Extraction of phyllanthusols A and B from Phyllanthus acidus and analysis by capillary electrophoresis.

Abstract

Extracts of roots Phyllanthus acidus were examined by free zone capillary electrophoresis, micellar electrokinetic chromatography (MEKC), and MEKC using the sweeping technique which involves application of a negative potential to the inlet end of the capillary and very much longer than conventional injection times. The latter technique, using a buffer of 50 mM sodium dihydrogen phosphate (pH 2) containing 80 mM sodium dodecylsulphate and 30% methanol was found to allow complete resolution of the active constituents of P. acidus, phyllanthusols A and B, from each other and from other extracted components in under 30 min. Several other components could be detected when hydrodynamic injection times of 500 s were used. The separation, combined with an appropriate extraction procedure and using an internal standard of proguanil, permitted quantification of both phyllanthusols. Calibrations were linear over the range 2-8 micrograms/mL for phyllanthusol A, and 1-4 micrograms/mL for phyllanthusol B. Within-day and day-to-day repeatability RSDs were below 10%, and the precision of extraction RSD was around 14%. The limits of quantification and detection were 0.55 and 0.24 microgram/mL, respectively.