Biological reduction of AgNO3 was carried out initially as follows: The reaction mixture was prepared by adding 1.5 mL of the plant leaf extracts to 1 mL of 0.01 M AgNO3 solution and the volume was made up to 10 mL with deionized water in a 25 mL volumetric flask and kept in ambient temperature (25 7 0.5 °C) for 24 h.