Methaneseleninic acid

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The structure of methaneseleninic acid

A seleninic acid is an organoselenium compound and an oxoacid with the general formula RSeO2H, where R ≠ H. It is the second member of the family of organoselenium oxoacids, which also include selenenic acids and selenonic acids, which are RSeOH and RSeO3H, respectively. The parent member of this family of compounds is methaneseleninic acid (CH3SeO2H), also known as methylseleninic acid or "MSA".

Preparation[edit]

Methaneseleninic acid is conveniently synthesized through oxidation (3% hydrogen peroxide) of commercially available dimethyl diselenide.[1]

MeSeSeMe + H2O2 → 2MeSeO2H

Seleninic acids can be prepared by oxidation of selenoesters with one equivalent of dimethyldioxirane (DMDO). Use of excess DMDO affords little studied selenonic acids (RSeO3H).[2]

RSeC(O)R' + DMDO → RSeO2H
RSeC(O)R' + excess DMDO → RSeO3H

Selenenic acids, formed during the syn-elimination of selenoxides, undergo spontaneous disproportionation into the corresponding seleninic acids and diselenides:

2 RSeOH → RSeO2H + 1/2 RSeSeR

Structure, bonding, properties[edit]

Methaneseleninic acid, from decomposition of Se-methylselenocysteine Se-oxide but also available commercially, has been characterized by X-ray crystallography.[3] The configuration about the selenium atom is pyramidal, with Se-C = 1.925(8) Å, Se-O = 1.672(7) Å, Se-OH = 1.756(7) Å, the angle OSeO = 103.0(3)°, the angle HO-Se-C = 93.5(3)°, and the angle OSeC = 101.4(3)°. The structure is isomorphous to that of methanesulfinic acid [4] Optical isomers of methaneseleninic acid can be isolated as chiral crystals by recrystallization from a mixture of methanol and toluene. The absolute configuration of one of the enantiomers was determined by X-ray crystallography. Optically active methaneseleninic acid was stable toward racemization in the solid state, although it racemized very rapidly in solution.[5] Benzeneseleninic acid (C6H5SeO2H) had been previously characterized by X-ray methods[6] and its optical resolution reported.[7]

Reactions and applications in synthesis[edit]

Seleninic acids (particularly areneseleninic acids) are useful catalysts for hydrogen peroxide epoxidations, Baeyer–Villiger oxidations, oxidations of thioethers, etc.; peroxyseleninic acids (RSe(O)OOH) are thought to be the active oxidants.[8][9][10]

Anticancer activity[edit]

Methaneseleninic acid shows "potent" anticancer activity and is considered to be an excellent compound for studying the anticancer effects of selenium in vitro.[11] Methaneseleninic acid shows superior in vivo inhibitory efficacy toward human prostate cancer compared to selenomethionine or selenite (ion).[12] It has recently been reported that methaneseleninic acid enhances the efficacy of paclitaxel for treatment of triple-negative breast cancer,[13] that methaneseleninic acid functions as an aromatase inhibitor, of possible use in therapy for estrogen receptor-positive breast cancer in postmenopausal women,[14] that methaneseleninic acid shows promise as a sensitizing agent for ABT-737-induced apoptosis of several cancer lines,[15] and that methaneseleninic acid restricts tumor growth in the nude mouse model of metastatic breast cancer[16] and Lewis lung carcinoma in mice.[17]

Methaneselenol (CH3SeH) can be produced in vivo by reduction of methaneseleninic acid and may in fact be the key metabolite responsible for selenium’s anticancer activity[1][18] through generation of superoxide.[19] The reduction of methaneseleninic acid by mammalian thioredoxin reductase has been studied.[20]

References[edit]

  1. ^ a b Ip, C.; Thompson, H.J.; Zhu, Z.; Ganther, H.E. "In vitro and in vivo studies of methylseleninic acid: evidence that a monomethylated selenium metabolite is critical for cancer chemoprevention". Cancer Res. 2000, 60, 2882–2886.
  2. ^ Abdo, M.; Knapp, S. "Biomimetic seleninates and selenonates." J. Am. Chem. Soc. 2008, 130, 9234–9235. doi: 10.1021/ja8034448
  3. ^ Block, E.; Birringer, M.; Jiang, W.; Nakahodo, T.; Thompson, H. J.; Toscano, P. J.; Uzar, H.; Zhang, X.; Zhu, Z. "Allium chemistry: Synthesis, natural occurrence, biological activity, and chemistry of Se-alk(en)ylselenocysteines and their γ-glutamyl derivatives and oxidation products." J. Agric. Food Chem. 2001, 49, 458–470. doi: 10.1021/jf001097b
  4. ^ Seff, K.; Heidner, E. G.; Meyers, M.; Trueblood, K. N. "The crystal and molecular structure of methanesulfinic acid." Acta Crystallogr., Part B 1969, 25, 350–354.
  5. ^ Nakashima, Y.; Shimizu, T.; Hirabayashi, K.; Yasui, M.; Nakazato, M.; Iwasaki, F.; Kamigata, N. "Optically active seleninic acid: Isolation, absolute configuration, stability, and chiral crystallization." Bull. Chem. Soc. Jpn. 2005, 78, 710–714. doi: 10.1246/bcsj.78.710
  6. ^ J. H. Bryden, H.; McCullough, J. D. "The crystal structure of benzeneseleninic acid." Acta Cryst. 1954. 7, 833–838. doi:10.1107/S0365110X54002551
  7. ^ Toshio, S.; Watanabe, I.; Kamigata, N. "Optically active seleninic acids: optical resolution and stability." Angew. Chem., Int. Edn. 2001, 40, 2460–2462. doi: 10.1002/1521-3773(20010702)40:13<2460::AID-ANIE2460>3.0.CO;2-Q
  8. ^ ten Brink, G.-J.; Fernandes, B. C. M.; van Vliet, M. C. A.; Arends, I. W. C. E.; Sheldon, R. A. "Selenium catalyzed oxidations with aqueous hydrogen peroxide. Part I. Epoxidation reactions in homogeneous solution." J. Chem. Soc., Perkin Trans., 1 2001, 224–228. doi: 10.1039/b008198l
  9. ^ ten Brink, G.-J.; Vis, J.-M.; Arends, I. W. C. E.; Sheldon, R. A. "Selenium-Catalyzed Oxidations with Aqueous Hydrogen Peroxide. 2. Baeyer-Villiger Reactions in Homogeneous Solution." J. Org. Chem. 2001, 66, 2429–2433. doi: 10.1021/jo0057710
  10. ^ Mercier, E. A.; Smith, C. D.; Parvez, M.; Back, T. G. "Cyclic Seleninate Esters as Catalysts for the Oxidation of Sulfides to Sulfoxides, Epoxidation of Alkenes, and Conversion of Enamines to α-Hydroxyketones." J. Org. Chem 2012, 77, 3508–3517. doi: 10.1021/jo300313v
  11. ^ Zhao, H.; Whitfield, M. L.; Xu, T.; Botstein, D.; Brooks, J. D. "Diverse effects of methylseleninic acid on the transcriptional program of human prostate cancer cells." Molecular Biology of the Cell, 2004, 15, 506–519. doi:10.1091/mbc.E03–07–0501
  12. ^ Li, G. X.; Lee, H. J.; Wang, Z.; Hu, H.; Liao, J. D.; Watts, J. C.; Combs, G. F., Jr.; Lu, J. "Superior in vivo inhibitory efficacy of methylseleninic acid against human prostate cancer over selenomethionine or selenite." Carcinogenesis 2008, 29, 1005–1012.
  13. ^ Qi, Y.; Fu, X.; Xiong, Z.; Zhang, H.; Hill, S.M.; Rowan, B.G.; Dong, Y. "Methylseleninic acid enhances paclitaxel efficacy for the treatment of triple-negative breast cancer." PLoS One 2012, 7, e31539 doi: 10.1371/journal.pone.0031539
  14. ^ Gao, R.; Zhao, L.; Liu, X.; Rowan, B.G.; Wabitsch, M.; Edwards, D.P.; Nishi, Y.; Yanase, T.; Yu, Q.; Dong, Y. "Methylseleninic acid is a novel suppressor of aromatase expression." J. Endocrinol. 2012, 212, 199–205.doi: 10.1530/JOE-11-0363
  15. ^ Yin S, Dong Y, Li J, Fan L, Wang L, Lu J, Vang O, Hu H. "Methylseleninic acid potentiates multiple types of cancer cells to ABT-737-induced apoptosis by targeting Mcl-1 and Bad." Apoptosis 2012, 17, 388–399. doi: 10.1007/s10495-011-0687-9.
  16. ^ Wu, X.; Zhang, Y.; Pei, Z.; Chen, S.; Yang, X.; Chen, Y.; Lin, D.; Ma, R.Z. "Methylseleninic acid restricts tumor growth in nude mice model of metastatic breast cancer probably via inhibiting angiopoietin-2." BMC Cancer 2012, 12, 192. doi: 10.1186/1471-2407-12-192
  17. ^ Yan, L.; DeMars, L.C. "Dietary supplementation with methylseleninic acid, but not selenomethionine, reduces spontaneous metastasis of Lewis lung carcinoma in mice" Int. J. Cancer 2012, 131, 1260–1266. doi: 10.1002/ijc.27355
  18. ^ Ip, C.; Dong, Y.; Ganther, H. E. "New concepts in selenium chemoprevention". Cancer Metastasis Rev. 2002, 21, 281–289.
  19. ^ Spallholz, J.E.; Shriver, B.J.; Reid, T.W. "Dimethyldiselenide and methylseleninic acid generate superoxide in an In vitro chemiluminescence assay in the presence of glutathione: Implications for the anticarcinogenic activity of L-selenomethionine and L-Se-methylselenocysteine." Nutrition Cancer 2001, 40, 34–41. doi: 10.1207/S15327914NC401_8
  20. ^ Snider, G.; Grout, L.; Ruggles, E. L.; Hondal, R. J. "Methaneseleninic acid is a substrate for truncated mammalian thioredoxin reductase: Implications for the catalytic mechanism and redox signaling. Biochemistry 2010, 49, 10329–10338. doi:10.1021/bi101130t