Two speed blender

The preparation of plant extracts was described by Chitemerere and Mukanganyama [12 ]. Briefly, plant samples were ground in a two-speed blender (Cole Parmer Instrument Co., Vernon Hills, USA). A volume of 8 ml of ethanol was added to 2 g of grounded powder and shaken for 5 min on a vortex mixer and left for 10 min. The plant suspension was then transferred into a syringe and filtered into a small glass vial. The sterile suspension was filtered again using 0.45 μM Millipore sterile filter (Sigma-Aldrich, Taufkirchen, Germany) into a labelled small glass vial. Ethanol was left to evaporate overnight in fume hood with an air stream. A constant dry weight of each extract was obtained and the residues were stored at 4°C.

The preparation of plant extracts was previously described [11 ]. Briefly, 2 kg of C. zeyheri leaves were ground in a two speed blender (Cole Parmer Instrument Co., Vernon Hills, USA) and extracted with 8 L of absolute ethanol at room temperature. Extract was filtered through fine cloth and filtrate was decanted into preweighed labeled container. The solvent was removed under a stream of air in a fume cupboard at room temperature. The amount of solid extract was weighed and recorded.

Callistemon citrinus leaves were collected from the University of Zimbabwe, Department of Biochemistry, Harare, Zimbabwe, latitude −17.7840, longitude 31.0530. The plant identity was authenticated and classified by Mr. Christopher Chapano, a taxonomist at the National Herbarium and Botanic Gardens (Harare, Zimbabwe). Leaves were separated and dried at a temperature of 50°C in an oven (Memmert, Schwabach, SRG, Germany) for three days. The dried leaves were ground to obtain a powder using a two-speed blender (Cole Parmer Instrument Company, Connecticut, USA), to optimise the solvent contact during the extraction. To each of the two plastic beakers, 50 g of the leaf powder was added. A 50 : 50 v/v solution of ethanol : water solvent solution was added to one beaker and the other, a 50 : 50 (v/v) solvent solution of dichloromethane (DCM) and methanol, was added. The two beakers were covered with foil paper and left to stand for 24 hours at room temperature with occasional swirling. Two filter papers (12.5 cm diameter, Sharkskin, 10347511, USA) were placed in two separate funnels and through one the ethanol: water extract was further filtered and to the other the DCM: methanol extract in solvent was filtered. These were filtered into two well-labeled beakers. The two samples were left to dry for 10 days under a stream of air from a fan.