In vitro radical scavenging potential and toxicopathological implications of administration of aqueous leaf extract of Eucalyptus obliqua L.Her. (Myrtaceae) in Wistar rats

This study evaluated the in vitro antioxidant potential and toxicological effects of aqueous leaf extract of Eucalyptus obliqua via acute and 28-day once daily treatments in Wistar rats. In the acute toxicity test, rats were orally administered the extract up to 5000 mg/kg. The sub-chronic toxicity study was performed by once daily oral administration with the extract at 200, 400, 500, and 1000 mg/kg body weight for 28 days. The control rats received sterile distilled water. Biochemical and hematological indices were determined and a histopathological examination was carried out. The extract showed marked antioxidant effects that could be ascribed to its phytoconstituents. The LD50 was estimated to be >5000 mg/kg body weight. Except for the significantly modulated serum concentrations of high-density lipoprotein cholesterol, platelet and white blood cell counts, the extract revealed no significant (p > 0.05) effect on the biochemical and hematological indices in the treated animals compared to the control. Furthermore, there was no significant difference in weight gain of the treated rats and the control although there was a dose-dependent increase in food consumption of the extract-treated rats. These are indications of unlikely toxic tendency of the extract and were well supported by the no treatment-related infiltrations on the histoarchitectural features of the tissue sections of the investigated organs. Consequent upon these, the aqueous leaf extract of E. obliqua may be adjudged relatively non-toxic and practically safe at the investigated doses and within the period of exposure in this study.