Inhibitory effects of muscadine anthocyanins on α-glucosidase and pancreatic lipase activities

Inhibitory effects of the Noble muscadine grape extracts and the representative phytochemicals for anthocyanins (i.e., cyanidin and cyanidin-3,5-diglucoside) on two enzymes, that is, α-glucosidase and pancreatic lipase, were investigated regarding their antidiabetic activities. The study demonstrated that the anthocyanin extracts and the selected chemicals obeyed the competitive mode against the enzymes. The methanolic extracts of whole fruit and skin of the muscadine showed inhibitory activities against the α-glucosidase with their IC(50) values at 1.50 and 2.73 mg/mL, and those against the lipase at 16.90 and 11.15 mg/mL, respectively, which indicated that the muscadine extracts possessed strong antidiabetic activities. Particularly, the ethyl acetate (EtoAc) extract and the butanol (BuOH) extract exhibited much higher inhibitory activities against both enzymes than the CHCl(3) and water extracts, while the majority of anthocyanins existed in the BuOH fractions. Moreover, cyanidin exhibited a much stronger antidiabetic activity than cyanidin-3,5-diglucoside, suggesting that anthocyanins may have higher inhibitory activities after being digested. Further chromatographic analysis by high-performance liquid chromatography-mass spectrometry identified five individual anthocyanins, including cyanidin, delphinidin, petunidin, peonidin, and malvidin glycosides.     

Effects of polyphenolic compounds on tumor necrosis factor-α (TNF-α)-induced changes of adipokines and oxidative stress in 3T3-L1 adipocytes

Over the last few decades, obesity has become a global epidemic in both developed and developing countries. Recent studies have indicated that obesity is closely associated with chronic inflammation characterized by abnormal levels of adipocytokines and inflammatory cytokines in adipocytes. The aim of this work was to study the effects of 21 polyphenolic compounds on tumor necrosis factor-α (TNF-α)-induced changes of adipokines and oxidative stress in 3T3-L1 adipocytes. The results showed that p-coumaric acid, quercetin, and resveratrol have greater inhibition (p < 0.05) of a TNF-α-induced increase in the production of interleukin-6 (IL-6) among 21 tested polyphenolic compounds. p-Coumaric acid, quercetin, and resveratrol demonstrated inhibitions of TNF-α-induced changes in levels of monocyte chemoattractant protein-1 (MCP-1), plasminogen activator inhibitor-1 (PAI-1), and intracellular reactive oxygen species (ROS) in 3T3-L1 adipocytes. Furthermore, p-coumaric acid, quercetin, and resveratrol increased levels (p < 0.05) of secreted adiponectin, superoxide dismutase (SOD), glutathione (GSH), glutathione peroxidase (GPx), and glutathione S-transferase (GST) in TNF-α-treated 3T3-L1 adipocytes. These results indicate that the inhibition of TNF-α-induced changes of adipokines and oxidative stress by some polyphenolic compounds might have further implications in preventing obesity-related pathologies.     

Andrographolide inhibits ICAM-1 expression and NF-κB activation in TNF-α-treated EA.hy926 cells

Several lines of evidence indicate that inflammation and endothelial cell dysfunction are important initiating events in atherosclerosis. Tumor necrosis factor-α (TNF-α), a pro-inflammatory cytokine, induces the expression of cell adhesion molecules and results in monocyte adherence and atheromatous plaque formation. Andrographolide (AP) is a major bioactive diterpene lactone in Andrographis paniculata that has anti-inflammatory activity. A previous study demonstrated the role of heme oxygenase 1 (HO-1) in the inhibition of TNF-α-induced ICAM-1 expression by AP. The present study investigated the effect of AP on the IKK/NF-κB signaling pathway, which mediates TNF-α-induced ICAM-1 expression in EA.hy926 cells. Similar to the previous study, AP inhibited TNF-α-induced ICAM-1 mRNA and protein levels, its expression on the cell surface, and subsequent adhesion of HL-60 cells to EA.hy926 cells. AP inhibited TNF-α-induced κB inhibitor (IκB) kinase (IKK) and IκBα activation, p65 nuclear translocation, NF-κB and DNA binding activity, and promoter activity of ICAM-1. Although AP increased the intracellular cAMP concentration and induced the phosphorylation of cAMP response element-binding protein (CREB), knocking down CREB protein expression by transfecting the cells with CREB-specific small interfering RNA did not relieve the inhibition of ICAM-1 expression by AP. Taken together, these results suggest that AP down-regulates TNF-α-induced ICAM-1 expression at least in part via attenuation of activation of NF-κB in EA.hy926 cells rather than through activation of CREB. The results suggest that AP may have potential as a cardiovascular-protective agent.     

Protective effects of anthocyanins against amyloid β-peptide-induced damage in neuro-2A cells

Alzheimer's disease is neuropathologically characterized by amyloid β-protein (Aβ) deposition, resulting in neurotoxicity. Herein, we focused on the prevention of anthocyanins from amyloid-mediated neurodysfunction. The data demonstrated that combined exposure of Aβ(1-40) and Aβ(25-35) to Neuro-2A cells resulted in reactive oxygen species (ROS) production and perturbation of calcium homeostasis. The expressions of LXRα, ApoE, ABCA1, and seladin-1 genes were significantly down-regulated upon Aβ challenge. β-Secretase, the rate-limiting enzyme that catalyzes amyloid precursor protein transform to Aβ, was up-regulated by Aβ treatment. For the duration of Aβ stimulation, malvidin (Mal) or oenin (Oen; malvidin-3-O-glucoside) was added, and the protective effects were observed. Mal and Oen showed protective effects against Aβ-induced neurotoxicity through blocking ROS formation, preserving Ca(2+) homeostasis, and preventing Aβ-mediated perturbation of certain genes involved in Aβ metabolism and cellular defense. The present study implicates anthocyanin as a potential therapeutic candidate for the prevention of amyloid-mediated neurodysfunction.     

The effects of biocidal treatments on metabolism in soil—IV. The decomposition of fumigated organisms in soil

To calculate the biomass from the size of the flush that follows fumigation, the fraction (k) of the killed biomass C that is respired as CO₂ must be known. This was measured for a range of organisms: two yeasts Succharomyces cerevisiae and Candida utilis), two fungi (Cylindrocarpon sp. and Penicillium chrysogenum), an actinomycete (Streptomyces clavuligerus), seven bacteria (Aerobacter aerogenes, Bacillus subtilis, Clostridium histolyticum, Escherichia coli, Microccus lysodeikticus, Pseudomonas fluorescens and Nitrosomonas europaea) and a soil invertebrate (Lumbricus terrestris). The organisms were mixed with soil and fumigated; the consumption of O₂, evolution of CO₂ and mineralization of N were then measured under the standard conditions used to measure the flush. Control values obtained with fumigated soil alone were deducted, assuming that the added organisms did not cause a priming action. Taking all the organisms together, 50·0 ± 8·2% of the C originally present was mineralized in the 10 days following fumigation, giving a mean value of 0·5 for k.Experiments with earthworms showed that fumigation with CHCl₃ did not appreciably increase the amounts of C and N mineralized from organisms that were already dead and that k was independent of the amount of organism added.From a consideration of the results in this and in the preceding three papers, it is concluded that the flush following fumigation can be used to give a rough measure of the amount of biomass in a soil.     

Short‐term effects of manganese toxicity on ribulose 1,5 bisphosphate carboxylase in tobacco chloroplasts

The short‐term effects of manganese (Mn) toxicity on ribulose 1,5 bisphosphate carboxylase EC 4.1.1.39 (Rubisco) activity and concentration in tobacco (Nicotiana tabacum L. ‘KY 17') chloroplasts were examined. The activity of the enzyme from both Mn‐treated and control plants was determined 6,12,18, 24, and 48 h after introduction of Mn (80 mg/L). Enzyme activity was determined by monitoring rates of carbon dioxide (¹⁴CO₂) fixation into acid stable products. A decrease in the enzyme's activity in experimental plants was noted after 48 h of exposure. Visible symptoms, such as chlorosis and decreased leaf size, were also observed after 48 h of Mn exposure in experimental plants. Using Rocket Immunoelectrophoresis, no appreciable differences between Rubisco concentration levels of the experimental plants and the control plants were noted indicating that the effect on Rubisco activity is a post‐translational phenomenon and that Rubisco is not being degraded at an accelerated rate. Manganese accumulated in the experimental plants to concentrations as high as 3282 μg/g dry wt as determined by atomic absorption spectrophotometry. A shuttling mechanism for Mn between young and old leaves was indicated by an observed decrease in the concentration of Mn in the young leaf tissue between 12 and 18 h after treatment.     

The effects of biocidal treatments on metabolism in soil—VI. Fumigation with carbon disulphide

Used in high concentration as a soil fumigant, CS₂ was broadly similar to CHCl₃ in its effects on metabolism in soil; the amount of N mineralised in 10 days increased roughly 10-fold. the O₂ consumption almost tripled and the evolution of CO₂ more than doubled. However, the effects of CS₂ were consistently slightly less than those of CHCl₃.Used at low concentration (10 μg.g^?1 soil) on a soil rich in organic matter (2.93% organic C), CS₂ stopped nitrification completely, almost without other effect on soil respiration and mineralisation of N. In contrast, when used on a poorer soil (1.07% organic C) even 10 μgCS₂.g_?1 soil was sufficient to cause a detectable increase in both respiration and mineralisation of N, in addition to stopping nitrification.     

IFN-γ induction on carbohydrate binding module of fungal immunomodulatory protein in human peripheral mononuclear cells

FIP-fve is a protein that is isolated from Flammulina velutipes . Its known immunomodulatory activities are elicitation of the production of type II interferon from human peripheral mononuclear cells (hPBMCs) and hemagglutination. How the target receptors mediate activation of FIP-fve-induced immunomodulatory effects remains to be elucidated. This study postulates the three-dimensional structures to determine whether the carbohydrate binding module family 34 (CBM-34) on FIP-fve is conserved to site N of Thermoactinomyces vulgaris R-47 α-amylase I. Experimental site-directed mutagenesis data as well as ligand-specific binding competition assay are adopted to identify the key residues W24, T28, D34, T90, I91, and W111 of FIP-fve that participate in binding to polysaccharides that are linked to the membrane of immune cells. Treatments of hPBMCs with tunicamycin and deglycosylation enzymes that removed the carbohydrate moieties reduced the secretion of IFN-γ induction from hPBMCs. In conclusion, the experiments herein demonstrated the ligand-binding CBM-34 on FIP-fve and ligand-like glycoproteins on the surface of hPBMCs must be required to induce physiological immunomodulatory effects.     

The effects of straw return on potassium fertilization rate and time in the rice–wheat rotation

In order to investigate the effects of straw return on potassium (K) fertilizer application rate and time in the rice–wheat rotation, field experiments were conducted at three sites. The results showed that when the K rate was decreased to 70% of the recommended K dosage, crop yields showed no significant decrease. With K fertilization only at rice phase, crop yields showed no marked difference compared with that provided K fertilizer both at wheat and rice seasons. Though the NH₄OAc-extracted K and HNO₃-extracted K differed slightly among the treatments, the soil apparent K balance was negative without K fertilization. With crop straw fully incorporated, the recommended K dosage could be at least reduced by 30% at the experimental sites and the K fertilizer could be applied only at rice phase. A further hypothesis can be made that the best K rate was the amount of K took away by crop grain. In the long run, straw return combined with K fertilization would be an effective method to maintain soil K fertility and productivity.     

Long-term effects of intensive rice–wheat and agroforestry based cropping systems on build-up of nutrients and budgets in alluvial soils of Punjab,India

ABSTRACT

A detailed study was conducted to investigate the long-term effects of rice–wheat and poplar-based agro-forestry systems existing on a large area for last 25 years on the distribution of macro as well as micronutrients in surface soils, as well as their profiles. To achieve these objectives, profile soil samples (0–150 cm) were collected from 10 randomly scattered locations each from rice–wheat and poplar-based agro-forestry systems and analyzed for various physico-chemical properties. The results of our investigation revealed that pH, EC, OC available N, P and K reported significantly higher levels in agro-forestry as compared to rice–wheat system. On the other hand, DTPA-extractable and total Zn, Cu, Fe and Mn were significantly higher in D1 (0–15 cm), D2 (15–30 cm) and D3 (30–45 cm) depths of rice–wheat system which may be attributed to the reduced conditions prevailing during rice crop. Nutrient budgeting also assessed the impact of crop removal and fertilizer inputs along with recycling of crop residue and leaf litter. Also, the build-up of available nutrient status in surface layer (0–15 cm) and soil profiles (0–150 cm) continuously under these two systems helped in maintaining agricultural sustainability and soil fertility over a long period of time.     

Hydrolysis of cellobiose by β-glucosidase in the presence of soil minerals - Interactions at solid-liquid interfaces and effects on enzyme activity levels

Extracellular enzymatic activities in soils are essential for the cycling of organic matter. These activities take place in multiphase environments where solid phases profoundly affect biocatalytic activities. Aspergillus niger is ubiquitous in soils; its β-glucosidase plays an important role in the degradation of cellulose, and therefore in the global carbon cycle and in the turnover of soil organic matter. However, the information on the interactions of this protein with soil minerals is very limited, and even less is known about their consequences for the hydrolysis of the natural substrate cellobiose. We therefore characterised the sorptive interactions of this enzyme with the soil minerals montmorillonite, kaolinite and goethite and quantified the resulting changes in the hydrolysis rate of cellobiose. Fractions of adsorbed protein, and the resulting catalytic activity loss, were lower for montmorillonite than for kaolinite and goethite at given experimental conditions; adsorption was 9.7 ± 7.3% for montmorillonite, 70.3 ± 3.1% for kaolinite and 71.4 ± 1.8% for goethite, respectively. Adsorption of the protein to the minerals caused a total decrease in the catalytic activity of 18.8 ± 3.4% for kaolinite and 17.9 ± 4.7% for goethite whereas it was not significant for montmorillonite. The average catalytic activity lost by the pool of adsorbed molecules was 26.8% for kaolinite and 25.0% for goethite. Both the amount of adsorbed protein and the resulting loss of catalytic activity were found to be independent of the specific surface areas yet were influenced by the electrical properties of the mineral surfaces. Under the experimental conditions, montmorillonite and kaolinite are negatively charged whereas goethite is positively charged. However, because of the adsorption of phosphate anions from the buffer, a charge reversal took place at the surface of goethite. This was confirmed by zeta (ζ)-potential measurements in phosphate buffer, revealing negative values for all the tested minerals. Indeed goethite interacted with the enzyme as a negatively charged surface: the amount of adsorbed protein and the resulting catalytic activity loss were very similar to those of kaolinite. Our results show that, even if an important fraction of β-glucosidase is adsorbed to the minerals, the catalytic activity is largely retained. We suggest that this strong activity retention in presence of soil minerals results from a selective pressure on A. niger, which benefits from the activity of the adsorbed, and thus stabilized, enzyme pool.     

Combined effects of plant growth‐promoting rhizobacteria and genistein on nitrogen fixation in soybean at suboptimal root zone temperatures

Application of plant growth‐promoting rhizobacteria (PGPR) or the plant to bacteria signal molecule genistein has been shown to increase nodulation and nitrogen (N) fixation by soybean [Glycine max (L.) Merr.] over a range of root zone temperatures (RZTs) and, specifically, off‐sets at least some of the ill‐effects of low RZTs. Two sets of controlled‐environment experiments, one on a growth bench and the other in a greenhouse, were conducted to examine the combined ability of both PGPR and genistein to reduce the negative effects of low RZT on soybean nodulation and N fixation. Each of two the PGPR strains, Serratia proteamaculans 1–102 and Serratia liquefaciens 2–68 were co‐inoculated with Bradyrhizobium japonicum USDA 110 preincubated with 17.5 (somewhat inhibitory), and 15°C (very inhibitory). At RZTs of 25 and 17.5°C PGPR strains and genistein in combination increased the number of nodules and the amount of Nn fixed. The most stimulatory effect was observed at 17.5°C for the combination: S. proteamaculans 1–102 plus B. japonicum USDA 110 pre‐incubated in 15 μM genistein under greenhouse conditions. For most treatment combinations the stimulatory effects of PGPR and genistein were additive at RZTs of 17.5 and 25°C. Surprisingly, the combination of these two factors resulted in antagonism at the very inhibitory RZT of 15°C. The results suggest that the negative effects of certain low RZTs could be more effectively off‐set by combined treatments of PGPR plus geneistin pre‐incubation of rhizobial cultures than by their individual treatment.     

The effects of biocidal treatments on metabolism in soil—II. Gamma irradiation,autoclaving, air-drying and fumigation

Respiration and mineralisation of N were measured in a set of contrasting soils that had either been autoclaved, air-dried, fumigated (with chloroform or methyl bromide) or exposed to gamma radiation. The soils used were a manured and an unmanured arable soil, an acid and a neutral woodland soil, an arable sandy soil and an organic soil under grass. With the exception of the acid woodland soil, the flushes of decomposition (i.e. the increases in O₂ consumption, CO₂ evolution and N mineralisation that occurred when the treated soil was inoculated and incubated for 10 days) were in the order: air-drying < CH₃Br ? CHCl₃ < irradiation < autoclaving. All of the treatments, except air-drying, decreased the ratio (C mineralised after treatmcnt)/(N mineralised after treatment). All of the treatments increased the amount of 1N K₂SO₄ extractable organic C, autoclaving causing by far the greatest increase.Neither of the fumigants increased respiration in the acid soil over the whole 10 day period, although N mineralisation was slightly increased. Irradiation, air-drying and autoclaving did, however, produce a flush in the acid soil, the order being: irradiation < air-drying < autoclaving. A soluble substrate, extracted from yeast cells by ultrasonic disintegration, decomposed to about the same extent in neutral and in acid soil. When ¹⁴C labelled glucose was added to the acid soil and incubated for 52 days, the retention of labelled C was slightly greater (31·6%) than in a comparable near-neutral soil (28·8%). However, the flush that followed fumigation of the acid soil was only half that in the near-neutral soil, suggesting that less biomass is formed under acid conditions. Liming increased the size of the flush in an acid soil.For soils from the same field but under different management, the size of the flush caused by CHCl₃ is in the order: grassland > cropped arable > bare fallow. The flush is much more sensitive to differences in soil management than is the total amount of soil organic matter; a fallowed soil lost half its organic C in 10 yr whereas the increase in respiration that followed fumigation fell to one-seventh its original value. Two Nigerian soils behaved similarly; a soil that had been 2 years under cultivation contained only 16% less total organic C than an adjacent soil still under secondary forest, yet the flush in the cultivated soil was half that in the forest soil. The amount of substrate metabolised during the flush is thus very sensitive to changes in soil management that alter the amount of fresh organic matter entering the soil each year.     

Phosphorus‐deficiency effects on response of symbiotic N2 fixation and carbohydrate status in soybean to atmospheric CO2 enrichment

The impact of phosphorus (P) deficiency on response of symbiotic N₂ fixation and carbohydrate accumulation in soybean (Glycine max [L.] Merr.) to atmospheric CO₂ enrichment was examined. Plants inoculated with Bradyrhizobium japonicum MN 110 were grown in growth chambers with controlled atmospheres of 400 and 800 μL CO₂ L^‐1 and supplied either 1.0 mM‐P (P‐sufficient) or 0.05 mM‐P (P‐deficient) nitrogen (N)‐free nutrient solution. When plants were supplied with sufficient P, CO₂ enrichment significantly increased whole plant dry mass (83%), nodule mass (67%), total nitrogenase activity (58%), and N (35%) and P (47%) accumulation at 35 days after transplanting (DAT). Under sufficient P supply, CO₂ enrichment significantly increased starch concentrations in nodules compared to the normal atmospheric CO₂ treatment. Under normal CO₂ levels (400 μL L^‐1) nonstructural carbohydrate concentration (starch plus soluble sugar) was significantly higher in leaves of P‐deficient plants than in leaves of P‐sufficient plants in which nonstructural carbohydrate concentration exhibited a strong diurnal pattern. Under deficient P supply whole plant dry mass, symbiotic N₂‐fixation parameters, and N and P accumulation were not enhanced by atmospheric CO₂ enrichment. Phosphorus deficiency decreased nonstructural carbohydrate accumulation in nodules at the end of a 10‐day period in which functional activity was developing by 86% relative to P‐sufficient controls. While P deficiency elicited significant increases in the nonstructural carbohydrate concentration in leaves, it caused significant decreases in the nonstructural carbohydrate concentration in nodules over the diurnal cycle from 30 to 31 DAT. Collectively, these results indicate that the lack of a symbiotic N₂‐fixation response to atmospheric CO₂ enrichment by P‐deficient plants may be related to the decreased carbohydrate status of nodules.     

Ellagic acid inhibits oxidized low-density lipoprotein (OxLDL)-induced metalloproteinase (MMP) expression by modulating the protein kinase C-α/extracellular signal-regulated kinase/peroxisome proliferator-activated receptor γ/nuclear factor-κB (PKC-α/ERK/PPAR-γ/NF-κB) signaling pathway in endothelial cells

Previous studies have shown that vascular endothelium-derived matrix metalloproteinases (MMPs) contribute to the destabilization of atherosclerotic plaques, a key event triggering acute myocardial infarction. In addition, studies have reported that the PKC-MEK-PPARγ signaling pathway is involved in oxidized low-density lipoprotein (oxLDL)-induced expression of MMPs. Ellagic acid, a phenolic compound found in fruits and nuts, has potent antioxidant, anti-inflammatory, and anticancerous properties. However, the molecular mechanisms underlying its antiatherogenic effects remain to be clarified. This study aimed to assess whether the effects of ellagic acid on the fibrotic markers MMP-1 and MMP-3 are modulated by the PKC-ERK-PPAR-γ signaling pathway in human umbilical vein endothelial cells (HUVECs) that have been exposed to oxLDL. It was found that ellagic acid significantly inhibited oxLDL-induced expressions of MMP-1 and MMP-3. Pretreatment with ellagic acid and DPI, a well-known ROS inhibitor, attenuated the oxLDL-induced expression and activity of PKC-α. In addition, ellagic acid as well as pharmacological inhibitors of ROS, calcium, and PKC strongly suppressed the oxLDL-induced phosphorylation of extracellular signal-regulated kinase (ERK) and NF-κB activation. Moreover, ellagic acid ameliorated the oxLDL-induced suppression of PPAR-γ expression. In conclusion, the data suggest that ellagic acid elicits its protective effects by modulating the PKC-α/ERK/PPAR-γ/NF-κB pathway, resulting in the suppression of ROS generation and, ultimately, inhibition of MMP-1 and MMP-3 expression in HUVECs exposed to oxLDL.     

Antioxidant activity and protective effect of anthocyanin oligomers on H₂O₂-triggered G2/M arrest in retinal cells

In this study, the free-radical-scavenging properties of anthocyanin oligomers for 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, alkyl radical, and hydroxyl radical were evaluated using electron spin resonance (ESR) spectroscopy. The DPPH radical, alkyl radical, and hydroxyl radical scavenging activity of anthocyanin oligomers increased in a dose-dependent manner, with the 50% inhibitory concentration (IC??) value of 13.0, 14.0, and 448.0 μg/mL, respectively. The inhibitory effect of anthocyanin oligomers on lipid peroxidation was examined with ferric thiocyanate (FTC) and thiobarbituric acid (TBA). The inhibitory activity of anthocyanin oligomers was found to be comparable to that of vitamin E. In addition, anthocyanin oligomers enhanced the activities of superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), glutathione peroxidase (GPx, EC 1.11.1.9), and glutathione-S-transferase (GST, EC 2.5.1.18) in ARPE-19 cells. In addition, anthocyanin oligomers inhibited the H?O?-induced G2/M phase arrest in ARPE-19 cells. Taken together, the present results demonstrate that anthocyanin oligomers have high antioxidative activity.