Luteolin is a flavone, a type of flavonoid, with a yellow crystalline appearance.
Luteolin is the main yellow dye from the Reseda luteola plant, used for dyeing since at least the first millennium B.C. Luteolin was first isolated in pure form, and was named in 1829 by the French chemist, Michel Eugène Chevreul. Chevreul named luteolin on p. 144: "J'ai fait des recherches sur la composition de la gaude, j'ai obtenu le principe colorant critalisé par sublimation; je l'ai nommé lutéolin." (I have done some research on the composition of weld; I obtained the principal colorant [which I] crystallized via sublimation; I have called it "luteolin".)However, Perkin claimed (without citing a source) that Chevreul had isolated luteolin as early as 1814–1815. See:
Luteolin is a phytochemical present in leaves, bark, flower blossoms, pollens, various vegetables, and herbs.
History of discovery The luteolin empirical formula was determined by the Austrian chemists Heinrich Hlasiwetz and Leopold Pfaundler in 1864. ; see pp. 44–45. Hlasiwetz and Pfaundler melted quercitrin with potassium carbonate. Among the reaction's products, they found paradatiscetin, whose empirical formula they determined to be C15H10O6 (p. 94). They concluded that although luteolin and paradatiscetin were isomeric (i.e., had the same empirical formula), they were distinct compounds. From p. 94: "Das Luteolin scheint demnach wohl als isomer oder metamer mit unserer Substanz betrachtet werden zu können. Eine Identität beider liegt jedoch nicht vor, denn an einer Probe Luteolin fanden wir die charakteristischen Farben-reactionen nicht, welche das Paradatiscetin kaum verwechseln lassen." (Luteolin thus seems to be able to be regarded perhaps as an isomer or metamer of our substance [viz, paradatiscetin]. However, the two are evidently not identical, for upon a test of luteolin, we did not find the characteristic color reactions, which hardly allows paradatiscetin to be confused [with it].) In 1896, the English chemist Arthur George Perkin proposed the correct structure for luteolin. See p. 803. Perkin's proposed structure for luteolin was confirmed in 1900 when the Polish-Swiss chemist Stanisław Kostanecki (1860–1910) and his students A. Różycki and J. Tambor synthesized luteolin.
Natural occurrences Luteolin is most often found in leaves, but it is also present in rinds, barks, clover blossoms, and ragweed pollen. It has also been isolated from the aromatic flowering plant, Salvia tomentosa in the mint family, Lamiaceae. It is present in raw peppermint and thyme.
Other dietary sources include celery, broccoli, artichoke, green pepper, parsley, dandelion, perilla, chamomile tea, carrots, olive oil, rosemary, navel oranges, and oregano. It is present in the seeds of the palm Aiphanes aculeata.
Research Although preliminary laboratory research has been conducted on luteolin, there is no clinical evidence to indicate that its presence in consumed plant foods has any effect on human health or diseases.
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