Medicinal plants (Dravyaguna)

How Plant Extracts are Prepared

The collected plant material (plant parts: stems, leaves, flowers, roots, bark etc.) is dried in a ventilated oven at 45 oC for 24 H, and subsequently milled to a fine powder by means of an IKA Universal Mixer M20 (or other type). An amount of 20.0 g of the dried plant powder is weighed in an Erlenmeyer of 100 ml to which 70 ml of hexane (purity grade 99 %) is added (the plant sample has to be submerged with solvent) for pre-extraction. The Erlenmeyer is placed in a sonicator-bath (Branson 8210 or some other type) and sonicated at a temperature 40 oC during 30 minutes. The mixture is filtered using paper filter, followed by washing the Erlenmeyer with 20 ml of hexane and then with 50 ml of hexane. The filtrate is poured in a round-bottomed flask and the solvent is concentrated in vacuo (at about 11 mm Hg) up to 5-10 ml by means of rotavapor, utilizing a water bath at 40 oC. This residue is brought in a 30-ml vessel to let the solvent evaporate. The open vessel is left overnight in a well-ventilated hood in order to evaporate the last traces of the solvent in the hexane pre-extract.