Antihistaminic and antieicosanoid effects of oleanolic and ursolic acid fraction from Helichrysum picardii

Helichrysum picardii Boiss. & Reuter is a Mediterranean vegetal species from the Asteraceae family. From the methanolic extract of the aerial flowering parts of this plant, a fraction of two pentacyclic triterpenes has been isolated. Gas chromatography revealed that the triterpene isomers ursolic and oleanolic acids comprised 69% and 29% respectively of the composition of this fraction. The triterpene isomeric fraction was tested in two phagocyte cell systems. It inhibited compound 48/80-induced histamine release from rat peritoneal mast cells in an approximately percentage of 45% at 100 μM and myeloperoxidase secretion from A23187-ionophore-stimulated rat peritoneal leukocytes in a significant manner at doses of 50 and 100 μM. Furthermore, the triterpene isomers very significantly and dose-dependently inhibited generation of the cyclo-oxygenase metabolite prostaglandin E₂ (41% inhibition at 50 μM) and the 5-lipoxygenase metabolite leukotriene B₄ (79% inhibition at 50 μM) from activated rat leukocytes. This anti-eicosanoid activity of the triterpene fraction was more potent than that produced by the pure triterpene oleanolic acid used for comparision, indicating a stronger action of the ursolic acid, the major compound of the isolated triterpene fraction. From these data, it can be suggested that the triterpene isomers oleanolic and ursolic acids present in the medicinal plant Helichrysum picardii contribute to the anti-inflammatory profile of this vegetal species.