Seventeen saponins isolated from the root of
Pulsatilla koreana were examined for their
in vitro cytotoxic activity against the human solid cancer cell lines, A-549, SK-OV-3, SK-MEL-2, and HCT15, using the SRB assay method, and their
in vivo antitumor activity using BDF1 mice bearing Lewis lung carcinoma (LLC). The saponins 5—17, with a free acidic functional group at C-28 of aglycon, exhibited moderate to considerable cytotoxic activity, however, the saponins 1—4, esterified with a trisaccharide at C-28 of aglycon, did not exhibit cytotoxic activity (ED
50; >300 μ
M). Among them, oleanolic acid 3-
O-α-
L-rhamnopyranosyl-(1→2)-[β-
D-glucopyranosyl-(1→4)]-α-
L-arabinopyranoside (10) exhibited the most potent cytotoxic activity (ED
50; 2.56, 2.31, 1.57, 8.36 μ
M, respectively).
In vivo test, hederagenin 3-
O-α-
L-rhamnopyranosyl-(1→2)-[β-
D-glucopyranosyl-(1→4)]-α-
L-arabinopyranoside (6, Inhibition Ratio, IR; 66.9%) exhibited more potent antitumor activity than taxol (IR; 35.8%) and doxorubicin (IR; 62.1%). Also, hedragenin 3-
O-β-
D-glucopyranosyl-(1→4)-
O-β-
D-glucopyranosyl-(1→3)-
O-α-
L-rhamnopyranosyl-(1→2)-α-
L-arabinopyranoside (17, IR; 50.3%) exhibited potent antitumor activity. These two saponins were identically comprised of a hederagenin aglycon moiety and a sugar sequence
O-α-
L-rhamnopyranosyl-(1→2)-α-
L-arabinopyranoside at C-3 of the hederagenin, suggesting that the two elements are essential factors for the antitumor activity.
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