Identification of oxidation products of (-)-epigallocatechin gallate and (-)-epigallocatechin with H(2)O(2)

(-)-Epigallocatechin gallate (EGCG) and (-)-epigallocatechin (EGC) are two important antioxidants in tea. They also display some antitumor activities, and these activities are believed to be mainly due to their antioxidative effects. However, the specific mechanisms of antioxidant action of tea catechins remain unclear. In this study are isolated and identified two novel reaction products of EGCG and one product of EGC when they were reacted separately with H(2)O(2). These products are formed by the oxidation and decarboxylation of the A ring in the catechin molecule. This study provides unequivocal proof that the A ring of EGCG and EGC may also be an antioxidant site. This study also indicates an additional reaction pathway for the oxidation chemistry of tea catechins.     

Chemoenzymatic synthesis of homochiral (R)- and (S)-karahanaenol from (R)-limonene

Terpinolene oxide, a monoterpene belonging to the p-menthane group, is easily derived from naturally abundant (R)-limonene. It was isomerized with montmorillonite clay catalyst to karahanaenone (2,2, 5-trimethylcyclohept-4-en-1-one) by ring enlargement. The enantiomers of the corresponding alcohol, karahanaenol (2,2, 5-trimethylcyclohept-4-en-1- ol), known for their individual organoleptic properties, were resolved through Pseudomonas cepacia lipase mediated enantiospecific alcoholysis of its acetate derivative.     

Excretion of (14)C-fumonisin B(1), (14)C-hydrolyzed fumonisin B(1), and (14)C-fumonisin B(1)-fructose in rats.

14C-Fumonisin B(1) (FB(1)) was produced by Fusarium proliferatum M-5991 in modified Myro liquid medium and purified to >95% purity with a specific activity of 1.7 mCi/mmol. Nine male and nine female F344/N rats were each dosed by gavage with 0.69 micromol of (14)C-FB(1), (14)C-hydrolyzed FB(1), or (14)C-FB(1)-fructose/kg body weight. Urinary excretion of (14)C-FB(1) and (14)C-FB(1)-fructose was 0.5% and 4.4% of the total dose, respectively, and was similar between male and female rats. Urinary excretion of (14)C-hydrolyzed HFB(1) was significantly greater (P > 0.05) in female rats as compared with male rats (17.3% vs 12.8% of the total dose, respectively). There were no significant (P > 0.05) differences in biliary excretion of the three fumonisin compounds with a mean of 1. 4% of the dose excreted at 4 h after dosing. Lesser amounts continued to be excreted up to 9.25 h after dosing. Although biliary excretion of the (14)C-FB(1), (14)C-hydrolyzed FB(1), and (14)C-FB(1)-fructose was similar, increased urinary excretion of the (14)C-hydrolyzed FB(1) as compared to (14)C-FB(1) and (14)C-FB(1)-fructose indicated a greater absorption of the hydrolyzed form.     

Kinetic Speciation of Ni(II) in Model Solutions and Freshwaters: Competition of Al(III) and Fe(III)

The competing ligand exchange method was used to investigate the competitive binding of Ni(II) by Al(III) and Fe(III) in model aqueous solutions and freshwaters. Graphite furnace atomic absorption spectrometry and adsorptive cathodic stripping voltammetry were used to monitor the rate of uptake of the Ni by Chelex 100 chelating resin and dimethylglyoxime as the competing ligands, respectively. The results have revealed that Ni(II)–humate complexes were more labile in presence of the mixture of Al(III) and Fe(III), compared to the lability of the Ni(II)–humate complexes when only one of the two, Al(III) or Fe(III), was present. The environmental significance of this work is that in model solutions simulating freshwater containing humic substances and the target trace metal Ni(II) and cations, Al(III) and Fe(III), the competitive binding of Ni(II), Al(III) and Fe(III) by humic substances makes Ni(II)–humate complexes labile, releasing free Ni²⁺–aqua complex, which reported to be toxic.     

Effect of pH on interaction between As(III) or As(V) and manganese(IV) oxide

The efficiency of As(III) oxidation by MnO₂, and retention of oxidation products varies with system pH. Maximum retention by hydrous Mn(IV) oxide occurs at pH < 5, declining at higher pH to about half total As at pH 10. The adsorption capacities of pyrolusite and cryptomelane at pH ～6.5 for As(V) species were 10 and 25 mmol kg^?1, respectively. HMO surface saturation (～10 mmol kg^?1) was reached with equilibrium As(V) levels of 5 to 8 × 10^?6 M but this was supplemented at higher levels by an absorption process where uptake increased linearly with concentration (e.g., 68 mmol kg^?1 with 2 × 10^?5 M As(V)). Added As(III) was avidly oxidized and most product retained at pH 3. At higher pH increasing amounts of As(III) remained unoxidized due to initial reactions apparently blocking access to internal pores. Added Na⁺ reduced the amount of As retained by the HMO, with the phosphate salt having a significant effect. Extraction studies confirmed that most As could be released by exposure to reducing agents or chelating agents (EDTA). The environmental significance of the results has been considered.     

Anthocyanins from maize (Zea mays) and reed canarygrass (Phalaris arundinacea)

Flowers of maize, Zea mays, and reed canarygrass, Phalaris arundinacea, contain the same anthocyanins: cyanidin 3-glucoside, cyanidin 3-(6' '-malonylglucoside), cyanidin 3-(3' ',6' '-dimalonylglucoside), peonidin 3-glucoside, peonidin 3-(6' '-malonylglucoside), and peonidin 3-(dimalonylglucoside). The latter pigment has previously not been reported to occur in plants. Structure elucidations were primarily based on homo- and heteronuclear two-dimensional NMR and electrospray MS. During the isolation procedure using various mixtures of H(2)O, CF(3)CO(2)H, and CH(3)OH, and during storage in NMR solvent (CF(3)CO(2)D/CD(3)OD; 1:19, v/v) methyl esterification of the free acid function of the malonyl units of the pigments occurs. The acylated anthocyanins constitute more than 80% and 40% of the anthocyanins in P. arundinacea and Z. mays, respectively. Flowers and leaves of maize, Zea mays, contain the same anthocyanins in nearly equal relative proportions.     

锑/磷在膨润土和高岭土的竞争吸附

采用批处理法研究了锑/磷(Sb/P)在膨润土和高岭土上的竞争吸附等温线和动力学,并考察了pH的影响。结果表明:Sb和P吸附符合Langmuir或Freundlich方程(R~2=0.945 0~0.998 3,P0.000 1),存在极强的竞争吸附:P共存时Sb吸附容量(Q_(max))显著降低,分别从0.86和10.21 mmol/kg(先Sb后P)降低到0.64和2.61 mmol/kg(先P后Sb);Sb共存时P吸附亲合性(K)明显降低,分别从1.47和7.47 L/mmol(先P后Sb)降低到0.68和2.34 L/mmol(先Sb后P)。Sb和P的吸附总体随pH升高而降低,但相比高岭土,膨润土上的吸附受pH影响更大,意味着高岭土有更多配位吸附、膨润土有更多电性吸附。准二级动力学方程很好地拟合它们的竞争吸附(R~20.994,P0.000 1),并且在Sb/P共存下,膨润土对P吸附弱而慢(q_e=0.36 mmol/kg,,k_2=0.064 6 kg/(mmol·min))、对Sb吸附虽弱但快(q_e=0.19 mmol/kg,k_2=0.076 9 kg/(mmol·min));高岭土对P吸附强更快(q_e=0.66 mmol/kg,k_2=0.591 kg/(mmol·min))、对Sb吸附虽强但慢[q_e=0.39 mmol/kg,k_2=0.052 4 kg/(mmol·min)]。因此,Sb对P吸附的抑制在膨润土上更明显(主要是静电吸附竞争),P对Sb吸附的抑制则在高岭土上更突出(主要是配位吸附竞争)。     

Phenolic profile of quince fruit (Cydonia oblonga Miller) (pulp and peel)

Qualitative and quantitative analyses of phenolic compounds were carried out on quince fruit samples from seven different geographical origins in Portugal. For each origin, both pulp and peel were analyzed by reversed-phase HPLC-DAD and HPLC-DAD/MS.The results revealed differences between the phenolic profiles of pulps and peels in all studied cases. The pulps contained mainly caffeoylquinic acids (3-, 4-, and 5-O-caffeoylquinic acids and 3,5-dicaffeoylquinic acid) and one quercetin glycoside, rutin (in low amount). The peels presented the same caffeoylquinic acids and several flavonol glycosides: quercetin 3-galactoside, kaempferol 3-glucoside, kaempferol 3-rutinoside, and several unidentified compounds (probably kaempferol glycoside and quercetin and kaempferol glycosides acylated with p-coumaric acid). The highest content of phenolics was found in peels.     

黄芪多糖及皂甙提取工艺研究

黄芪多糖和皂甙是药用皂芪的两个主要有效成分。该文探讨了黄芪多糖(ASP)和皂甙(AS)的提取工艺,研究了从黄芪中同时得到多糖和皂甙的提取工艺。采用先醇提后水提的方法,确定了合适的醇提次数和浓度。另外,还研究了超滤法与树脂吸附法相结合的工艺,可以同时得到高含量的多糖和皂甙产品     

Biotransformation of (R)- and (S)-terpinen-4-ol by the larvae of common cutworm (Spodoptera litura)

(R)-Terpinen-4-ol was mixed in an artificial diet at a concentration of 1 mg/g of diet, and the diet was fed to the last instar larvae of common cutworm (Spodoptera litura). Metabolites were recovered from frass and analyzed spectroscopically. (R)-Terpinen-4-ol was transformed mainly to (R)-p-menth-1-en-4,7-diol. Similarly, (S)-terpinen-4-ol was transformed mainly to (S)-p-menth-1-en-4,7-diol. The C-7 position (allylic methyl group) of (R)- and (S)-terpinen-4-ol was preferentially oxidized.     

Competition from Cu(II), Zn(II) and Cd(II) in Pb(II) Binding to Suwannee River Fulvic Acid

This is a study of trace metal competition in the complexation of Pb(II) by well-characterized humic substances, namely Suwannee River Fulvic Acid (SRFA) in model solutions. It was found that Cu(II) seems to compete with Pb(II) for strong binding sites of SRFA when present at the same concentration as Pb(II). However, Cd(II) and Zn(II) did not seem to compete with Pb(II) for strong binding sites of SRFA. These two metals did compete with Pb(II) for the weaker binding sites of SRFA. Heterogeneity of SRFA was found to play a crucial role in metal–SRFA interactions. The environmental significance of this research for freshwater is that even at relatively low Pb(II) loadings, the metals associated with lead in minerals, e.g. Cu(II), may successfully compete with Pb(II) for the same binding sites of the naturally occurring organic complexants, with the result that some of the Pb(II) may exist as free Pb²⁺ ions, which has been reported to be one of the toxic forms of Pb in aquatic environment.     

Occurrence of fumonisins B(2) and B(4) in retail raisins

Concerns that raisins may be contaminated by fumonisins stem from the persistent occurrence of Aspergillus niger spores on raisins and the recent discovery of fumonisin production by A. niger on grapes, which leads to the widespread occurrence of fumonisin B(2) in wine. This study presents an LC-MS/MS survey of fumonisins in retail raisins. In 10 of 21 brands collected in Denmark, Germany, and The Netherlands, fumonisins B(2) and B(4) were detected at levels up to 13 and 1.3 μg/kg, respectively. Only fumonisin B(2) has been detected in wine, so the presence of fumonisin B(4) in raisins suggests that the fumonisins are produced mainly during the drying process concomitant with the decreasing water activity. Analysis of multiple packages from one manufacturer showed a 3-fold package-to-package variation, suggesting that a few raisins per package are contaminated.     

Brassinosteroid (BR) and arbuscular mycorrhizal (AM) fungi alleviate salinity in wheat

This study was conducted to assess the impacts of brassinosteroide (BR), arbuscular mycorrhizal (AM) fungi, Glomus mosseae and their interactions on salt stress tolerance in Triticum aestivum L. After foliar spraying of mycorrhizal and non-mycorrhizal plants by 5 µM epibrassinolide, they were subjected to 0 and 150 mM sodium chloride (NaCl) for 2 weeks. The experiment was conducted in a randomized complete block design, replicated 4 times. Our results showed a probable potential of BR and/or AM fungi in improving salt tolerance of plants. Total phenol and proline content increased in BR and/ or AM treatments. AM fungi promoted plant growth, including leaf area, shoot and root dry weights, and lengths under saline condition. Moreover, BR improved growth parameters except root dry weights and lengths. This study indicated that BR and/or AM fungi may contribute to improve salt tolerance of the plant.     

Flavor composition of cashew (Anacardium occidentale) and marmeleiro (Croton species) honeys

The aim of this work was to characterize the volatile fractions of two Brazilian honeys known as caju and marmeleiro. The volatile components were isolated by a column extraction technique using acetone as the extraction solvent. Totals of 59 and 36 volatile compounds were definitely or tentatively identified in the caju and marmeleiro honeys, respectively, using reference substances, mass spectral libraries, and the odor qualities of the compounds eluted from the GC column. Aroma extraction dilution analysis allowed the tentative identification of furfuryl mercaptan, benzyl alcohol, delta-octalactone, gamma-decalactone, eugenol, benzoic acid, isovaleric acid, phenylethyl alcohol, and 2-methoxyphenol as impact volatile compounds in the caju honey. In the marmeleiro honey, only isovaleric acid, gamma-decalactone, benzoic acid, and vanillin were considered to be potent odorants. This study showed that the medium- to high-boiling volatile compounds are important contributors to the characteristic aroma of these honeys.     

N-Nitrosation of myosmine yields HPB (4-hydroxy-1-(3-pyridyl)-1-butanone) and NNN (N-nitrosonornicotine)

N-Nitrosonornicotine (NNN) is formed by synthetic or biological N-nitrosation of the tobacco alkaloid nornicotine. Following metabolic activation of NNN, DNA and protein adducts are formed releasing 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB), an actual biomarker to differentiate between tobacco smokers and passive smokers. NNN and HPB can be prepared in a new one-step reaction by N-nitrosation of the nicotinoid myosmine which has been found not only in tobacco but also in nut products. The reaction was tested also in human gastric juice. The formation rate of NNN and HPB depends on the pH value in the reaction solutions. This is important under the aspect of myosmine uptake by humans from other biological sources and subsequent biological activation. The new reaction pathway indicates that human exposure to nicotinoid nitrosation products seems to be not restricted exclusively to tobacco.     

Quantitation of (R)- and (S)-linalool in beer using solid phase microextraction (SPME) in combination with a stable isotope dilution assay (SIDA)

A stable isotope dilution assay (SIDA) was developed for the quantitation of both linalool enantiomers using synthesized [2H(2)]R/S-linalool as the internal standard. For enrichment of the target compound from beer, a solid phase microextraction method (SPME) was developed. In comparison to the more time-consuming extraction/distillation cleanup of the beer samples, the results obtained by SPME/SIDA were very similar, even under nonequilibration conditions. Analysis of five different types of beer showed significant differences in the linalool concentrations, which were clearly correlated with the intensity of the hoppy aroma note as evaluated by a sensory panel. In addition, significant differences in the R/S ratios were measured in the beers. The SPME/SIDA yielded exact data independently from headspace sampling parameters, such as exposure time or ionic strength of the solution.     

Differential thermal analysis (DTA) and thermogravimetry (TG) of soil humus substances

DTA and TG data as well as infra red spectra and elementary analysis of chernozem- and podzolicsoil humic and fulvic acids revealed two structures — aromatic and aliphatic in their molecules. The aromatic structure predominates in humic acids, the aliphatic in fulvic acids.