Isoflavonoids Daidzein Research Articles

Metabolomics Differences of Glycine max QTLs Resistant to Soybean Looper.

Quantitative trait loci (QTLs) E and M are major soybean alleles that confer resistance to leaf-chewing insects, and are particularly effective in combination. Flavonoids and/or isoflavonoids are classes of plant secondary metabolites that previous studies agree are the causative agents of resistance of these QTLs. However, all previous studies have compared soybean genotypes that are of dissimilar genetic backgrounds, leaving it questionable what metabolites are a result of the QTL rather than the genetic background. Here, we conducted a non-targeted mass spectrometry approach without liquid chromatography to identify differences in metabolite levels among QTLs E, M, and both (EM) that were introgressed into the background of the susceptible variety Benning. Our results found that E and M mainly confer low-level, global differences in distinct sets of metabolites. The isoflavonoid daidzein was the only metabolite that demonstrated major increases, specifically in insect-treated M and EM. Interestingly, M confers increased daidzein levels in response to insect, whereas E restores M’s depleted daidzein levels in the absence of insect. Since daidzein levels do not parallel levels of resistance, our data suggest a novel mechanism that the QTLs confer resistance to insects by mediating changes in hundreds of metabolites, which would be difficult for the insect to evolve tolerance. Collective global metabolite differences conferred by E and M might explain the increased resistance of EM.

From Persian Gulf to Indonesia: interrelated phylogeographic distance and chemistry within the genus Peronia (Onchidiidae, Gastropoda, Mollusca)

The knowledge of relationships between taxa is essential to understand and explain the chemical diversity of the respective groups. Here, twelve individuals of the panpulmonate slug Peronia persiae from two localities in Persian Gulf, and one animal of P. verruculata from Bangka Island, Indonesia, were analyzed in a phylogenetic and chemotaxonomic framework. Based on the ABGD test and haplotype networking using COI gene sequences of Peronia specimens, nine well-supported clades were found. Haplotype network analysis highlighted a considerable distance between the specimens of P. persiae and other clades. Metabolomic analysis of both species using tandem mass spectrometry-based GNPS molecular networking revealed a large chemical diversity within Peronia of different clades and localities. While P. persiae from different localities showed a highly similar metabolome, only few identical chemical features were found across the clades. The main common metabolites in both Peronia species were assigned as polypropionate esters of onchitriols and ilikonapyrones, and osmoprotectant amino acid-betaine compounds. On the other hand, the isoflavonoids genistein and daidzein were exclusively detected in P. persiae, while cholesterol and conjugated chenodeoxycholic acids were only found in P. verruculata. Flavonoids, bile acids, and amino acid-betaine compounds were not reported before from Onchidiidae, some are even new for panpulmonates. Our chemical analyses indicate a close chemotaxonomic relation between phylogeographically distant Peronia species.

Flavonoid levels rather than soil nutrients is linked with Fusarium community in the soybean [Glycine max(L.) Merr.] rhizosphere under consecutive monoculture

As potent allelochemicals, flavonoids are believed to be associated with the development of soil-borne diseases. Fusarium species infection is responsible for soybean [Glycine max(L.) Merr.] root rot. However, it is uncertain if and how flavonoids influence rhizosphere Fusarium communities under consecutive soybean monoculture. Quantitative real-time PCR and pyrosequencing were used to study the Fusarium community. Spectrophotometric techniques and ultra-performance liquid chromatography (UPLC) were used to quantify flavonoids and daidzein and genistein levels, respectively. In field soil, the sizes of Fusarium community were higher from 6 to 13 years monoculture than from 1 to 3 years. The abundance of Fusarium community was significantly positively correlated with rhizosphere concentrations of the flavonoids and isoflavonoids daidzein and genistein levels. Consecutive monocultured soil selectively inhibited or stimulated certain Fusarium species, F. oxysporum remaining the most abundant. The application of daidzein and a mixture of daidzein and genistein to soil affected the Fusarium community depending on the incubation time and ranging from inhibition to promotion over time. Consecutive soybean monoculture results in shifts in the composition and size of rhizosphere Fusarium community. The Fusarium community was strongly influenced by total flavonoids, in particular daidzein and genistein, rather than soil properties.

Research of the phytoestrogens content in soybean and chickpea flour

The object of the research is the Krasnokutsky 195 chickpea variety, the Almaz soybean variety, and the 2018 harvest from the Agrotek collection nursery (Kyiv, Ukraine). One of the most problematic places is the ambiguous attitude of many scientists regarding the qualitative and quantitative content of phytoestrogens in leguminous grains. During the study, the method of differential spectrophotometry is used. It is established that native soymean and chickpea grains are carriers of 36.8 and 22.3 % phytoestrogens. During germination, drying and grinding of legumes, the content of phytoestrogens decreases to 15.6 % in soybean flour and to 13.3 % in chickpea flour. The use of KI as a medium for germinating soybean grains, and NaHSeO3 as a medium for germinating chickpea grains, reduces the content of phytoestrogens by 2.7 and 1.6 %, respectively. It is determined that all experimental samples have an absorption peak at λ=400 nm, which corresponds to the content of isoflavonoids daidzein in them. Samples of flour from germinated soybean and chickpea grains in solutions of mineral salts have an absorption peak at λ=225 nm, which corresponds to the content of isoflavonoids in daidzin. It is established that the germination of legumes in solutions of mineral salts does not affect the content of biohanin and formononetin. In samples with chickpea flour sprouted in a NaHSeO3 solution, an increase in genistein content by 60 % relative to the control is observed. The carried out complex of studies allows to state that there is a need to study the effect of soybean and chickpea flour germinated in KI and NaHSeO3 solutions, respectively, on biological objects.The results obtained in the study are the scientific basis for the correction of the diets of people with endocrine disorders and require special dietary nutrition.

Transcriptome analysis of Pueraria candollei var. mirifica for gene discovery in the biosyntheses of isoflavones and miroestrol

BackgroundPueraria candollei var. mirifica, a Thai medicinal plant used traditionally as a rejuvenating herb, is known as a rich source of phytoestrogens, including isoflavonoids and the highly estrogenic miroestrol and deoxymiroestrol. Although these active constituents in P. candollei var. mirifica have been known for some time, actual knowledge regarding their biosynthetic genes remains unknown.ResultsMiroestrol biosynthesis was reconsidered and the most plausible mechanism starting from the isoflavonoid daidzein was proposed. A de novo transcriptome analysis was conducted using combined P. candollei var. mirifica tissues of young leaves, mature leaves, tuberous cortices, and cortex-excised tubers. A total of 166,923 contigs was assembled for functional annotation using protein databases and as a library for identification of genes that are potentially involved in the biosynthesis of isoflavonoids and miroestrol. Twenty-one differentially expressed genes from four separate libraries were identified as candidates involved in these biosynthetic pathways, and their respective expressions were validated by quantitative real-time reverse transcription polymerase chain reaction. Notably, isoflavonoid and miroestrol profiling generated by LC-MS/MS was positively correlated with expression levels of isoflavonoid biosynthetic genes across the four types of tissues. Moreover, we identified R2R3 MYB transcription factors that may be involved in the regulation of isoflavonoid biosynthesis in P. candollei var. mirifica. To confirm the function of a key-isoflavone biosynthetic gene, P. candollei var. mirifica isoflavone synthase identified in our library was transiently co-expressed with an Arabidopsis MYB12 transcription factor (AtMYB12) in Nicotiana benthamiana leaves. Remarkably, the combined expression of these proteins led to the production of the isoflavone genistein.ConclusionsOur results provide compelling evidence regarding the integration of transcriptome and metabolome as a powerful tool for identifying biosynthetic genes and transcription factors possibly involved in the isoflavonoid and miroestrol biosyntheses in P. candollei var. mirifica.

Mechanical and aesthetics compatibility of Brazilian red propolis micellar nanocomposite as a cavity cleaning agent

BackgroundPropolis is a natural substance produced by bees and is known to have antimicrobial activity. Our aim was to evaluate the antimicrobial effect of micellar nanocomposites loaded with an ethyl acetate extract of Brazilian red propolis as a cavity cleaning agent and its influence on the color and microtensile bond strength (μTBS) of the dentin/resin interface.MethodsAn ultra-performance liquid chromatography coupled with a diode array detector (UPLC-DAD) assay was used to determine the flavonoids and isoflavones present in an ethyl acetate extract of Brazilian red propolis (EARP) and micellar nanocomposites loaded with EARP (MNRP). The antimicrobial activity of EARP and MNRP was tested against Streptococcus mutans, Lactobacillus acidophilus, and Candida albicans. One of the following experimental treatments was applied to etched dentin (phosphoric acid, 15 s): 5 μL of MNRP (RP3, 0.3%; RP6, 0.6%; or RP1, 1.0% w/v), placebo, and 2% chlorhexidine digluconate. Single Bond adhesive (3 M/ESPE) was applied and a 4-mm-thick resin crown (Z350XT, 3 M/ESPE) was built up. After 24 h, the teeth were sectioned into sticks for the μTBS test and scanning electron microscopy. Spectrophotometry according to the CIE L*a*b* chromatic space was used to evaluate the color. Data were analyzed using one-way ANOVA and the Tukey test or Kruskal-Wallis test and the same test for pairwise comparisons between the means (P < 0.05).ResultsThe UPLC-DAD assay identified the flavonoids liquiritigenin, pinobanksin, pinocembrin, and isoliquiritigenin and the isoflavonoids daidzein, formononetin, and biochanin A in the EARP and micellar nanocomposites. EARP and MNRP presented antimicrobial activity against the cariogenic bacteria Streptococcus mutans and Lactobacillus acidophilus, and for Candida albicans. ΔE values varied from 2.31 to 3.67 (P = 0.457). The mean μTBS for RP1 was significantly lower than for the other groups (P < 0.001). Dentin treated with RP1 showed the shortest resin tags followed by RP6 and RP3.ConclusionsThe EARP and (MNRP) showed antimicrobial activity for the main agents causing dental caries (Streptococcus mutans and Lactobacillus acidophilus) and for Candida albicans. MNRP at concentrations of 0.3 and 0.6% used as a cavity cleaner do not compromise the aesthetics or μTBS of the dentin/resin interface.

Identification of an isoflavone glycoside hydrolyzing b-glucosidase in the seeds of the desert legume Prosopis cineraria

Legumes, in general, are rich in glycosidic isoflavone conjugates, whereby specific b-glucosidases act to release the free aglycones that could serve in plant-microbe interactions and defense. Prosopis cineraria is an important legume tree, bearing medicinally useful and edible pods, generally growing in extreme arid/semi-arid zones of Rajasthan. However, specific phytochemical-cum-metabolic profiles are lacking for the same. Therefore, the present investigation undertook phytochemical and metabolic screening of the pods/seeds of P. cineraria for the presence of putative isoflavonoids viz. genistein and daidzein, their glycosides and b-glucosidase(s) capable of catalyzing the glycoside hydrolysis. Extraction and identification of these two aglycone forms of the above isoflavonoids were performed with solvent partition chromatography and Fluorescent/High Performance Thin Layer Chromatography, respectively. Furthermore, optimization of the isoflavone conjugate-specific b-glucosidase activity with respect to pH optima, temperature and time were carried out. The partially purified enzyme showed a temperature optima of 50°C and pH optima of 4.5. The enzyme also demonstrated activity towards natural substrates daidzin and genistin which are glycosides of isoflavonoids daidzein and genistein respectively. The methanolic extracts of the seeds of P. cineraria indicated the presence of related isoflavonoids which needs to be further validated.

Ethanolic extract of Salvia officinalis alter vascular endothelial growth factor gene expression and its receptors in the mouse endometrium at preimplantation

Salvia officinalis contains steroid and isoflavonoid coumestrol, daidzein, and genistein which are considered as phytoestrogens. Isoflavones are alternatives to hormone replacement treatment. No studies have been conducted on the effect of S. officinalis extraction on endometrial angiogenesis yet. The adult female mice in the test group received an ethanolic extract of the S. officinalis (100 mg/kg) once a day for 14 days then pseudopregnancy was induced. Uterine horns were removed for molecular and histological assessment in each group. Motic image software was used to assess the quantitative vascular parameters, and real-time PCR was done to determine vascular gene expression in the endometrium. Data analysis on gene expression showed a decrease in rate of vascular endothelial growth factor (VEGF) gene expression (1.559). VEGF receptor gene expression is accompanied by an increase in the rate of kinase insert domain protein receptor (KDR) gene expression (2.504) and FMS-like tyrosine kinase 1 (FLT1) gene expression (0.606). Although there was no significant difference in vascular density between control and test groups, a significant difference (p ≤ 0.05) was evident in the intravascular area between control and test groups at preimplantation time. It is concluded that S. officinalis may affect on implantation media because decidual angiogenesis has a main role in the maintenance of pregnancy at implantation time.

Occurrence of isoflavonoids in Brazilian common bean germplasm (Phaseolus vulgaris L.).

Common bean (Phaseolus vulgaris) is present in the daily diet of various countries and, as for other legumes, has been investigated for its nutraceutical potential. Thus, 16 genotypes from different gene pools, representing seven types of seed coats and different responses to pathogens and pests, were selected to verify their isoflavone contents. The isoflavonoids daidzein and genistein and the flavonols kaempferol, myricetin, and quercetin were found. Grains of the black type showed the highest concentrations of isoflavonoids and were the only ones to exhibit daidzein. IAC Formoso, with high protein content and source of resistance to anthracnose, showed the greatest concentration of genistein, representing around 11% of the content present in soybean, as well as high levels of kaempferol. Arc 1, Raz 55, and IAC Una genotypes showed high content of coumestrol. The results suggest the use of IAC Formoso to increase the nutraceutical characteristics in common bean.

Immunochemical and HPLC identification of isoflavonoids in the Apiaceae family

Ethanolic extracts of 23 species of the Apiaceae family were analyzed for their flavonoid and isoflavonoid content, using the following methods: high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS); semi-preparative HPLC with Enzyme Linked Immunosorbent Assay (HPLC-ELISA); and immunoaffinity extraction (IAE). Rutin and quercetin-3-glucoside were the most abundant flavonoid glycosides and the most abundant flavonoid aglycone was apigenin. The isoflavonoids daidzein, genistein, sissotrin and formononetin were also found. The estimated content of individual compounds ranged from 1 to over 800 mg/kg (dry weight) for flavonoids, and from 0.2 to over 60 mg/kg for isoflavonoids. The probable reason why isoflavonoids have rarely been reported in the Apiaceae previously is that they occur in far smaller quantities than in families usually associated with isoflavonoids, such as the Leguminosae, but the sensitive methods used made their detection possible.

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.

Secondary Metabolites from Glycine soja and Their Growth Inhibitory Effect against Spodoptera litura

The wild soybean (Glycine soja Sieb. et Zucc) has been reported to be relatively resistant to insect and pathogenic pests. However, the responsible secondary metabolites in the aerial part of this important plant are largely unknown. From the aerial part of G. soja, 13 compounds were isolated and identified, including seven isoflavonoids (1-7), a cyclitol (8), two sterol derivatives (9 and 10), and three triterpenoids (11-13). Compound 7 is a new isoflavonoid, and compounds 9 and 10 are reported as natural products for the first time. The growth inhibitory activity of 1, 3, 4, and 8 against the larvae of Spodoptera litura was investigated. The most abundant isoflavonoid in the aerial part of G. soja, daidzein (1), which could not be metabolized by S. litura, was found to inhibit the insect larvae growth significantly in 3 days after feeding diets containing the compound. Compounds 3, 4, and 8, which could be partially or completely metabolized, were inactive. Our results suggested that the isoflavonoid daidzein (1) might function as a constitutive defense component in G. soja against insect pests.

Retinylisoflavonoid as a Novel Membrane Antioxidant

We report a novel molecular dyad as an antioxidant, retinylisoflavonoid, with a retinal analogue C(22)-aldehyde and the isoflavonoid daidzein covalently linked. Its physicochemical properties, pK(a) (pK(a1) = 8.45, pK(a2) = 11.42), oxidation potential (1.03 V vs NHE), and Log(10) partition (Log P = 1.96), as well as the Trolox equivalent antioxidant capacity (TEAC = 0.4), have been characterized. Spectroscopic and quantum chemical investigations have revealed the following unique structural characters: (i) Either free in solution or included in liposomal membranes, the C(22)-aldehyde moiety of retinylisoflavonoid is coplanar with the B-ring of daidzein owing to the strong intramolecular hydrogen bonding C(14')=O···HO-B4'. Accordingly, the C(22)-aldehyde moiety extends its π-conjugation significantly to the B-ring. (ii) The inherent amphiphilicity of retinylisoflavonoid allows the C(22)-aldehyde moiety embedded in the lipid phase of the liposomes, whereas the daidzein counterpart stays at the membrane surface, in effect facilitating interior-to-surface radical communication. As the result, the antilipooxidation activity of retinylisoflavonoid is improved significantly in protecting membrane lipids compared to the parent compounds alone or in combination, and importantly, the performance is more prominent under higher-level oxidative stress. This work provides an advanced case study of new antioxidant development based on optimized electronic and molecular structures.

Fast Regeneration of Carotenoids from Radical Cations by Isoflavonoid Dianions: Importance of the Carotenoid Keto Group for Electron Transfer

Electron transfer to radical cations of beta-carotene, zeaxanthin, canthaxanthin, and astaxanthin from each of the three acid/base forms of the diphenolic isoflavonoid daidzein and its C-glycoside puerarin, as studied by laser flash photolysis in homogeneous methanol/chloroform (1/9) solution, was found to depend on carotenoid structures and more significantly on the deprotonation degree of the isoflavonoids. None of the carotenoid radical cations reacted with the neutral forms of the isoflavonoids while the monoanionic and dianionic forms of the isoflavonoids regenerated the oxidized carotenoid. Electron transfer to the beta-carotene radical cation from the puerarin dianion followed second order kinetics with the rate constant at 25 degrees C k(2) = 5.5 x 10(9) M(-1) s(-1), zeaxanthin 8.5 x 10(9) M(-1) s(-1), canthaxanthin 6.5 x 10(10) M(-1) s(-1), and astaxanthin 11.1 x 10(10) M(-1) s(-1) approaching the diffusion limit and establishing a linear free energy relationship between rate constants and driving force. Comparable results found for the daidzein dianion indicate that the steric hindrance from the glucoside is not important suggesting the more reducing but less acidic 4'-OH/4'-O(-) as electron donors. On the basis of the rate constants obtained from kinetic analyses, the keto group of carotenoids is concluded to facilitate electron transfer. The driving force was estimated from oxidation potentials, as determined by cyclic-voltametry for puerarin and daidzein in aqueous solutions at varying pH conditions, which led to the standard reduction potentials E degrees = 1.13 and 1.10 V versus NHE corresponding to the uncharged puerarin and daidzein. For pH > pK(a2), the apparent potentials of both puerarin and daidzein became constants and were E degrees = 0.69 and 0.65 V, respectively. Electron transfer from isoflavonoids to the carotenoid radical cation, as formed during oxidative stress, is faster for astaxanthin than for the other carotenoids, which may relate to astaxanthins more effective antioxidative properties and in agreement with the highest electron accepting index of astaxanthin.

A‐ring ortho‐specific monohydroxylation of daidzein by cytochrome P450s of Nocardia farcinica IFM10152

The bioconversion of the isoflavonoid daidzein using whole cell Nocardia farcinica IFM10152 showed two kinds of major metabolic modifications, i.e. mono-hydroxylation and subsequent O-methylation. The major hydroxylated products of daidzein prior to the O-methylation reaction were 3',4',7-trihydroxyisoflavone (3'-ODI), 4',6,7-trihydroxyisoflavone (6-ODI) and 4',7,8-trihydroxyisoflavone (8-ODI), which are mono-hydroxylated at the ortho position of each hydroxyl group of daidzein. To identify monooxygenases playing a key role in the monohydroxylation of the A-ring of daidzein, all genes of 27 cytochrome P450s from N. farcinica IFM10152 were cloned and transformed into a E. coli BL21 (DE3) host system. By this enzymatic reaction using the mutants and the genome sequence analysis of N. farcinica IFM10152, it was revealed that nfa12130 and nfa33880 P450 genes clustered with their own ferredoxins and ferredoxin reductases (nfa12140+nfa12150 and nfa338870+nfa33860, respectively) are responsible for the hydroxylation of the A-ring of daidzein, and their major reaction products were 6-ODI and 8-ODI, respectively.

Stereospecificity of Daidzein metabolism leading to S-Equol by human intestinal bacterium

S-Equol, a metabolite of the isoflavonoid daidzein in the human intestine, shows the most active estrogen activity. Stereospecific production of S-equol by a human intestinal anaerobic bacterium strain Julong732 was studied. Julong732 was known to metabolize dihydrodaidzein (DHD) into S-equol tetrahydrodaidzein (THD) [1] but its metabolic stereospecificity has not yet been elucidated. DHD and THD were prepared, and their stereoisomers were separated by reverse-phase and chiral stationary-phase high-performance liquid chromatography. The absolute configurations of DHD enantiomers and four THD stereoisomers were assigned by 1H NMR, 13C NMR, and CD spectroscopies [2,3]. The reaction of the cell-free extract with DHD showed that only 3S-DHD was transformed into 3S-equol. When each of the four stereoisomers of THD was reacted with the cell-free extract of Julong732, only 3R,4S-THD was metabolized by the extract, producing S-equol. 7,4'-Dihydroxyisoflav-3-ene (dehydroequol, DE), a putative intermediate during the anaerobic metabolism of DHD, was unable to produce S-equol.

Нepatoprotective properties of polyphenolic complexes from woodand cellular culture of maackia amurensis

Annot For finding-out of a role of separate groups of polyphenols in realization hepatoprotective properties of maksar we investigate activity of polyphenolic complexes (PPC) from duramen and cellular culture of maakia amur. Experiments are carried out on 40 not purebred white rats with an experimental СCl4-hepatites. Therapeutic efficiency of researched objects estimated on their influence on survival rate of animals, morphological and biochemical parameters of a liver and wheys of blood. In rat's CCl4-hepatitis PPC from duramen and cellular culture of maakia amur reduce the acute toxity of tetrachloromethane, decrease the necrosis of hepatocytes and cellural infiltration of liver's parenchyma, prevent from development of fatty and protein dystrophy of a liver, normalize the activity of amino transferase, ƒ-glutamyltransferase in blood, the concentration of proteins and lipids, stimulate conjugation of bilirubin. The therapeutic effect of PPC of cellular culture is more evident. The hepatoprotective action is caused by a presence of isoflavonoids daidzein, retuzin, genistein, afromozin, formononetin, orobol, tektorigenin, maakiain and medicarpin. PPC from a culture of cells doesn't influence on a level of cholesterol in blood, that apparently is caused by an absence of mono- and dimeric stilbenes in its structure.

Are flavonoids agonists or antagonists of the natural hormone 17β‐estradiol?

Are flavonoids agonists or antagonists of the natural hormone 17β‐estradiol?

The Isoflavonoid Daidzein Attenuates the Oxidative Damage Induced by Polychlorinated Biphenyls on Cultured Chicken Testicular Cells

The soy isoflavonoid daidzein (DAI) is one of the most abundant phenolic compounds in the human diet and in animal feedstuffs. Daidzein possesses a wide spectrum of physiological and pharmacological functions related to human health. The aim of this study was to evaluate the effect of DAI on oxidative damage induced by a potential carcinogen, polychlorinated biphenyl. Testicular cells were dispersed from 18-d-old chicken embryos and exposed to DAI alone or in combination with a mixture of polychlorinated biphenyls, Aroclor 1254 (A1254), in culture. Oxidative damage was estimated by measuring the lipid peroxidation and superoxide dismutase activities and glutathione content. Results showed that DAI (10 μg/mL) increased germ cell numbers, which were inhibited by cotreatment with the estrogen receptor antagonist tamoxifen at 0.1 μg/mL. Exposure to A1254 (10 μg/mL) reduced superoxide dismutase activity and glutathione content but increased lipid peroxidation significantly. However, simultaneous supplementation with 10 μg/mL of DAI restored these parameters. The above results indicated that DAI may exert weak estrogenic activity, and more important, that DAI may display an antioxidant effect to prevent oxidative damage induced by the oxidant A1254.

Puerarin and Conjugate Bases as Radical Scavengers and Antioxidants: Molecular Mechanism and Synergism with β-Carotene

The 4'-hydroxyl group of puerarin, a C-glycoside of the isoflavonoid daidzein, was shown, using 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) radical cation and stopped-flow spectroscopy and by comparison with the 7-propylpuerarin (A ring derivative) and 4'-propylpuerarin (B ring derivative), to be a more efficient radical scavenger as compared to the 7-hydroxyl group by a factor of 2, a difference increasing upon deprotonation. The difference in radical scavenging agreed with the oxidation potentials (cyclic voltammetry in acetonitrile, 0.1 M Bu4NBF4 at 25 degrees C): E/mV=862+/-3 for puerarin, 905+/-10 for 7-propylpuerarin, and 1064+/-2 for 4'-propylpuerarin relative to ferrocene/ferricenium. In aqueous solution, the reduction potential was shown to decrease for increasing pH, and deprotonation of the 4'-hydroxyl group increased radical scavenging more than deprotonation of the 7-hydroxyl group. The 7-hydroxyl was found to be more acidic (pKa1=7.20+/-0.01 in puerarin and pKa=7.23+/-0.01 in 4'-propylpuerarin) than the 4'-hydroxyl group (pKa2=9.84+/-0.08 in puerarin and pKa=9.51+/-0.02 in 7-propylpuerarin); aqueous solution, ionic strength of 0.1, and 25 degrees C. In phosphatidyl choline liposome of pH 7.4, puerarin and beta-carotene each showed a modest antioxidant activity measured as prolongation of the lag phase for formation of conjugate dienes and using the water-soluble radical initiator APPH with effects of puerarin and beta-carotene being additive. For the lipophilic initiator AMVN, the antioxidative effect decreased for puerarin and increased for beta-carotene as compared to APPH and showed a clear synergism. A regeneration of beta-carotene, effective in the liposome lipid phase as antioxidant, from the cation radical by deprotonated forms of puerarin was demonstrated in 9:1 chloroform/methanol using laser flash photolysis with k2=2.7x10(4) L mol-1 s-1 for the bimolecular process between the cation radical and the puerarin dianion.