Preparation of extract Phytochemistry or plant chemistry is a distinct discipline some where here in between natural product organic chemistry and plant biochemistry and is closely related to both. It is concerned with the enormous variety of organic substances that are elaborated and accumulated by plants and deals with the chemical structures of these substances their biosynthesis turn over and metabolism their natural distribution and their biological function. In all these operations, methods are needed for separation, purification and identification of the many different constituents present in plants.
First the botanical identity of the plant studied must be authenticated by an acknowledged authority. The plants may be dried before extraction. It is essential that the drying operation is carried out under controlled conditions to avoid too many chemical changes occurring. It should be dried as quickly as possible with out using higher temperature. The dried plant material than made into coarsely powdered using mechanical grinder and preserved in air tight container. The powdered plant is continuously extracted in soxhlet apparatus with range of organic solvents depending upon the polarity of the solvent. The aqueous extract may be obtained by maceration process. The extract obtained is concentrated usually by rotary evaporator, which will concentrate bulky solution down to small volume without bumping at temperature between 30 to 400C. Extraction of volatile compounds from plant needs special precautions.
Preparation of bark extract The dried and powdered stem bark was subjected to preliminary phytochemical screening for qualitative detection of phytoconstituents. The dried and coarsely powdered stem bark (100 g) was extracted successively with petroleum ether (40-60ºC), chloroform (59.5-60ºC), ethyl acetate (76.5-77.5ºC), and ethanol (90%) in a soxhlet extractor by continuous hot percolation. Finally the marc was macerated with chloroform water. Each time before extracting with the next solvent of higher polarity the powdered drug (marc) was dried in a hot air oven below 50ºC for 10 minutes. Each extract was concentrated by distilling off the solvent, which was recovered subsequently. The concentrated extracts were evaporated to dryness and the extracts obtained with each solvent were weighed.
Preparation of leaf extract The dried and powdered leaf was subjected to preliminary phytochemical screening for qualitative detection of phytoconstituents. The dried and coarsely powdered leaf (100 g) was extracted successively with petroleum ether (40-60ºC), chloroform (59.5-60ºC), ethyl acetate (76.5-77.5ºC), and ethanol (90%) in a soxhlet extractor by continuous hot percolation. Finally the marc was macerated with chloroform water. Each time before extracting with the next solvent of higher polarity the powdered drug (marc) was dried in a hot air oven below 50ºC for 10 minutes. Each extract was concentrated by distilling off the solvent, which was recovered subsequently. The concentrated extracts were evaporated to dryness and the extracts obtained with each solvent were weighed.
