Pre-clinical acute oral toxicity and subacute neurotoxicity risk assessments on sprague dawley rats treated with single dose or repeated doses of flavonoid-enriched fraction extracted from Oroxylum indicum leaves

Oroxylum indicum possesses promising flavonoid secondary metabolites. However, translation of these compounds into clinical practice for neurological disease treatment is halted as the toxicity and safety profile of the plant extracts are yet to be determined. This study was conducted to assess the acute oral toxicity and subacute neurotoxicity that could be imposed by the flavonoid-enriched fraction (FEF) extracted from O. indicum leaves, by strictly following the procedures set in Organization for Economic Co-operation and Development (OECD) Guidelines No.420 and 424. It was found that at the highest dosage (2000 mg/kg b.wt), no death or toxicity-related behavioral changes were observed. No significant alteration in hematological and serum biochemical parameters beyond the standard laboratory range was observed. Detailed histopathological examination, as verified by clinical pathologist, revealed absence of detectable inflammation, changes in any macroscopic and microscopic tissue abnormalities in all vital organ of the treated rats. Moreover, neurological functional test of rats treated with repeated doses of FEF for 28 d also showed absence of neurological abnormality, suggesting negative long term side effects of this fraction on the animal. In conclusion, this study presented valuable pre-clinical safety validation of a high-quality herbal medicinal product, setting the foundation for its future application in clinical setting.