Comparison of flavonoids and isoflavonoids as antioxidants

Quantitative analysis combined with chromatographic fingerprint for comprehensive evaluation of Xiaoer Chaigui Tuire granules by HPLC-DAD

Quantitative analysis of eight major components combined with chromatographic fingerprint based on high performance liquid chromatography coupled with diode array detector (HPLC-DAD) was developed for the quality evaluation of Xiaoer Chaigui Tuire granules (XCTG), a traditional Chinese medicine (TCM) preparation. Each compound was analyzed by comparing its retention time and UV spectrum of each chromatographic peak with the corresponding retention time and UV spectrum of each standard compound. Baseline separation was achieved on an Agilent Zorbax SB-C18 column with gradient elution of acetonitrile and 0.1% (v/v) phosphoric acid. The developed method was validated by linearity, precision, repeatability, stability and recovery and was subsequently applied to quality evaluation of 12 batches of XCTG with similarity analysis, principal component analysis and cluster analysis. Quantitative analysis combined with HPLC fingerprint could offer an efficient, reliable and practical approach for quality evaluation of XCTG.

Seed metabolomic study reveals significant metabolite variations and correlations among different soybean cultivars

Soybean [Glycine max (L.) Merr.] is one of the world's major crops, and soybean seeds are a rich and important resource for proteins and oils. While "omics" studies, such as genomics, transcriptomics, and proteomics, have been widely applied in soybean molecular research, fewer metabolomic studies have been conducted for large-scale detection of low molecular weight metabolites, especially in soybean seeds. In this study, we investigated the seed metabolomes of 29 common soybean cultivars through combined gas chromatography-mass spectrometry and ultra-performance liquid chromatography-tandem mass spectrometry. One hundred sixty-nine named metabolites were identified and subsequently used to construct a metabolic network of mature soybean seed. Among the 169 detected metabolites, 104 were found to be significantly variable in their levels across tested cultivars. Metabolite markers that could be used to distinguish genetically related soybean cultivars were also identified, and metabolite-metabolite correlation analysis revealed some significant associations within the same or among different metabolite groups. Findings from this work may potentially provide the basis for further studies on both soybean seed metabolism and metabolic engineering to improve soybean seed quality and yield.

Nature and consequences of non-covalent interactions between flavonoids and macronutrients in foods

Many of the potential health benefits of flavonoids have been associated with their specific chemical and biological properties including their ability to interact and bind non-covalently to macronutrients in foods. While flavonoid-protein interactions and binding have been the subject of intensive study, significantly less is understood about non-covalent interactions with carbohydrates and lipids. These interactions with macronutrients are likely to impact both the flavonoid properties in foods, such as their radical scavenging activity, and the food or beverage matrix itself, including their taste, texture and other sensorial properties. Overall, non-covalent binding of flavonoids with macronutrients is primarily driven by van der Waals interactions. From the flavonoid perspective, these interactions are modulated by characteristics such as degree of polymerization, molecular flexibility, number of external hydroxyl groups, or number of terminal galloyl groups. From the macronutrient standpoint, electrostatic and ionic interactions are generally predominant with carbohydrates, while hydrophobic interactions are generally predominant with lipids and mainly limited to interactions with flavonols. All of these interactions are involved in flavonoid-protein interactions. While primarily associated with undesirable characteristics in foods and beverages, such as astringency, negative impact on macronutrient digestibility and hazing, more recent efforts have attempted to leverage these interactions to develop controlled delivery systems or strategies to enhance flavonoids bioavailability. This paper aims at reviewing the fundamental bases for non-covalent interactions, their occurrence in food and beverage systems and their impact on the physico-chemical, organoleptic and some nutritional properties of food.

Flavonoids from tartary buckwheat induce G2/M cell cycle arrest and apoptosis in human hepatoma HepG2 cells

The cytotoxicity and antioxidant activity on human hepatoma cell line HepG2 of three flavonoids homogenous compounds from tartary buckwheat seeds and bran, namely quercetin, isoquercetin, and rutin, were investigated. The total antioxidant competency detection results indicated that the antioxidant capacity of quercetin was the strongest in a biological response system. A [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay showed that quercetin exhibited the strongest cytotoxic effects against the HepG2 cell line. Flow cytometric analysis indicated that quercetin significantly increased the production of reactive oxygen species, and led to the G2/M phase arrest accompanied by an increase of apoptotic cell death after 48 h of incubation. Quercetin-induced cell apoptosis was shown to involve p53 and p21 up-regulation, Cyclin D1, Cdk2, and Cdk7 down-regulation. These results suggested that the induction of G2/M arrest, apoptosis, and cell death by quercetin may associate with increased expression of p53 and p21, decrease of Cyclin D1, Cdk2, and Cdk7 levels, and generation of reactive oxygen species in cells. This study will help to better understand and fully utilize medicinal resources of plant flavonoids.

Sophoricoside fails the embryo implantation by compromising the uterine endometrial receptivity at implantation "window" of pregnant mice

Sophoricoside (SOPH) is an isoflavone glycoside isolated from the fruits of Sophora japonica. Since its first isolation in 1961, there are rare findings about the effects of SOPH on reproductive system. In the present study, the pregnant mice administrated by different doses of SOPH were used to explore the effect of SOPH on embryo implantation, especially on the endometrial receptivity. The statistical results showed that the number of implanted embryos was gradually declining along the increasing dose of SOPH. When the administrated dose of SOPH was 600 mg/kg per day, great changes were observed in the exposed uterine morphology and up-regulated progesterone receptor (PR) and down-regulated estrogen receptor α (ERα), E-cadherin, matrix metalloproteinase-2 (MMP-2) and integrin β3 were also found in SOPH-exposed uterine. These findings demonstrated that SOPH exposure reduced the number of implanted embryos in a dose-dependent manner and failed the embryo implantation through altering the morphology of uterine and compromising the endometrial receptivity.

Apigenin has anti-atrophic gastritis and anti-gastric cancer progression effects in Helicobacter pylori-infected Mongolian gerbils

ETHNOPHARMACOLOGICAL RELEVANCE

Apigenin, one of the most common flavonoids, is abundant in celery, parsley, chamomile, passionflower, and other vegetables and fruits. Celery is recognized as a medicinal vegetable in Oriental countries to traditionally treat inflammation, swelling, blood pressure, serum lipid, and toothache. In this study, we investigated apigenin treatment effects on Helicobacter pylori-induced atrophic gastritis and gastric cancer progression in Mongolian gerbils.

MATERIALS AND METHODS

Five to eight-week-old Mongolian gerbils were inoculated with Helicobacter pylori for four weeks without (atrophic gastritis group) or with N'-methyl-N'-nitro-N-nitroso-guanidine (MNNG) (gastric cancer group) in drinking water, and were then rested for two weeks. During the 7th-32th (atrophic gastritis group) or the 7th-52th (gastric cancer group) weeks, they were given various doses (0-60 mg/kgbw/day) of apigenin. At the end of the 32th (atrophic gastritis group) or the 52th (atrophic gastritis group) week, all Mongolian gerbils were sacrificed using the CO2 asphyxia method. The histological changes of Helicobacter pylori colonization, neutrophil and monocyte infiltrations, and atrophic gastritis in both atrophic gastritis and gastric cancer Mongolian gerbils were examined using immunohistochemistry stain and Sydney System scoring.

RESULTS

Apigenin treatments (30-60 mg/kgbw/day) effectively decreased atrophic gastritis (atrophic gastritis group) and dysplasia/gastric cancer (gastric cancer group) rates in Mongolian gerbils. Apigenin treatment (60 mg/kgbw/day) significantly decreased Helicobacter pylori colonization and Helicobacter pylori-induced histological changes of neutrophil and monocyte infiltrations and atrophic gastritis in both atrophic gastritis and gastric cancer Mongolian gerbils.

CONCLUSIONS

Apigenin has the remarkable ability to inhibit Helicobacter pylori-induced atrophic gastritis and gastric cancer progression as well as possessing potent anti-gastric cancer activity.

Antioxidant activity of selected natural polyphenolic compounds from soybean via peroxyl radical scavenging

Excellent antioxidantsviaSPLET in aqueous solution, moderate antioxidantsviaHAT in lipid medium.

On the radical scavenging activity of isoflavones: thermodynamics of O-H bond cleavage

We have performed Density Functional Theory B3LYP/6-311++G** calculations of reaction enthalpies of antioxidant action mechanisms for nine isoflavones. O-H bond dissociation enthalpies, ionization potentials, proton dissociation enthalpies, proton affinities and electron transfer enthalpies related to Hydrogen Atom Transfer (HAT), Single Electron Transfer-Proton Transfer (SET-PT) and Sequential Proton-Loss Electron-Transfer (SPLET) mechanisms were investigated in gas- and solution-phases. Studies on the radical scavenging ability of isoflavones, contrary to various flavonoids, are still scarce. Thus, understanding of its thermodynamics can be considered beneficial. The selection of isoflavones (daidzein, formononetin, genistein, biochanin A, prunetin, 6-hydroxydaidzein, glycitein, orobol and santal) enables us to evaluate the effects of various structural features, such as the presence of methoxy (4'-OMe, 6-OMe, 7-OMe) and hydroxy (3'-OH, 5-OH, 6-OH) groups, on studied reaction enthalpies. The obtained results show that HAT can be attributed predominantly to the B ring, while SPLET takes place preferentially in the A ring, as was also indicated in experimental works.

Class III peroxidases are activated in proanthocyanidin-deficient Arabidopsis thaliana seeds

BACKGROUND AND AIMS

It has previously been shown that proanthocyanidins (PAs) in the seed coat of Arabidopsis thaliana have the ability to scavenge superoxide radicals (O2(-)). However, the physiological processess in PA-deficit seeds are not clear. It is hypothesized that there exist alternative ways in PA-deficient seeds to cope with oxidative stress.

METHODS

The content of hydrogen peroxide (H2O2) and its relevance to the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidases was investigated in both wild-type and PA-deficit mutant seeds. A biochemical staining approach was used to detect tissue localizations of peroxidase activities in PA-deficit mutant seeds.

KEY RESULTS

PA-deficient mutants possess significantly lower levels of H2O2 than the wild-type, despite their higher accumulation of superoxide radicals. Screening of the key antioxidant enzymes revealed that peroxidase activity was significantly over-activated in mutant seeds. This high peroxidase activity was mainly confined to the seed coat zone. Interestingly, neither ascorbate peroxidase nor glutathione peroxidase, just the guaiacol peroxidases (class III peroxidases), was specifically activated in the seed coat. However, no significant difference in peroxidase activity was observed in embryos of either mutants or the wild-type, although gene expressions of several candidate peroxidases were down-regulated in the embryos of PA-deficient seeds.

CONCLUSIONS

The results suggest that enhanced class III peroxidase activity in the seed coat of PA-deficient mutants is an adaptive strategy for seed development and survival.

Quercetin and daidzein β-apo-14'-carotenoic acid esters as membrane antioxidants

Esterification by β-apo-14'-carotenoic acid was found to have opposite effects on antioxidant activity of quercetin (at B4', B3' hydroxyl) as of daidzein (at A7 hydroxyl) in phosphatidylcholine liposomes. The daidzein ester had increased activity, while quercetin had a significant decreased activity. Quantum mechanical calculations using density function theory (DFT) indicate a modest decrease in bond dissociation enthalpy, BDE, for (weakest) hydrogen-oxygen phenolic bond in daidzein from 368.4 kJ · mol(- 1) to 367.7 kJ · mol(- 1) compared to a significant increase in quercetin from 329.5 kJ · mol(- 1) to 356.6 kJ · mol(- 1) upon derivatization. These opposite changes in tendency for hydrogen atom transfer from phenolic groups to lipid radicals combined with an increase in A-to-B dihedral angle from 0.0° to 36.4° and in dipole moment from 0.40 D to 6.01 D for quercetin upon derivatization, while less significant for daidzein (36.4°-36.7° and 3.26 D-7.87 D, respectively), together provide a rationale for the opposite effect of esterification on antioxidation.

The influence of common metal ions on the interactions of the isoflavone genistein with bovine serum albumin

The interaction of genistein with bovine serum albumin (BSA) has been characterized via UV-vis, fluorescence spectroscopy and Circular Dichroism (CD) measurements under physiological conditions. In this study, we have investigated the effect of some common metal ions on the binding of genistein with BSA using fluorescence studies. The fluorescence data reveal that the binding affinity of genistein to BSA increases in presence of certain metal ions. The possibility of non-radiative energy transition from the donor tryptophan to the acceptor genistein has been observed in absence and presence of metal ions. The observed similarities in the values of efficiency of energy transfer (E) and the separation between the donor and acceptor (r) in both the cases may be correlated with the complexation between the genistein and metal ions, which is also observed from the UV-vis studies. The changes in enthalpy (ΔH°) and entropy (ΔS°) of the interaction were found to be -14.64 kJ mol(-1) and +42.75 J mol(-1)K(-1) respectively. These values indicate the involvement of electrostatic interactions along with a hydrophobic association that results in a positive entropy change. CD analysis shows that there is a slight increase in the% α-helical content of BSA on binding with genistein at lower molar ratios. Warfarin and ibuprofen displacement studies in accordance with the molecular docking show that genistein binds to site I (subdomain IIA) of BSA.

In vitro anti-inflammatory effect of apigenin in the Helicobacter pylori-infected gastric adenocarcinoma cells

Infection with Helicobacter pylori causes extensive gastric epithelial cell inflammation which may progress to atrophic gastritis, intestinal metaplasia, and even gastric adenocarcinoma. Apigenin (4',5,7-trihydroxyflavone) is widely distributed in fruits and vegetables, and is a well-known antiinflammatory supplement with low cytotoxicity. In this study, we investigated the anti-inflammatory effects of apigenin in H. pylori-infected MKN45 cells, for which IκBα, cyclooxygenase-2 (COX-2), intercellular adhesion molecule-1 (ICAM-1), reactive oxygen species (ROS), interleukin-8 (IL-8), IL-6, IL-1β, and mucin-2 (MUC-2) expressions were examined. Apigenin treatments (9.3-74 μM) significantly increased the IκBα expression, and thus inhibited nuclear factor kappa B (NF-κB) activation, and the inflammatory factor (COX-2, ICAM-1, ROS, IL-6, and IL-8) expressions decreased. The ROS levels decreased partially based on the intrinsic scavenging property of apigenin. In summary, apigenin treatments effectively inhibited NF-κB activation and the related inflammatory factor expressions, as well as increased MUC-2 expression in the H. pylori-infected MKN45 cells. The compound shows great potential as a candidate agent for the inhibition of H. pylori-induced extensive gastric epithelial cell inflammation.

Dietary flavonoid genistein induces Nrf2 and phase II detoxification gene expression via ERKs and PKC pathways and protects against oxidative stress in Caco-2 cells

SCOPE

Flavonoids have well-known antioxidant, anti-inflammatory, and anti-cancer activities. Isoflavone genistein is considered a potent antioxidant agent against oxidative stress. Although several mechanisms have been proposed, a clear antioxidant mechanism of genistein is still remained to be answered.

METHODS AND RESULTS

In this study, we focused on the concerted effects on expression of Nrf2 and phase II enzyme pathway components. Transient transfection assays, RT-PCR and immunoblot analysis were performed to study its molecular mechanisms of action. In Caco-2 cells, treatment with genistein markedly attenuated H(2)O(2) -induced peroxide formation; this amelioration was reversed by buthionine sulfoximine(GCLC inhibitor) and zinc protoporphyrin(HO-1 inhibitor). Genistein increased HO-1 and GCLC mRNA and protein expression. Genistein treatment activated the ERK1/2 and PKC signaling pathway; therefore increased Nrf2 mRNA and protein expression. The roles of the ERK1/2 and PKC signaling pathway were determined using PD98059 (ERK1/2 inhibitor) and GF109203X (PKC inhibitor) and RNA interference directed against Nrf2. Both inhibitors and siNrf2 abolished genistein-induced HO-1 and GCLC protein expression. These results suggest the involvement of ERK1/2, PKC, and Nrf2 in inducing HO-1 and GCLC by genistein.

CONCLUSION

Our studies show that genistein up-regulated HO-1 and GCLC expression through the EKR1/2 and PKC /Nrf2 pathways during oxidative stress.

Apigenin attenuates copper-mediated β-amyloid neurotoxicity through antioxidation, mitochondrion protection and MAPK signal inactivation in an AD cell model

Apigenin, belonging to a less toxic and non-mutagenic flavone subclass of flavonoids, has been reported to possess numerous biological activities beneficial to health. Although evidence has shown apigenin might exert its protective effects by reducing the toxicity induced by amyloid-β peptides (Aβ), the precise mechanism is unclear. In the present study, we investigated the in vitro neuroprotective activity of apigenin interrelated with amyloid toxicity and mental homeostasis in an Alzheimer's disease (AD) cell model and explored its potential signal transduction. Our results showed that apigenin protected neurons against Aβ-mediated toxicity induced by copper, which was characterized by increasing neuronal viability and relieving mitochondrial membrane dissipation and neuronal nuclear condensation. Further, we demonstrated that apigenin did not provide sufficient effect on decreasing β-amyloid precursor protein (AβPP) expression and lowering Aβ(1-42) secretion, but conserved redox balance by increasing intracellular glutathione levels and enhancing cellular superoxide dismutase and glutathione peroxidase activities, reduced intracellular reactive oxygen species (ROS) generation, blocked ROS-induced p38 mitogen-activated protein kinases (p38 MAPK)- MAPKAP kinase-2 (MK2)-heat shock protein 27 (Hsp27) and stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK)-c-Jun signaling pathways, preserved mitochondrial function, and then regulated apoptotic pathways. In conclusion, apigenin could exert neuroprotection against Aβ-induced toxicity in the presence of copper mainly through the mechanisms that regulate redox imbalance, preserve mitochondrial function, inhibit MAPK pathways, and depress neuronal apoptosis.

FTIR, (1)H NMR and EPR spectroscopy studies on the interaction of flavone apigenin with dipalmitoylphosphatidylcholine liposomes

Apigenin (5,7,4'-trihydroxyflavone) is a cancer chemopreventive agent and a member of the family of plant flavonoids. Apigenin interaction with liposomes formed with dipalmitoylphosphatidylcholine (DPPC) was investigated by means of FTIR spectroscopy, (1)H NMR and EPR techniques. Fluorescent microscopy and electron microscopy were applied to study the apigenin effects on colon myofibroblasts and human skin fibroblasts. The strong rigidifying effect of apigenin with respect to polar head groups was concluded on the basis of the action of the flavone on partition coefficient of Tempo spin label between the water and lipid phases. The ordering effect was also found in hydrophobic region at the depth monitored by 5-SASL and 16-SASL spin labels. The inclusion of apigenin to the membrane restricted the motional freedom of polar head groups lowering penetration of Pr(3+) ions to the membranes. The (1)H NMR technique supported also the restriction of motional freedom of the membrane in the hydrophobic region, especially in the zone of CH(2) groups of alkyl chains. FTIR analysis showed that apigenin incorporates into DPPC liposomes via hydrogen bonding between its own hydroxyl groups and lipid polar head groups in the C-O-P-O-C segment. It is also very likely that hydroxyl groups of apigenin link with polar groups of DPPC by water bridges. Electron and fluorescence microscopic observations revealed changes in the internal membrane organization of the examined cells. In conclusion, the changes of the structural and dynamic properties of membranes can be crucial for processes involving tumor suppression signal transduction pathways and cell cycle regulation.

Concentration-dependent effects of the soy phytoestrogen genistein on the proteome of cultured cardiomyocytes

The soy-derived phytoestrogen genistein (GEN) has received attention for its potential benefits on the cardiovascular system by providing direct protection to cardiomyocytes against pathophysiological stresses. Here, we employed a proteomic approach to study the concentration-dependent effects of GEN treatments on cardiomyocytes. Cultured HL-1 cardiomyocytes were treated with low (1μM) and high (50μM) concentrations of GEN. Proteins were pre-fractionated by sequential hydrophilic/hydrophobic extraction and both protein fractions from each treatment group were separated by 2D gel electrophoresis (2DE). Overall, approximately 2,700 spots were visualized on the 2D gels. Thirty-nine and 99 spots changed in volume relative to controls (p<0.05) following the low- and high-concentration GEN treatments, respectively. From these spots, 25 and 62 protein species were identified by ESI-MS/MS and Mascot database searching, respectively. Identified proteins were further categorized according to their functions and possible links to cardioprotection were discussed. MetaCore gene ontology analysis suggested that 1μM GEN significantly impacted the anti-apoptosis process, and that both the low and high concentrations of GEN influenced the glucose catabolic process and regulation of ATPase activity. This proteomics study provides the first global insight into the molecular events triggered by GEN treatment in cardiomyocytes.

Design, synthesis, and analysis of the quantitative structure-activity relationships of 4-phenyl-acyl-substituted 3-(2,5-dimethylphenyl)-4-hydroxy-1-azaspiro[4.5]dec-3-ene-2,8-dione derivatives

A series of 4-phenyl-acyl-substituted 3-(2,5-dimethylphenyl)-4-hydroxy-1-azaspiro[4.5]dec-3-ene-2,8-dione derivatives were designed and synthesized, and their structures were characterized using (1)H NMR (or (13)C NMR), mass spectrometry, and elemental analysis. The bioactivities of the new compounds were evaluated. These compounds exhibited good inhibition activities against bean aphids (Aphis fabae) and carmine spider mite (Tetranychus cinnabarinus), and 4-phenyl acyl esters showed stronger bioactivity than 4-arylesterases and alkyl esters. The results showed that compound 8-I-e, which contains a para-methoxy group on the phenyl acyl, and compound 8-I-m, which contains a para-trifluoromethyl group on the phenyl acyl, displayed potent insecticidal activity against A. fabae and T. cinnabarinus respectively. The insecticidal activity showed a clear structure-activity relationship, confirming the importance of the flexible bridge. The DFT/B3LYP/6-31(d) level method was used to calculate molecular geometries and electronic descriptors. These factors included total energy, charge distribution, and the linear orbital level of the title compounds. Quantitative structure-activity relationship studies were performed on these compounds using quantum-chemical and physicochemical parameters as independent variables and insecticidal activity as a dependent variable. Insecticidal activity was most closely correlated (r > 0.8) with quantum chemical and physicochemical parameters.

Biotransformation of sophoricoside in Fructus sophorae by the fungus Schizophyllum commune

Biotransformation of sophoricoside in Fructus sophorae was performed with Schizophyllum commune. Sophoricoside was firstly metabolized to 4',5,7-trihydroxyisoflavone (2), and then to 4',7-dihydroxy-5-methoxyisoflavone (3) and 5,7-dihydroxy-4'-methoxyisoflavone (4) as determined by NMR and MS analyzes. The content of compound (2) was increased by more than 30-fold, and compound (3) is a new product that showed good cytotoxic activity with an IC(50) of 12.1 nmol/ml against MCF-7 cells.

Modulation of anti-oxidation ability by proanthocyanidins during germination of Arabidopsis thaliana seeds

Proanthocyanidins (PAs) as the end products of flavonoid biosynthetic pathway mainly accumulate in seed coat but their biological function is largely unknown. We studied the anti-oxidation ability in seed coat and germination changes under externally applied oxidative stresses in PAs-deficient mutants of Arabidopsis. Germination of PAs-deficient mutant seeds was faster than that of wild-type under low or no oxidative stress, suggesting a PAs-induced inhibition of germination. When the applied oxidative stress was high, germination of PAs-deficient mutants was lower than that of wild-type, suggesting a loss of PAs-related anti-oxidation ability in the mutants. Using ABA signaling mutants, our studies demonstrated that both ABA signaling pathway and PAs were important for the response to serve oxidative stress during seed germination. However, the discrepancy of the response between abi mutants and PAs mutants to oxidative stress suggests that ABA signaling pathway may not play a major role in PAs' action in alleviating oxidative stress. Under low or no oxidative stress, germination was mainly determined by the ABA content in seed and the PAs-deficient mutant seeds germinated faster due to their lower ABA content than wild-type. However, oxidative injury inhibited germination when PAs-deficient seeds germinated under high oxidative stress. Wild-type exhibited higher germination under the high oxidative stress due to the PAs' anti-oxidation ability. Oxidative stress applied externally led to changes in endogenous PAs contents that coincided with the expression changes of PAs biogenesis genes. PAs modulated the activities of some key enzymes that controlled the levels of reactive oxygen species and the anti-oxidation capacity during the seed germination. This work suggests that PAs contribute to the adaptive mechanism that helps germination under environmental stresses by playing dual roles in both germination control and anti-oxidation reaction.

Reaction dynamics of flavonoids and carotenoids as antioxidants

Flavonoids and carotenoids with rich structural diversity are ubiquitously present in the plant kingdom. Flavonoids, and especially their glycosides, are more hydrophilic than most carotenoids. The interaction of flavonoids with carotenoids occurs accordingly at water/lipid interfaces and has been found important for the functions of flavonoids as antioxidants in the water phase and especially for the function of carotenoids as antioxidants in the lipid phase. Based on real-time kinetic methods for the fast reactions between (iso)flavonoids and radicals of carotenoids, antioxidant synergism during protection of unsaturated lipids has been found to depend on: (i) the appropriate distribution of (iso)flavonoids at water/lipid interface, (ii) the difference between the oxidation potentials of (iso)flavonoid and carotenoid and, (iii) the presence of electron-withdrawing groups in the carotenoid for facile electron transfer. For some (unfavorable) combinations of (iso)flavonoids and carotenoids, antioxidant synergism is replaced by antagonism, despite large potential differences. For contact with the lipid phase, the lipid/water partition coefficient is of importance as a macroscopic property for the flavonoids, while intramolecular rotation towards coplanarity upon oxidation by the carotenoid radical cation has been identified by quantum mechanical calculations to be an important microscopic property. For carotenoids, anchoring in water/lipid interface by hydrophilic groups allow the carotenoids to serve as molecular wiring across membranes for electron transport.

Apigenin-induced suicidal erythrocyte death

Apigenin, a flavone in fruits and vegetables, stimulates apoptosis and thus counteracts cancerogenesis. Erythrocytes may similarly undergo suicidal cell death or eryptosis, characterized by cell shrinkage and phosphatidylserine exposure at the cell surface. Triggers of eryptosis include increase of cytosolic Ca(2+) activity ([Ca(2+)](i)), ceramide formation and ATP depletion. The present study explored the effect of apigenin on eryptosis. [Ca(2+)](i) was estimated from Fluo3-fluorescence, cell volume from forward scatter, phosphatidylserine exposure from annexin V binding, hemolysis from hemoglobin release, ceramide utilizing antibodies, and cytosolic ATP with luciferin-luciferase. A 48 h exposure to apigenin significantly increased [Ca(2+)](i) (≥ 1 μM), increased ceramide formation (15 μM), decreased ATP concentration (15 μM), decreased forward scatter (≥ 1 μM), and increased annexin V binding (≥ 5 μM) but did not significantly modify hemolysis. The effect of 15 μM apigenin on annexin V binding was blunted by Ca(2+) removal. The present observations reveal novel effects of apigenin, i.e. stimulation of Ca(2+) entry, ceramide formation and ATP depletion in erythrocytes with subsequent triggering of suicidal erythrocyte death, paralleled by cell shrinkage and phosphatidylserine exposure.

Chain length effects in isoflavonoid daidzein alkoxy derivatives as antioxidants: a quantum mechanical approach

Daidzein, an isoflavonoid with known prooxidative effects in heterogeneous lipid/water systems, changes to an antioxidant for 7-n-alkoxy derivatives of daidzein. For an alkyl length increasing from 4 to 8, 12, and 16 carbons, the oxidation potential decreases gradually from 1.09 V (vs NHE) for daidzein (D) to 0.94 V for D16 in tetrahydrofuran as determined by cyclic voltammetry at 25 °C. The prooxidative effects transform into antioxidative effects from D8 with a maximal effect for D12 for aqueous phase initiation of lipid oxidation in liposomes despite a gradual decrease in Trolox equivalent antioxidant capacity (TEAC) with increasing alkyl chain length. Quantum mechanical calculations using density functional theory (DFT) showed that the bond dissociation energy of the O-H bond of the 4'-phenol is constant along the homologue series in contrast to Δμ, the change in dipole moment upon hydrogen atom donation, which increases for increasing chain length. The frontier orbital energy gap goes through a maximum for D12. The change in the A-to-B dihedral angle upon hydrogen atom donation further shows a maximum for D12 of 6.45°. The importance of these microscopic properties for antioxidative activity was confirmed by a change in liposome fluorescence anisotropy using a fluorescent probe showing maximal penetration into the lipid bilayer for D12 along the homologue series.

β-carotene radical cation addition to green tea polyphenols. Mechanism of antioxidant antagonism in peroxidizing liposomes

Green tea polyphenols, (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), and (-)-epigallocatechin gallate (EGCG), all showed antioxidative effect in liposomes for lipid oxidation initiated in the lipid phase (antioxidant efficiency EC > EGCG > ECG > EGC) or in the aqueous phase (EC ≫ EGC > EGCG > ECG) as monitored by the formation of conjugated dienes. For initiation in the lipid phase, β-carotene, itself active as an antioxidant, showed antagonism with the polyphenols (EC > ECG > EGCG > EGC). The Trolox equivalent antioxidant capacity (TEAC EGC > EGCG > ECG > EC) correlates with the lowest phenol O-H bond dissociation enthalpy (BDE) as calculated by density functional theory (DFT). Surface-enhanced Raman spectroscopy (SERS) was used to assess the reducing power of the phenolic hydroxyls in corroboration with DFT calculations. For homogeneous (1:9 v/v methanol/chloroform) solution, the β-carotene radical cation reacted readily with each of the polyphenol monoanions (but not with the neutral polyphenols) with a rate approaching the diffusion limit for EC as studied by laser flash photolysis at 25 °C monitoring the radical cation at 950 nm. The rate constant did not correlate with polyphenol HOMO/LUMO energy gap (DFT calculations), and β-carotene was not regenerated by an electron transfer reaction (monitored at 500 nm). It is suggested that the β-carotene radical cation is rather reacting with the tea polyphenols through addition, as further evidenced by steady-state absorption spectroscopy and liquid chromatography-mass spectroscopy (LC-MS), in effect preventing regeneration of β-carotene as an active lipid phase antioxidant and leading to the observed antagonism.

Medical radiation countermeasures for nuclear and radiological emergencies: Current status and future perspectives

Nuclear and radiological emergencies (NREs) occurred globally and recent incidences in India are indicating toward the need for comprehensive medical preparedness required both at incident site and hospitals. The enhanced threat attributed toward insurgency is another causative factor of worry. The response capabilities and operational readiness of responders (both health and non-health service providers) in contaminated environment need to be supported by advancement in R & D and technological efforts to develop prophylactics and radiation mitigators. It is essential to develop phase 1 alternatives of such drugs for unseen threats as a part of initial preparedness. At the incident site and hospital level, external decontamination procedures need to be standardized and supported by protective clothing and Shudika kits developed by INMAS. The medical management of exposure requires systematic approach to perform triage, resuscitation and curative care. The internal contamination requires decorporation agents to be administered based on procedural diagnostics. Various key issues pertaining to policy decisions, R & D promotion, community awareness, specialized infrastructure for NREs preparedness has been discussed. The present review is an attempt to provide vital information about the current status of various radiation countermeasures and future perspective(s) ahead.

Xenobiotic effects on ovarian preantral follicles

Women are born with a finite population of ovarian follicles, which are slowly depleted during their reproductive years until reproductive failure (menopause) occurs. The rate of loss of primordial follicles is determined by genetic and environmental influences, but certain toxic exposures can accelerate this process. Ionizing radiation reduces preantral follicle numbers in rodents and humans in a dose-dependent manner. Cigarette smoking is linked to menopause occurring 1-4 yr earlier than with nonsmokers, and components of smoke, polycyclic aromatic hydrocarbons, can cause follicle depletion in rodents or in ovaries in vitro. Chemotherapeutic agents, such as alkylating drugs and cisplatin, also cause loss of preantral ovarian follicles. Effects depend on dose, type, and reactivity of the drug, and the age of the individual. Evidence suggests DNA damage may underlie follicle loss induced by one common alkylating drug, cyclophosphamide. Occupational exposures have also been linked to ovarian damage. In an industrial setting, 2-bromopropane caused infertility in men and women, and it can induce ovarian follicle depletion in rats. Solvents, such as butadiene, 4-vinylcyclohexene, and their diepoxides, can also cause specific preantral follicle depletion. The mechanism(s) underlying effects of the latter compound may involve alterations in apoptosis, survival factors such as KIT/Kit Ligand, and/or the cellular signaling that maintains primordial follicle dormancy. Estrogenic endocrine disruptors may alter follicle formation/development and impair fertility or normal development of offspring. Thus, specific exposures are known or suspected of detrimentally impacting preantral ovarian follicles, leading to early ovarian failure.

Phenol acidity and ease of oxidation in isoflavonoid/β-carotene antioxidant synergism

Regeneration of β-carotene from the β-carotene radical cation by the 4'-propylpuerarin anion (second-order rate constant=1.5×10(9) L mol(-1) s(-1) in methanol/chloroform=1:9 (v/v) solution at 25 °C as determined by laser flash photolysis) was found to be marginally slower than regeneration by the 7-propylpuerarin anion (2.3×10(9) L mol(-1) s(-1)), in agreement with the 7-propylpuerarin anion being more reducing (E'=0.56 V vs NHE) than the 4'-propylpuerarin anion (E'=1.01 V vs NHE). The potentials were calculated from E°=1.12 and 1.44 V (vs NHE) as determined by cyclic voltametry in aqueous solution and pKa=9.51 and 7.23 obtained previously for 7-propylpuerarin and 4'-propylpuerarin, respectively. The less reducing but more acidic 4'-propylpuerarin showed less antioxidant activity in liposome of pH 7.4, but more significant antioxidant synergism with β-carotene than the more reducing but less acidic 7-propylpuerarin for oxidation initiated in the liposome lipid phase. Electrostatic effects are concluded to be important in the regeneration of β-carotene from the radical cation in the water/lipid interface because approximately 50% of 4'-propylpuerarin is present as the anion, whereas only 0.5% of 7-propylpuerarin is present as the anion. In contrast, penetration of the undissociated phenolic group into the lipid phase, more significant for 7-propylpuerarin than for 4'-propylpuerarin according to the calculated water/lipid partition coefficients, becomes important for the chain-breaking action in lipid oxidation of the puerarin derivatives as models for (iso)flavonoids and their glycosides.

PlaNet: combined sequence and expression comparisons across plant networks derived from seven species

The model organism Arabidopsis thaliana is readily used in basic research due to resource availability and relative speed of data acquisition. A major goal is to transfer acquired knowledge from Arabidopsis to crop species. However, the identification of functional equivalents of well-characterized Arabidopsis genes in other plants is a nontrivial task. It is well documented that transcriptionally coordinated genes tend to be functionally related and that such relationships may be conserved across different species and even kingdoms. To exploit such relationships, we constructed whole-genome coexpression networks for Arabidopsis and six important plant crop species. The interactive networks, clustered using the HCCA algorithm, are provided under the banner PlaNet (http://aranet.mpimp-golm.mpg.de). We implemented a comparative network algorithm that estimates similarities between network structures. Thus, the platform can be used to swiftly infer similar coexpressed network vicinities within and across species and can predict the identity of functional homologs. We exemplify this using the PSA-D and chalcone synthase-related gene networks. Finally, we assessed how ontology terms are transcriptionally connected in the seven species and provide the corresponding MapMan term coexpression networks. The data support the contention that this platform will considerably improve transfer of knowledge generated in Arabidopsis to valuable crop species.

Effects of genistein on ovarian follicular development and ovarian life span in rats

Recently, studies reported that neonatal genistein treatment inhibited breakdown of oocyte nests and increased oocyte survival, resulting in multi-oocyte survival in adult mice. However, whether the inhibition effect in ovarian follicular development exists also in other stages during ovarian development (e.g. adult or climacteric) is unknown. So far, few studies have investigated the effect of genistein in adult or pre-menopausal ovarian follicular development and follicular reserves. We investigated ovarian follicular development in 4-month and 15-month-old rats after 4 weeks and 4 months treatment with genistein in a dose of 160 mg/kg d. Genistein-treated rats obtained a higher percentage of primordial follicles by 4 months of age and a greater number of surviving follicles at 15 months of age compared to a control group (P<0.05). In addition, vaginal cytology showed that age-dependent cessation of regular estrus was delayed for 2 months in the genistein-treated group than control group. These results suggest that genistein alters rat ovarian follicular development and increases the number of surviving follicles, which may prolong ovarian reproductive life.

Thermodynamic versus kinetic control of antioxidant synergism between β-carotene and (iso)flavonoids and their glycosides in liposomes

Antioxidant synergism (or antagonism) between plant (iso)flavonoids (daidzein, baicalein, and quercetin) or their glycosides (puerarin, baicalin, and rutin) and β-carotene in phosphatidylcholine liposomes (pH 7.4) with oxidation initiated thermally by the lipophilic free radical initiator 2,2'-azobis(2,4-dimethylvaleronitrile) (AMVN) and followed by the formation of conjugated dienes did not depend simply on the bond dissociation enthalpy (BDE) of the phenol O-H bond or the HOMO/LUMO energy gap based on density functional theory (DFT) calculations. Rate of regeneration of β-carotene from the β-carotene radical cation as the one-electron oxidation product of the lipid phase antioxidant by the monoanion form of the (iso)flavonoids in homogeneous (1:9 v/v methanol/chloroform) solution, as studied by laser flash photolysis and occurring on a microsecond time scale with biphasic kinetics, was in better agreement with the observed nonadditive antioxidative effects. However, correcting the observed (pseudo)-first-order rate constant for β-carotene regeneration for water/lipid distribution of the (iso)flavonoids provided an almost correct ordering of the (iso)flavonoids, according to the nonadditive effects with β-carotene on lipid oxidation.

Examining the genomic influence of skin antioxidants in vitro

A series of well-known, purified antioxidants including: Resveratrol, Epigallocatechin Gallate (EGCG), Genistein, Rosavin, Puerarin, Chlorogenic Acid, Propolis and two newer unexplored isoflavonoids isolated from Maclura pomifera (Osage Orange) including Pomiferin and Osajin, were applied to Normal Human Dermal Fibroblasts (NHDF) and Normal Human Dermal Keratinocytes (NHEK) for 24 hours. The resulting treated cells were then examined using human gene microarrays supplied by Agilent. These chips typically have somewhere on the order of 30,000 individual genes which are expressed in the human genome. For our study, this large list of genes was reduced to 205 principal genes thought to be important for skin and each individual ingredient was examined for its influence on the culled list of genes. Working on a hypothesis that there may be some common genes which are either upregulated or downregulated by all or most of these ingredients, a short list of genes for each cell line was developed. What appears to emerge from these studies is that several genes in the gene pool that was screened are influenced by most or all of the molecules of interest. Genes that appear to be upregulated in both cell lines by all the ingredients include: ACLY, AQP3, COX1, NOS3, and PLOD3. Genes that appear to be downregulated in both cell lines by all ingredients include only PGR.

Chrysin suppresses IL-6-induced angiogenesis via down-regulation of JAK1/STAT3 and VEGF: an in vitro and in ovo approach

Chrysin, 5,7-dihydroxyflavone, possesses many biologic properties. This study aimed to investigate the effects and molecular mechanisms of chrysin on IL-6-induced angiogenesis in vitro and in ovo. Chicken chorioallantoic membrane assay, an in ovo angiogenesis assay, showed chrysin significantly suppressed IL-6-induced neovascularization. Furthermore, chrysin significantly suppressed human umbilical vein endothelial cell (HUVECs) migration and tube formation. The signaling pathway involved in chrysin-related antiangiogenesis was also investigated. The data indicated that chrysin is able to down-regulate the expression of glycoprotein 130 (gp130), soluble IL-6 receptor (IL-6R), phosphorylated JAK1 and STAT3, and VEGF in HUVECs. The IL-6-induced binding of STAT3 was significantly suppressed by chrysin. Moreover, chrysin did not further suppress VEGF expression with STAT3 knocked down. Taken together, the results show that chrysin suppresses IL-6-induced angiogenesis through modulation of the sIL-6R/gp130/JAK1/STAT3/VEGF signaling pathway. Chrysin may provide new therapeutic potential for IL-6-induced pathological angiogenesis.