Effects of scutellariae radix extract and its components (baicalein, baicalin, and wogonin) on the experimental elevation of aqueous flare in pigmented rabbits.

PURPOSE To evaluate the possible inhibitory effects of hot water extract of Scutellariae radix and its major components (baicalein, baicalin, and wogonin) on experimental elevation of aqueous flare in pigmented rabbits. METHODS To produce aqueous flare elevation in rabbits, prostaglandin E(2) (PGE(2)), 25 microg/mL, was applied to the cornea with the use of a glass cylinder, or lipopolysaccharides (LPS), 0.5 microg/kg, were injected into an ear vein. Animals were pretreated by the oral administration of 150 g/day of food containing 0.02%, 0.07%, or 0.2% (w/w) extract of Scutellariae radix for 5 days, or by intravenous injection of baicalein, baicalin, or wogonin, 60 microg/kg or 600 microg/kg, 30 minutes before experimental uveitis was induced. Aqueous flare was measured with a laser flare-cell meter. Aqueous flare intensity was expressed as the area under the curve (AUC) in arbitrary units. RESULTS The AUC of PGE(2)- and LPS-induced aqueous flare elevation was 1,343 and 5,066 arbitrary units, respectively. Pretreatment by oral administration of 0.07% or 0.2% extract of Scutellariae radix did not inhibit PGE(2)-induced aqueous flare elevation (AUC: 1,252 and 1,210, respectively), but it did inhibit LPS-induced aqueous flare elevation (AUC: 2,248 and 1,973, respectively). Pretreatment by intravenous injection of 600 microg/kg of baicalein, baicalin, or wogonin inhibited LPS-induced aqueous flare elevation (AUC: 2,289, 2,163, and 1,509, respectively). Pretreatment with 60 microg/kg of wogonin also inhibited LPS-induced aqueous flare elevation (AUC: 1,980). CONCLUSION Hot water extract of Scutellariae radix may have an inhibitory effect on experimental anterior uveitis induced by LPS in pigmented rabbits.