Optimization of the separation of flavonoid glycosides and rosmarinic acid from Mentha piperita on HPTLC plates

Caffeetannins and flavonoid glycosides have been analyzed in polar solvent extracts from leaves of Mentha piperita (Lamiaceae). Peppermint extracts and individual compounds isolated from the leaves were investigated by TLC with horizontal development on unmodified silica gel (HPTLC Si 60, HPTLC LiChrospher Si 60) and on silica gel chemically modified with polar (HPTLC NH2, HPTLC CN) and non-polar groups (HPTLC RP-18W). The mobile phase acetone-acetic acid, 85 + 15 (v/v), enabled successful separation on the aminopropyl adsorbent; water-methanol, 60 + 40 (v/v), was best on the octadecyl adsorbent. These simple methods can be very useful for rapid estimation of components of peppermint leaves or extracts.