Pyrones

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Pyrones

 

ketopyrans, heterocyclic compounds, oxo derivatives of pyrans. The simplest pyrones are α-pyrone, or coumalin, a colorless liquid with the odor of new-mown hay (boiling point, 206°-209°C), and γ-pyrone, colorless crystals (melting point, 31°–32°C).

Pyrones are highly reactive. For example, they react with ammonia and primary amines and are reduced readily; α-pyrone enters into the Diels-Alder reaction. Pyrones may be produced by decarboxylation of their derivatives, pyronecarboxylic acids (coumalic and chelidonic acids, respectively). Pyrone derivatives are widespread in nature. Tonka beans contain benzo-α-pyrone, or coumarin; opium contains meconic acid; and celandine sap contains chelidonic acid. Certain plant pigments are γ-pyrone derivatives.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
harzianum was not very clearly illustrated yet to date, the theory of metabolite as an inhibitor of pathogen growth has been supporting by many researchers (Dennis and Webster, 1971a, b; Okuda et al., 1982; Claydon et al., 1987; Ghisalberti et al., 1990), the inhibitor include simple aromatic compounds, some polyketides as pyrones and butenolides, volatile terpenes, isocyano metabolites, and relatively non-polar substances.
In fact, some potential therapeutic actions, namely, anxiety, tension, and restlessness, of standardized extracts of kava-kava roots have been attributed to kava pyrones, desmethoxyyangonin 6, and (+/-)-methysticin through inhibition of platelet MAO-B [36].
Hider, "Effects of the pyrones, maltol and ethyl maltol, on iron absorption from the rat small intestine," Journal of Pharmacy and Pharmacology, vol.
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Kava pyrones and resin: studies on GABAA, GABAB and benzodiazepine binding sites in rodent brain.
Chemical studies carried out on Brazilian Piperaceae species have revealed the occurrence of pyrones, lignoids and chromenes besides various amides bearing isobutyl, pyrrolidine, dihydropyridone and piperidine moieties (Parmar et al.
However, basidiomes may also contain high concentrations of toxins, such as phenols, pyrones, and heterocyclic nitrogen complexes.
Pyrolysis rearranges guaiacols, catechols, syringols, vanillins, furancarboxaldehydes, isoeugenol, pyrones, acetic acid, formic acid, and other carboxylic acids (Piskorz et al.
Surface acidity and basicity were calculated on the basis of the assumption that 0.05 M NaHC[O.sub.3] neutralises carboxyl groups only (the strongest acid fraction), 0.05 M NaOH neutralises acidic groups including carboxyl, lactones, and phenols, 0.25 M NaOH neutralises total acidity (carboxyl, lactones, phenols, carbonyls, and any other acidic species), and HCl neutralises all basic groups including ketones, pyrones, and chromens (Boehm 1994; Chun et al.