In chemistry, a NONOate is a compound having 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 symbol ...

R¹R²N−(NO⁻)−N=O, where R¹ and R² are

alkyl In organic chemistry, an alkyl group is an alkane missing one hydrogen. The term ''alkyl'' is intentionally unspecific to include many possible substitutions. An acyclic alkyl has the general formula of . A cycloalkyl is derived from a cycloa ...

groups. One example for this is ''1,1-diethyl-2-hydroxy-2-nitrosohydrazine'', or ''diethylamine dinitric oxide''. These compounds are unusual in having three sequential

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

atoms: an

amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen Hydrogen is the chemical element wi ...

functional group In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the re ...

, a bridging NO⁻ group, and a terminal

nitrosyl In organic chemistry, nitroso refers to a functional group in which the nitric oxide () group is attached to an organic moiety. As such, various nitroso groups can be categorized as ''C''-nitroso compounds (e.g., nitrosoalkanes; ), ''S''-nitroso ...

group. In contact with

water Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...

, these compounds release NO ( nitric oxide).

pH-dependent decomposition of NONOates

Most NONOates are stable in alkaline solution above pH 8.0 (e. g. 10 mM

NaOH Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly caustic base and alkali ...

) and can be stored at −20 °C in this way for the short term. To generate NO from NONOates, the pH is lowered accordingly. Typically, a

dilution Dilution may refer to: * Reducing the concentration of a chemical * Serial dilution, a common way of going about this reduction of concentration * Homeopathic dilution * Dilution (equation), an equation to calculate the rate a gas dilutes *Tradema ...

of the stock NONOate solution is made in a

phosphate In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid . The phosphate or orthophosphate ion is derived from phosph ...

buffer (pH 7.4; tris buffers can also be used) and incubated at room temperature for the desired time to allow NO to accumulate in solution. This is often visible as bubbles at high NONOate

concentration In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: '' mass concentration'', ''molar concentration'', '' number concentration'', ...

s. Incubation time is important, since the different NONOates have different

half-lives Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable at ...

(''t''_½) in phosphate buffer at pH 7.4. For example, the half-life of MAHMA NONOate under these conditions is ~3.5 minutes, whilst the ''t''_½ of DPTA NONOate is 300 minutes. This is often useful in biological systems, where a combination of different NONOates can be used to give a sustained release of nitric oxide. At pH 5.0, most NONOates are considered to

decompose Decomposition or rot is the process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts. The process is a part of the nutrient cycle and is ...

almost instantaneously.

References

{{Nitric oxide signaling Nitrosyl compounds