Application of column chromatography and preparative TLC for isolation and purification of coumarins from Peucedanum tauricum Bieb. fruits

Column chromatography and normal- and reversed-phase TLC have been used for the purification, separation, and isolation of coumarins from the fruits of Peucedanum tauricum Bieb. (Umbelliferae = Apiaceae). Preliminary purification of the coumarin sediment obtained from a petroleum ether extract was performed by preparative column chromatography on silica gel with a gradient of ethyl acetate in dichloromethane as mobile phase, and by preparative reversed-phase thin-layer chromatography with 90% aqueous MeOH as mobile phase. Preparative normal-phase TLC with cyclohexane and ethyl acetate as mobile phase, then re-chromatography with more selective mobile phase mixtures of ethyl acetate, dichloromethane, n-heptane, and acetonitrile enabled isolation of four crystalline coumarins (A-D). All the steps of these procedures were monitored by analytical TLC (with detection by UV illumination at lambda = 366 nm and densitometric scanning at lambda = 320 nm). Isolated crystalline coumarins were identified by comparison with standards in analytical TLC and in RPHPLC with gradient elution, and by melting point (m.p.) measurement and UV spectroscopy. Two were identified as isoimperatorin (A), and bergapten (C); this is the first time these compounds have been isolated from P tauricum Bieb.