The efficiency comparison of ramentaceone isolation from Drosera aliciae plants using normal and reversed- phase preparative liquid chromatography techniques

Preparative HPLC is a profitable technique for receiving usable amounts of substances from various mixtures. The work presents two ramentaceone isolation procedures from a chloroform extract obtained from Drosera aliciae Raym.-Hamet (Droseraceae) cultured in vitro using normal- and reversed-phase preparative liquid chromatography (NP-, RP-PLC). A LiChroprep RP-18, 12µm, 250×16.8mm column and mixture of methanol: water 8:2 v/v as solvent were used in the reversed phase mode. Samples of plant extracts were also separated using a LiChrosorb silica gel column (200×16.8mm, 10µm) and a mixture of n- hexane/methyl t-butyl ether 9:1 v/v was used as mobile phase (NP-PLC). The mobile phase flow rate was 7 mL/min (in the reversed phase mode) and 5mL/min (in the normal phase mode). The HPLC column was backflushed after elution of ramentaceone in each analysis to remove strongly adsorbed compounds. Step elution is an alternative to backflush, however, it requires activation of the PLC column. For a specified purity of products the maximum level of column overloading, efficiency of process and productiveness of PLC- columns were compared. The process efficiency was defined as an amount of received substance in a unit of time. Under the NP-PLC conditions we received about 10mg ramentaceone of 99,80% purity in one experiment and under the RP-PLC conditions 2mg of 92,50% purity. Run time was 60min and 40min for NP-PLC and RP-PLC, respectively. Productiveness of the PLC- column was defined as an amount of substance of maximum purity received in unit of time in relation to column cross section area. Productiveness of NP-PLC column was found to be 4,5µg/cm²min, concerning the the RP-PLC column it was only 1,3µg/cm²min.

Acknowledgements: State Committee for Scientific Research, Grant No KBN 0430/P04/2004/26