Preparation of the plant extract

The mature seeds of B. coriacea Engler were collected from Nsukka town in February, 2009 and identified by a taxonomist Mr A. O. Ozioko of the Bioresources Development and Conservation Centre (BDCP), Nsukka where voucher specimens were also deposited. Ground Buchholzia coriacea seeds were extracted according to Alanis et al. (2005). The seeds were pulverized into fine powder in a mill. The powdered plant materials were stored in sealed cellophane bags in order to protect them from light. In the methanol extract (70%), nitrogen gas was used to evaporate the solvent. To further ensure that all the water was removed, the extract was freeze dried (Edward’s high vacuum Crawley, England). The extract was stored at 4 °C until use.