Fresh leaves of OS were used for the study. The entire quantity of the leaves that was necessary for the whole study was collected at once. The leaves were dried under shade, powdered and the ethanolic extract was prepared The method involves extraction by percolation at room temperature using 70% ethanol. Five liters of 70% ethanol was taken in a 10-l glass container and 500 g of the dried leaf powder was mixed with it. The container was well stoppered, and kept at room temperature for 7 days. It was shaken five to six times daily. On 8th day, the supernatant was decanted, filtered and stored. The residue was put back in the container. Two liters of ethanol was added and it was repercolated for 2 days. The preparation was filtered and the filtrate was added to the first filtrate. The residue was repercolated once more, i.e. for the third time by adding 2 L of ethanol and was filtered after 2 days. The filtrate collected in all the three stageswas pooled. The solvent from the filtrate was removed by evaporation under vacuum below 50 ◦C until the final product was obtained in the form of a residue. The yield of the final product during the extraction procedure was 20% (w/w) in terms of dried starting material. The residue was stored in the refrigerator until further use.