Cytotoxicity and single-dose oral toxicity testing for rice bran supercritical CO₂ extract

The aim of this study was to evaluate the toxicity of rice bran supercritical CO₂ extract (RB-SCE) in vitro and in vivo. A cytotoxicity assay revealed no inhibitory effects on cell viability in a mouse leukemic monocyte macrophage cell line (RAW 264.7) after 24-h incubation with 0.16 or 0.32 μg/mL of RB-SCE. RB-SCE was administered to male and female Sprague-Dawley rats at 2,500, 5,000, or 10,000 mg/kg to evaluate acute oral toxicity. Mortality, clinical symptoms, and body weight changes were monitored for two weeks. Animals were then euthanized and necropsies performed. Clinical symptoms included soft stool, diarrhea, and soiled perineal region. No significant changes in body weight were observed in treatment groups compared to the control. In addition, necropsy revealed no abnormal finding at any dosage. The approximate lethal dose (ALD) of RB-SCE was estimated at >10,000 mg/kg for both sexes and orally administered RBSCE was deemed safe.