Materials and Methods: Phytochemical constituents from the ethanol extract of C. fistula were identified by qualitative techniques and gas chromatography-mass spectroscopy (GC-MS). Twenty male Wistar rats were randomly assigned into four groups of five rats each. Group A, the control, received 0.2ml of corn oil each daily for 7 days; Group B rats were given 100mg/kg b.w. of Cassia fistula extract, Group C were given 200mg/kg b.w. of the extract while the rats in Group D were given 300mg/kg b.w ethanol extract of Cassia fistula orally for 7 days. Blood samples were collected afterward for determination of haematological parameter while plasma biochemistry was carried on the plasma after 7 days of treatment with the extract. Frequency of micronucleated polychromatic erythrocytes was also determined from blood Giemsa stained smear.

Results: Qualitative analyses revealed the presence of tannins, saponins, alkaloids, anthraquinones, cardenolides, and phenols. In GC-MS analysis, 19 compounds including phytol, oleic, myristic acids etc. were detected from the ethanol leaf extract of C fistula.

Oral treatment of Cassia fistula was found to be safe up to the 300mg/kg b.w dose because haematological and biochemical parameters in treated rats were comparable to the untreated control. In fact, the extract showed nephroprotective and hepatoprotective activity at 200 mg/kg.

Conclusion: This study showed that ethanol leaf extract of Cassia fistula is not toxic upt to 300 mg/kg b.w, instead the extract showed some protective effects on liver and kidney functions at the 200 mg/kg b.w dose. This dosage should therefore be explored further for therapeutic purposes.