Toxicological Studies of Ethanolic Extract of Emilia praetermissa Milne-Redh (Asteraceae) in Rats

Aims: The objective of the present study was to determine the acute and subchronic toxicity of the ethanolic extract of E. praetermissa in rats.

Place and Duration of Study: Department of Animal Biology & Physiology (Animal Physiology Laboratory) and Department organic chemistry (Laboratory of medicinal chemistry), Faculty of Science, University of Yaoundé I. Between January and November 2016.

Methodology: Acute toxicity (single administration, 2000 mg/kg) and sub chronic toxicity (28 days: 10 rats per group 5 males and 5 females) given, respectively, distilled water, 250, 500 and 1000 mg/kg of extract every 24 h orally) were conducted according to OECD guidelines No. 423. Satellite controls and satellite test groups received, respectively, distilled water and extract (1000 mg/kg). Body weight was recorded on day 1 and once a week for six weeks. The animals were sacrificed on the 29th day and blood biochemical and hematological parameters were measured. Histological examination of tissue specimens of liver, kidney and lungs was performed after hematoxylin-eosin staining.

Results: Extract showed significant increase in relative weights of liver in males at 500 and 1000 mg/kg. Dose 1000 mg/kg showed significant increase in relative kidney weights in both sexes. Extract-treated males showed significant increases (500 and 1000 mg/kg) of total white blood cell and platelet counts, while female rats showed no significant increase of total WBC counts. Biochemical study showed, in male rats, significant decreases in HDL-cholesterol (at 1000 mg/kg). Serum transaminases (ASAT, ALAT), total protein and creatinine also increased in male rats at 1000 mg/kg. In female rats, biochemical study revealed significant decreases in HDL-cholesterol at 1000 mg/kg and significant decreases in HDL-cholesterol, and increased levels of ASAT, ALAT, total protein and creatinine at 1000 mg/kg (vs. control female rats). Microscopically, there were hepatic (parenchymal leucocyte infiltration, nuclear enlargement and intense margination) and renal (mesengeal hyperplasia) and lung (atelectasis) tissue lesions at high doses supporting by the hematological observations.

Conclusion: Acute toxicity study of the extract revealed that its LD50 is above 2.0 g/kg bw in rats. Subacute toxicity study suggests that high doses of the extract taken for long periods can result in toxic effects in liver, lungs and kidneys.