Oxindole (2-indolone) is an

aromatic In organic chemistry, aromaticity is a chemical property describing the way in which a conjugated system, conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibits a stabilization stronger than would be expected from conjugati ...

heterocyclic A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic organic chemistry is the branch of organic chemistry dealing with the synthesis, proper ...

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

with the formula . It has a bicyclic structure, consisting of a six-membered

benzene Benzene is an Organic compound, organic chemical compound with the Chemical formula#Molecular formula, molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar hexagonal Ring (chemistry), ring with one hyd ...

ring fused to a five-membered

nitrogen Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...

-containing ring. Oxindole is a modified

indoline Indoline is an aromatic heterocyclic organic compound with the chemical formulation C8H9N. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered nitrogen-containing ring. The compound is based on the ind ...

with a substituted carbonyl at the second position of the 5-member indoline ring. Classified as a cyclic amide, it is a pale yellow solid.

Formation and reactions

Oxindole is derived in nature from

tryptophan Tryptophan (symbol Trp or W) is an α-amino acid that is used in the biosynthesis of proteins. Tryptophan contains an α-amino group, an α-carboxylic acid group, and a side chain indole, making it a polar molecule with a non-polar aromat ...

, formed by gut bacteria ("normal flora"). It is normally metabolized and detoxified from the body by the liver. In excess, it can cause sedation, muscle weakness, hypotension, and coma. Patients with

hepatic encephalopathy Hepatic encephalopathy (HE) is an altered level of consciousness as a result of liver failure. Its onset may be gradual or sudden. Other symptoms may include movement problems, changes in mood, or changes in personality. In the advanced stag ...

have been recorded to have elevated serum oxindole levels. Treatment with

phosphorus pentasulfide Phosphorus pentasulfide is the inorganic compound with the formula (empirical) or ( molecular). This yellow solid is the one of two phosphorus sulfides of commercial value. Samples often appear greenish-gray due to impurities. It is soluble in ...

gives the thione.

Oxindoles

Beyond the parent compound, the oxindole structure is present in many compounds including, for example,

rhynchophylline Rhynchophylline is an alkaloid found in certain ''Uncaria'' species (Rubiaceae), notably '' Uncaria rhynchophylla'' and '' Uncaria tomentosa''. It also occurs in the leaves of '' Mitragyna speciosa'' (kratom) and Mitragyna tubulosa, a tree native ...

, 3-methyloxindole, and

semaxanib Semaxanib (INN, codenamed SU5416) is a tyrosine-kinase inhibitor drug designed by SUGEN as a cancer therapeutic. It is an experimental stage drug, not licensed for use on human patients outside clinical trials. Semaxanib is a potent and sele ...

. : left, Rhynchophylline, a naturally occurring oxindole is a medicinal used as an NMDA antagonist and a calcium channel blocker.

References

{{reflist Indolines Lactams Oxindoles,