Comparative study of phenolic acids from underground parts of Rheum palmatum L., R. rhaponticum L. and R. undulatum L.
In three species of <em>Rheum</em> L. genus growing in Poland the composition of phenolic acids was determined. By 2D-TLC method the following acids were identified: ellagic, chlorogenic, gallic, protocatechuic, homoprotocatechuic, caffeic, α-resorcilic, p-hydroxyphenylacetic, p-hydroxybenzoic, p-coumaric, syringic, vanillic and ferulic. There are no substantial qualitative differences among the complex of phenolic acids in the investigated species. The RP-HPLC method was used for quanitative determination of phenolic acids. The amount of individual phenolic acids ranged between 2.2 µg/g and 147.8 µg/g in air-dry rhizome. The content of ferulic acid is the highest in all the examined cases. The total amount of the tested phenolic acids in <em>Rheum undulatum</em> L., <em>R. palmatum</em> L., and <em>R. raponticum</em> L. was respectively 346.4 µg/g, 229.8 µg/g, and 195 µg/g.