Semi-preparative isolation of crocins from saffron (Crocus sativus L.)

Two-step, low-pressure liquid chromatography has been used to isolate crocins, the most abundant compounds in the hydroalcoholic extract of saffron. A mixture of styrene-divinylbenzene copolymer and modified starch polymers was used as stationary phase. A 600 mm x 15 mm i.d. column was used in the first step; the best resolution was achieved by gradient elution with an aqueous methanol gradient with the methanol content changing from 50 to 95%. The highest yield of crocins from this step was achieved by use of 20 mL of 300 mg mL(-1) saffron extract. Under these conditions the yellow pigments of the saffron extract were separated into twenty fractions. In the second step use of a 700 mm x 8 mm i.d. column resulted in crocin-1 [crocetin (di-beta-D-gentobisyl) ester], crocin-2 [crocetin (mono-beta-D-gentobisyl-mono-beta-D-glycoside) ester], and crocin-3 [crocetin (beta-D-gentobisyl)-ester] with purity as high as 99.04%, 97.40%, and 96.70%, respectively.