Safety Evaluation of Scutellaria baicalensis: Acute and 26-Week Repeated-Dose Oral Toxicity Studies in Rats

Scutellaria baicalensis root is widely used in traditional medicine and functional foods, but information on its long-term toxicity remains limited. This study evaluated the acute and 26-week repeated-dose oral toxicity of S. baicalensis root extract (SBE) in male and female Sprague–Dawley rats under Good Laboratory Practice conditions. In the acute study, SBE was administered once at 2500 or 5000 mg/kg, followed by 14 days of observation. In the repeated-dose study, SBE was administered at 500, 1000, or 2000 mg/kg/day for 26 weeks, followed by a 4-week recovery period. No mortality occurred in either study. Acute administration caused only transient, non-adverse clinical signs, and the minimum lethal dose was >5000 mg/kg. Repeated administration at 2000 mg/kg/day increased relative liver weight and urinary ketone grades in both sexes, while absolute liver weight and serum triglycerides increased in females. These findings were considered treatment-related but non-adverse, without corroborating clinical, serum biochemical, or histopathological evidence of organ injury. The no-observed-effect level and no-observed-adverse-effect level were 1000 and 2000 mg/kg/day, respectively, and no target organ of toxicity was identified. These findings provide preclinical safety information for acute and long-term oral exposure to SBE.