RESUMEN
Background: Ocimum gratissimum is an ethnopharmacological plant with numerous healing potentials. But there is paucity in scientific literature on its impact on the blood cells. Aim and Objective: The present study was intended to evaluate the dose and time-dependent effect of aqueous leaf extract of Ocimum gratissimum on some haematological in albino Wistar rats. Methods: Twenty four rats were randomly assigned to four equal groups. Group 1 was control, groups 2, 3 and 4 were given 450 mg/kg, 800 mg/kg and 1800 mg/kg respectively of the extract daily for 30 days. All rats had free access to water and rat chow. Results: The result showed a significantly lower RBC count in groups 3 and 4 when compared with control (p<0.05 and p<0.01 respectively). PCV was significantly lower in group 4 than control (p<0.05). Platelet count was significantly lower in group 4 than control (p<0.05) and group 2 (p<0.05). A significant increase in WBC count was observed in groups 2 and 3 when compared with control (p<0.05 and p<0.01 respectively). A significant reduction in neutrophil count was observed in groups 2, 3 and 4 compared with control (p<0.05; p< 0.05 and p<0.01 respectively). There were significant increases in lymphocyte counts in groups 2, 3 and 4 when compared with control (p<0.05, p<0.01 and p<0.01 respectively). There were no significant changes in MCV, MCH and MCHC in the groups. Conclusion: In conclusion, aqueous leaf extract of Ocimum gratissimum causes reduction in RBC count, PCV, platelet count and neutrophil count but causes increases in total WBC count and lymphocyte count.