Two-Dimensional Thin-Layer Chromatography of Structural Analogs. Part I: Graft TLC of Selected Coumarins

Coumarins are natural, biologically active substances, normally found in complex mixtures. Unfortunately their separation causes many difficulties, because of to their similar chemical structure and physicochemical properties. A new, reliable method has been established for analysis of coumarin fractions present in selected fruit. extracts. The substances were separated in chromatographic systems that enabled use of orthogonal separation mechanisms (i.e. characterized by different selectivity). The greatest selectivity differences were obtained by use of two chromatographic systems first dimension CN-silica with 30% ACN in H2O as mobile phase (triple developed) and second dimension SiO2 with 35% AcOEt in n-heptane as mobile phase (triple developed), or first dimension SiO2 with 35% AcOEt in n-heptane as mobile phase (triple developed) and second dimension RP-18 with 55% MeOH in H2O as mobile phase. The aforementioned two-dimensional TLC systems were used for separation of coumarin fractions present in extracts from Archangelica officinalis, Pastinaca sativa and Heracleum sphondylium fruits.