Novel phenylpropanoid glycosides from Polygonum pensylvanicum

The plant kingdom continues to be a major source of novel natural products with potential for use as drugs or pharmaceutical agents. A plant of current interest is Polygonum pensylvanicum (Polygonaceae). An ethanolic extract of the whole plant demonstrated significant inhibition of PKC activity with an IC;The major components responsible for the inhibition of PKC activity in Polygonum pensylvanicum, vanicoside A (6) and vanicoside B (7), were previously reported. In more recent work, an efficient isolation Scheme has been developed to facilitate the separation of related phenylpropanoid glycosides from P. pensylvanicum. A continuous liquid-liquid partition of the ethanolic extract between ethyl acetate and water was used in the initial step of the improved Scheme. The crude ethyl acetate fraction was then examined using a constant neutral loss mass spectroscopy experiment to help identify more than ten homologues of the vanicosides. These homologues were targeted for isolation via HPLC-MS followed by preparative TLC for final purification. The structural elucidation of four of these homologues (vanicosides C-F) was established primarily by analysis of proton nmr, homonuclear correlated (COSY) nmr, fast atom bombardment (FAB) mass spectroscopy, and derivatization experiments. Vanicosides C and D were determined to be derivatives of hydropiperoside, vanicoside E was determined to be a derivative of vanicoside A, and vanicoside F was determined to be a derivative of vanicoside B. The structures of these principles were determined to be 2...