Diphenylarsinic acid produces behavioral effects in mice relevant to symptoms observed in citizens who ingested polluted well water.

Citizens in an area of Kamisu City, Ibaraki, Japan had exhibited unusual health problems, and pollution of well water by diphenylarsinic acid (DPAA) was found in the area. We examined the effects of DPAA on various behaviors in mice. DPAA was administered to mice through free intake of drinking water for 27 weeks (subchronic exposure) or 57 weeks (chronic exposure), and behavior was examined during exposure. DPAA at 30-100 ppm increased ambulatory activity and the response rate of the shuttle type discrete conditioned avoidance response of mice. DPAA reduced coordination ability on the fixed rod at 100 ppm. DPAA at 7.5-15 ppm also reduced coordination on the rotating rod, although these doses of DPAA did not affect coordination on the fixed rod. Chronic exposure to 7.5-15 ppm of DPAA produced anti-anxiety-like effects in the elevated plus maze test, whereas subchronic exposure to 100 ppm of DPAA produced anxiogenic-like effects. Neither subchronic nor chronic exposure to 7.5-100 ppm of DPAA affected learning ability and/or memory, as evaluated using the passive avoidance response. Exposure to 15-30 ppm of DPAA for 52 weeks did not alter weights of the cerebrum and cerebellum or amounts of neuron marker protein TUJ-1 or astrocyte marker protein glial fibrillary acidic protein in the cerebellum of mice. Behavioral effects observed in mice seem relevant to symptoms observed in patients from Kamisu City.

Isolation and properties of a 2-chlorovinylarsonic acid-degrading microorganism.

2-Chlorovinylarsonic acid (CVAOA) is a stable abiotic metabolite of lewisite 1 that has been identified in lewisite dumps. There have been no reports of microbial degradation of CVAOA, so we isolated and examined CVAOA-degrading microorganisms. CVAOA contains arsine, which is toxic to microbial growth. We therefore used the simple organic chemical, ethylene, as a sole carbon source in initial screening for suitable microbes. We isolated several microorganisms from sewage sludge and soil. Two strains, NK0505 and NK0506, could be grown on CVAOA as the sole carbon source and were identified by 16S rRNA sequencing as Nocardia carnea NK0505 and Rhodococcus opacus NK0506. Because N. carnea NK0505 was slightly more active in degrading CVAOA, we used it for further degradation studies. Strain NK0505 utilized about 90% of CVAOA (50 ppm) within 5 days; at higher concentrations of CVAOA no degradation occurred over a 10-day period. We identified 1-chloro-1,2-dihydroxyethane, ethylene glycol, glycolic acid, and arsenic acid as degradation products of CVAOA. Epoxy formation on alkylarsine was not confirmed. CVAOA is probably further metabolized via these compounds in the tricarboxylic acid cycle. Strain NK0505 could also degrade but-3-enylarsonic acid, trichloroethylene, isoprene, and 1,3-butadiene, but utilization of tetrachloroethylene and acetylene did not occur.

Degradation of arylarsenic compounds by microorganisms.

Microorganisms were not directly accumulated when soil contaminated to about 0.5 mM with diphenylarsinic acid (DPAA) was used as the sole source of carbon. However, using toluene as the carbon source yielded several isolates, which were then used in cultivation with DPAA as the sole source of carbon. By these methods, Kytococcus sedentarius strain NK0508, which can grow in up to 0.038 mM DPAA, was isolated. The toxicity of DPAA retarded the growth of K. sedentarius and the direct accumulation of DPAA-utilizing microorganisms from environmental samples. This strain can utilize about 80% of DPAA and phenylarsonic acid as the sole source of carbon for 3 days. Degradation products of DPAA were determined to be cis, cis, muconate and arsenic acid. When K. sedentarius was cultivated with methylphenylarsinic acid and diphenylmethylarsine, about 90% and 10% degradation of the two compounds, respectively, were observed. Diphenylmethylarsine oxide, possibly synthesized by methylation of DPAA, was detected as one of the transformation products. These results suggest that degradation is initiated by splitting of the phenyl groups from the arylarsenic compounds with subsequent hydroxylation of the phenyl groups and ring opening to yield cis, cis, muconate.

Microbial treatment of bis (2-ethylhexyl) phthalate in polyvinyl chloride with isolated bacteria.

In this study, we investigated the use of microbes to degrade and remove bis (2-ethylhexyl) phthalate (DEHP), a common plasticizer and a suspected endocrine disruptor, exuding from polyvinyl chloride. Four species of bacteria that utilize DEHP as their sole carbon source were isolated from garden soil, one of which, strain NK0301, was markedly more efficient than the others in degrading DEHP and was chosen for further studies. Strain NK0301 was a coryneform bacterium (1.5x1.0 microm) identified as Mycobacterium sp. from its 16S rDNA sequencing homology. It readily degraded DEHP to two major products determined by gas chromatography/mass spectrometry to be 2-ethylhexanol and 1,2-benzenedicarboxylic acid. Other phthalate esters, suspected of being endocrine disruptors, were also tested and all except two could be utilized by strain NK0301 as their sole source of carbon. When strain NK0301 was cultivated on polyvinyl chloride sheets containing DEHP as the plasticizer, it removed up to 90% of DEHP in 3 d. Following this treatment, the polyvinyl chloride sheets did not exude DEHP to artificial saliva.

Degradation of dioxins by cyclic ether degrading fungus, Cordyceps sinensis.

Use of the cyclic ether degrading fungus, Cordyceps sinensis strain A to degrade dibenzo-p-dioxin (DD), 2,3,7-trichlorodibenzo-p-dioxin (2,3,7-triCDD) and octachlorodibenzo-p-dioxin (octaCDD) has revealed a new degradation pathway for dioxins. Catechols and other possible degradation products were synthesized to facilitate the identification, detection and quantification of these products, and phenylboronate was used for the derivatization and analysis of dihydroxylated degradation products. Degradation of DD yielded catechol, which was further metabolized to cis,cis-muconate. 2,3,7-triCDD yielded mono- and dichloro-catechol as well as catechol itself; and the cis,cis-muconates were also detected. octaCDD gave mono- to trichloro-catechol as well as catechol, and the cis,cis-muconates were also found. For all tested dioxin samples dechlorination resulted in replacement of chlorine with hydrogen, and no hydroxylation was observed. It appeared that dechlorination may occur in the degradation of octaCDD to catechols and possibly in the subsequent degradation of chlorinated catechols and/or chlorinated cis,cis-muconates to further breakdown products.

Complexes of diphenylarsinic acid and phenylarsonic acid with thiols: a 1H and 13C NMR study.

The high toxicity of diphenylarsinic acid, found in ground water and well water as a probable consequence of the inappropriate disposal of warfare agents, prompted us to study the reaction, monitored by 1H and 13C NMR spectroscopy, of the compound and its monophenyl analogue, phenylarsonic acid, with cellular thiols as represented, in particular, by glutathione. Glutathione reduced the phenylarsenic acids to trivalent forms and complexed them: diphenylarsinic acid to a monoglutathione adduct and phenylarsonic acid to a diglutathione adduct. The complexes were characterized by 1H and 13C NMR spectroscopy and mass spectrometry. The NMR spectra showed the diastereotopic nature of the two phenyl groups in the diphenylarsinic acid-glutathione compound, and of the two glutathione residues in the phenylarsonic acid-diglutathione complex. The stereochemistry of thiol compounds of phenylarsonic acid was further explored by 1H and 13C NMR spectroscopy of the L-cysteine complex. The diphenylarsinic acid-glutathione complex was stable below pH 12 but at higher pH the complex dissociated into diphenylarsinous acid and reduced glutathione. The released diphenylarsinous acid then oxidized to diphenylarsinic acid with a half-life of about 7 h at pH 13 and at room temperature.

Degradation of 1,4-dioxane and cyclic ethers by an isolated fungus.

By using 1,4-dioxane as the sole source of carbon, a 1,4-dioxane-degrading microorganism was isolated from soil. The fungus, termed strain A, was able to utilize 1,4-dioxane and many kinds of cyclic ethers as the sole source of carbon and was identified as Cordyceps sinensis from its 18S rRNA gene sequence. Ethylene glycol was identified as a degradation product of 1,4-dioxane by the use of deuterated 1,4-dioxane-d8 and gas chromatography-mass spectrometry analysis. A degradation pathway involving ethylene glycol, glycolic acid, and oxalic acid was proposed, followed by incorporation of the glycolic acid and/or oxalic acid via glyoxylic acid into the tricarboxylic acid cycle.

Microbial production and vaporization of mono-(2-ethylhexyl) phthalate from di-(2-ethylhexyl) phthalate by microorganisms inside houses.

Laboratory workers were bothered by an irritation that caused coughing during the cultivation of microorganisms that degraded di-(2-ethylhexyl) phthalate (DEHP). The authors found that mono-(2-ethylhexyl) phthalate (MEHP), a known cause of asthma, was released during the degradation of DEHP. At its highest production and vaporization rate, the amount was almost equal to that of the DEHP starting material. It appeared that transport into the atmosphere depended on its adsorption on dust particles. The authors attempted to cultivate several microorganisms from house materials, especially those composed of rotting polyvinyl chloride. And microorganisms produced MEHP in the culture medium. In addition, MEHP was produced from DEHP by several stock microorganisms. Thus, MEHP could easily be produced from DEHP by microorganisms in the environment. In Japan, there are many cases of asthma with unknown causes. If MEHP is one of causes, then preventive measures against some cases of asthma could be taken.