Acute and Sub-Acute Toxicological Evaluation of Aqueous Leaf Extract of Nauclea latifolia (Rubiaceae) in Albino Rats

Objective: Parts of Nauclea latifolia Smith (Rubiaceae) have been used extensively in ethnomedicine. Despite increasing popularity, there is paucity of information regarding its safety. We therefore evaluated the toxicological profile of the aqueous leaf extract.

Methods: Acute doses were administered and the animals were observed for signs and symptoms for 14 days. In the sub-acute evaluation, the rats were given oral doses of 0.5, 1 and 2.5 g/kg/day for 28 consecutive days after which hematological and biochemical analyses were done. Kidneys, livers, spleens, lungs and hearts of the rats were assessed histologically.

Results: There were no signs of toxicity up to an acute maximum dose of 10 g/kg. In the sub-acute evaluation, weight initially gained was lost by the 28th day but organ-to-body weight ratios were not significantly affected. Platelet count decreased significantly (P<0.001) but packed cell volume increased significantly (P<0.01) in the extract-treated groups. Alkaline phosphatase level increased significantly (P<0.01) in the group that received 2.5 g/kg/day. Plasma sodium decreased significantly (P<0.001) in all the extract-treated groups. The levels of other hematological parameters and enzymes (aspartate aminotransferase, alanine aminotransferase) were not significantly altered. The levels of total protein, albumin, bilirubin, urea, creatinine and potassium also remained comparable with the control group. Histology showed acute tubular necrosis at the dose of 2.5 g/kg/day and acute lung inflammation and bronchopneumonia at all dose levels.

Conclusions: While low doses of the aqueous extract appear safe, the daily use of high doses above 0.5 g/kg may be injurious to health.