?1 (α‐glucosidase) and 124.9 µmol L^?1 (α‐amylase), respectively. Further study of compound 2 revealed a non‐competitive inhibitory activity against α‐glucosidase using Lineweaver‐Burk plots. CONCLUSION: These results suggested that Ecklonia cava can be used for nutritious, nutraceutical and functional foods in diabetes as well as for related symptoms. Copyright © 2009 Society of Chemical Industry     

A novel common single primer multiplex polymerase chain reaction (CSP‐M‐PCR) method for the identification of animal species in minced meat

BACKGROUND: Minced meat species adulteration is a severe problem. In this study a common single primer multiplex polymerase chain reaction (CSP‐M‐PCR) method was applied to the identification of five species (chicken, cattle, sheep, pig and horse) in minced meat products. CSP was designed as a common adapter at the 5′‐end of species‐specific reverse primers and employed in giving different length fragments from the respective meat species. RESULTS: Species‐specific DNA fragments could be identified in a single PCR reaction by mixing CSP, Chicken‐R, Cattle‐R, Sheep‐R, Pig‐R and Horse‐R primers in the ratio 1:0.01:0.01:0.01:0.01:0.10 (where ‘1’ represents 0.5 mmol L^?1). The specific DNA fragments could be efficiently amplified by CSP‐M‐PCR with > 5 µmol L^?1 species‐specific primers, except for 50 µmol L^?1 Horse‐R. A detection limit of 0.5 g kg^?1 was determined for both single species of minced meat and all species of five kinds of minced meat. CONCLUSION: The CSP‐M‐PCR method simplified the PCR reaction system and removed the inconsistent amplification efficiency from different primers. This highly sensitive, reproducible and rapid method could potentially be used as a screening or identifying assay to test for the presence of species or ingredients in minced meat and other meat products. Copyright © 2008 Society of Chemical Industry     

Broad bean and pea by‐products as sources of fibre‐rich ingredients: potential antioxidant activity measured in vitro

BACKGROUND By‐products generated during the processing of plant food can be considered a promising source of dietary fibre as a functional compound. The dietary fibre composition, soluble sugars and antioxidant activity of the extractable polyphenols of pea and broad bean by‐products have been analysed in this study. RESULTS: Total dietary fibre using AOAC methods plus hydrolysis (broad bean pod: 337.3 g kg^?1; pea pod: 472.6 g kg^?1) is higher (P < 0.05) in both by‐products than with the Englyst method (broad bean pod: 309.7 g kg^?1; pea pod: 434.6 g kg^?1). The main monomers are uronic acids, glucose, arabinose and galactose in broad bean pods. However, pea pods are very rich in glucose and xylose. The soluble sugars analysed by high‐performance liquid chromatography in both by‐products have glucose as the most important component, followed by sucrose and fructose. The ferric reducing antioxidant power (broad bean pod: 406.4 µmol Trolox equivalents g^?1; pea pod: 25.9 µmol Trolox equivalents g^?1) and scavenging effect on 2,2‐diphenyl‐1‐picrylhydrazyl radical (EC₅₀ of broad bean pod: 0.4 mg mL^?1; EC₅₀ of pea pod: 16.0 mg mL^?1) were also measured. CONCLUSIONS: Broad bean and pea by‐products are very rich in dietary fibre, particularly insoluble dietary fibre and their extractable polyphenols demonstrate antioxidant activity. Therefore they might be regarded as functional ingredients. Copyright © 2011 Society of Chemical Industry     

Elevated carbon dioxide affects fruit flavor in field‐grown strawberries (Fragaria × ananassa Duch)

The effect of elevated carbon dioxide on fruit quality and aroma volatile composition in field‐grown strawberries (Fragaria × ananassa Duch) was studied. Elevating the ambient CO₂ concentration (ambient + 300, and ambient +600 µmol mol^?1 CO₂) resulted in high fruit dry matter, fructose, glucose and total sugar contents and low citric and malic acid contents. High CO₂ growing conditions significantly enhanced the fruit content of ethyl hexanoate, ethyl butanoate, methyl hexanoate, methyl butanonate, hexyl acetate, hexyl hexanoate, furaneol, linalool and methyl octanoate. Thus, the total amounts of these compounds were higher in berries grown in CO₂‐enriched conditions than those grown in ambient conditions. The highest CO₂ enrichment (600 µmol mol^?1) condition yielded fruit with the highest levels of these aroma compounds. Copyright © 2004 Society of Chemical Industry     

Anti‐acetylcholinesterase,antidiabetic, anti‐inflammatory,antityrosinase and antixanthine oxidase activities of Moroccan propolis

Biological properties of Moroccan propolis have been scarcely studied. In the present work, the total phenols and flavonoids from 21 samples of propolis collected in different places of Morocco or 3 supplied in the market were determined, as well as the in vitro capacity for inhibiting the activities of acetylcholinesterase, α‐glucosidase, α‐amylase, lipoxygenase, tyrosinase, xanthine oxidase and hyaluronidase. The results showed that samples 1 (region Fez‐Boulemane, Sefrou city) (IC₅₀ = 0.065, 0.006, 0.020, 0.050, 0.014 mg mL^?1) and 23 (marketed) (IC₅₀ = 0.018, 0.002, 0.046, 0.037, 0.008 mg mL^?1) had the best in vitro capacity for inhibiting the α‐amylase, α‐glucosidase, lipoxygenase, tyrosinase and xanthine oxidase activities, respectively. A negative correlation between IC₅₀ values and concentration of phenols, flavones and flavanones was found. These activities corresponded to the generally higher amounts of phenols and flavonoids. In the same region, propolis samples have dissimilar phenol content and enzyme inhibitory activities.