Luteolin is a very representative natural flavonoid, belonging to the weakly acidic tetrahydroxyflavonoids. It is widely distributed in the plant kingdom, mainly in medicines such as honeysuckle, chrysanthemum, nepeta, white-haired selfhen grass, and vegetables such as thyme, Brussels sprouts, cabbage, cauliflower, beet, broccoli and carrots. It is also distributed in the form of glycosides in celery, green pepper, perilla leaves, and the fruit shell of Arachis hypogaea Chemicalbook, white-haired selfhen grass (Ajugadecumbus), Lonicera japonica Thunb, Gentianaceae plant Gentianopsis paludosa, and Valeriana amurensis Smir of Patriniaceae. Pure luteolin is a yellow crystalline powder.
It is a golden needle-shaped substance separated from ethanol and containing one crystal water. It is soluble in ethanol and ether; slightly soluble in hot water, and difficult to dissolve in cold water. The aqueous solution is pleasing light yellow, and it is soluble in 10% sodium hydroxide aqueous solution and is dark yellow. It is stable under normal conditions.