SOME EMPIRICAL ASPECTS ON THE PRACTICAL USE OF FLASH CHROMATOGRAPHY AND MEDIUM PRESSURE LIQUID-CHROMATOGRAPHY FOR THE ISOLATION OF BIOLOGICALLY-ACTIVE COMPOUNDS FROM PLANTS

The applications of flash chromatography and medium pressure liquid ch romatography (MPLC) for the isolation of pure compounds from plants ar e presented with the emphasis on the practical aspects of both techniq ues. The pressure for flash chromatography, which operates at about 1- 2 bars, is provided by an aquarium pump or several pumps in parallel. The simple necessary glass apparatus, which can be constructed in a gl ass blowing workshop, are described diagrammatically. The practical op eration of the technique is included. Up to 200 grams of crude plant e xtract can be readily separated in a single run. The approximate relat ionship among sizes of samples, columns and fractions collected is giv en. MPLC can be used as a complement to flash chromatography. The pres sure required is in the range of 5-20 bars and it can be provided by a piston pump with a variable flow rate, Crude plant extract fractionat ed by flash chromatography can be further purified by MPLC to give pur e materials. Up to 50 grams of semipurified fraction can be convenient ly chromatographed in a single run. The use of gradient elution is ess ential for the success of both flash chromatography and MPLC A gradien t can be constructed between any two miscible organic solvents. Initia lly, the polarity is increased slowly and more steeply toward the end of the separation. A brief guideline for the use of various normal pha se column packing materials is given. An example illustrating the util ization of the two techniques in a multigram scale isolation of pure c ompounds from the plant Curcuma xanthorrhiza Roxb. (Zingiberaceae) is described.