Quantification of main bioactive metabolites from saffron (Crocus sativus) stigmas by a micellar electrokinetic chromatographic (MEKC) method

Saffron is an expensive spice, cultivated in many regions of the world. Its chief metabolites include crocins, which are responsible for the coloring ability, safranal, which is the main essential oil constituent, and picrocrocin which is the main bitter constituent of the spice. A simple micellar capillary electrochromatographic (MEKC) method capable of quantifying all three types of main constituents was established. The pH, sodium dodecyl sulphate (SDS) content and electrolyte concentration of the background electrolyte was optimized. A simple extraction protocol was developed which can extract all metabolites of different polarity from the saffron stigmas. Optimal background electrolyte composed of 20 mM disodium phosphate, 5 mM sodium tetraborate, 100 mM SDS, pH was set 9.5. Optimal extracting solvent was the background electrolyte, incubated with the sample for 60 min. The proposed method allows quantification of picrocrocin, safranal, crocetin- Di-(β-d-gentiobiosyl) ester and crocetin (β-d-glycosyl)-(β-d-gentiobiosyl) ester within 17.5 min, with limit of detection values ranging from 0.006 to 0.04 mg/ml, from a single stigma.