Biol Pharm Bull. 2001 Sep; 24(9): 1012-5.

Inhibition of itch-scratch response by fruits of Cnidium monnieri in mice.

Basnet P, Yasuda I, Kumagai N, Tohda C, Nojima H, Kuraishi Y, Komatsu K.

Research Center for Ethnomedicines, Institute of Natural Medicine, Sugitani, Toyama, Japan.

We previously screened the anti-itching activities of 33 herbal medicines in substance P (SP)-induced itching model mice. One of the most potent antipruritogenic extracts, the methanol extract of fruits of Cnidium monnieri (Cnidii Fructus) was studied further. The chloroform-soluble fraction of the methanol extract markedly inhibited SP-induced scratching. Among 10 subfractions of the chloroform-soluble fraction, the CS-3 fraction had the most potent inhibitory effect on scratching. Each of 3 subfractions of CS-3 showed significant anti-scratching activities. However, inhibitory potencies were not different among the three and weaker than that of CS-3 itself at a same dose. These 3 subfractions of CS-3 mainly contained xanthotoxin, isopimpinellin, bergapten, imperatorin and osthol. Single administration of osthol did not inhibit SP-induced scratching, and imperatorin very weakly subsided scratching. These results suggest that the strong antipruritic action was focused on the CS-3 fraction of the C. monnieri methanol extract, and it might result from the combined effects of these coumarin derivatives, or by undetermined minor compounds.