[Pharmacological studies on leaf of Arctostaphylos uva-ursi (L.) Spreng. I. Combined effect of 50% methanolic extract from Arctostaphylos uva-ursi (L.) Spreng. (bearberry leaf) and prednisolone on immuno-inflammation].

The effect of 50% methanolic extract (U-ext) from Bearberry leaf on immuno-inflammation was studied by contact dermatitis caused by picryl chloride (PC-CD) in mice. The combined effect of U-ext and prednisolone was also investigated by using similar experimental model. When given orally twice immediately before and 16 h after the application of PC-CD, U-ext did not show an inhibitory effect on the swelling induced by PC-CD while it exhibited a significant therapeutic effect at a dose of 100 mg/kg or more once 24 h after the application. When U-ext (p.o.) and prednisolone (s.c.) in a given portion were simultaneously administered, the inhibitory effect was more potent than that of prednisolone alone in both administration immediately before and 16 h after or once 24 h after the application. Arbutin isolated from U-ext also increased the inhibitory effect of prednisolone similarly to that of U-ext. These results suggest that Bearberry leaf possesses a therapeutic effect against immuno-inflammation induced by PC-CD and also increases the inhibitory effect of prednisolone, and its active principle may be arbutin.