Preparation of plant extracts
About 200g of Grevillea powder was soaked in Methanol and Dichloromethane at a sample: solvent ratio of 1:20 (w/v) for 48 h at 24°C. The mixture was filtered in glass containers over cotton wool. The mixture was homogenized at 60°C for 4 h using a homogenizer (IKA, Germany). The extracts were filtered using the filter paper, concentrated at 60°C using a rotary evaporator (Polylab, India) and freeze-dried for 24 h. All freeze-dried extracts were stored at 4°C prior to further experiments. All experiments were repeated in triplicate. The same procedure was repeated using sugarcane, maize, bamboo, Cypress, and Eucalyptus extract.