Antipruritic effects of the aerial part of Oxalis corniculata

Background: The discovery of antipruritic substances is expected to help patients with chronic and severe pruritus, such as atopic dermatitis. We previously searched for natural products with antipruritic activity using in vivo assay systems, through evaluation of the inhibitory effect on scratching behavior induced by compound 48/80 (COM, a mast cell degranulation agent) in a mouse model of chronic itch, which was developed originally to investigate blood stasis and stress. The result of our search revealed the antipruritic activity of the fresh aerial part of Oxalis corniculate (FAOC). Dried whole plants of O. corniculata have been used in Chinese herbal medicine for their effects on pyresis, urticaria and sedation. Several flavonoid derivatives have been isolated from the whole plants, but their antipruritic activity is unknown.

Aim: To determine the antipruritic effects of the FAOC and it’s active compounds.

Methods: The activity were measured as previously described. The extracts (100 mg/kg) were administered p.o. 1hr before injection of COM. The structures of compounds were identified with authentic samples by comparing the LC-MS data.

Results: A MeOH extract of the FAOC significantly inhibited COM-induced scratching behavior. Bioassay-guided fractionation of MeOH extract led to the identification of isoorientin, orientin, isovitexin and swertisin. The antipruritic effects of the compounds and the identification of other active compounds are presently under investigation.

Conclution: Our findings showed that the FAOC may provide new leads for the discovery of antipruritic substances for the treatment of the itching sensation that accompanies allergic reactions.