[Pharmacological study on Arctostaphylos uva-ursi (L.) Spreng. II. Combined effects of arbutin and prednisolone or dexamethazone on immuno-inflammation].

A study was carried out to examine the combined effect of arbutin isolated from the leaves of Arctostaphylos uva-ursi (L.) Spreng. (Bearberry leaf) and prednisolone or dexamethazone on Type IV allergic reaction-induced immuno-inflammation. Contact dermatitis caused by picryl chloride (PC-CD) and sheep red cell delayed type hypersensitivity (SRBC-DTH) in mice was not inhibited by the oral application of arbutin at 2 divided doses immediately before and 16 h after the application, but arbutin at doses of 10, 50 mg/kg 24 h after the application speedily decreased the swelling of PC-CD and SRBC-DTH. Arbutin plus prednisolone or dexamethazone showed the inhibitory effect on the swelling of PC-CD and SRBC-DTH stronger than that of prednisolone or dexamethazone alone. Prednisolone and dexamethazone decreased the weight of thymus and spleen in intact, PC-CD and SRBC-DTH mice, but arbutin did not show these effects. These results suggest that arbutin may increase the inhibitory action of prednisolone and dexamethazone on PC-CD and SRBC-DTH, but further investigations are required to understand the mechanism involved.