2.2 Preparation of Extracts
Three different types of extracts were prepared for each of the thirty herbs and spices using water, 96% ethanol
or hexane as solvents. Extracts were prepared by mixing spice preparation with sterile distilled water, ethanol or
hexane respectively, in a 1:10 ratio followed by shaking in the dark for 24 h at room temperature using a
universal shaker (Analytica Ltd, Ireland). The mixtures were vacuum filtered through a Whatman No. 4 filter
paper, centrifuged at 3800g for 30 min, the supernatants were collected and filtered through 0.2 μm filters
(Sarstedt, Germany). The filtrates were evaporated to dryness under vacuum at 70 °C for water extracts, and at
40 °C for ethanol and hexane extracts respectively, using a vacuum evaporator (Genvac Inc., NY, USA).
Concentrated extracts were subsequently stored at 4 °C until use.