Physocalycoside, a new phenylethanoid glycoside from Phlomis physocalyx Hub.-Mor.

A new phenylethanoid tetraglycoside, physocalycoside (2), was isolated from the aerial parts of Phlomis physocalyx. Its structure was identified as 3-hydroxy-4-methoxy-β-phenyl-ethoxy-O-[α-L-rhamnopyranosyl-(1→2) -α-L-rhamnopyranosyl-(1→3)] -4-O-ferulyl-[β-D-glucopyranosyl-(1→6)]-β-D-glucopyranoside, on the basis of spectroscopic evidence: In addition, one known iridoid glucoside, lamiide (1) and five known phenylethanoid glycosides, wiedemannioside C (3), verbascoside (= acteoside) (4), leucosceptoside A (5), martynoside (6), and forsythoside B (7) were also characterized. Compounds 2-7 demonstrated radical scavenging properties towards the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical.