**3.1 Procedure of sample preparation**

A representative sample was taken and it was grounded with blender so that 75 % of that grounded portion can pass through a 20-mesh sieve, then thoroughly the subsample portion was mixed. 50 g of ground sample was weighed out into a clean conical flask that can be tightly sealed. 250 mL of methanol (70 % methanol diluted in water) extraction solution was added to the ground sample and the flask was sealed. Then the conical flask containing the sample was shaken for 3 min. The sample was allowed to settle down, then the top layer of extract was filtered through a Whatman #1 filter paper and the filtrate sample was collected. The prepared extract was diluted at 1:20 with distilled water. Sample was ready for testing without further preparation.
