Dose-dependent changes in some haematological parameters during short-term administration of Hibiscus sabdariffa Calyx aqueous extract (Zobo) in Wistar albino rats.

The extract of Hibiscus Sabdariffa L. (MALVACEAE) is popularly consumed and assumed to have haematological benefits, but no scientific investigations are known in the literature to have been conducted to corroborate this claim. The present study was therefore conducted to evaluate the effects of Hibiscus Sabdariffa L. Calyx extract on some haematological parameters (Haemoglobin, haematocrit, total white blood cells and differentials) in rats, with a view to determining its medicinal usefulness in the treatment of anaemia. Proximate analysis on dry matter basis, and mineral clement analysis were carried out on dried calyx of Hibiscus Sabdariffa L. Different doses of aqueous extract of Hibiscus Sabdariffa L calyx extract (200 - 1000 mg/ kg body wt.) were administered orally by intra Ocsophageal cannulation to four groups of six animals (rats) per group for 14 days. Venous blood samples were collected from each animal in all the groups including the control group on days 0 and 14 of the experiment for haematological investigations. Paired stat analysis of day 0 and day 14 results was done for each group using student's T-test. Proximate and mineral analysis of dry calyx confirmed the presence of some nutrients, e.g. protein, mineral elements (potassium) and Vitamin C in the calyx. After 14 days of the extract administration, significant elevations were observed in haematocrit (P = 0.03) and haemoglobin (P = 0.004) in the groups of animals given doses of 200 mg and 400 mg per kg (P < 0.05) while the groups given high doses revealed significant reductions (P 0.031) in the haematocrit but not in haemoglobin. This study suggests that, aqueous extract of Hibiscus Sabdariffa L. calyx used in this experiment had beneficial effects on the red cells at low doses (200 mg-400 mg/kg) which may not be sustained at higher doses. However, the long-term effects and the possible mechanism (s) of action of the extract should be studied before a recommendation could be made.