Biologically active triterpene saponins from the root of the medicinal plant Polygala senega L.

摘要

Polygala senega L., known as senega root, is an indigenous plant to the Canadian prairies traditionally used as an expectorant.; In this work, the isolation of pure saponin compounds from crude saponin extracts and their biological evaluation are reported. Using reverse-phase low-pressure liquid column chromatography and semi-preparative HPLC, eight saponin compounds were isolated and their structure partially elucidated primarily by LC-MS, FAB-MS and NMR techniques. All were found to be triterpenoid saponins with a common aglycone, presenegenin, to which sugar moieties are attached via ether and ester bonds at positions C-3 and C-28, respectively. The HPLC analysis, which indicated a baseline separation between the eight saponins, and spectroscopic data for the isolated saponin compounds, PS 1 (m/z = 1847), PS 2 (m/z = 1601), PS 3 (m/z = 1703), PS 4 (m/z = 1455), PS 5 (m/z = 1571), PS 6 (m/z = 1557), PS 7 (m/z = 1425) and PS 8 (m/z = 1587), are presented.; Evaluation of immunological activities of isolated saponins revealed that there was a preferential increase of the IgG2a subclass, and upon in vitro secondary antigen stimulation, high IL-2 and IFN-gamma levels were observed in spleen cell cultures from Polygala senega saponins-immunized animals. The saponins were tested for their toxicity by lethality in mice and were found to be less toxic at the same dose than their counterpart Quil A. This study has shown the potential of these compounds to be considered as natural sources of vaccine adjuvants, since their biological activity was comparable to Quillaja saponaria saponins that have long been used as adjuvants in vaccine formulations.; Cytotoxic activity against human breast cancer cell line, MDA-MB231, and colon cancer cell line, WiDr, was also detected, although these are only preliminary findings.