Products of thymine oxygenation by a non-heme oxygenation model, Fe(II)(MeCN)6(2+)-Ac2O-H2O2, and the transition state model between oxoiron and thymine.

Oxidative thymine damage was investigated using a new non-heme oxygenation model, Fe(MeCN)6(2+)-H2O2-Ac2O, based on high-spin Fe(MeCN)6(2+) in a non-aqueous solution, Ac2O-MeCN. Thymine and 1,3-dimethylthymine oxidized by the system gave the corresponding trans-thymine glycol derivatives in good yield. Thymineglycol is equivalent to an oxidative product as a measure of oxidative DNA damage in living cells. It is suggested that the activation of Fe(MeCN)6(2+)-H2O2-Ac2O in Ac2O-MeCN forms the oxoiron O=Fe(IV)(AcO)(MeCN)4(+) as an active species via a hetelolytic two-electron mechanism, not a Haber-Weiss-Fenton-type reaction with a one-electron process by treatment with a radical scavenger. In addition, we also demonstrated the transition state (TS) for the interaction between thymine and O=Fe(IV)(AcO)(MeCN)4(+) in the triplet spin (spin multiplicity; M=3). This model of oxidative thymine damage may provide new insight into the oxidative mechanism of thymine glycol production in non-aqueous reactions of thymine.

Release of 4-nonylphenol from a silicone tube implanted in mice.

Silicone tubes are commonly used as a tool for long-term steroid treatment in animals. However, the release rates of steroids from these tubes have not yet been accurately determined. We measured the amounts of 4-nonylphenol (NP) remaining in tubes implanted in mice to obtain accurate release rates for original amounts of 20 or 1,000 microg NP in silicone tube implants. We achieved an accurate figure for the release rate from the tube, calculated using the total recovery from both the contents of the tube and the silicone matrix of the tube. The regression curve for the remaining amount of NP, as a percentage of the original amount (1,000 microg) was calculated as y (%) = 83.033 - 3.4722t + 0.0375t(2), where t is the number of days after implantation. The mean release rate over 56 days was 1.6% of the original amount per day.

Effects of synthetic para-nonylphenol isomers administered chronically throughout pregnancy and lactation on reproductive system of mouse pups.

The aim of this study was to analyze the effects of synthetic para-nonylphenol isomers administered chronically throughout pregnancy and lactation on the reproductive system of mouse pups. The two synthetic isomers used in this study showed higher (3E22NP) or lower (44NP) estrogen receptor (ER) binding activity on in vitro yeast assay than a commercial NP (NPmix). Female mice were implanted with a tube filled with one of three NPs and estradiol-17 ß (E2) before mating. The tube was kept in the mice throughout pregnancy and lactation period, until their pups had weaned at 28 days of age (PND 28). The data indicated that in males, NPs decreased body weight in some dose groups on PND28 and increased weights of testes and epididymides. However, the rate of seminiferous tubules having elongate spermatids (steps 10-16) decreased significantly in NPs and E2 treated groups, except for the 44NP groups. In female mice, NPs and E2 increased weights of ovaries, uterus and vagina in the pups in some dose groups on PND 28. However, there were no differences in the day of vaginal opening and numbers of corpus lutea. The present study demonstrates that the effects of these two isomers of NP on the pup reproduction at PND 28 are not quite different, despite them showing different levels of ER binding activity using in vitro yeast assay.

Separation, synthesis and estrogenic activity of 4-nonylphenols: two sets of new diastereomeric isomers in a commercial mixture.

Two sets of new diastereomeric 4-nonylphenol (NP) isomers [4-(3,4-dimethylheptan-4-yl)phenol (344NP, NP-J, L) and 4-(3,4-dimethylheptan-3-yl)phenol (343NP, NP-K, P)] were separated from a commercial NP mixture. The mixture of these diastereomers was synthesized at the same time by a single Friedel-Crafts reaction of 3,4-dimethyl-4-heptanol and phenol, and the mixture was separated into individual NPs by HPLC equipped with Hypercarb column. For the first time, in this study the stereostructure-estrogenic activity relationship of NP diastereomers was investigated. The NP isomers (NP-L and NP-P) having the beta-methyl group over the benzene ring were found to be 2-4 times more estrogenic than their diastereomers (NP-J and NP-K). In the case of the other set of diastereomer [4-(3,5-dimethylheptan-3-yl)phenol, (353NP, NP-E, G)] containing gamma-methyl group in the molecule, the gamma-methyl proton signal (delta 0.49) in the more estrogenic isomer (NP-G) also appeared in a higher field than the corresponding methyl signal (delta 0.76) of the less estrogenic isomer (NP-E).

The chloroplast avoidance response decreases internal conductance to CO2 diffusion in Arabidopsis thaliana leaves.

The relationship between chloroplast arrangement and diffusion of CO(2) from substomatal cavities to the chloroplast stroma was investigated in Arabidopsis thaliana. Chloroplast position was manipulated by varying the amount of blue light and by cytochalasin D (CytD) treatment. We also investigated two chloroplast positioning mutants. Chloroplast arrangement was assessed by the surface area of chloroplasts adjacent to intercellular airspaces (S(c)). Although it has been previously shown that long-term acclimation to high light is linked with a large S(c), we found that the short-term chloroplast avoidance response reduces S(c). This effect was not apparent in the blue-light-insensitive phot2 mutant, which did not show the avoidance response. As expected, the smaller S(c) induced by the avoidance response was coupled to a similar decrease in internal conductance. This reduction in internal conductance resulted in an increased limitation of the rate of photosynthesis. The limiting effect of S(c) on internal conductance and photosynthesis was also shown in chup1, a mutant with a constant small S(c) as the result of an unusual chloroplast arrangement. We conclude that chloroplast movements in A. thaliana can rapidly alter leaf morphological parameters, and this has significant consequences for the diffusion of CO(2) through the mesophyll.

Syntheses and estrogenic activity of 4-nonylphenol isomers.

Eight branched 4-nonylphenol (NP) isomers, which were identified from commercially available NP reagent, 4-(1-ethyl-1,4-dimethylpentyl)phenol (NP-C), 4-(1,1-dimethyl-3-ethylpentyl)phenol (NP-D), 4-(1,3-dimethyl-1-ethylpentyl)phenol (NP-E(G)), diastereomeric mixture), 4-(1,1,4-trimethylhexyl)phenol (NP-F), 4-(1-methyl-1-n-propylpentyl)phenol (NP-H), 4-(1,1-dimethyl-2-ethylpentyl)phenol (NP-I), 4-(1,1,2-trimethylhexyl)phenol (NP-M), and 4-(1-ethyl-1-methylhexyl)phenol (NP-N), were synthesized by two different synthetic methods starting from 4-benzyloxyacetophenone or phenol. The chemical structures of the synthesized compounds were confirmed by MS and NMR spectroscopy. The estrogenic activities of these synthetic NP isomers were tested and exhibited different activities on the recombinant yeast screen system. NP-I was found to exhibit three times greater estrogenic activity than the commercial NP mixture.

Historical distribution of PCDDs, PCDFs, and coplanar PCBs in sediment core of Ariake Bay, Japan.

Persistent organic pollutants, particularly polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), coplanar polychlorinated biphenyls (co-PCBs) and toxic equivalent quantity (pg TEQ g(-1)) were determined in sediment samples collected from Ariake Bay, Japan. The total concentration of PCDDs/DFs in surface sediment of the Yabe River (17,000 pg g(-1) dry wt) was approximately 2.5-fold higher than that of the Chikugo River (7,000 pg g(-1) dry wt) which has the highest flow amount of about 40% inputting to the northern Bay. The congener profile suggested that dioxin sources could be close to the study area. The PCDDs concentration (12,000 pg g(-1) dry wt) in the sediment layer, which was corresponding to the 1960s, was reflected on the pentachlorophenol (PCP) contamination occurring at that time in Ariake Bay. The reflecting of PCP in the sediment core was significantly considered by hierarchical cluster analysis. Based on isomer-specific analysis, the tetrachlorodibenzo-p-dioxin composition showed a gradual increase from 1978-1982 toward the surface, indicating that the pollution source at that period might be more influenced by chloronitrofen than PCP. This fact was supported, based on the ratio of Sigma PCDD to Sigma PCDF concentration. The PCDDs/DFs-derived TEQ contributed more than 90% of the SigmaTEQ (PCDDs/DFs and co-PCBs) in all the detected sediment layers. The contribution of PCBs to the total TEQ was low; however, an increasing historical trend of concentration was clearly observed.

Estrogen equivalent concentration of 13 branched para-nonylphenols in three technical mixtures by isomer-specific determination using their synthetic standards in SIM mode with GC-MS and two new diasteromeric isomers.

Thirteen isomers of branched para-nonylphenols (para-NP) in three technical mixtures were isomer-specifically determined using their synthesized standards by SIM of structurally specific ions, m/z 135, 149 or 163 with GC-MS. Of the 13 isomers, four isomers, 4-(2,4-dimethylheptan-4-yl)phenol, 4-(4-methyloctan-4-yl)phenol, 4-(3-ethyl-2-methylhexan-2-yl)phenol (3E22NP) and 4-(2,3-dimethylheptan-2-yl)phenol synthesized for their determinations were first used as standard substances. The 13 isomers in the technical mixtures individually occurred at mass percent portion of more than 2%. The total mass percent portions in the mixtures from Tokyo Chemical Industry (TCI), Aldrich, and Fluka covered with 89+/-2%, 75+/-4% and 77+/-2%, respectively. The abundance of 4-(3,6-dimethylheptan-3-yl)phenol in the three mixtures was the largest with 11.1+/-2% to 9.9+/-0.3%, while that of 4-(2-methyloctan-2-yl)phenol was the smallest with 2.9+/-0.3% to 3.0+/-0.2%. Additionally, structures of four new isomers of more than 1% portion present in a technical mixture were elucidated as two pairs of diastereomeric isomers: two types of 4-(3,4-dimethylheptan-4-yl)phenol (344NP) and those of 4-(3,4-dimethylheptan-3-yl)phenol (343NP). By estrogenic assay of 13 isomers with yeast estrogen screen system, the activity of 3E22NP was the highest, while that of 4-(3-methyloctan-3-yl)phenol was the least. Their relative activities to that of 3E22NP were individually calculated. Estrogenic equivalent concentrations of the three technical mixtures were predictively evaluated. The ratio of the EEC to the conventional concentration, total mass percent portions of the 13 isomers in technical mixtures were 0.208 for TCI, 0.206 for Aldrich and 0.205 for Fluka. The predicted estrogenic activity of measured concentration of para-NP in technical mixtures was approximately 5-fold greater than the measured estrogen agonist activity.

Organochlorine pesticides in the sediment core of Gwangyang bay, South Korea.

The nine organochlorine pesticides (OCPs) in the sediment samples taken from Gwangyang Bay, which is a heavy chemical industrial region in South Korea, are analyzed to evaluate their contaminations during the past 50 years. The vertical distributions of SigmaOCPs concentration in the sediment core were in good agreement with the temporal amount of pesticides used in South Korea except for the top sediment layer. The DDTs were predominant, their concentrations ranging from 78.0 to 202 pg/g dry wt and attributed more than 60% to SigmaOCPs in all the sediment layers. Based on the ratio of DDT metabolite compositions, the DDT contamination in the top layer might be caused from recent input. This is due to the highest residual concentration of OCPs in the top layer. Although HCB and mirex have been unregistered as pesticides in South Korea, two compounds were detectable in all of the sediment samples in the range from 0.243 to 16.7 pg/g dry wt in the study area. The emission source of HCB in the sediment core could be estimated to be due to incomplete combustion in the industrial chemical processes rather than pesticide application. Regarding horizontal distribution of SigmaOCPs, the concentration was slightly higher than for the inner bay than the outer bay. The OCPs in the sediments of Gwangyang Bay were compared with those of other countries by hierarchical cluster analysis and principal component analysis.

Vertical distributions of persistent organic pollutants (POPs) caused from organochlorine pesticides in a sediment core taken from Ariake bay, Japan.

Persistent organic pollutants (POPs) of organochlorine pesticides such as dichlorodiphenyl trichloroethane (DDTs) and its metabolites, hexachlorobenzene (HCB), heptachlor, chlordane compounds (CHLs), aldrin, dieldrin, endrin, mirex and isomers of hexachlorocyclohexane (HCHs), were analyzed in sediment cores collected from Ariake Bay, Japan. Although Chikugo River has the largest flow in Ariake Bay, the total concentration of POPs in surface sediment was found in St.3, mouth of the Yabe River, where that level was two times higher than St.1, mouth of the Chikugo River. It could be assumed that the potential source of POPs contamination is relatively close to this study area. Relatively high residue levels of HCB, HCHs and DDTs in sediment core were found during the period from 1967 to 1970. In this layer, the HCB concentration investigated in sediment cores of Ariake Bay was maximum, 2.6 ng g(-1) dry weight and higher than that of Tokyo Bay and subsequently detected in deeper sediment cores. The ratio of (DDD+DDE)/SigmaDDTs was high in top sediments (0-2 cm). Although there was a concentration of DDTs in the top sediment, it was noticed that DDT emission did not cause direct input of DDT recently. The HCHs determined in upper sediment cores might be originated from long-range accumulation in environment after dispersing of technical-grade HCH. Moreover, the CHLs, dieldrin and heptachlor concentrations were detected and recently increased in sediment core. POPs in sediment cores of Ariake Bay based on the possibility of PCP contamination during the early 1960s were reflected.

Estrogen equivalent concentration of individual isomer-specific 4-nonylphenol in Ariake sea water, Japan.

Concentrations of 4-nonylphenol (NP) were determined by isomer-specific quantification of individual NP isomers based on relative response factor (RRF) quantification with GC-MS in combination with steam distillation extraction. Concentrations of NP in the Ariake Sea decreased with distance from the river mouth (St.A; 49 ng NP/l) to offshore areas (St.C; 11 ng NP/l). Even the least concentration in water from St.C in Ariake Sea was sufficient to have adverse effects on barnacles. The isomers, NP1-NP14 were separated by GC-PFC and identified structurally with NMR. The isomers varied in estrogenic activity with NP7 exhibiting the greatest estrogenic activity with a potency that was approximately 1.9 x 10(-3) that of 17beta-estradiol (E2) in recombinant yeast screen system. The coefficient of variation (CV) of NP isomer's concentrations among three samples at St.A, B and C were 4-75%. This suggests that NP isomers might be independently degraded in aquatic environmental samples. The predicted estrogenic activity of measured concentrations of NP in Ariake Sea was 2.7-3.0-fold greater than the measured estrogen agonist activity.

Variation in estrogenic activity among fractions of a commercial nonylphenol by high performance liquid chromatography.

Estrogenic activity by recombinant yeast screen assay of the commercial NP was considerably higher when compared with that of n-nonylphenol (n-NP). Fractionation of the commercial NP by high performance liquid chromatography (HPLC) afforded seven isomers: 4-(1,3-dimethyl-1-propyl-butyl)-phenol, 4-(1,1,3-trimethyl-hexyl)-phenol, 4-(1,1-dimethyl-3-ethyl-pentyl)-phenol, 4-(1,1,4-trimethyl-hexyl)-phenol, 4-(1-methyl-1-propyl-pentyl)-phenol, 4-(1,1,2-trimethyl-hexyl)-phenol and 4-(1-ethyl-1-methyl-hexyl)-phenol. The structures of these isomers were determined by GC-MS and nuclear magnetic resonance spectroscopy (NMR). All of these isomers possessed tertiary alpha-carbon in their chemical structures. Another tertiary NP, 4-(1,1-dimethyl-heptyl)-phenol was synthesized in the present study and this synthetic NP also exhibited the estrogenic activity. One fractionated compound was identified as one of decylphenol, 4-(1-ethyl-1,4,4-trimethyl-pentyl)-phenol. The isomer, 4-(1,1,4-trimethyl-hexyl)-phenol exhibited the highest estrogenic activity corresponding to 1/10000 that of 17beta-estradiol (E2). The activity of n-NP was the least. This suggests that it may be possible to develop a technical NP mixture with relatively low estrogenic activity.