Arsenic Compounds in Higher Fungi

In 50 mushroom species (56 samples) from Slovenia, Switzerland, Brazil, Sweden, The Netherlands and USA, total arsenic was determined by radiochemical neutron activation analysis (RNAA). Arsenic concentrations ranged from 0.1 to 30 μg g⁻¹ (dry mass). Arsenic compounds were determined in methanol extracts from the mushrooms by HPLC–ICP–MS. The aim of the study was not only to quantify arsenic compounds in mushrooms but also to uncover trends relating the methylating ability of a mushroom to its taxonomic or evolutionary status. The main arsenic compound found in many mushrooms (various puffballs, Agaricales and Aphyllophorales) was arsenobetaine. Arsenate [As(V)] was the main arsenic species in Laccaria fraterna and Entoloma rhodopolium and arsenite [As(III)] in Tricholoma sulphureum. A mixture of arsenite and arsenate was present in Amanita caesarea. Dimethylarsinic acid (DMA) and methylarsonic acid were present in many mushrooms, but generally as minor components. In Laccaria laccata, Leucocoprinus badhamii and Volvariella volvacea, DMA was the major metabolite. Arsenocholine (AC) and the tetramethylarsonium ion were present in a few species, generally at low concentrations, except for Sparassis crispa, in which AC was the main compound. Tri- methylarsine oxide was not found in any of the mushrooms. In some species small amounts of unknown compounds were also present. The possible taxonomic significance of the metabolite patterns and the predominance of arsenobetaine in more advanced fungal types are discussed. © 1997 John Wiley & Sons, Ltd.     

Arsenic Compounds in Zoo- and Phyto-plankton of Marine Origin

Major water-soluble arsenic compounds accumulated in some zoo- and phyto-plankton were identified. Zooplankton were collected at sampling stations in the Sea of Japan by a Norpac net towed from 600 m depth to the surface. Phytoplankton were cultivated under axenic conditions. Water-soluble arsenic compounds were extracted repeatedly from plankton tissues by aqueous methanol. The arsenic compounds in the extracts were analyzed by HPLC–ICP/MS. Among zooplankton analyzed in the present study, two carnivorous species, i.e. Amphipoda ( Themisto sp.) and Sagittoidea ( Sagitta sp.), contained arsenobetaine as the dominant arsenic species. Arsenobetaine was the major species in Euphausiacea ( Euphausia sp.), also. The most abundant arsenic compound in the herbivorous Copepoda species ( Calanus sp.), on the other hand, was an arsenic-containing ribofuranoside with a sulfate ester group, and arsenobetaine was only a minor component. Phytoplankton contained arsenic-containing ribofuranosides apparently in a species-speific manner. The arsenic compounds in zooplankton seem to reflect their feeding habit; i.e. carnivorous species eating zooplankton or other small animals accumulate arsenobetaine, while herbivorous ones eating phytoplankton accumulate arsenic-containing ribofuranosides as major arsenic compounds.     

Arsenic Compounds in Terrestrial Organisms II: Arsenocholine in the Mushroom Amanita muscaria

Arsenic compounds were identified and quantified in the mushroom Amanita muscaria, collected close to a facility that had roasted arsenic ores. The powdered dried mushrooms were extracted with methanol/water (9:1), the extracts were concentrated and the concentrates were dissolved in water. The resulting solutions were chromatographed on anion-exchange, cation-exchange and reversed- phase columns. Arsenic was detected on-line with an ICP–MS detector equipped with a hydraulic high-pressure nebulizer. Arsenite, arsenate, dimethylarsinic acid and the tetramethylarsonium cation were minor arsenic compounds (∼2% each of the total 22 mg kg⁻¹ dry mass), and arsenobetaine, arsenocholine (∼15% each) and several unidentified arsenic compounds (∼60%) were the major arsenic compounds in Amanita muscaria. The presence of arsenocholine (detected for the first time in a terrestrial sample) was ascertained by matching retention times in the anion-exchange, cation- exchange and reversed-phase chromatograms with the retention time of synthetic arsenocholine bromide and chromatographing extracts spiked with arsenocholine bromide. © 1997 John Wiley & Sons, Ltd.     

The Chemistry of Simple Phosphorus-Carbon Compounds

With the aid of selected examples an overview is given of the development trends in phosphoruscarbon chemistry over the past few years. An attempt is made to demonstrate the relationships between various parameters and properties such as constitution, basicity, substitution by functional groups, reaction behavior etc. of the compounds. In the case of basis compounds containing methylphosphorus groups the state of development of industrially interesting processes is also outlined. In addition, the synthesis of a few bifunctional phosphorus-carbon compounds which can be employed as comonomers in the production of polymers is described.     

Metal-Boron Compounds – Problems and Perspectives

“True” metal-boron compounds have been known for about ten years. The bonding between the metal and boron atoms can vary widely in nature: Not only simple covalent bonds are encountered but also coordinate bonds and boron-metal multicenter bonds. Furthermore, π complexes of transition metals with boron-nitrogen systems and metal complexes containing boron(I) compounds as ligands have recently also been prepared.     

Boron-Phosphorus Compounds and Multiple Bonding

Boron-phosphorus compounds have not been as thoroughly studied as their boron-nitrogen counterparts. Until recently many classes of B-P compounds that had been well established in B-N chemistry were either unknown or poorly characterized. This statement is particularly true for compounds involving possible multiple bonding between boron and phosphorus. For example, detailed structural information on simple monomeric phosphino-boranes, R₂BPR′₂, did not become available until 1986 even though the isoelectronic SiC double bonded species, the silenes, had already been reported. However, new work has shown that it is possible to prepare and characterize several novel types of boron-phosphorus compounds with varying degrees of multiple B—P bonding. These include not only monomeric phosphinoboranes but also phosphanediylborates (borylphosphides), three- and four-membered rings (diphosphadi-boretanes), boron phosphorus analogues of borazine, B-P skeletal analogues of allyl cations and anions, butadiene and cage compounds. Structural, spectroscopic (mainly NMR) and theoretical studies reveal some important differences between B-P and B-N compounds which in many cases can be traced to the presence of a high inversion barrier at phosphorus that reduces the π interaction. This usually causes compounds such as R₂BPR′₂ to associate through σ bonding between B and P. Supporting evidence for this view comes from species that involve phosphorus and nitrogen in competitive π bonding with a boron p orbital in which the dative interaction between B and N is dominant and the phosphorus center remains pyramidal. Recently published work has shown that steric and electronic factors can be used to favor π bonding and give an approximately planar system. Furthermore, theoretical studies reveal that p? p π overlap in a planar B-P system is of similar efficiency to its B-N analogue. Good examples are seen in the phosphanediyl borates, the boron-phosphorus analogues of borazine and the π-allyl cations, whose molecular configurations and B—P bond lengths support strong boron—phosphorus π bonding.     

Three New Phenol Compounds from Iris dichotoma Pall.

Three new phenolic compounds, irisdichototins D, E, and F ( 1 – 3 , resp.) were isolated from the stems of Iris dichotoma. The structures of the new compounds were elucidated by spectroscopic analyses, including 2D‐NMR techniques.     

Disubstituted Azidotetrazoles as Energetic Compounds

Base‐catalyzed activation of the C? F bond in the trifluoromethylazo‐substituted cyclic and acyclic alkanes provides a route to disubstituted azidotetrazoles. For example, the reaction of 1,2‐bis(trifluoromethylazo)ethane with four equivalents of NaN₃ gave the alkyl‐bridged bis(5‐azido‐1H‐tetrazol‐1‐yl)‐1,2‐dimine, N,N′‐bis(5‐azido‐1H‐tetrazol‐1‐yl)‐1,2‐diiminoethane, in 75 % yield (see scheme).

     

Arsenic compounds in terrestrial organisms. IV. Green plants and lichens from an old arsenic smelter site in Austria

Two lichens and 12 green plants growing at a former arsenic roasting facility in Austria were analyzed for total arsenic by ICP–MS, and for 12 arsenic compounds (arsenous acid, arsenic acid, dimethylarsinic acid, methylarsonic acid, arsenobetaine, arsenocholine, trimethylarsine oxide, the tetramethylarsonium cation and four arsenoriboses) by HPLC–ICP–MS. Total arsenic concentrations were in the range of 0.27 mg As (kg dry mass)⁻¹ (Vaccinium vitis idaea) to 8.45 mg As (kg dry mass)⁻¹ (Equisetum pratense). Arsenic compounds were extracted with two different extractants [water or methanol/water (9:1)]. Extraction yields achieved with water [7% (Alectoria ochroleuca) to 71% (Equisetum pratense)] were higher than those with methanol/water (9:1) [4% (Alectoria ochroleuca) to 22% (Deschampsia cespitosa)]. The differences were caused mainly by better extraction of inorganic arsenic (green plants) and an arsenoribose (lichens) by water. Inorganic arsenic was detected in all extracts. Dimethylarsinic acid was identified in nine green plants. One of the lichens (Alectoria ochroleuca) contained traces of methylarsonic acid, and this compound was also detected in nine of the green plants. Arsenobetaine was a major arsenic compound in extracts of the lichens, but except for traces in the grass Deschampsia cespitosa, it was not detected in the green plants. In contrast to arsenobetaine, trimethylarsine oxide was found in all samples. The tetramethylarsonium cation was identified in the lichen Alectoria ochroleuca and in four green plants. With the exception of the needles of the tree Larix decidua the arsenoribose (2′R)‐dimethyl[1‐O‐(2′,3′‐dihydroxypropyl)‐5‐deoxy‐β‐D ‐ribofuranos‐5‐yl]arsine oxide was identified at the low μg kg⁻¹ level or as a trace in all plants investigated. In the lichens an unknown arsenic compound, which did not match any of the standard compounds available, was also detected. Arsenocholine and three of the arsenoriboses were not detected in the samples. Copyright © 2000 John Wiley & Sons, Ltd.     

Speciation of Arsenic Compounds in the Urine of Rats Orally Exposed to Dimethylarsinic Acid Ion Chromatography with ICP–MS as an Element-Selective Detector

A combined ion chromatography (IC) with inductively coupled plasma mass spectrometry (ICP—MS) system as an element-selective detector has been used for the determination of arsenic compounds. Seven arsenic compounds were separated by cation-exchange chromatography. Subsequently, the separated arsenic compounds were directly introduced into the ICP—MS and were detected at m/z =75. Detection limits for the seven arsenic compounds ranged from 0.8 to 3.8 μg As/l. The IC–ICP–MS system was applied to the determination of arsenic compounds in the urine of dimethylarsinic acid (DMAA)-exposed rats. DMAA was the most abundant arsenic compound detected. Arsenous acid, monomethylarsonic acid and trimethylarsine oxide were also detected.     

Immunotoxicity of Organic Arsenic Compounds in Marine Animals

In the present study, we demonstrated for the first time the immunotoxic effects of organic arsenic compounds in marine animals, namely arsenocholine [AsCho; trimethyl(2-hydroxyethyl)arsonium cation], arsenobetaine [AsBe; the trimethyl(carboxymethyl)arsonium zwitterion] and the tetramethylarsonium ion (TetMA), to murine principal immune effector cells (macrophages and lymphocytes), comparing them with the effects of inorganic arsenicals in vitro . Inorganic arsenicals (arsenite and arsenate) showed strong cytotoxicity to both macrophages and lymphocytes. The concentration of arsenite that reduced the number of surviving cells to 50% of that in untreated controls (IC₅₀) was 3–5 μmol dm⁻³, and the cytotoxicity of arsenate (IC₅₀=100 μ-1 m mol dm⁻³) was lower than that of arsenite. Compared with these findings, trimethylarsenic compounds in marine animals, AsCho and AsBe, were less toxic even at a concentration over 10 mmol dm⁻³ to both macrophages and lymphocytes; however, TetMA had weak, but significant, cytotoxicity to these cells (IC₅₀ was about 6 mmol dm⁻³).     

Withanolide Compounds from the Flower of Datura metel L.

Three new withanolide compounds named baimantuoluoline A ( 1 ), B ( 2 ), and C ( 3 ) and the two known withanolides withafastuosin E ( 4 ) and withametelin C ( 5 ) were isolated from the fraction exhibiting activity for psoriasis in the flower of Datura metel L. The three new structures were determined as (5α,6α,7α,12β,15β,22R)‐6,7‐epoxy‐5,12,15‐trihydroxy‐1‐oxowitha‐2,24‐dienolide ( 1 ), (5α,6β,15β,22R)‐ 5,6,15,21‐tetrahydroxy‐1‐oxowith‐24‐enolide ( 2 ), and (5α,6β,12β,22R)‐5,6,12,21‐tetrahydroxy‐27‐methoxy‐1‐oxowitha‐2,24‐dienolide ( 3 ) on the basis of extensive spectroscopic data (HR‐ESI‐MS, ¹H‐ and ¹³C‐NMR, ¹H,¹H‐COSY, HSQC, HMBC, and NOESY) (withanolide=22‐hydroxyergostan‐26‐oic acid δ‐lactone).     

Electrode Reactions Involving Arsenic and Its Inorganic Compounds

The available information on the electrochemical properties of arsenic and its inorganic compounds is generalized. Processes of practical value are considered. These include the formation of free arsenic from solutions as a solid phase in the form of powder or galvanic coatings; the synthesis of arsine, arsenic acid, and arsenates; and use of electrochemical techniques for the waste water purification.     

Tetracyanoquinodimethane Reduction by Complexed Guanidinyl‐Functionalized Aromatic Compounds

In this work, we report on the reduction of tetracyanoquinodimethane (TCNQ) with dicationic complexes of guanidinyl‐functionalized aromatic (GFA) electron donors. In contrast to reduction with free GFAs, milder reduction conditions were achieved, and this led to semiconducting materials with extended TCNQ π stacking. The charge on the TCNQ units was estimated from the structural data obtained by single‐crystal X‐ray diffraction analysis and from IR spectroscopic data. The electrical conductivity was studied and the activation energy of the semiconducting materials was estimated from the temperature dependence of the conductivity.     

Natural Dietary Compounds in the Treatment of Arsenic Toxicity

Chronic exposure to arsenic (As) compounds leads to its accumulation in the body, with skin lesions and cancer being the most typical outcomes. Treating As-induced diseases continues to be challenging as there is no specific, safe, and efficacious therapeutic management. Therapeutic and preventive measures available to combat As toxicity refer to chelation therapy, antioxidant therapy, and the intake of natural dietary compounds. Although chelation therapy is the most commonly used method for detoxifying As, it has several side effects resulting in various toxicities such as hepatotoxicity, neurotoxicity, and other adverse consequences. Drugs of plant origin and natural dietary compounds show efficient and progressive relief from As-mediated toxicity without any particular side effects. These natural compounds have also been found to aid the elimination of As from the body and, therefore, can be more effective than conventional therapeutic agents in ameliorating As toxicity. This review provides an overview of the recently updated knowledge on treating As poisoning through natural dietary compounds. This updated information may serve as a basis for defining novel prophylactic and therapeutic formulations.     

Analysis of Organotin Compounds via a Thermabeam® LC–MS Interface

Selected organotin compounds, relating to antifouling paints, have been analysed using a particle beam interface system designed for use on liquid chromatography–mass spectrometry (LC–MS) instruments. The resultant mass spectra matched those obtained from conventional electron-impact (EI) techniques, and consistent data over several injections and different elution times were obtained. Data obtained from tributyltin, dibutyltin, monobutyltin, triphenyltin and diphenyltin (each as the chlorides) are presented. This interface has been shown to maintain sample and therefore spectral integrity for these compounds and is of potential use in further investigations relating to organotin environmental pollution.