Abstract
Purpose:
Baicalein (5,6,7-trihydroxyflavone) is a natural flavonoid (flavone) originally derived from the root of Scutellaria baicalensis. We have previously demonstrated that baicalein suppresses the net Cl- transport and fluid movement across the excised ciliary epithelium, potentially reducing the aqueous humor formation and intraocular pressure (IOP). The inhibitory effect of baicalein is possibly mediated by the inhibition of swelling-activated Cl- channels in non-pigmented ciliary epithelial cells. In this study, we aim to evaluate the IOP-lowering ability of baicalein in Sprague-Dawley (SD) rats.
Methods:
Adult 2-4 months old male SD rats were used. Intraperitoneal injection of baicalein was administered once daily for a period of 4 weeks. In the treatment group, baicalein was applied at a concentration of 4mg/kg in the first 2 weeks followed by a higher concentration of 40mg/kg in the last 2 weeks. Saline solution was used in the control group throughout the experiment. The measurements of IOP were conducted in both eyes under anesthesia by a rebound tonometer.
Results:
Intraperitoneal injection of baicalein significantly lowered baseline IOP in SD rats in vivo. After treatment with baicalein at a concentration of 4mg/kg, baicalein-treated SD rats have a lower IOP of 1.2±1.0mmHg as compared to the saline-treated controls (N=8; P<0.05). Subsequently, at a higher concentration of baicalein (40mg/kg), the hypotensive effect was progressively increased to 2.7±1.3mmHg after 4-week of treatment (N=8; P<0.01). The ocular hypotensive effects of baicalein at concentrations of 4mg/kg and 40mg/kg were 9% and 20%, respectively, over the baseline IOP.
Conclusions:
Baicalein seems to be a good candidate for glaucoma therapy in view of its ocular hypotensive effect. Whether or not these findings can be applied in human subjects are yet to be established and validated.
Keywords: 568 intraocular pressure •
503 drug toxicity/drug effects