Elsevier

Phytochemistry

Volume 69, Issue 3, February 2008, Pages 585-606
Phytochemistry

Review
Biologically active compounds of semi-metals

https://doi.org/10.1016/j.phytochem.2007.09.018Get rights and content

Abstract

Semi-metals (boron, silicon, arsenic and selenium) form organo-metal compounds, some of which are found in nature and affect the physiology of living organisms. They include, e.g., the boron-containing antibiotics aplasmomycin, borophycin, boromycin, and tartrolon or the silicon compounds present in “silicate” bacteria, relatives of the genus Bacillus, which release silicon from aluminosilicates through the secretion of organic acids. Arsenic is incorporated into arsenosugars and arsenobetaines by marine algae and invertebrates, and fungi and bacteria can produce volatile methylated arsenic compounds. Some prokaryotes can use arsenate as a terminal electron acceptor while others can utilize arsenite as an electron donor to generate energy. Selenium is incorporated into selenocysteine that is found in some proteins. Biomethylation of selenide produces methylselenide and dimethylselenide. Selenium analogues of amino acids, antitumor, antibacterial, antifungal, antiviral, anti-infective drugs are often used as analogues of important pharmacological sulfur compounds. Other metalloids, i.e. the rare and toxic tellurium and the radioactive short-lived astatine, have no biological significance.

Graphical abstract

The present state of knowledge in the chemistry of organic compounds of semi-metals from different organisms is reviewed. They include, e.g., the boron-containing antibiotics or the silicon compounds present in “silicate” bacteria. Arsenic is incorporated into arsenosugars, arsenobetaines or volatile methylated arsenic compounds, selenium is incorporated into selenocysteine that is found in some proteins. Other metalloids, i.e. the rare and toxic tellurium and the radioactive short-lived astatine, have no biological significance.

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Introduction

In the periodic table of elements, semi-metals (metalloids) are found along the line that distinguishes metals from nonmetals. Together with metals and nonmetals, metalloids form one of the three categories of chemical elements as classified by ionization and bonding properties (Rochow, 1966, Venugopal and Luckey, 1978). They have some of the qualities of both metals and nonmetals. Unlike the true metals, metalloids are usually semiconductors rather than conductors and have therefore received intensive attention from the computer and electronics industries. Their relative abundance in the environment is summarized in Table 1.

When involved in chemical bonding, the metalloids again exhibit intermediate qualities. They are capable of taking electrons from most metals and will readily lose electrons to most nonmetals. Their electronegativity values are also mid-range. They usually establish covalent bonding, ionic bonding being rather rare.

The reactivity of the metalloids depends on the counter-element. Boron acts as a nonmetal when reacting with sodium yet as a metal when reacting with fluorine. In organic compounds, they can substitute other elements such as sulfur. Boron and arsenic form compounds with lipids, sugars, phenols, organic acids and some polymers. Organic arsenic compounds are components of the food chains of many organisms including humans and may play important biological roles in them. Selenium is found in living organisms in its soluble inorganic forms and as protein-bound and free seleno-amino acids and volatile organoselenium compounds. Most small organic selenium compounds in living cells are isologues of sulfur amino acids or their derivatives. The interactions of silicon with living matter are vitally important for some bacteria, which release silicon from aluminosilicates through the secretion of organic acids, or for unicellular algae – diatoms for which it serves as the basic building block of their bodies. Tellurium is highly toxic and is not thought to be required by biological systems; the highly radioactive astatine is so rare in nature that the existence of biological astatine compounds is highly improbable.

Section snippets

Boron

Boron is a ubiquitous element in rocks, soil, and water, its average concentration ranging from ∼1 mg/kg in fresh water to ∼100 mg/kg in rocks (Steinberg, 1964).

Tetrahedral borate or boronate complexes have been shown to be involved in enzyme inhibition. Serine proteases were proposed to be inhibited by boric acid (Antonov et al., 1968), and simple borates have been patented as protease stabilizers in liquid detergent formulations (Hora and Kivits, 1981, Severson, 1985).

Serine hydrolase enzymes

Silicon

Silicon, tetravalent metalloid, is less reactive than its chemical analogue carbon. It is the second most abundant element in the Earth’s crust, making up 25.7% of it by weight. Elemental silicon is not found in nature. It occurs mainly in the form of silicon dioxide – silica – and silicates that contain silicon, oxygen, and metals. Amethyst, agate, quartz, rock crystal, flint, jasper, and opal are some of the forms in which the oxide appears. Granite, asbestos, feldspar, clay, hornblende, and

Arsenic

Arsenic, the twentieth most abundant element in the Earth’s crust, is widely distributed in the environment, mainly associated with sulfide minerals. Its content in soils is 0.5–35 mg/kg (Yan-Chu, 1994, Walsh and Keeney, 1975, Leonard, 1991). The most important anthropogenic arsenic sources are the smelting of Cu, Ni, Pb, and Zn ores and the burning of fossil fuels in households and power plants. Coal burning causes the emission of arsenic by volatilization of As4O6, which condenses in the flue

Selenium

The relative proportion of selenium in the environment is very low. In the Earth’s crust, selenium is present in a concentration of 0.05–0.09 mg/kg. Its level in sea water is usually 0.45 μg/kg, in stream water 0.2 μg/kg. In compounds, selenium is present as Se2−, Se2+, Se4+, and Se6+. In general, it is present in the environment in elemental form or in the form of selenide (Se2−), selenate SeO42-, or selenite SeO32-. In soils, the identity and amounts of the various oxidation state species depend

Tellurium

The principal source of tellurium is the anode sludges produced during the electrolytic refining of blister copper. It is also a component of dusts from blast furnace refining of lead. Tellurium is a relatively rare element that has no significant biological role. Tellurium and tellurium compounds are considered to be toxic and need to be handled with care. Organotellurium compounds damage cells, e.g., by oxidizing sulfhydryl groups and depleting endogenous reduced glutathione in a variety of

Astatine

It has been estimated that the whole Earth’s crust contains less than 44 mg astatine and this element can thus be considered one of the rarest naturally occurring elements on Earth. All isotopes of this radioactive element have short half-lives and are products of several radioactive decay series. Because of the very low half-life of its isotopes, the radioactive astatine has no significance for living systems.

Acknowledgement

The review was written within the frames of the Institutional Research Concept AV0Z50200510.

Tomáš Řezanka was born in Prague, graduated from the Charles University, Prague, Czech Republic in 1979. In 1980, he begun to work in the Institute of Microbiology, and he obtained the Ph.D. degree in Microbiology in 1984. His main area of research is the study of the chemistry of natural products from unusual sources where he focuses on the structure elucidation via physical methods, especially NMR and MS, and other chemical–physical methods.

He has published widely on microbial lipids,

References (171)

  • T. Ishii et al.

    Oligosaccharides generated by partial hydrolysis of the borate--rhamnogalacturonan II complex from sugar beet

    Phytochemistry

    (1998)
  • T. Ishii et al.

    Isolation and characterization of a boron--rhamnogalacturonan-II complex from cell walls of sugar beet pulp

    Carbohydr. Res.

    (1996)
  • T. Ishii et al.

    Pectic polysaccharide rhamnogalacturonan II is covalently linked to homogalacturonan

    Phytochemistry

    (2001)
  • N. Kroger et al.

    Pleuralins are involved in theca differentiation in the diatom Cylindrotheca fusiformis

    Protist

    (2000)
  • M. Lahaye et al.

    NMR analysis of the chemical structure of ulvan and of ulvan-boron complex formation

    Carbohydr. Polym.

    (1998)
  • W.H. Li et al.

    A survey of arsenic species in Chinese seafood

    Food Chem. Toxicol.

    (2003)
  • J.F. Ma et al.

    Silicon uptake and accumulation in higher plants

    Trends Plant Sci.

    (2006)
  • T. Maitani et al.

    Hydride generation-flame atomic-absorption spectrometry as an arsenic detector for high-performance liquid-chromatography

    J. Chromatogr.

    (1987)
  • T.J. McCluskey et al.

    Enzyme catalyzed alpha, beta-elimination of selenocystathionine and selenocystine and their sulfur isologs by plant-extracts

    Phytochemistry

    (1986)
  • S. McSheehy et al.

    Identification of dimethylarsinoyl-riboside derivatives in seaweed by pneumatically assisted electrospray tandem mass spectrometry

    Anal. Chim. Acta

    (2000)
  • M.E. Merrifield et al.

    Arsenic binding to Fucus vesiculosus metallothionein

    Biochem. Biophys. Res. Commun.

    (2004)
  • M.J. Abedin et al.

    Uptake kinetics of arsenic species in rice plants

    Plant Physiol.

    (2002)
  • A.O. Adeyemi et al.

    Fungal degradation of calcium-, lead- and silicon-bearing minerals

    Biometals

    (2005)
  • C. Almela et al.

    Arsenosugars in raw and cooked edible seaweed: characterization and bioaccessibility

    J. Agric. Food Chem.

    (2005)
  • V.K. Antonov et al.

    Bifunctional reversible inhibitors of proteolytic enzymes interaction between α-chemotrypsin and hexylboron acid

    Dokl. Akad. Nauk. SSSR

    (1968)
  • M. Arai et al.

    Boromycin abrogates bleomycin-induced G2 checkpoint

    J. Antib.

    (2004)
  • W. Bains et al.

    Silicon chemistry as a novel source of chemical diversity in drug design

    Curr. Opin. Drug Discov. Dev.

    (2003)
  • R. Banker et al.

    Tenuecyclamides A–D, cyclic hexapeptides from the cyanobacterium Nostoc spongiaeforme var. Tenue

    J. Nat. Prod.

    (1998)
  • L. Banszky et al.

    Sulphate metabolism of selenate-resistant Schizosaccharomyces pombe mutants

    J. Gen. Appl. Microbiol.

    (2003)
  • B.L. Bassler et al.

    Intercellular signaling in Vibrio harveyi – sequence and function of genes regulating expression of luminescence

    Mol. Microbiol.

    (1993)
  • B.L. Bassler et al.

    Multiple signaling systems controlling expression of luminescence in Vibrio harveyi – sequence and function of genes encoding a 2nd sensory pathway

    Mol. Microbiol.

    (1994)
  • P.F. Bell et al.

    Contrasting selenate sulfate interactions in selenium-accumulating and nonaccumulating plant-species

    Soil Sci. Soc. Am. J.

    (1992)
  • J. Bender et al.

    Uptake and transformation of metals and metalloids by microbial mats and their use in bioremediation

    J. Ind. Microbiol.

    (1995)
  • S.J. Benkovic et al.

    Identification of borinic esters as inhibitors of bacterial cell growth and bacterial methyltransferases, CcrM and MenH

    J. Med. Chem.

    (2005)
  • D.K. Bhumbla et al.

    Arsenic mobilization and bioavailability in soils

  • M. Birringer et al.

    Trends in selenium biochemistry

    Nat. Prod. Rep.

    (2002)
  • J. Boesekem

    The use of boric acid for the determination of the configuration of carbohydrates

    Adv. Carbohydr. Chem.

    (1949)
  • M.A. Bryszewska et al.

    Characterization of selenium compounds in rye seedling biomass using Se-75-labelling/SDS-PAGE separation/gamma-scintillation counting, and HPLC–ICP-MS analysis of a range of enzymatic digests

    Anal. Bioanal. Chem.

    (2005)
  • J.J. Camacho-Cristo´bal et al.

    Boron deficiency decreases plasmalemma H+-ATPase expression and nitrate uptake, and promotes ammonium assimilation into asparagine in tobacco roots

    Planta

    (2007)
  • T.G. Chasteen et al.

    Biomethylation of selenium and tellurium: microorganisms and plants

    Chem. Rev.

    (2003)
  • T.S.S. Chen et al.

    Biosynthesis of the boron-containing macrodiolide antibiotic aplasmomycin

    J. Am. Chem. Soc.

    (1979)
  • T.S.S. Chen et al.

    Biosynthesis of the boron-containing macrolide antibiotic aplasmomycin by Streptomyces griseus

    J. Am. Chem. Soc.

    (1981)
  • X. Chen et al.

    Structural identification of a bacterial quorum-sensing signal containing boron

    Nature

    (2002)
  • R.V. Cooney et al.

    Arsoniumphospholipid in algae

    Proc. Natl. Acad. Sci. U.S.A.

    (1978)
  • W.R. Cullen et al.

    Bioaccumulation and excretion of arsenic compounds by a marine unicellular alga, Polyphysa-peniculus

    Appl. Organomet. Chem.

    (1994)
  • J.E. Curran et al.

    Genetic variation in selenoprotein S influences inflammatory response

    Nat. Genet.

    (2005)
  • F. Dannel et al.

    Update on boron in higher plants – uptake, primary translocation and compartmentation

    Plant Biol.

    (2002)
  • Davies, D.H., Norris, G.L.F., 1980. Growth promotion. US Patent...
  • F. Della Ragione et al.

    Escherichia coli S-adenosylhomocysteine/5′-methylthioadenosine nucleosidase. Purification, substrate specificity and mechanism of action

    Biochem. J.

    (1985)
  • D.S. Domingues et al.

    Boron transport in Eucalyptus. 2. Identification in silico of a putative boron transporter for xylem loading in eucalypt

    Gen. Mol. Biol.

    (2005)
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    Tomáš Řezanka was born in Prague, graduated from the Charles University, Prague, Czech Republic in 1979. In 1980, he begun to work in the Institute of Microbiology, and he obtained the Ph.D. degree in Microbiology in 1984. His main area of research is the study of the chemistry of natural products from unusual sources where he focuses on the structure elucidation via physical methods, especially NMR and MS, and other chemical–physical methods.

    He has published widely on microbial lipids, including very long chain fatty acids from blue-green algae and he is the author and co-author of more than 180 scientific papers, including six books. He is currently a Senior Principal Scientist in the Institute of Microbiology where he continues with the endeavors into the Chemistry of Natural Products.

    Karel Sigler graduated from the Czech Technical University in Prague, Czech Republic, in 1964. Though he majored in nuclear chemistry, his interests took him to biological sciences. In 1965, he joined the Institute of Microbiology, Czechoslovak Academy of Sciences, obtaining the Ph.D. degree in biology in 1970 and the D.Sc. degree in biological sciences in 1990. His main area of research has been cell biology and biophysics, with special reference to bioenergetics and membrane phenomena. His interest in xenobiotics and other substances affecting cellular processes brought him to the study of natural products and their impact on living organisms. He has published widely on membrane transport phenomena in different types of cells (plants, animals, yeast) and on the effect of chemical and other stressors on cellular processes. He is the author and co-author of more than 130 scientific papers, 1 patent and 1 book. He is currently a Senior Scientist at the Institute of Microbiology where he pursues his biophysical studies and has started exploring the realm of chemistry and biological effects of natural products.

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