Methaneseleninic acid (methylseleninic acid or MSA) is an

organoselenium compound Organoselenium compounds (or seleno-organic) are chemical compounds containing carbon-to-selenium chemical bonds. Organoselenium chemistry is the corresponding science exploring their properties and reactivity. Selenium belongs with oxygen and sulf ...

, a

seleninic acid A seleninic acid is an organoselenium compound and an oxoacid with the general formula , where R ≠ H. Its structure is . It is a member of the family of organoselenium oxoacids, which also includes selenenic acids and selenonic acids, which are ...

with the

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...

. Its structure is .

Preparation

Methaneseleninic acid is conveniently synthesized through oxidation of commercially available dimethyl diselenide by 3%

hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3%� ...

. : Seleninic acids can be prepared by oxidation of selenoesters with one equivalent of dimethyldioxirane (DMDO). Use of excess DMDO affords little studied

selenonic acid A selenonic acid is an organoselenium compound containing the SeO3H functional group. Selenonic acids are the selenium analogs of sulfonic acids. Examples of the acid are rare. Benzeneselenonic acid is a white solid. It can be prepared by the o ...

s (). : : Selenenic acids, formed during the ''syn''-elimination of

selenoxide Organoselenium compounds (or seleno-organic) are chemical compounds containing carbon-to-selenium chemical bonds. Organoselenium chemistry is the corresponding science exploring their properties and reactivity. Selenium belongs with oxygen and sulf ...

s, undergo spontaneous

disproportionation In chemistry, disproportionation, sometimes called dismutation, is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation states. More generally, the term can b ...

into the corresponding seleninic acids and diselenides: :

Structure, bonding, properties

Methaneseleninic acid, from decomposition of ''Se''-methylselenocysteine ''Se''-oxide but also available commercially, has been characterized by X-ray crystallography. 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 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.

Anticancer activity

Methaneseleninic acid shows potential anticancer activity and is a model for studying the anticancer effects of selenium ''

in vitro ''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in biology an ...

''. Methaneseleninic acid shows superior ''in vivo'' inhibitory efficacy toward human

prostate cancer Prostate cancer is cancer of the prostate. Prostate cancer is the second most common cancerous tumor worldwide and is the fifth leading cause of cancer-related mortality among men. The prostate is a gland in the male reproductive system that sur ...

compared to

selenomethionine Selenomethionine (SeMet) is a naturally occurring amino acid. The L-selenomethionine enantiomer is the main form of selenium found in Brazil nuts, cereal grains, soybeans, and grassland legumes, while ''Se''-methylselenocysteine, or its γ-glut ...

selenite (ion) Selenite refers to the anion with the chemical formula . It is the oxyanion of selenium. It is the selenium analog of the sulfite ion, . Thus selenite is pyramidal and selenium is assigned oxidation state +4. Selenite also refers to compounds t ...

. It has recently been reported that methaneseleninic acid enhances the efficacy of

paclitaxel Paclitaxel (PTX), sold under the brand name Taxol among others, is a chemotherapy medication used to treat a number of types of cancer. This includes ovarian cancer, esophageal cancer, breast cancer, lung cancer, Kaposi's sarcoma, cervical cancer ...

for treatment of

triple-negative breast cancer Triple-negative breast cancer (TNBC) is any breast cancer that lacks or show low levels of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) overexpression and/or gene amplification (i.e. the tum ...

, that methaneseleninic acid functions as an aromatase inhibitor, of possible use in therapy for

estrogen receptor Estrogen receptors (ERs) are a group of proteins found inside cells. They are receptors that are activated by the hormone estrogen ( 17β-estradiol). Two classes of ER exist: nuclear estrogen receptors (ERα and ERβ), which are members of the ...

-positive

breast cancer Breast cancer is cancer that develops from breast tissue. Signs of breast cancer may include a lump in the breast, a change in breast shape, dimpling of the skin, milk rejection, fluid coming from the nipple, a newly inverted nipple, or a re ...

postmenopausal Menopause, also known as the climacteric, is the time in women's lives when menstrual periods stop permanently, and they are no longer able to bear children. Menopause usually occurs between the age of 47 and 54. Medical professionals often d ...

women, that methaneseleninic acid shows promise as a sensitizing agent for

apoptosis Apoptosis (from grc, ἀπόπτωσις, apóptōsis, 'falling off') is a form of programmed cell death that occurs in multicellular organisms. Biochemical events lead to characteristic cell changes (morphology) and death. These changes incl ...

induced by the Bcl-2-family inhibitor ABT-737 in several cancer lines, and that methaneseleninic acid restricts tumor growth in the

nude mouse A nude mouse is a laboratory mouse from a strain with a genetic mutation that causes a deteriorated or absent thymus, resulting in an inhibited immune system due to a greatly reduced number of T cells. The phenotype (main outward appearance) of t ...

model of

metastatic breast cancer Metastatic breast cancer, also referred to as metastases, advanced breast cancer, secondary tumors, secondaries or stage IV breast cancer, is a stage of breast cancer where the breast cancer cells have spread to distant sites beyond the axillary l ...

and

Lewis lung carcinoma Lewis lung carcinoma is a tumor that spontaneously developed as an epidermoid carcinoma in the lung of a C57BL mouse. It was discovered in 1951 by Dr. Margaret Lewis of the Wistar Institute and became one of the first transplantable tumors. Models ...

in mice. Methaneselenol () can be produced ''in vivo'' by reduction of methaneseleninic acid and may in fact be the key metabolite responsible for selenium’s anticancer activity through generation of

superoxide In chemistry, a superoxide is a compound that contains the superoxide ion, which has the chemical formula . The systematic name of the anion is dioxide(1−). The reactive oxygen ion superoxide is particularly important as the product of the ...

. The reduction of methaneseleninic acid by mammalian

thioredoxin reductase Thioredoxin reductases (TR, TrxR) () are enzymes that reduce thioredoxin (Trx). Two classes of thioredoxin reductase have been identified: one class in bacteria and some eukaryotes and one in animals. In bacteria TrxR also catalyzes the reduction ...

has been studied.

References

{{reflist Organoselenium compounds Organic acids Selenium(II) compounds