Effects of oral administration of Gardeniae fructus extract and intravenous injection of crocetin on lipopolysaccharide- and prostaglandin E2-induced elevation of aqueous flare in pigmented rabbits.

Abstract

The purpose of this study was to evaluate the effects of extracts of Coptidis rhizoma, Phellodendri cortex and Gardeniae fructus, which are medicinal herbs in Orengedoku-to (Huanglin-Jie-Du-Tang in Chinese), and crocetin (a major component of Gardeniae fructus) on experimental elevation of aqueous flare in pigmented rabbits. To produce aqueous flare elevation, 0.5 microg/kg lipopolysaccharide (LPS) was injected into the ear vein, or prostaglandin E2 (PGE2) 25 microg/ml, was applied to the cornea by means of a glass cylinder. Animals were pretreated by oral administration of 150 g/day of food containing 0.15% (w/w) extract powder of Coptidis rhizoma, 0.10% (w/w) extract powder of Phellodendri cortex or 0.15% (w/w) extract powder of Gardeniae fructus for 4 days, or by intravenous injection of crocetin, 0.3, 3, 30 or 300 microg/kg, 30 minutes before aqueous flare elevation. 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. The AUC of LPS- and PGE2-induced aqueous flare elevation was 4685 and 1386 arbitrary units, respectively. Pretreatment by oral administration of 0.15% (w/w) extract of Coptidis rhizoma or 0.10% (w/w) extract of Phellodendri cortex did not inhibit LPS-induced aqueous flare elevation. Pretreatment by oral administration of 0.15% extract of Gardeniae fructus suppressed LPS-induced aqueous flare elevation (AUC: 1411 arbitrary units). Pretreatment by intravenous injection of 3, 30 or 300 microg/kg of crocetin-inhibited LPS-induced aqueous flare elevation in a dose-dependent manner. Pretreatment with 3 or 30 microg/kg of crocetin did not inhibit PGE2-induced aqueous flare elevation, but 300 microg/kg of crocetin inhibited PGE2-induced aqueous flare elevation (AUC: 918 arbitrary units).